Forrest's 383

[oldLenny]

Can you keep us informed on the performance of the 383? I am very curious of a "crate motors" bolt in performance. I was at a car show yesterday in town and saw about 5 "fresh" 502's between fenderwells in old rods. Very yummy. Is this the same beast you get from the Marine division? One as well had a Procharger on it. First time I have seen one. Very neat installation...

[Forrest]

Lenny, if it isn't one thing it another. Now I know how GeneD feels from time to time. My 383 is a budget build up using an $1199 SECO Performance (http://www.secoperformance.com)/Wheeler Motorsports 4-bolt two-piece seal short block which contains their made in USA steel crank, "stage 2" (whatever that means) 5.7" rods, and United Engines & Machine Claimer performace pistons (http://www.kb-silvolite.com/Claimer/Intro%20page.html). I also used a pair of 441 castings 76cc open-chamber heads which yields a 9.8:1 static compression ratio with these pistons. These heads were modified by a prevoius owner, but never used, to accept Manley stainless steel 2.02" intake and 1.60" exhaust valves, and I picked them up for $350 for the pair. To furthur cut cost, I used Manley stamped steel rockers, but I did pop for the Crane valve springs that to match the Crane PowerMax H-272-2 flat tappet cam kit (http://www.cranecams.com/master/apps/chevy13.htm#3.hydralic). Other parts include. ARP head, rod (included with the short block), and intake bolts, a Weiand Stealth intake manifold, a 600 CFM Holley vacuume secondary marine carb (ebay), Mallory marine magnetic distributor (ebay), Holley marine mechanical fuel pump, and a Chris Craft cast-aluminum oil pan. Enough of that. As of now, I have about 45 minutes of in-the-drive-way cam break-in time on the engine. If you read about it in another thread (http://www.donzi.net/ubb/Forum1/HTML/000670.html), you will see that I have been plagued with condensation water in my gas tank. Well, tonight I sucked all of the gasoline out of the X-18's tank through the gas filler and put that fuel in my car and my van. I know that the gas was dry since I watched it all flow though a clear vinyl hose. Finally, I sucked out the remainder minus what's at the very bottom of the tank. Tomorrow, I will remove the sending unit and suck it dry using my battery-powered drill pump. Then somehow, I'm going to inspect the tank for corrosion damage. I just hope like hell that it doesn't need to be removed. Anyway, I still smell like petrol, and for that reason, I'm going to hit the shower at this time. I hope to tell you how it runs, very soon.

Here is a pic of the 383 before installation:

http://imagehost.auctionwatch.com/bin/imageserver.x/000e5ad0/bowtiekid/x18motor.jpg

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Forrest

[This message has been edited by Forrest (edited 08-22-2000).]

[GEOO]

Forest,
Nice Engine!!! Looks Clean!!
I used to get water in my tank though the vent on the side of the hull. I installed a vent cap with a splash gaurd. Works much better. The vent sucks in when the fuel goes out. GEOO

[This message has been edited by GEOO (edited 08-22-2000).]

[Jamesbon]

Forrest,
Nice! Are you using the long or short water pump? I'm having trouble finding an alternator bracket for my 383 using a short pump, and Stainless Marine exhaust. If nothing turns up, I'll be forced to fabricate something.

Thanks...Nathan

[Forrest]

Thanks GEOO! In compairson to your small block engine, it's a basic boat motor!

Nathan, that alternator bracket is the stock unit from a Mercrusier 250/280 TRS (http://216.37.204.3/mercruiser/merc.asp?show_frames=72629ta+7262901+7262901.gif+i o_list) and uses a short water pump. The only alignnment problems that I had was with the power steering pump when using those aluminum pulleys. I had to cut some spacers for the PS pump mount to make it work.

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Forrest

[This message has been edited by Forrest (edited 08-23-2000).]

[BERTRAM BOY]

Hey Forrest,
What kind of exhaust manifolds are those? Thanks,
BERTRAM BOY

[Forrest]

Those are older, but never used, GIL Hi-Tork manifolds.

OK, I got the gas tank cleaned up and took the X-18 out for a ride on Friday. Wow! The 383 makes about half the noise of the 302 that I run in my 16 Donzi. I don't even think I will need mufflers with this setup. Being a cautious kind of guy, I decided to take it easy and break it in right. For that reason, I decided to do some light cruising up and down the St. Marks River. After about an hour of idle to 2500 to 3500 RPM cruising, I decided to run her out to the St. Marks Light House which is located on the mouth of the St Marks River where it opens to the Gulf of Mexico. Oh, the new engine ran so nice, and it was extra nice on the Gulf with a two- to two-and-a half-foot chop. The GPS said that we were clipping along at 38 to 42 MPH. After running a couple of miles out in the Gulf it turned around and headed back to the marina to check thing over. The run out from the marina is about eight miles to where I turned around, so I would guess that it was about a 15 miles no stop round trip back to the no-wake zone. On the way back in, the 383 was sounding really good, so I decided to give it a little burst of throttle, you know, just to feel some power. Oh yea! But when I let off the throttle, I heard a sort of strange squealing sound for about a second or two and then quit. Great oil pressure, temp is rock steady at 160-degrees, 3500 RPM, hay, all looks well . . . then, what happened to the power? Why do I need to give it more throttle to get 3500 RPM? Everything sounds OK? Maybe a plug went bad. I don't know. As soon as I let off of the throttle at the no-wake zone. The 383 sounded like doggie-do-do and stalled. I started it back up, but it wouldn't idle. I lifted the hatch and ran the engine at high idle and looked and listened but saw and heard nothing unusual. I next looked over the transom and noticed that more exhaust pressure (volume) was coming from the starboard pipe than the port pipe. It must be a bad plug. . . or something. Well, I was able to get the boat to high-idle back to the ramp. After getting back to my house/shop. I pulled the plugs and saw that the all look fine except that #4 was a little wet with gas. Well GeneD, stick me that same camshaft, dude! Zero compression on #4! Not 50, not 20, but zero! The engine turns so smoothly, though. No clunks, chunks, clacks, scrapes, or anything.

I took the engine is out of the X-18 and put it up on the engine stand. This afternoon I plan to disassemble it, but I can tell you already what is wrong with this thing. This engine uses hyperutectic pistons. Apparently, when this short block was built, the numb-headed assembler probably set the ring gap too tight for even grandma to take trips to the grocery store. So what happened? Hyperutectic pistons hold lots of heat in the crown. This causes the upper ring to expand. If there is not enough ring gap, the ends of the ring will butt together. When this happens the ring immediately seizes in the bore, and when the piston goes on the down stroke, it pops the crown of the piston off and leave it sitting squarely in the bore. This explains why the engine turns over smoothly and will actually run on the other seven. At this point, I just hope the bore is not damaged. If the bore is good, I hope to replace the piston (the weight is marked on the piston for a weight matched replacement), lightly hone the cylinders, replace and re-gap all the rings. What a bitch, but now I know that I had better pull the pistons out of the other two still-in-the-box 383 short blocks that are sitting in my dining room and check the ring gaps.

Moral of the story, "He who don't check ring gap on short block take camshaft where sun don't shine!"

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Forrest

[CDMA]

Forrest,

Do you buy 383's by the dozen?

[GeneS]

Forrest,

Those Wheeler short blocks are sold without a warranty but I was able to get a replacement by calling Wheeler direct and pleading my case. The first one I bought had a crack in the lifter valley. My buddy bought one earlier this summer and now it has spun the front main bearing.

Hey, what do you do for a dip stick? My block has a drivers-side dip stick boss and my exhaust manifold does not have enough space between the block and the exhaust.

I bought a Mercruser oil-pan dip stick but it is a rusted-up piece of crap.

What do you do with your dip-stick? (No jokes please)

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Gene Schmidt
'74 X-18 "Chi Chi"

[This message has been edited by GeneS (edited 08-28-2000).]

[Forrest]

Thanks Gene for the info. I let Dale at Seco know, but I'm going to take a look first. If all it needs is a new piston, I'll deal with it here and now. If the bore is trashed, I'll be on on the phone with Wheeler. Also, after hearing about that other 383 spinning a main, I think that while it's torn down, I'll be checking all clearences.

See you at Lakepoint!


Oh yea, dipstick. I use the type that connects to the bottom of the oil pan. Like the one shown here (http://216.37.204.3/mercruiser/merc.asp?show_frames=72629ta+7262917+7262917.gif+i n_list). Also, the cast aluminum pan that I am using has plugs on both sides of the pan. One side gets the dipstick, the other gets the oil drain hose. The dipstick tube has to route to the outside of the exhaust manifold.

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Forrest

[This message has been edited by Forrest (edited 08-28-2000).]

[GeneD]

This whole Donzi motor thing is out of control...
I blew a piston in my 'new' 1986 motor. The machine shop guy was skeptical that is was a new (left over) motor until he saw the original GM piston.
Thing is, this piston was not what I would consider 'blown'. There is no hole in it. I couldn't detect any cracks. The top of the piston has what appears to be water intrusion pitting (intake valve side) and one side (same side) definitely got hot and there is scoring on it. The rings lost tension and are ridged top and bottom. The compression ring is warped. The ring gap is also the width of the Grand Canyon. About a full 1/16 of an inch.
Hey! At least I don't have to worry about the gap being too tight!
The bearing on that rod was also shot, but the crank was beauty.
Spark plugs looked fine.
I just can't account for all the smoke coming out of the valve covers.
It probably didn't help that the crankcase was over full. How that happened is a complete mystery.
Boats, car and motorcycles. You gotta love em!

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GeneD
007
Melbourne, Florida

[GEOO]

Forrest, Sorry to hear of your trouble!!! Well at least 7 worked. My engine lost a rocker arm stud the first day on the dyno. I guess it's a part of boating. I wonder what an outsider would think of us. I take 8 monthes to get engine together and running OK. Gene's running then repairing, Forrest troubles, the list goes on... Good thing it's a hobby for us... Hey it's all in the fun. Right??? GEOO

[Forrest]

My bust folks. Ring butting was not the problem. I just pulled
the valve cover and noticed that the exhaust valve for #4 cylinder had seized in the valve guide causing the the exhaust valve to stay open. Since the valve was open, the rocker arm fell to one side and bent the push rod. There is no problem with this Wheeler Motorsport 383 short block. Now the question is, why did the stainless-steel valve seize in the valve guide? Bent valve? Valve guide clearence too tight. Hay, my local machine shop did my heads. Stay tuned . . . the head will come off later tonight and pictures will follow.

Yea, great hobby George, and loads of fun, too! Keeps me off of the streets and out of the bars at night. Just think of what trouble you might be doing if you didn't have that X-18/Arneson project to play with.

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Forrest

[This message has been edited by Forrest (edited 08-28-2000).]

[Gearhead99]

Forrest,

The valve sticks cause the guide is too tight, usually. Or the valve got REAL HOT and expanded to stick. Either way the valve stem clearance sounds to tight.

When you pull head don't forget to inspect top of piston for damage from hitting the valve.

Dave

[This message has been edited by Gearhead99 (edited 08-28-2000).]

[Forrest]

Dave, you hit that one right on the money. The valve did stick in the guide and yep, it hit the top of the piston. No damage what so ever to the piston though, but the same can't be said for the valve. There is signs of galling on the valve stem and in the guide. I think that I better remove both heads and take them both back over to the machine shop to check and adjust the clearence on all 16 just in case there is another with the same problem ready to happen . . . You know, these 441 heads have cast iron valve guides and they have been in storage at a guy's house in St. Petersburg, FL, for some time before I bought them. The heads had some surface corrosion in places and for that reason, I took them to the machine shop and had them bead-blast, touch up the the seats, and then resurfaced. I bet you that that either there was some corrosion in the valve guide or some shop grit ended up in between the valve stem and the valve guide. At least now I don't have to get into the bottom end. Bronze valve guides do make a lot of since.

Hay, the parts list is not too bad this time! . . . and that is especially good, since I need to cough up the balance of $500 to pick up the new upholstery for the 16 from Bilt-Rite on Wednesday. Just in time for Eufaula!

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Forrest

[This message has been edited by Forrest (edited 08-28-2000).]

[Owen]

Forrest, I'm curious.
Before you saw that the valve had stuck, how did you come up with the "ring-butted-pop-the-top-of
the-piston-off theory"? Never heard of that one.

[GeneD]

An experienced mechanic is probably the worst diagnostictician. We have seen it all and of course we expect the worst at all times. We weave an intricate web of failures in our minds, hoping for the best of course, but being prepared for the worst.
My theory on Forrest's previous diagnosis is that a bad valve never entered his mind since he had the work done to his heads at the local machine shop. And as all backyard mechanics will tell you, we trust our machine shop guys to the death. We have to.
The ring thing was probably in the back of his head due to a past experience.

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GeneD
007
Melbourne, Florida

[GeneS]

Hey Forrest,

Did you check you pushrod length? If too long or too short the rocker will push on the valve stem off-center. It will bend, gall, sieze like that (I just snapped my fingers).
This is what I am told by the motor dudes down at Sonny's anywho.



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Gene Schmidt
'74 X-18 "Chi Chi"

[Forrest]

Owen, hyperutectic pistons holds much more heat than forged or cast pistons in the crown, and for that reason, the top ring must have a gap that is much wider than that found on a forged or cast piston. For example, a hyperutectic piston in a marine engine that rides in a 4" bore needs a top ring gap of 0.030" to 0.045". That is a lot of gap! That same piston running in a street car needs a ring gap of 0.015" to 0.020". This is still more gap than that you would find on any correctly setup forged or cast piston running in a 4" bore by 50% to 100%. Now, since the piston crown gets so hot, the top ring will expand accordingly, and if properly setup, the gap will close but not touch. If the gap is set without enough clearance, the ring ends will touch together with sufficient force to bind in the bore, usually at the top of it's travel. When the piston starts on its way back down, the ring stays put in the bore at that point, but the downward force generated by the rotating assembly literally pulls the piston apart, leaving the piston's crown or at least the piston's land and top ring stuck at the top of the bore. The skirt, second ring, and oil scraper ring will just ride up and down in the bore, only without a crown, just like nothing happened. The only problem is that you have zero compression.

Ring butting is (or was) a typical problem that people ran into who built engines with hyperutectic pistons since many builders don't want to put too much ring gap on a piston so as to reduce blow-by and compression loss. These 383 short blocks were built for "Claimer" racing and for that reason, the should have at least 0.030" (and hopefully more) of top ring gap. Though I have not measured that gap, I am thankful that at this point ring butting does not appear evident on this short block. One other thing hyperutectice piston makers recommend, and everyone dislikes this one, is that total timing should be reduced by 2 to 4 degrees to further reduce the chance of ring butting. They also go on to say that ring butting can occur with ring gaps as wide as 0.060" if the timing is excessive, running to lean, too high peak cylinder pressures (too much compression, not enough cam), detonation, and pre-ignition, etc . . .

Makes you want to consider forged pistons on your next engine build!

GeneS, using stock length push rods, Manley stamped steel rockers. Geometry seems correct, but will double check.



[This message has been edited by Forrest (edited 08-29-2000).]

[Gearhead99]

Forrest,

Glad to hear it wasn't a piston. Lots cheaper and easier to fix. Not to sound redundant, but do your self a favor. When you have both heads off and you find, hopefully, that you only have problems with one hole. Clean everything up real good. Get lots of light and really check that piston that made contact with the valve. Reason I say so. When the valve hits it is toward the edge of the piston, where the valve relief are. It can "pucker" the piston top out so as to hit the cylinder wall ever so slightly and now your piston has a bulge in the crown that expands with temperture and doesn't clearance right. Also, I have seen. Not to pour cold water on a _________ on. The top ring land. Between the top ring and the piston top be pushed down ever so slightly so as the piston gets hot the ring will seize in the ring land. Better safe then sorry. Unless you love to pull these engines down.

Lastly, invest in some roller rockers, they are worth the money.

[Emmo]

Man, am I glad I own a Ford! The original lasted 29 years and the $2300 (list) long block is beefier, has more torque and more horsepower and has given me absolutley no problems http://www.donzi.net/ubb/biggrin.gif

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Emmo mailto:emmette@emmette.comemmette@emmette.com</A>

[Owen]

Thanks Forrest for that great explanation. I've never spent much time hopping up engines, just
making them stock again. I instantly thought "Stuck Valve," I guess it pays to be simple minded sometimes.

[GeneD]

Dave, is this the reason I blew my piston?
Sounds good to me!
All the damage was done on that side of the piston.

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GeneD
007
Melbourne, Florida

[Gearhead99]

Gene,

Probably why. It blew, but detonation is the most probable cause running the motor WOT for long durations. The timing has to come back. When Florida Highway Patrol had all those Mustangs early on they lunched every motor. Why?? cause the timing stayed up to far and wouldn't come back on the top end and the motors detonated till the pistons were eaten up. The later, replacement, blocks had the ECM bring the timing back and installed forged pistons.

[Forrest]

Thanks Dave, I going to to check it out very closely. I really don't like going through an engine the second time, much less the third. Yea, I shouldn't be so cheap. I think that I'll pop for a set of roller rockers before it all goes back together. make that three sets . . . I'll be building the 383 motors for the Magnum soon.

Also, my PC at home died after the local power company did some tricks with the power on Tuesday. It's dead. Gets power, but won't boot, no video output, useless . . . and that's why I haven't be posting or checking my e-mail lately. Anyway, it was a junky PC, and I was due for another soon . . . but not now!

Lucky for me, Edie let me use her PC.

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Forrest

[This message has been edited by Forrest (edited 08-31-2000).]

[GeneD]

Forrest,
I have an opportunity to get a practically new set of Edlebrock roller rockers for $80. I am reluctant to get them seeing how the guy told me they wouldn't fit under the stock valve covers. Is this true? And if so, what can you get that is taller and still retain the stock exhaust? Should I get the manifolds from Scot B?

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GeneD
007
Melbourne, Florida

[GEOO]

Gene,
I've seen guys put two gaskets under the covers to lift them up. On my new engine I had to slot the holes on the cover and slid the cover towards the carb. Have a great Weekend!!! GEOO

[BERTRAM BOY]

Gene D.,
I'm using roller tipped rocker in my truck with stock valve covers. No problems at all. Are you looking for full roller rockers or just roller tipped rockers? .
BERTRAM BOY

[This message has been edited by BERTRAM BOY (edited 09-01-2000).]

[GeneD]

BB,
No they are full roller rockers.
I too have the roller tips in the Corvette, and they are very nicely tucked away under the stock Corvette aluminum valve covers.
I would just HATE to put the tall covers on. Especially on the new motor.
It just seems like too good of an offer to pass up. What are we talking about? 5-15 HP increase? And from what I am told, you see a tremendous decrease in oil temperature. This is from the Crane Cams tech guy.
Two gaskets? Even on the new style? I'm willing to try...I guess...

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GeneD
007
Melbourne, Florida

[Gearhead99]

Gene,

I have Cranes on my Ford engine and I run two, thick, gaskets and removed the baffles. No problem. I glued the gaskets together with contact cement and installed the Chrysler style breathers on my valve covers. Works like a champ.

You NEED full roller rockers. Think of the friction and wear you are avoiding when its twisting 5 grand.

Dave

P.S. Still no 2.5, still looking though. The 5.7 4-bolt motor I took out of truck is history. Rod broke took cam and block with it.

[Gearhead99]

Gene,

One more thought. You can make a spacer that will fit between two gaskets. I use to have a set of Fords, but gave them away. Made them out of a piece of 1/4 inch plexiglass. Traced a valve cover and gasket on to the paper that is on plexiglass and cut it out with a sabre saw and drill. Worked great too.

You can usually leave the baffles in then, if you want.

Dave

[Rob]

Forrest, I would look pretty closely at this stuck valve problem. I have been a machinist in a former life, and performed valve jobs on many SBC heads. In my opinion, a clearance problem between valve stem and guide as root cause is not very likely. Guides usually wear at the top and the bottom of the guide due to the pressure from the valve train geometry. You can test the wear by inserting a valve stem from the back side of the guide and see how much side to side slop there is. Valves are unlikely to stick in these slightly worn guides. Conversely if the guide was replaced sticking is also unlikely. To replace a guide you drill out the existing guide and insert a new, unsized blank (interferance fit). You then use a reamer to size the ID of the guide. However, if you were to forget the reaming step, the valve won't fit into the new guide. So the system is pretty foolproof.

I'm wondering if Gene S. isn't on the right track with his pushrod length theory.

Also, did I read in an earlier post in this thread that you sucked the gas out of your tank w/a drill motor? I got into big trouble doing this when I replaced the tank in my 16. Apparently when the pump started to suck the tank dry, heat from the friction in the pump ignited the fumes. Luckily the resulting explosion was not too big, I was able to extingush the fire quickly and the boat was not hurt (did burn my hands a bit thought) I now understand there are special impellers to be used when pumping flammable liquids.

[Forrest]

Rob, I haven't had a chance to take the heads back to the machine shop yet. But before I do, I want to pull out a few more valves to see what's going on in the guides. As I said in a previous post, these 441 heads were purchased used, and already been upgraded with a three angle valve job and 2.02"/1.60" stainless valves. The reason that I got them so cheap, and that I didn't just bolt them on was that they had surface corrosion on them from being stored for a few years in a damp place. I took them to the machine shop to have them disassembled, the corrosion removed (they did that by bead blasting), the seats touched up as needed, install new valve seals and my matching Crane valve springs, and did a resurface job. If now figure that either the was some corrosion in the iron valve guide(s) that was not caught or ???? But it does seem though that if the valve stem didn't slide in smoothly, the machinist would had caught it immediately.

So, what you are saying is if the pushrod is too long, it may cause the rocker to produce enough side thrust against the valve stem to cause excessive wear on the guide and the valve stem? The block has been decked and the heads has been resurfaced and least twice and probably more.

Also, what is the correct procedure to check for proper push rod length?

Oh yea, looking back, sucking gas out of the tank with a drill motor pump is a pretty dumb move - even if it's with a battery drill. Actually, I used the drill to start a siphon rather than to suck the tank dry. After removing the fuel by siphon, I removed the sending unit from the tank and used an garden hose powered siphon pump that I bought years ago to remove the last few ounces of fuel and water. After that, I notice some trash still on the bottom of the tank. In order to remove it, I rounded up two shop vacs. The first shop vac was run with the hose hooked up to the blower end which provided lots fresh air through the fuel tank filler and allowed the fumes to blow out of the tank through the removed sending unit's hole. After about an hour of forced ventilation, I took the second shop vac and taped an eight-foot section of 5/8" clear-vinyl tubing to the vacuum hose on the suction side. I then place the suction shop vac on the ground and with fresh air still blowing into the tank, I was able to somewhat safely vacuum the trash out of the bottom of the tank. It's totally clean now, and didn't blow myself up! I also, replace the filler hose and vent hose with some new USCG approved stuff. After all of that, I also found that "dirt daubers" had totally plugged the tank vent fitting on the side of the hull. What next? That required removing the fitting, reaming it out with a piece of wire, and washing it out with water. I'm now fairly sure that the fuel tank suitable for filling now.

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Forrest

[Rob]

There are three factors that can combine to cause pushrods to become too long. The first two you identified, block decking and head milling. The third is installed height on the valves. Ginding the seats lowers the valves in the head as does grinding the face of the valves. The result is the tip of the valve stem ends up higher relative to it's position prior to grinding. The machinist should grind the end of the stem to help compensate. They should also check the installed height if they suspect the heads have undergone multiple valve jobs, or if they are installing a new set of valves/seats (which I believe you are doing).

I'm not sure what the correct method is for identifying if you have a situation where the pushrod length is too long-but I'm sure someone else here will.

Good luck with finding the issue. Nothing is more frustrating than doing all the work to put in a new engine only to find out there is something wrong and have to take it back out.

[BigGrizzly]

Installed valve stem height is used so people doing valve jobs don't have to change pushrods. Assembled spring height is also checked and shimmed accordingly. This is done to keep lever angle of the rocker arm from running off the stem. Lash caps are some times used for more surface area to prevent this, not just for shimming or strength. I use roller tip or full rollers rocker arms on my motors, again not for performance, but for durability. When using high lift cams the tip of the rocker pushes on the stem moving it foward and back, causing wear in the guide. This is why guides wear intake to exhaust. Since all valves spin, unless pinned, there can be no other reason guides wear like that. This may be not all but part of your problem. I know there are exceptions to all rules and theories. this has stopped my guide wear problems with big cams.

[BillG]

I believe the rocker tip should be in the center of the valve stem at half lift. This should be the correct geometry for the rocker, valve interface.
Bill G

[GeneS]

Hey Forrest,

It is easy to check your valve train geometry. After you have put everything together take a heavy "Sharpy" marking pen and paint the top of the valve stem black. Turn the motor over several revolutions so that the rocker works on the top of the valve stem. Then take the rockers off and look at the mark that is left. The black should be worn away so that there is a silver line to show where the rocker was bearing on the stem. This line should pass through the center of the stem and across the diameter. If the silver line is either inside or outside of the center of the stem, then you need to shorten or lenthen the pushrods.

Most likely, your pushrods are too long since the heads have been surfaced and the block decked.

We should have talked to Randy about this in Eufaula, eh?



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Gene Schmidt
'74 X-18 "Chi Chi"

[Forrest]

Thanks Gene, I will check the push rod length upon reassembly; however, I don't think that is what caused the problem. Last night I removed all the valves and I found that the valve stems on all the exhaust valves were galled and overheated from friction from what appears to be lack of lubrication. The intakes look like I just put them in. These heads have perfect-circle type lip valve seals on both the intake and exhaust valves. I'm no expert in this area, but in the past on performace engines I would either see no seals on the exhasut or umbrella type seals. These seals were installed at the recommendation of my machine shop and he assured me that I should use seals on the exhaust side as well. Personally, I don't see how the exhaust valve stems can be lubricated with such a tight lip seal around the stem, but people tell me that they will get lubricated just fine, even with seals. I can see that with the intakes due to the vacuum in the intake port, but the exhaust has hot gasses under pressure in the port, which in my mind, would seem to force oil away from the valve stem and guide.

Would someone please set me straight on the valve seal subject?

Also, GendD if you don't want those roller rockers, I'll take 'em off you hands.

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Forrest

[Gearhead99]

Forrest,

I doubt that the valve stems are galled from having a seal on the stem. More so from overheating that makes them expand and get tight in the guide.

You put a seal on the exhaust so that oil will not run down the stem when the engine is shut off too. This will create lots of carbon build up on the back surface of the valve head. Also, when the exhaust valve is at rest, not opened, oil can run down it.

I think that you are looking in the wrong place for the cause of your valve galling.

Poor octane, water circulation and timing can cause the exhaust valve to get REAL HOT. Also, lean mixture.

Hope that helps.

[Forrest]

Now I'm really confused. That engine ran that day no more than one hour, never over 3500 RPM except for one quick burst over 4000. The engine has no more than 2-1/2 hours on it total with the other hour running in the driveway at 1500 to 2500 RPM. There was new 93 octane Shell with lead substitute additive, 34-degrees total timing, factory jetting in 600 cfm 4010 type marine carburetor, closed cooling system rock steady at 160-degrees, plugs a little white (could be richened up a little) but piston tops and stainless valve heads were oily and evenly discolored slighty brown. The last ten minutes of running on that engine was done at high idle to return to the ramp.

Maybe I should think about getting a high flow circulation pump from Edelbock, Weiand, etc. The one that is on there is a rebuilt automotive unit and maybe doesn't have enough flow.

New parts are on order. I guess that I should get a few people to look at it before I make the repair. Thanks everyone, for all the help.

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Forrest

[This message has been edited by Forrest (edited 09-09-2000).]

[BigGrizzly]

Forest, to answer the valve seal question, I think lack of lubrication is part or most of the problem.I don't think the addition of this seal but assembley of the valve in the guide-no lube or poor quality stuff. As for heat causing the problem, unlikely. Exhaust valve stems are smaller in diameter than the intakes (measure yours) because of the extra heat involved. Unless some bozo sold you intake valves for the exhaust. As for the seals. Lets put this in perspective. At idle (750 Rpms)the valve goes up and down 375 times pre minute ( remember this is a four stroke) with the fource of a jackhammer and will ram enough oil down past the seal to lubricate the stem. I have never had a problem because the seal was too tight.
I just had a terrible though! Did you break the cam in, or start it up and let it idle? On flat tappet cams you should start it up and run it at 2000 Rpms for 20 minuts, before idling engine. This is to get oil slpashed all over the inside the engine, not just on the cam. I have gotten away without doing this a couple of times. I have learned my lesson. I lost a very special camshaft and a cylinder head because I didn't follow the rules. I have heard it said "you don't have do this with rollers". My answer to that is "I don't think so Tim".
Randy

Sorry just read your breakin times. Pizza got in the way of the screen. This is hard ---trying to read, listening to Lady Grizzly and Little Grizzly whining "when are we going together with those people again. We had so much fun.".

[This message has been edited by BigGrizzly (edited 09-09-2000).]