Thread: 78 camaro z28 stalling

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Originally Posted by thesals

yup that would most likely be ring failure.... i'd reccomend .030 over not .060 over..... the thinner the walls get the bigger chance of blowin your motor....luckily a 350 is the most inexpensive motor to do a rebuild on..... how much power are you looking to get? stock, a little extra, a ton, or just flat out too much?

i was thinking .30 would be better on the motor
just under a ton and more then a little extra! would like to bring it to 350to400hp. not sure what stock was 200hp maybe?. thanks!

350 to 400 is easily possible.... even more easy if you stroked it to a 383... theres plenty of builds... theres a list out there i dont have the site bookmarked but theres a list of truly proven power builds for 350s.... gives you what kind of horsepower on each one.... i'm sure someone will put up a link pretty soon since i mentioned it... wait nevermind i found it http://www.ryanscarpage.50megs.com/combos1.html

Nothing to do with how the engine runs, but hook up that kickdown when you get it running. The tranny will shift better and last much longer.

Originally Posted by dugdamoose

I did a cyl. leakdown test on # 6 cyl. I brought the piston to tdc (both valves were even) and hooked my compression tester up (took out the valve stem) then i unplugged the guage and hooked up my air hose and i could hear air but couldnt figure out where it was comming from.

If you have both valves even, they might both be open if that is on the wrong cycle. What I mean to say is there are two times where the valves might appear to be both closed, but in actuality, during the exhaust and intake cycle, they might both be overlapingly open. The second cycle is when you make compression and that would be the time to do that test. If you tested during the wrong cycle, you would have air escaping both back through the intake as well as the exhaust pipes.

Originally Posted by dugdamoose

I took off the fill cap and I could actually feel air comming out the fill hole. Does that sound like rings?

I'm assuming that when you say, "fill cap", you mean the rad cap? If that is the case, your head gaskets need replacing or a head might be cracked. So no, worn rings would never send air into the cooling chambers however it might send air into the valve covers areas, so if you mean the "oil fil cap", then yes, the rings might be the problem. Just try and be a little more specific so we don't have to guess as to what it is that you are referring to, thanks.

Originally Posted by dugdamoose

I will probably rebuild the motor. Does it matter with hp if I go .030 over or
.060 over? I mean if I go .060 over will it make much difference in horsepower.

You will gain about 5 cubic inches which would translate into an additional 1.5% hp. but as was already stated, it would probably not be in your interest to do that. Why not go .030 this time and then in a few years if and when you need to do a rebuild, then go with .040 etc.

man you are having a time with this project ....... been there , know the feeling, as far as the torque converter, on the jack stands it should idle in gear with the brakes holding the rear wheels still and idle, work it a little kinda like rolling up at a crowded stop sign, stop and go a few times, try reverse as well .... if you need one , i have found that a 2500 stall converter will give you about 1000-1500 RPM true stall for idle in gear, 5500 is good for about 4500 , i use a 5500 with a transbrake but without using the trans brake i get about 4000 max without pulling too hard to hold, your engine sounds like it has some serious problems , the man is right .030 would be best for a driver , just enough to clean up the walls and it will not have cooling problems like i have with right at 500 cid from a 454, doesnt work too well on a hot day on the street with a big stock rad. oh well , i hate that you are having so much trouble but you will get it all worked out, now would be the time to upgrade your parts in the engine valvetrain, rods,pistons and maye even crankshaft,a friend bought some eldebrock alum. heads for his '50 "sb chevy engine" he is a very well known, many world championships, (drag racing) , big cube pro mod engine builder, and we looked at them very carefully and close and they are very nice with a lot of very nice machine work there, something you may want to look at , he got the vortec heads to run fuel injection on, very nice , gonna work well, good luck , hope this helps you some
c ya later

just another thought if you are having any doubts about your valves seating on any cylinder. loosen the adj, nuts for that cyl. completely, now you know the valves are as closed as they can be and do the leakdown again, if it is blowing out the exhaust or the carb (intake) it is a valve, filler cap would be rings, expect a little air from all though, none of this is a perfect seal so a little is acceptable, very little though, look at the rocker arms and the one closest to the exhaust port on the exhaust manifold would be the exhaust valve and the same applies to the intake valves, again good luck , gatta go now , c ya

hey. i had to remove the entire front spoiler and bumper. my engine hoist wouldnt fit all the way under the car. the nose (not factory) swoops out so far the bottom of the hoist would push up against it. anyway the engine is out now.
took the intake and heads off. all of the pistons say .030 stamped on top. so i'm already bored out, i can wiggle piston#6 just by placing my hand on top of it and move it side to side.i dont see any scoring on the cyl walls. (could just new rings fix this?) or should i have it bored to 040 over? thanks!

depending on cylinder bore you have to mic it to be sure you might be able to get a mild hone and just rering it, replace all bearings, get crank polished and rods shot peened, replace all main bolts and rod bolts as well as timing chain and head bolts along with gaskets, if you are competent enough to do most of it yourself it'll cost you a few hundred bucks and come out like a new motor..... if valves look a little bad then go ahead and have the valves cut

just when things couldnt get worse! for starters i stripped the 350 motor down. the cam lobes started out looking ok then they started looking worse toward the back. actually a few could pass for round. now lets talk pistons they are all stamped 030 . i (gently) tap out #1 piston(i was getting 170-180psi) when i took the compression test earlier. the top ring was broken in half. #2 cam out(ring broken)and boy they are sharp! i'm missing a piece of my thumb! every piston except for one had either the top ring or middle ring broken i think one had both broken. but the cyl. walls look good and so do the pistons. the rod bearings looked ok a couple had a few minor scratches. and the crank bearings looked ok. normal looking ware. the crank bearings are clevite 77. 10 82 010 MB2547p and the rear main # clevite 77 7-81 010 MB2548p. so when i order my new bearings i need to get .010 ? suppose i get a new crank would i have to get .010 bearings? can i re-use the forged pistons i already have. just buy new moly rings? thanks!

My guess is that the guy who built the engine did not leave enough ring end gap. But if the bearings look good, reuse them. A new cam is in order. I would also hone the cylinders.

If you choose to buy a new crank, you will be going with stand bearings.

who can give me some advise on this? im thinking about going with a 383 stroker kit for my 350sbc. i figure what the heck if im going to rebuild ,might just as well go with more hp. so the question is has anyone done one and what should i expect? or should i just leave the stock crank alone? my heads are 64cc camel hump heads 67-69. thanks!