Built up a 350 for the car. Same shortblock it had (std bore 350, 880 block, 4 bolt main, low miles).

Installed vortec heads on .015 steel head gaskets. Comp XR276HR roller cam and lifters, Com roller tip magnum rockers and comp pushrods. Edelbrock performer RPM on top with the nice multilayer intake gaskets.

Fired up, runs ok, but either I didn't use enough silicone at the rear intake end seal or it blew it out. Obvious leak right by where the oil pressure port plug is located. Oil and vapor/smoke (not sure which yet) coming out.

I'm concerned that either the head gasket(s) failed or the intake gaskets...but wondering if maybe it could be a mis adjusted rocker preload holding a valve open, or...??

I hate to pull this thing back out, but am not sure of options for diagnoses that don't require major disassembly

Any thoughts?

 

Did you use the correct gasket or did you just use silicone on rear of intake ? And your talking an oil leak right ? What is the deal with mentioning valve issues ?

 

I used silicone, as that's what is included in the felpro kit. I haven't seen anyone actually use an end seal gasket in MANY years.

There's an oil leak, which seems odd to me since that end seal is well above the valley. It almost seems pressurized, which is why I mentioned either gasket or valve issues. Just spitballing and wondering if a valve is not closing fully.

 

Are you sure that the leak isn't coming from the oil pressure port or fittings? Make certain of that first. You'd be astonished as to how much oil can come out of a tiny leak there.

 

I would not worry about a valve unless the motor is popping. Do you have the PCV hooked up ? And also CA Legal Vette has good advice.

 

Pull the intake off and have a look.............. just saying

 

You do have breathers or a pcv valve hooked up, right?

 

you didn't say whether or not the block was decked. that's a common
problem if the block is milled and the intake sits up on the heads just enough to not quite seal the front or back of the block. sometimes it can be fixed by slotting the holes in the manifold ever so slightly.in fact edelbrock acctually does this sometimes as on their airgap manifolds

 

Bet you have a simple leak somewhere on your oil sender.

Cant really see it as the oil will appear clear. got fooled by that one swore up and down it was a rear main on a new motor thank god I didnt pull it.

Usually something simple dont overthink it and tear your motor down.

 

It is amazing how much oil, vapor, mess can come out of non sealed manifold to block ends.

clean it thuroughly with brake clean and blow dry with an air compressor. Then cover the whole area with a product called "the right stuff" It is what I use all over during engine assembly.

If that doesn't work it is pull the intake time and start over

http://www.permatex.com/products/our...he-right-stuff

 

Did you use a Vortec specific intake? The ports are different than standard SBC.

 

ok, to answer some questions...

It's definitely not the oil pressure plug. I can clearly see the back of the intake manifold and it's coming from the rear seal.

I didn't deck the block, but there's no telling if the previous owner did. The motor appeared to be a 300hp 350 crate motor. It had standard heads and a cast iron intake. nothing remarkable or notable anywhere. Nothing to indicate it had ever been bored.

I put vortec heads on it, and a vortec intake. I did notice the intake angle looked a little odd compared to the heads, but it only looked noticeable when I had inadvertently grabbed the wrong intake gaskets. Once I got the thicker rubber/steel ones it seemed to sit fine. I did buy both the heads and intake used though. The heads were checked out by the machine shop and given a valve job along with an otherwise clean bill of health.

I did have both a PCV and a breather in place. In fact I didn't even have the oil cap in the valve cover yet when I fired it up. It seemed to have a lot of vapor (smoke/steam? too early to tell) coming from the openings in the valve cover.

I'm hoping it's just the intake, but I am worried about how it seemed pressurized. I hate to find out the head gaskets didn't seal. I had reservations about using the .015 steel gaskets instead of the .039 standard ones, but so many people had good luck with them when doing a vortec swap, especially with the factory dished pistons that I went ahead and did it. Used ARP head bolts and torqued to 72 lbs/ft

 

Sealing up the back and front of the intake is a little tricky.
1) clean all oil residue off the sealing surfaces
2) VERY THICK 3/8-7/16 bead from corner to corner.
3) this varies and many people forget to do it but let the silicon sit for 15-20 minutes until it just starts to firm up but its still tacky.
4) drop manifold straight down one shot. If you have to move it more than a 1/4 redo it.
5)torque in correct order.
Never had one leak

 

Just did a roller cam swap,head gasket change out with a Felpro 1094 .015 gasket.Took compression readings before and after to make sure gasket was sealing.Compression was increased with new gasket and cam.Head gasket is rubber embossed and should seal well.Test fit intake to check fit.Parts don't always fit like they are supposed.You want the surfaces as clean as possible.As mentioned above use the Right Stuff on the intake manifold it seals very well.Have done two intake installs with it and no leaks.Did you put a high enough bead on the china wall?My write up http://forums.corvetteforum.com/c3-t...-cam-swap.html

 

Saw it. even posted in it

Did you install the head gaskets right out of the package or did you copper coat them? I have seen people go both ways.

 

This was two days ago:

This was yesterday:




ok, so today I need to come up with a plan. Yesterday I fired the car up (after what seemed like WAY too much work, and it sounded fine. Stalled after about 30 seconds. Would NOT restart no matter what. Checked and double checked everything. I have fuel, air and spark. Only thing left is compression. Pulled a plug, check. ****!! about 60psi. Check the other side. Same thing. So an hour later I have the heads back off. Really hard to tell what happened. Pistons don't look steam cleaned, yet there's a hint of water in the oil. Valves and combustion chambers look fine. Only thing I can see is what looks like maybe less than ideal sealing around the some bolt holes by the head gasket, and some areas between 3 and 5 as well as 4 and 6 that look to have less copper contact than the rest of the motor.

Trying to decide whether to clean it all up, skip the thin steel gaskets and give up the half point or so of compression as well as the ideal squish area and go back to a standard .039 head gasket. Or, should I give the steel gaskets another go and depend on the ARP head bolts to maybe take a little more torque this time? Maybe skip the copper coat?

IDK at this point.. but it's nice weather, so today is the day to make something happen I guess.

 

Go with the thicker gasket , and put that behind ya .I realize a point here or there is nice but in real world driving you not going to miss anything.

 

Did you use sealer on the head gasket bolts?

 

yeah you can still seem remnants of it in the holes in some of those pictures. Maybe I didn't use enough, which would explain the very minor amount of coolant I found in the oil. If you look close at the pics that show the lifter valley you can see the oil is just slightly milky.

 

Apparently your head gaskets didn't seal. Probably the block is not perfectly true. Go with the.040" composition gaskets and be done with it. You won't miss the half point compression. That doesn't explain your oil leak though. That is probably the intake manifold. Make sure you have at least 3/8" bead of silicone and lower the manifold straight down. I have used silicone here for every engine I have built in the last 30 years and never had a leak. (At least not at the intake. )