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Barry Eller
08-05-2007, 06:24 PM
I've come to the conclusion that my Dr. buddy that degreed my camshaft has it 90 degrees out. He is a Ford guy and set up the dial indicator on the starboard side piston. I was thinking the small "O" on the cam gear should line up on the bottom (6:00) with the crankshaft gear "O" on top. He degreed the cam with the camshaft gear "O" at 12:00. Crankshaft gear at 12:00.
I readjusted my valves today and I still have no compression. It has to be the camshaft being 90 degrees out. Am I right?:bonk:
Now, can I remove balancer, lower oil pan, remove timing cover and chain to correct this condition with out removing the port head and re-degreeing all over?
My thoughts are to rotate the either the cam gear 90 degrees or the crankshaft and reinstall the chain.
I need advice. :confused:
Thanks, hot, tired and bummed out...

BigGrizzly
08-05-2007, 06:36 PM
I have done this many times I have installed many a cam only removing the intake to put in new lifters. Loosen all the rockers or remove them set the the harmonic balancer to TDC. To do this just turn the balancer(with out sparks on holes is easier) to the 0 in the timing plate or arrow. Pull the balancer and timing chain cover without turning anything. Reset the chains correctly and reassemble.

Barry Eller
08-05-2007, 07:40 PM
Thanks Grizz,

Am I correct about the positions of the "0's" being at 6:00 on the camshaft when the crankshaft is TDC and the "0" is at 12:00.

How close can I get to having the camshaft "timed" by rotating the cam gear 90 degrees without a degree wheel and dial indicator?

Should I mark the chain in someway to make sure I'm not a tooth off?

Any tricks you could pass on would be appreciated!

Rootsy
08-06-2007, 06:18 AM
Thanks Grizz,
Am I correct about the positions of the "0's" being at 6:00 on the camshaft when the crankshaft is TDC and the "0" is at 12:00.
How close can I get to having the camshaft "timed" by rotating the cam gear 90 degrees without a degree wheel and dial indicator?
Should I mark the chain in someway to make sure I'm not a tooth off?
Any tricks you could pass on would be appreciated!

yes. camshaft mark @ 0600 and Crankshaft mark @ 1200...

Barry Eller
08-06-2007, 10:41 AM
I just talked with a Tech here at work about my no compression condition. He thinks the camshaft overlap and my adjusting valves the way you adjust them with a stock cam is my problem. The cam 0 and crankshaft 0 align after one turn. Two turns of the cam to one turn ofthe crankshaft.

So I'll try readjusting the valves another way he told me about. He says with my cam profile, the exhaust and intake valves are never completely closed at TDC due to the overlap.

Any ideals on this? Sound right?

VetteLT193
08-06-2007, 10:45 AM
Thanks Grizz,
Am I correct about the positions of the "0's" being at 6:00 on the camshaft when the crankshaft is TDC and the "0" is at 12:00.
How close can I get to having the camshaft "timed" by rotating the cam gear 90 degrees without a degree wheel and dial indicator?
Should I mark the chain in someway to make sure I'm not a tooth off?
Any tricks you could pass on would be appreciated!

Without using a degree wheel you can get close (much closer than 90 degrees out!!), but it's worth the 20 bucks to at least use a wheel... I'm sure a local auto parts store will have one for even less than that.

mrfixxall
08-06-2007, 12:22 PM
I've come to the conclusion that my Dr. buddy that degreed my camshaft has it 90 degrees out. He is a Ford guy and set up the dial indicator on the starboard side piston. I was thinking the small "O" on the cam gear should line up on the bottom (6:00) with the crankshaft gear "O" on top. He degreed the cam with the camshaft gear "O" at 12:00. Crankshaft gear at 12:00.
I readjusted my valves today and I still have no compression. It has to be the camshaft being 90 degrees out. Am I right?:bonk:
Now, can I remove balancer, lower oil pan, remove timing cover and chain to correct this condition with out removing the port head and re-degreeing all over?
My thoughts are to rotate the either the cam gear 90 degrees or the crankshaft and reinstall the chain.
I need advice. :confused:
Thanks, hot, tired and bummed out...

did he leave it at those positions? if he did then your 180 deg off..
loosen all the rockers or take them off and pump the cylinders with air to make sure you didnt bend any valves first...on timing chain gears you line the dots either camgear at 6:00 and crank gear at 12:00 or cam gear at 12:00 and crank gear at 6:00 like mentioned...

RickR
08-06-2007, 02:03 PM
http://www.compcams.com/catalog/018.html

Barry Eller
08-13-2007, 06:48 PM
The way Doc degreed the camshaft works fine. The camshaft doesn't know where the dots are. One turn over and the engine fired after getting the valves adjusted properly.

However, if I had installed the distributor at that position, it would have been 180 out.

Cuda
08-13-2007, 07:26 PM
So I'll try readjusting the valves another way he told me about. He says with my cam profile, the exhaust and intake valves are never completely closed at TDC due to the overlap.
Any ideals on this? Sound right?
Nope, doesn't sound right to me. It would never develop compression unless both valves are closed, even briefly.

Barry Eller
08-13-2007, 07:33 PM
They are not closed together at TDC. They close together earlier, 4 degrees before TDC.

VetteLT193
08-14-2007, 11:34 AM
They are not closed together at TDC. They close together earlier, 4 degrees before TDC.

I don't get it...

TDC should be the top of the piston's travel during the compression stroke... During the compression stroke both valves are shut, and will remain shut until the exhaust stroke.

It should be:
Compression stroke: both shut
Power stroke: both shut
Exhaust Stroke: exhaust open (then at the end the intake can open)
Intake Stroke: intake open (exhaust can be open for the first part of this stroke)

It sounds like you are not at TDC, but at the point between intake and exhaust stroke, where the piston is also at it's high point.

Barry Eller
08-14-2007, 05:20 PM
To clarify, the reason I didn't have compression was my valves were too tight. Overlap in my camshaft would not let me adjust them in the conventional manner. With the amount of overlap I have, the intake and exhaust valve have a very small window to be closed at the same time. Not necessarily at TDC.

Hell, I don't completely understand it, but the Doc and our best Cadillac tech from work helped me with it. Both build drag cars, Doc has a 68' Mustang GT with a Ford 427 Cobra engine (a REAL Cobra 427). Mike has a 67 ProStock Nova with some kind of Dart block over 600CID. They know more than I do, they fixed everything for me and advised me on all of my set up. They do understand the difference between a marine engine and car set up. Doc is rebuilding the Radial engine for his Stearman Biplane, he is a anesthesiologist that was a mechanical engineer before going to med school.

I can't explain everything they told me they did, but it works, sounds like WWII artillery firing. Plus Doc lets me use his boat house and lift. All their labor cost me a few Budweisers and Bloody Marys. They are good friends and love to ride the Donzi. I even let them drive it, thats the least I could do for such good, TRUE friends.

Life is good...:yes:

Barry Eller
08-14-2007, 06:14 PM
Here is a scanned page from my OMC manual. This is how I originally adjusted the valve lash. This method does not work with a camshaft with as much lift and overlap as I now have. The valves were so tight, I had no compression.
Also a copy of my new camshaft specs.

I hope this will help someone to not make the mistakes I did.

And never be ashamed to ask for help!!! My Dr. buddy'as wife tells me he answers my calls faster than hers or the hospitals! :bonk:

Cuda
08-14-2007, 11:11 PM
I still believe it HAS to be closed at TDC, if not, you'd be losing power out the valves. The engine ONLY makes power on the downstroke after firing. It will fire before TDC, but the valves should still be closed. If yours has hydraulic lifters, they are all adjusted the same. I forget, it's either zero clearance and a half turn, or zero clearance and one turn. One is the old Ford 289's I always worked on, the other is the Chevy. If you have hydraulic lifters, that half or full turn is putting the pushrod about in the center of the travel of the hydraulic lifter. The only way adjusting the valves that would keep the valves open, if they are hydraulic, is by overtightening them, essentially making a solid lifter out of them, and then tightening them more than the bottom of the lifter's travel. Back in the day, I used to do just that if I had a lifter collapse. I'd just tighten it down to the bottom of the lifter's travel, then back it off a touch. :)

Cuda
08-14-2007, 11:25 PM
The way I adjust valves, it to put number one on TDC, on the compression stroke, then tighten the rockers down with one hand, while spining the pushrod with my other hand. When I can no longer spin the pushrod, I give it the half or full turn then. Last time I put a distributor in, I had it on TDC to install the distributor, and for the life of me couldn't figure out why it wouldn't run. I had it on TDC of the exhaust stroke.:bonk: Rather than pull the distributor back out, I just pulled the plug wires out of the distributor, and installed them 180 degrees off. :)

Lenny
08-14-2007, 11:51 PM
With the amount of overlap I have

are you not worried about reversion ???

Barry Eller
08-15-2007, 05:25 AM
are you not worried about reversion ???


I contacted Revolution Marine, the manufacturers of my exhaust, gave them the cam specs, they told me I would be fine. They stated their exhaust has not had reversion problems with cams with over .650+ lifts and more duration and overlap than I have.

My cam profile is supposed to be the Comp Cams version of the HP500's.

Check out the link to Revolution Marine Exhaust, the risers have a molded in dam that keeps water from coming back in the manifold.

] http://revolutionmarine.com/images/manifolds5.PDF


www.revolutionmarine.com


Cuda, I sat in the engine bay and pulled the engine over manually, while Mike adjusted the valves, ONE at a time. I'd pull slowly, and he would tell me when to stop. Yes, he was turning the push rods, and when he was satisfied, 1/2 turn tighter. They are hydraulic roller lifters with Comp Magnum roller tipped rockers. He told me with my cam, or any cam that is far from stock with overlap, you have to do them one at a time or they will be too tight.

Oh yes, we primed the oil pressure with a drill before adjusting.

VetteLT193
08-15-2007, 06:42 AM
I still believe it HAS to be closed at TDC, if not, you'd be losing power out the valves. ....

:yes:

The cam overlap, no matter how much it is, will not change TDC. I still think you are between the intake and exhaust stroke and need to cycle the piston one more stroke to find TDC.

If the valves are not closed, then all the compression would blow out the valve(s) that are open.

I googled this, it may help with a graphic: http://auto.howstuffworks.com/engine1.htm

The difference between that graphic and your big cam engine is you will have the intake valve open at the end of stroke 4(exhaust) and the exhaust valve won't close until after it gets into stroke 1 (intake).

VetteLT193
08-15-2007, 06:45 AM
If you read the bottom left of the attachment you posted about valve adjustment it's trying to say the same thing as I am... the valves shouldn't be moving at TDC (because they should be closed) so, if they are moving then you are on the wrong stroke.

Hope all this helps:bonk:

Barry Eller
08-15-2007, 07:56 AM
If you read the bottom left of the attachment you posted about valve adjustment it's trying to say the same thing as I am... the valves shouldn't be moving at TDC (because they should be closed) so, if they are moving then you are on the wrong stroke.
Hope all this helps:bonk:


I'm sure you are correct, my Gurus go way over my head when they explain anything.

It's running great! That is what matters most to me. We set initial timing at 12 degrees, ran it up to 3000 RPM's and it was at 32 Degrees. So everything seems to be proper. MSD distributor has 20 degree advance.

Cuda
08-15-2007, 08:30 PM
I'm sure you are correct, my Gurus go way over my head when they explain anything.
It's running great! That is what matters most to me. We set initial timing at 12 degrees, ran it up to 3000 RPM's and it was at 32 Degrees. So everything seems to be proper. MSD distributor has 20 degree advance.
Sounds like you have it right, now get out there and burn up some old dinosaurs. :)

Barry Eller
08-16-2007, 07:51 AM
Sounds like you have it right, now get out there and burn up some old dinosaurs. :)


I think I'll wait until the weather cools down! Pensacola Bay and the Gulf waters are HOT, and we are under attack by jellyfish. Can't get in the water to cool off. I still have to clean up the wiring, my main neg battery cable has to be replaced, as it is corroded in the middle, looks like a snake that just had a meal!

Don't mention Dean...Erin brings back memories of 1995, 95's Erin's eye passed over Gulf Breeze, I stepped outside and it was like they say about being in the eye. Quiet, eerily quiet.