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View Full Version : Jubilation...then misery!



Tony
06-11-2003, 08:18 PM
Finally, after reworking my thermostat/circulation/plumbing issues, I shake down the Ski Sporter today. All is going very well, consistent 155 degree temperature, +/- 5, at all operating ranges. Cupped prop biting great, no spin-outs through all manuevers. I'm recording rpm/mph data to compare my props and their recent cupping, I even bump into 60mph @ 5200 rpm, but only for a few seconds and that is speedo. 57mph @ 5000rpm, 52mph @ 4500rpm, 46mph @ 4000rpm...life and boating is good.

Also, I am thrilled to discover a slouch/lean driving position that puts me just below the windshield line...so no eye-watering issues at all and my hat stays on!

But not all will remain so blissful. After about two hours, and while running about 4800 rpm acrosss some chop, my trusty 302 coughs and wants to quit. I slow down gradually to idle, keeping her running, and pop the hatch to discover water everywhere. Apparently the stud that holds on the thermostat adapter (kind of an elbow piece that the housing mounts on top of) has come loose. Back at home I discover that both are 5/16 inserts, and BOTH are not holding. I ran a 5/16 by 1" bolt into one, and seem to get an O.K. bite, but the other one has only about 1/4" of decent threads and does not hold a bolt or the insert.

Barely room to do anything, plus I do not know what to try next. With access I imagine drilling a tad deeper into the manifold (Edelbrock F4B) and re-tapping. Are there any other options? How much deeper could I drill if I could?

Thanks for the advice, I am anxious to resolve this once and for all because I think I am near to having my boat fully dialed in.

Rootsy
06-11-2003, 08:43 PM
Tony, not a lot that is gonna do ya much good short of a longer bolt ot get into good thread if at all possible... but you have to get enough torque on the bolt so that it will not loosen up. if this works use loctite gasket eliminator on the gasket to keep it from leaking if you DO get a loose bolt (you may have to order this from online)... it is the best crap out there...

If it was me, i would take the time to remove the intake and insert the threads so that this never happens again... believe it or not i had to do this to a BRAND NEW edelbrock RPM Air-gap last summer... stud went in and proceeded to strip... with no torque on the fastener... just pulled the threads right out.. whatever aluminum they are casting these out of really BLOWS... i ended up inserting all 4 carb mounting stud holes.. took me an hour and i took it off my motor to keep shavings out of it...

Cuda
06-11-2003, 09:45 PM
Would a heli coil work?

MOP
06-11-2003, 10:15 PM
This problem is pops up a lot on the after market aluminum manifolds. They look great but many have poor quality castings. a Heli coil may do the job, but I much prefer to go with the inserts. With the inserts you are getting a lot more holding power, if you have a good machine shop close by they can order a wide range of sizes both length, width in any thread. If you can only get the lip style use it with Loctite on the insert then carefully grind it flush. Anything over 3/8 I go to the inserts, my feeling is the coils tend to twist slightly when you tighten in the aluminum no matter what you use on them. I've seen No it All's ruin these junk castings. Cast anything by nature is weak, never tighten anything much past what you can turn by holding the rachet by its head not the handle. Rely on good heavy snug tightening and good quality sealers let to cure as per the directions. If they were to cast this stuff like car parts and outboard stuff it would cost twice as much.

MOP
06-11-2003, 10:27 PM
Second note do you think there is enough meat to tap the holes to 3/8? if the holes go into the water passage drill them through then tap for 3/8-16 coarse thread holds much better in castings than fine and enlarge the holes to 3/8 in the part to be mounted. Then follow my tighetening instructions. To bad you are not local I am damn good at this stuff, can save most anything.

Tony
06-12-2003, 08:00 AM
Thanks Jamie and MOP. I guess I was hoping for an easy solution since I am NO damn good at this stuff! It looks like the best fixes will require some major dis-assembly. Even with pulling the engine's water pump to allow straight drilling access to the lower bolt hole...there is only about 8" between the front of the manifold and the cockpit liner! So it looks like I may try to pop the intake and go at it from there.

With any luck I may be boating by July!

Rootsy
06-12-2003, 09:56 AM
Tony,

you can get thread inserts (not heli-coil) from places such as mcmaster carr, motion industries and MSC. Not a big deal... you never plan to remove them so just use some 262 loctite (red permenant)on the external threads.

as far as torque. when you torque a thread you are effectively stretching the fastener to put it in tension and this is what keeps it from backing itself out, it is now essentially a clamp under load. the MORE thread face area that you have the more torque you can put on an internal thread, ie fine threads will support more load than a course thread. generally on a torqued fastener you want to achieve a tensile load which is about 75% of the fasteners yield. minumum engagement depth should be 1 1/2 times the diameter of the fastener in order to support your load on the threads. you can do a quick net search and find a table of fastener sizes and corresponding torques and clamping loads. Just tightening somethign down is quick and dirty but has zero accuracy. the problem with aluminum is that most folks OVER torque and the aluminum threads cannot support the loads that a steel thread can. if at all possible, in order to prevent thread gaulling and achieve accurate and repeatable torques lubricate your threads... least desireable is motor oil... next would be a teflon thread paste and the BEST BY A MILE... is ARP Moly Lube... it is worth it's weight in gold.

McGary911
06-12-2003, 11:14 AM
I've used Time-Certs which are threaded inserts. 2.7 porsche motors tend to pull head studs, and this is by far the best way to fix them. Helicoils just wont cut it.

Here's a quick rundown on time certs i found on the web:

The second, and probably superior method is the use of a "Time-Cert". Similarly the Time-Cert installs by drilling and tapping an oversize hole, then you screw in a steel threaded
sleeve, followed by a special tap that expands the bottom of the insert to lock it against the work piece. Both the Helicoil and Time-Cert are sold in individual size kits with everything
needed for several installations; spare coils or inserts of varying sizes and lengths are available.

Good luck, hopefully it wont keep you off the water for long.....

MOP
06-12-2003, 07:34 PM
An idea you may want to try is what was done to mine before I got it, I have an 8X12 hinged deck inspection hatch in front of the engine. It hides behind the seat back. It is a BLOOD saver for water pump changes, belt tightening and timing ETC. Worth double its weight in GOLD!

mphatc
06-12-2003, 07:54 PM
With 8" of room consider buying a right angle drill cheap at Home Depot, open up to the 3/8 x 16 as earlier suggested.

Mario L.

RickR
06-12-2003, 08:27 PM
I'm sure inserts are better but I used a heli-coil to repair a thermostat housing on an automotive aluminum manifold with good success.

I cannot remember if you have an open or closed cooling system. If it is open I would thing a heli-coil and a little hylomar on the gasket and threads would work fine.

NAPA makes a "Heli-Coil Thread Repair Kit" (#770-3046) that repairs a 3/8" thread (drill size 24/64) For you application you might also have to buy a "3/8x16 bottom tap"

Tony
06-12-2003, 08:47 PM
Good "bolt basics 101" explanation Jamie, and thanks also to those who provided info on inserts. In addition, the angle drill and hatch trap door are cool ideas. I will definitely print this post and save it if (when?) what I did today fails.

Without plug wires, water hoses, and the top of the thermo housing in the way, there is a BIT more room to manuever. So, after pulling the WEAK inserts out, I squirted some carb cleaner in the holes, ran a tap in and out a few times, and then a bolt to see how much thread I had to work with. With a 1/2" deep hole about the first 1/4" is stripped leaving the same amount decent in the back. So, with the perfect length bolt created with a lockwasher, I re-installed the adapter with new gaskets, thin layers of Permatex, modest torque, and Loctite Red on the bolts.

I will keep a close eye and if it does not work I will try either the angle drill to 3/8" idea or the insert w/ JB Weld idea. Lastly (keeping in mind my inexperience) would be to lift the manifold to drill and tap it properly.

Thanks a ton for the thoughts...hopefully I'm back in the water again!

Rootsy
06-12-2003, 09:23 PM
Tony,

you should have used blue loctite at the most on the threads, especially into aluminum.

i agree with rick, for sealant hylomar is great stuff, i use it exclusively on all of my head bolts which pass into the water passages. for intake ends i use permatex ultra black, for gasketed surfaces i use a thin coat of loctite gasket eliminator on the gasket...

as far as the intake removal... put that motor on TDC, mark the distributor housing location on both dist housing and intake, also mark rotor location on the housing... so you can initially index it all and get her in the right spot when you put her back in. undo all your hoses, drain all the water from the block (important one), etc... undo your fuel line, wiring, throttle cable from the carb, choke, temp sender, etc. pull the distributor and then remove the 8 intake bolts. pop her loose with a BIG screwdriver, this may take a little finess.

to reassemble, MAKE SURE ALL DEBRI is cleaned from the head and block surfaces. use a gasket scraper to clean surfaces. lay a towel in the valley to catch debri. vacuum it out if oyu have to but don't get ANYTHING in there, or down an intake port... keep it covered when not working on it. i recommend felpro intake manifold gaskets, namely with the heat riser blocked off if your intake and heads are so equipped and you have an electric choke. like i said, permatex ultra black for the end seals... toss the corks right in the garbage.. lay a good 1/4 inch bead from head to head (where the head and block meet) then lay the intake gasket in the bead at that junction. put a dab on top of the gasket at that junction also... leave it sit for about 30 minutes to just begin to setup... before you lay the permatex get (4) 5/16 cheapo - (read that grade 5) bolts (2 - 3 inches long), cut the heads off and saw a screwdriver slot in em.. thread em lightly into the cylinder head (intake manifold mounting holes) (only need 2 or 4 - 2 front and 2 rear) this allows you to slide the intake gaskets and intake manifold right down on without moving the gaskets and it helps keep the gaskets in place when setting in the permatex... start your intake bolts and lightly snug and then remove the alignment studs and put the rest of em in. beginning from the center and criss crossing torque in 2 steps to to specified torque... i recommend some arp moly lube on the threads and under the heads. retorque after running a heat cycle with the motor.

reinstall all the other happy stuff.

MOP
06-12-2003, 10:20 PM
Excellent post Rootsy :)