Thread: chevy 400 what could cause this?

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Hey everyone... I recently installed my chevy 400 into my 79 Trans am the engine is 40 over, 292/512 crane cam, ported iron 2.02-1.60 heads, new 3.75 stroke crank, holley 4160-750 cfm carb and a edelbrock eps permastar intake.
I bought the engine from a engine builder out of Indianapolis. This engine is suppose to produce 425HP. Well to make along story short I've had numerous problems with this beast that I have had to fix like the oil galley plug on the driver side beneath the head on the backside of the engine that was left out. Or the rear main seal that was incorrect for the application. The rear main seal should have been a aligned bore seal, thus causing a huge oil leak. Anyway I finally got all of that fixed and had the engine running strong when I was driving down the road about 40MPH and all hell broke loose I heard a pop and then a huge cloud of smoke out of my left exaust and then a bad knocking. I pulled over and then saw coolant pouring out of my left exhaust. I got the car home and pulled the plugs from the driver side and noticed the #5 cylinder spark plug had been dented/ bent and there was coolant in there as well as the #3 cylinder. The engine will turnover but knocks, I don't want to turn it over anymore. The engine only has 100 miles on it and was broken in correctly. Does anyone have any ideas what could have possibly happened?

Seems to me like you have a real case to go back to that engine builder and ask for a refund. As Streets said, sounds like water got into one of the cylinders from either a headgasket leak or a crack. Water does not compress so that is what is meant by hydraulicing. Water won't compress so something has to give, either a connecting rod, cylinder wall or combination of the two. Did you retorque the heads after initial break-in? From all the other things that were wrong it really sounds like shoddy workmanship on the assembly.

Pat

Thanks stu and streets for your input. What would be the best case scenario, in terms of $$$$$$ and ease of fix. I actually took the head off the engine after I received the engine because of the missing oil galley plug. I cleaned everything up well afterward and did everything by the book. Could any of this be my fault? I seem to think not because when it comes to my toys I'm pretty thoughraul- Idon't think I spelled that right.....Anyway does anybody else have anything else to say. I also would like to know how you get 425HP out this combo...

400 chevy engine - racing performance
block----------------------early 400 bored .040
crank----------------------new 3.75 stroke stock 400
rods-----------------------stock chevy 400 conditioned
pistons-------------------speed pro forged .040
rings-----------------------hastings moly .040
bearings-----------------clevite 77 .std
gaskets------------------fel- pro
bolts----------------------arp fasteners
camshaft----------------PBM/crane performance .292/.512 flat
tappet
lifters----------------------hydraulic
timing chain------------cloyes double roller
pushrods----------------stock
rockers-------------------stock
oil pump-----------------melling chevy m-55hv
heads---------------------stock reconditioned ported
valves---------------------2.02 stainless
timing cover------------stock chevy
oil pan--------------------stock chevy
valve covers-------------stock
damper-------------------stock

Streets,
What is that suppose to mean?

Means, the guy lied to ya, don't think 425 horse is possible with that combo....

what kind of horsepower could a guy expect out of that combo? anyone....

not much more power than there was to begin with, your cam and ported heads are the only thing that'll do anything for HP and, being the heads are just ported and were not replaced with better flowing heads such as edlebrock or even higher performance stock heads for other SBC's like camelhump heads or such like that. Sounds like you need to find another engine builder to fix the other guy's F%$% up.

Holy Cow Batman, you mean a bad head gasket can lead to bent rods! I do not know whose fault it is but the hydraulicing probably caused the bent rods and maybe perforated the cylinder walls. Admittedly the 400 siamese cylinders have only a very narrow sealing surface, but there are also no water holes there. Let me turn this around and ask Streets to tell me/us how to avoid this sort of destruction from a leak. Please go over the procedure of tightening down the heads on a 350 (of interest to me). In particular Tech1 has convinced me to use a 0.040" quench space and I was planning to use a 0.025" deck and a 0.015" Felpro gasket. Now I am worried that using a very thin head gasket may not seal properly and lead to a hydraulic disaster as above. Maybe the thing to do is to mill the block to a deck height of 0.010" and use a 0.025" gasket OR MAYBE BETTER mill the block to 0.000" deck height and use a 0.040" gasket? I need the answer to this question within the next week because that is the timeframe of preparation of my block. Again, maybe the best thing to do is to mill the block to a deck height of 0.005" and then use a standard gasket which compresses to 0.040" or 0.035". The question/problem is how to get good gasket sealing AND a small quench space of 0.040"-0.045".
I guess in order not to hijack the thread one might also ask can this tragedy be repaired with cylinder sleeves? I know most blocks can be sleeved without problem but IF he has a hole between cylinders can one safely sleeve the siamesed sylinders in a 400 block? That is the next thing our thread needs to know.

Summary:

1. What is the best way to seal head gaskets on a SBC?

2. What gasket to use with block milling to achieve 0.040" quench safely?

3. Offer to our friend the next step to repair his engine, can the 400 be sleeved?

Don Shillady
Retired Scientist/teen rodder

Come on Streets,

Sears can't sell torque wrenches that way and even I know there is a specific sequence to tighten the head bolts(I bought the Chiltons manual)! What about gasket thickness versus reliability? I bet the thinner gaskets are more difficult to do right? When you ran a blower on a 383 you must have taken some special care to make sure you didn't blow a head gasket with the extra pressure, so what did you do then?

Don Shillady
Retired Scientist/teen rodder

k, since no one else has answered this yet, I would go with either the decked block to 5 thousandths or 10...i went to a deck height of 9.010 and run almost 11.1 compression on 91 octane gas with absolutely no detonation, given I do have a big cam to bleed off some pressure, but the quench really helps. I think this gives a good combo of gasket and quench. I, as Streets did, would use o rings and studs if I was serious about my engine or had any boost on it, just to be sure and have the ability to really turn it up later without a teardown. To the poor fellow who detonated his new engine. It sounds not good to say the least, if that guy who put it together had any pride or whatever in his work, he should have offered some sort of warranty or even his word that he would 'help' you get it back together...even though I wouldn't really trust him again....since he put it together all wrong. Take the head off of the driver side and see what you have, it's the best and only sure way to tell. It sounds hooped enough to warrant taking the time and effort to take it all apart again. Then start ordering the parts!
As to the torqueing of the 350, its fairly simple, if you have the sequence in your Chilton's I don't have to explain it here. But always start in the middle and work out, same with headers, etc. The torqueing you should do in 2 or more steps. Firstly get them all in and finger tight, then torque to say 30 ft lbs and then maybe higher and then to your final torque or just do it from 30 to final, but use lube because torque is a shitty way of telling how well the bolt stretched to hold the head down, its more how much resistance there was to you turning it, so lube is required when torqueing. ok, good nuff

Don,
I have used the old tin head gaskets that were only .019 thick and had no leaking problem. I am using the copper head gaskets now they are .031 thick no problem. I like to apply a pretty good coat of copper coat spray on the gasket before putting it on, does it really help, I think so.

One man gang. Do you think you could have dropped a valve and cracked your cylinder wall or head therefore getting water in your engine? I agree you need to take the heads off and see what you have.
One other thing, I would get rid of those short 400 rods, you are asking for trouble with those if you plan on turning the motor over 4500 rpms. It will eventually throw one. The other thing with a 400 is you should run head studs and nuts to get a better seal on your head to your engine.

ok- 1st you'd be lucky to see 325 hp with that set up.
2nd- that 292 cam requires special springs because of the lift.
3rd- if you got water in the cylinder then you got a busted head from too much lift with that cam on stock heads.
OR you ran it too lean, and heated it up real good....I have never blown a head gasket so bad that it filled the cylinder, so I doubt this one.
Pick one & call the engine builder - if you can find him, and tell him to refund your money.

I have to agree with a few people. I know that a 400 and 403 are a lot different, but as far as the siamesed thing goes, it holds true. Chances are the fault is in the heads, gasket or the block. I personally ran a standard fel-pro gasket with RTV black near the water ports and had no problems. And as for 425 HP-HA! pick up a manual, and run a comparison to a stock 400 block. Add about 10-15% and youll be there.

Thanks guys for your input... I pulled the engine today and set it up on my stand and pulled the intake and head. The #3 and #5 pistons are toast. The pistons look as though they were starved of oil they also looked real heated up (brown). When I turned the engine over all pistons were working and going up and down. On top of the #3 piston almost looked like there was some kind of threaded screw or something...not real sure if it was or not because it was melted into the piston. What I don't get is why the damage would have spread over to the #5 piston. Is there anything else I should look for? The cylinders walls don't look bad, but the #3 cylinder has a slight scuff on one part. the #5 cylinder looks allright.
The engine was not hot when I was driving either it was at 190 degrees. Does anyone else have any thoughts? Can anyone come up with a combo using any of my parts from this Chevy 400 that makes a legit 425HP? All of your replies have been excellent. thanks a bunch!!!!

I would think that the screw looking thing that melted down was half of a keeper....