Head Gaskets

[Doug L.]

In another thread I told of my problems with a newly rebuilt (10 miles) L-84 engine. I'm still in the teardown process but am certain I have a blown head gasket. I had water in the #8 cylinder and in the oil pan, and since there is no water passage in the rear of the FI adaptor plate, the water must have entered the cylinder through the head gasket.

The heads were surfaced, as was the block (which they did without touching the stanmp pad). The pistons are new hypereutectic with the same head as originals, new Eagle rods, new valves, springs, seats and retainers. Everything was torqued to specs. I instructed the shop to use an 0.040" composition head gasket and will know later this week if they did. I plan to have the head magnafluxed when I get it off the block.

My question is about the new head gasket when I reassemble. Should I use an .040 composition gasket, or 2 each .020 steel gaskets like what was on the original engine, or something else? Should I coat whichever gasket I use with a sealer (aluminum hi-temp paint; copper gasket sealer, something else)? I don't want to have to go through this again.
Thanks-Doug

[Dan H.]

Re: Head Gaskets

Hi Doug, just a thought to check, the FI adapter plate does block off the rear/unused water passage in the head, which is next to #8 cylinder. If the bolts were loose in that area maybe you got some water pushing past the intake gasket into your cylinder? Murphy at work maybe? Hang in there!!!!
Dan

[Joe L.]

Re: Head Gaskets

In another thread I told of my problems with a newly rebuilt (10 miles) L-84 engine. I'm still in the teardown process but am certain I have a blown head gasket. I had water in the #8 cylinder and in the oil pan, and since there is no water passage in the rear of the FI adaptor plate, the water must have entered the cylinder through the head gasket.

The heads were surfaced, as was the block (which they did without touching the stanmp pad). The pistons are new hypereutectic with the same head as originals, new Eagle rods, new valves, springs, seats and retainers. Everything was torqued to specs. I instructed the shop to use an 0.040" composition head gasket and will know later this week if they did. I plan to have the head magnafluxed when I get it off the block.

My question is about the new head gasket when I reassemble. Should I use an .040 composition gasket, or 2 each .020 steel gaskets like what was on the original engine, or something else? Should I coat whichever gasket I use with a sealer (aluminum hi-temp paint; copper gasket sealer, something else)? I don't want to have to go through this again.
Thanks-Doug

Doug-----


Use Fel-Pro Permatorque Blue head gaskets. These will not leak water into the cylinders (or anywhere else, for that matter). These gaskets have a stainless steel ring around the cylinder bores and, when compressed, will not allow water into the cylinders or "blow out". If these were used in the rebuild, then I would say you problem is something other than head gaskets.

[Doug L.]

Re: Head Gaskets

Hi Dan,
Thanks for your thoughts on that possibility. It did occur to me and one of the adaptor plate to head bolts at that location was a little loose. I thought about torquing all the bolts and trying it again, but keep asking myself if it would be smarter to pull the head to see if the gasket is damaged. Its a question of going that much further, (pulling the distributor, adaptor plate and head) or having to pull everything apart a second time if it turns out the adaptor plate isn't the problem. I'm still chewing on that.
Doug

[Gene M.]

Re: Head Gaskets

Doug,
Before you go into any extensive tear down check the head bolt torques. Also the Fel-Pro Permatorque Blue head gaskets are a visual inspection. Thickness is checkable with a .035" feeler gauge between deck and head. I would assume the engine builder should have parts itemized on the bill too.

Using two head shim gaskets is an old 1963 solution for compression, not something I would suggest today.

Why is not the engine builder "looking after" this problem?

[Duke W.]

Re: Head Gaskets

I am not aware of any hypereutectic pistons that have the same dome size as the OE pistons. Manufacturer and part number, please?

Read the Fall 2009 Corvette Restorer article "Compression Ratio Explained". If you have to tear it down, you might as well take the measurements and put it back together with the proper compression ratio, and that depends on the installed camshaft and the highest octane commerically available fuel, which are...?

Check the block decks and heads for flatness with a machinists bar and .0015" feeler gage. Just because they are machined doesn't mean they are level.

If the heads and deck are level, and a thin gasket is needed to achieve your target CR a shim gasket is fine and they are available up to about .026". If you need a thick gasket to hit your target CR it does not make sense to use two shim gaskets. Us a correct thickness composition gasket.

The shop should have given you an itemized invoice with the list and price of all parts used. What manufacturer/part number head gasket was installed? Pistons? Camshaft? Valve springs?

Duke

[Doug L.]

Re: Head Gaskets

Hi Gene,
Thanks for your thoughts. Unfortunately the builder didn't list parts in that much detail. There is no indication as to the brand or thickness of the head gaskets.

You also have a good question about the builder not looking after the problem. I had one other problem last month that was directly attributable to them. A rear crankshaft seal that leaked because one end of one half had been sliced off at an angle. I found the problem and fixed it because I had the car in a different shop working on some other things that required the use of a lift when the oil started pouring out. The orignal builder was away for a week of racing so I replaced the seal and got them to reimburse me for time and labor. In this new case I'm not certain where the fault is, but the car is in my garage and I don't want to risk driving it. I'm also at the point of wanting to find the problem myself and getting compensation if it turns out to be their fault.

After removing the FI unit I have found that the adaptor (intake manifold) bolts are not tight. One was quite loose and just above the #8 cylinder. The others on the same side turned at ~20 ft lbs on the torque wrench. The manual says 25 to 35 ft lbs. These bolts don't get lockwashers. I don't know if I missed the very loose bolt with the torque wrench and the others have backed out on their own, or what may have happened. Those bolts were my doing. I have half way decided to remove these bolts, one at a time, apply lock-tite, and re-torque them. It isn't too big of a job to reinstall the FI unit, alternator and exhaust manifold to see if that solves the problem. If it doesn't I will have to remove everything again including the distributor, adaptor and head. I suppose if I'm going that route I may as well pull the valve cover and check the torque on the cylinder head bolts. Just one more gasket to replace.

[Tim S.]

Re: Head Gaskets

Given the fact you mentioned the heads were milled and the block decked, was the intake fitted to the engine? I just ran into the same problem with my L84. After camshaft break in, I had 20oz of water in the oil. After looking into things, the intake end tabs were split indicating the intake was not fitting properly. I consulted the machine shop I usually use (I bought the car with the short block completed and purchased a set of heads from another vendor) and that was the first thing he mentioned. I must say, he suggested checking the clearance between the intake and the block and further suggested the RTV method of sealing it up (I know, not FTP). After disassembly, I could see a trail of water from underneath the first intake bolt on the left side. It also appeared I was sucking oil on the left bank as well as water in cylinders 1 and 3.

Now, things are reassembled and vacuum tested to this point (waiting for another part) and the system held 22" of vacuum. If you like, I'll keep you posted. With some certainty, your intake may need some machining to properly fit the block and heads while utilizing the factory style rubber end tabs. I understand your frustration.

Tim

[John D.]

Re: Head Gaskets

HI Doug, Tim's answer and suggestion could very well be your problem. I know for a fact that D&A Corvette has an engine builder that has reworked the base plates /intakes of many FI restorations.

For Doug and anyone planning on installing a fuel injection unit. Complaint is the 3/8" nut behind the fuel meter (bowl) is almost impossible to install.
Here is one way to install it with ease. Use a 1/4" drive 9/16" swivel socket with a long 1/4" extension.

The adapter plate aka base plate aka FI intake manifold gets bolted on FIRST. Then the FI unit is 2nd.
If you have a 63 to 65 FI unit do not install it with a torgues wrench. Forget torgue specs on the FI unit. Why you ask? Because the casting is fragile and the legs are prone to crack. Now if the surfaces are straight and checked like Duke said no big deal.
Just tighten the FI unit up with some small wrenches as it's not going anyway. The base plate does need to be torgued. And to repeat if you had the head and block milled the geometry-the angle is most likely off.

The other day I compared the thickness of a set of NOS intake manifold gaskets with the current recut Fel-pro some call repros. The thickness is the same!!!
I was hoping the Fel-pro would be a tad thicker to help Doug out but it isn't.

Doug another thing to watch out for is if you do get the baseplate cut it's going to fit lower so the 12 bolt holes will have to be slotted. I hate seeing slotted bolt holes but sometimes you have to do it.

[Patrick B.]

Re: Head Gaskets

If you don't want to slot the FI intake, you can mill the intake manifold side of the heads to make up for head and block milling. I'm betting that 461 heads are a lot less rare and valuable than the FI manifold.

[Tim S.]

Re: Head Gaskets

I just fired my car back up again Doug and the problem is cured. I must of had a pretty good vacuum leak as well. The car runs fantastic now!

[Larry E.]

Re: Head Gaskets

In another thread I told of my problems with a newly rebuilt (10 miles) L-84 engine. I'm still in the teardown process but am certain I have a blown head gasket. I had water in the #8 cylinder and in the oil pan, and since there is no water passage in the rear of the FI adaptor plate, the water must have entered the cylinder through the head gasket.

The heads were surfaced, as was the block (which they did without touching the stanmp pad). The pistons are new hypereutectic with the same head as originals, new Eagle rods, new valves, springs, seats and retainers. Everything was torqued to specs. I instructed the shop to use an 0.040" composition head gasket and will know later this week if they did. I plan to have the head magnafluxed when I get it off the block.

My question is about the new head gasket when I reassemble. Should I use an .040 composition gasket, or 2 each .020 steel gaskets like what was on the original engine, or something else? Should I coat whichever gasket I use with a sealer (aluminum hi-temp paint; copper gasket sealer, something else)? I don't want to have to go through this again.
Thanks-Doug

Doug:
FWIW: When we rebuilt my 1970 LT1 we used GM#10185054 a composition (.041 compressed thickness) and it working fine as of now. You
can get more info on this gasket from the Chevrolet Performance guide #19260590. Larry
P.S. Could be FelPro makes this for GM but I do not know this for sure.