350 Chevy Troubles Help
Posted in Internal Engine Parts | Asked on Jun 2, 2010
Ok heres my dilemma. I started with a 76 chevy 350 block casting #3970010. The four bolt truck block. I disassembled the block completely and took it to the machine shop. I had them pressure/sonic test the block as well as perform the following machining. cylinder bore to .040″ over, align hone the mains, and square deck the block and install freeze plugs and cam bearings. I installed all new parts form Summit racing with the exception of the cylinder heads. 3/4 of the way through the buildup I decided to swap out cylinder heads and installed a set of aluminum heads. When the time came to fire it up for the first time it would try to start but not completely. When the distributor was pulled I noticed there was water in the oil. I determined this came from not replacing the head gaskets when swapping heads during the initial buildup. I thought theyd be OK since the engine was never ran. I was wrong. The engine was tore down and the head gaskets were replaced. Today I attempted to fire it up again. Still working out the timing. I didn’t try for long but it appears there’s water in the oil again. What could be causing this? My first assumption was a cracked block but I have a hard time accepting this because I know the people well who serviced the block and they would’ve said something. The other concern I have is the aluminum cylinder heads which are from Pro Comp which I never heard of except a article in super chevy from 2001. What’s another reason water could be getting in my oil?
There are 5 Answers
did they pressure test before the bore out to 40 thou over? maybe the problem happened then after the bore out? usually the test is to test the block to make sure it is good but 40 over is alot. also do a compression test once the engine is all togethere. the only other place is the heads and the intake manifold which doesn’t make sense you have to do some tests and not just trust the people who worked on it as thing do happen and not because anyone wanted it to happen
How much did they take off the block? .010 would be the max to me. Any more and your intake would need to be machined too so it will fit properly with the heads and block. Also anytime you remove the heads or intake you have to clean the surface and install new gaskets.You know the block is good so you also need to have the heads checked if they aren’t new. Follow the proper torque steps also. You also should know that to properly break in the cam you have to bring up the RPM to 2000-2200 for 1/2 hr as soon as it’s fired up, change the oil and baby the engine for about 1000 miles BEFORE you put your foot in it. The cam break-in procedure should have came with the cam. Make sure you don’t have a set of vortec heads. If so you need vortec intake for proper match.
It wasnt the head gaskets the 1st time nor this time. You can swap heads and keep the same gaskets if you never fired the engine or if engine hasnt been sitting for a long time with heads torqued down
My guess would be an intake mis alinment due to decking of the block and aftermarket alum heads.
What intake gaskets did you use.. The std blue fel pros from your rebuild kit will not work on those heads too well
How much was took off the block decks? The intake side of head needs to be machined or the intake its self cut to match. Also the end rails of intake some times needs grinding down on decked blocks
Pull your intake off and look for traces of water leakage from the 4 water ports on head.
Then clean up heads, sit new side gaskets on and sit your intake on.. Look at the front end of engine where intake and block meets.. Is there a gap, if so how big?
Other than the intake leak, the only other probs that will cause water to get into the oil is from a cracked block or head or a really messed up block deck or head gasket
Being its never been fired up, blown head gaskets are out of question.
But how are you torquing the heads down? Are you going in right order and to the right torque?
chevyrace is correct its the intake gaskets are leaking. my 454 has done this twice. take the intake [mine is aluminum] and turn it over and secure it in a vice or something and manually [with a flat file] go to work. this will show you in short order what condition the ports are in. if things are not to bad [warped or way out of alignment] you can file the ports and ends smooth for a even fit. now this is only “if” the block and intake are not way off . be sure you torque the intake down in proper sequence. save the old oil and use it in your chainsaw….good luck.
truck block may be the reason…I don’t have the casting number,s here but you should have that checked …truck block,s sometime,s are different than regular car block,s…usually are taller than car block,s ..but this depend,s on the block & what model it came from. this will affect head & intake angel,s which will affect gasket fit…especially if your using vortex head,s….also .040″ is a bit much…was it tested after boring or before. make sure you have premium gasket,s & make sure they fit correctly.. torque is another issue…be sure you do it correctly…the last issue is the head,s…just because they’re new doesn’t mean they’re matched to the block & over torquing aluminum head,s can easily crack them…be sure of what you have & what you have done…a cooling system/compression test will only tell you that you have a problem that you are already aware of…install the special cooling system dye, run it for a short time, tear it down & search for problem area,s with a ultraviolet / black light that will react with the dye..exposing any problem area,s….this dye is available at your local radiator shop & they can tell you where to obtain the correct light or possibly allow you to use their,s…good luck!