Do high compression heads eat head gaskets?

P

P.S.

Well-known member
Seems like the cars with high compression heads on them tend to go through head gaskets more often than those with stock heads. Is that true, or just a local coincidence?

Also seems like everyone is opting for high compression heads. It's getting difficult to find a car with the stock head on it still.
 
detonation can cause headgasket failure. running the wrong advance,,
high compression heads are more susceptible to these conditions as i see guys pulling the lever down and going
 
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Wha advance is recommended with a Snyder 5.5? Have been told to only use the silicone coated premium gasket and also told to use higher octane fuel are these correct

Thanks
 
I've only had one head gasket failure in over fifty years. The gasket that failed was a cheap steel clad gasket from J.C. Whitney. The gasket burned in two in the narrow area between the one and two cylinders. This happened with an original head after about 6 years and caused compression loss on the front two cylinders . I've ran high compression heads (5.9) since the mid ninties with copper clad Fel Pro gaskets with NO problems. I have ran my model A's with full advance at speed for over fifty years with NO bearing or head gasket problenms. There is a lot of confusion about the use of the spark lever and there is NO help for those that constantly fiddle with the spark lever.
 
Higher compression makes more heat and a faster burn, less advance necessary, and more susceptible to detonation. I don't know the Snyder head personally, but generally 26-28 degrees is about max for an HC head on an A, about half to 2/3 down on the spark lever. More than that and I would get detonation with a Weiand 7-1 head on hills and acceleration. However, I have had no problems with a Best composition head gasket on that head.
Anyone interested in mods to an A or B, from touring to Bonneville should have a copy of Jim Brierely's new book on performance modifications. Contact him for orders at jimb4e4@gmail.com The principals discussed in there will help any engine run better too.
 
The spark lever should be treated as if it was a vacuum or centrifugal advance and should be used as such depending on speed and load.
Blown out gaskets could be because the "new" head and block deck were not checked for flatness and just slapped together. Could be wrong head gasket. Could be spark timing as suggested. Could be not re checking the torque.
There are still a LOT of cars out there with the stock head.
 
I'm not sure that it is the higher compression head that is all the problem. Most head gaskets do not have the meat between the cylinders as an original bore block would use. Most gaskets seem to be for a 60 over and + bore, which really thins out the gasket between the cylinders, and may add to the blowouts..... Some of the gaskets out there look to be for a .125 bore....
 
One other thought in this. Without getting into a "whizzing contest", it has been noted here in the past that a certain manufacturer of hi-compression heads has been known to have had warpage issues after they have initially been run where the head loses its flatness. Once it has been through several hundred heat cycles (a couple thousand miles +/-), the heads can be resurfaced and they seem to remain flat afterwards. Just something to mull over.
 
The Felpro copper clad gaskets, second and third revision gaskets will handle .125 overbore. This is good in a way because most model A engines have been bored a few times. The area between the pistons is very narrow. I haven't had a problem with the Fel Pro gaskets used in my cars with 5.9 heads.
 
willobs said:
Wha advance is recommended with a Snyder 5.5? Have been told to only use the silicone coated premium gasket and also told to use higher octane fuel are these correct

Thanks
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No and no. I use the copper BEST gasket Snyder's sells and never have a failure. I have a 5.5 head on my car and you can believe me when I say I run it. I don't change into 3rd till 35 mph as a general rule. This gasket has been on for at least 3 years or more.
 
Just popped my head gasket on the Blue Ridge tour... between 3 & 4. Found it last night. The car has a decked flat Brumfield.

I think I was lugging it up and down the hills a little too hard, shifting gears, adjusting timing and splitting gears with the overdrive to find the right speed. But it just gave up the ghost.

If you are questioning the use of a higher compression head, I would recommend it. You will like the extra pep it gives you in driving. Even if you have to change a head gasket on occasion, that is simple work that can be done in an hour if you have the right tools and an extra gasket.

I think I'm going to try a Snyder's 6.0 head next. Or maybe run a cyclone head for a little while....



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Jason in TX said:
Just popped my head gasket on the Blue Ridge tour... between 3 & 4. Found it last night. The car has a decked flat Brumfield.

I think I was lugging it up and down the hills a little too hard, shifting gears, adjusting timing and splitting gears with the overdrive to find the right speed. But it just gave up the ghost.
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My opinion is detonation caused that to blow. From the pictures, likely caused by the lean fuel mixture and a tad too much timing. Did you check the deck of the block too??
 
Jason, I would also try a Fel-pro R3 or R2 gasket since it is smaller in the chambers and has a little more meat between cylinders. Looks like you have small enough cylinders to use one and have a better gasket.
 
How about the use of Chrome Moly studs , guaranteed not to stretch. If they work it would keep constant torque on the head.
 
Excellent info, thank you.

Some of you guys don't have head gasket failures at all, but some locals around here carry a spare not because it's a good idea, but because they go through head gaskets so frequently. Just had me worried.

My motor isn't overbored, and has a "low compression" head. Get around 55 lbs. per cylinder. Yet my car outclimbs a lot of other cars on the hills without having to downshift constantly. I think I'll stick with the stock head for now.
 
I think that a lot of head gaskets get replaced that really don't need to be repolaced. I've seen a lot of head gaskets replaced because the owner noticed grease in the radiator. Most model A's will have oily residue in the upper tank from years of improperly greasing the water pump. Some, when they see droplets coming out around the radiator cap when accelerating, automatically assume that they have a blown head gasket. A lot of times when the unknowing newby makes a RAZOO and removes the head, they end up wringing off a couple of head studs in the block , followed by dispare..
 
We used to place a 2" length of copper wire .020 in dia under the gasket between 1 and 2 and the same between 3 and 4 held in place by a dab of grease.
 
I was shown a head gasket of the older style today. The fire ring was double rolled. The first side was put on and was folded over the core then the other side was put on and the edge was folded over that. You ended up with 2 thickness of copper all around the fire ring instead of one as made now.
 
I'm reading this thread with trepidation because my '29 coupe supposedly came with a "6:1 head". Some newbie Q's:

(1) How can I identify exactly what head I have without removing it (which I don't want to do if not necessary);

(2) Should the head bolts be re-torqued as part of regular maintenance? The re-built engine had less than 100 miles on it when I got it;

(3) Is the head nut torque for this head still 55 ft/lbs as it would be for a standard head?;

(4) What are the signs of a blown head gasket and how is it diagnosed?;

Wanting to stay a-HEAD of the game in Oregon,
Mike
 
29er said:
I'm reading this thread with trepidation because my '29 coupe supposedly came with a "6:1 head". Some newbie Q's:

(1) How can I identify exactly what head I have without removing it (which I don't want to do if not necessary);

(2) Should the head bolts be re-torqued as part of regular maintenance? The re-built engine had less than 100 miles on it when I got it;

(3) Is the head nut torque for this head still 55 ft/lbs as it would be for a standard head?;

(4) What are the signs of a blown head gasket and how is it diagnosed?;

Wanting to stay a-HEAD of the game in Oregon,
Mike
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1. Do a compression check when the engine is warmed up.

2. I'd do a head retorque at least a few times.

3. What does the engine builder recommend?

4. Low power due to lost compression. See#1
 
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