21 stud head gasket fitment - overheating qun

Blownflatheaddeuce

Blownflatheaddeuce

Senior Member
Hey guys only played with 8BAs so new to this engine. I have a quick question re this; do 21 stud head gaskets only go on one way onto the deck?

I did a swap using new copper sandwich head gaskets and its getting hot REAL fast whereas before it ALWAYS ran cool.

Could I have screwed up and put them on wrong thereby blocking a water passage?

Any input would be much appreciated thanks !

BFD
 
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Re: 21 stud head gasket fitment

Is this a engine with the water pumps in the block or in the heads? What Mfg and part number gaskets?
 
Re: 21 stud head gasket fitment

Its a 37 pump in block, insert bearing engine ;)

I used a set of NOS copper sandwich Fitzgerald head gaskets
 
Re: 21 stud head gasket fitment

The 21 stud head gaskets go on either side or back to front they are mirror images of one end to the other. You can not get better gaskets than what you are using. You say prior to change it ran cool. Does that mean you changed to alum heads or some such thing?. If you did change to alum heads I would use composite gaskets. Also Terry asked if you are using the block off plates and using pump on the head style heads.
 
Re: 21 stud head gasket fitment

The gaskets should have a FRONT mark and some of the holes near ends are slightly larger at rear. The 2 or the same, so one side is flopped over in relation to other but front and back remain front and back.
 
Re: 21 stud head gasket fitment

Bruce, I couldnt see "FRONT" on either of the gaskets. Barnfind, the water pumps are in the block.

Something is wrong, I swapped out the cam and added a set of adjustables. All went ok with the swap.

Previously the car ran cool with thermostats, even in the summer time I could run it without the fan. It would take forever for the temp to rise and even when it did it ran cool.

The heads are cast iron, shaved .050" and the everything checked out clearance wise. When I fired the engine to break in the cam the tempo just RACED to 200+ within 5 min from a dead cold. Something is definately wrong. I would'nt think a .050" shave would cause such a problem.

The dist is a helmet which has'nt been touched. It was refitted to the engine after the cam swap with the engine on the #1 compression stroke both valves seated and the cam lined up correctly with the crank gear.

Bruce are you saying theres no way to screw up the gaskets? I can t see how a slightly mismatched water jacket hole could caue this overheating

What to check?
 
Re: 21 stud head gasket fitment

The potential screw up would be front to back. The difference in holes is not large but is visible. I don't know for sure that the difference in holes would be enough to cook off the rear cylinders, but getting more water aft was pretty certainly the intent...also, if you put both gaskets with seams the same way up, one head's holes would be different than the other one.
Both sides use same gasket, an earlier design shared with the pump in head 221, and one gasket will hence be upside down from other in terms of how the copper is crimped around cylinders.
I'd get in there and get holes the right way. Assuming careful work there is no reason not to reuse the same gaskets once hole location is verified.
Again...if you put gaskets in so the crimping was the same, one will be backwards. If the gaskets are installed with top different, both would be either right or wrong if hole size was not noticed. Starting from cold, does one side get hot faster?
 
Re: 21 stud head gasket fitment

Thanks Bruce, not sure but the temp gauge is on the drivers side head only.

I guess one should have the crimp up toward the head and the other facing the deck. Im not sure which side the crimping is from memory, so Ill pull the heads to check after draining the coolant.

Learn something everyday, Ill update tomorrow once I get in there.

Thanks to all and you Bruce, you're a champ !

BFD
 
Re: 21 stud head gasket fitment

From start up to 200 degrees in 5 minutes is pretty quick...I wonder if the sending unit got damaged during the gasket change?
 
Re: 21 stud head gasket fitment

On the heating time, just start it cold and see if one head gets too hot to touch significantly before the other. Checking up on the veracity of the gauge is a good idea, maybe with one of the electronic things.
But do get the bigger holes to the rear.
 
Re: 21 stud head gasket fitment

Are you running thermostats now? Could one or both be sticking? Have you tried with no thermostats?

Mart.
 
Re: 21 stud head gasket fitment

Yep the stats were fine when I pulled it down. Thsi thing ran COLD and I used to sruggle to get it up to temp in the cold weather. This was even with the mech fan removed.

Just pulled the drivers side head - the crimped fire ring was facing the cyl head side. Flipping the gasket from back to front all holes still line up.

There is no "FRONT" marking on the gasket and the water holes from on each vertical side of the gasket re all the same size !
 
Re: 21 stud head gasket fitment

pull both top hoses one at a time check flow ,Maybe gage or sender .timing ?Fiber wheel ,
 
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Re: 21 stud head gasket fitment

Getting so hot in that period of time is certainly indicative, as Mart suggests, of thermostat. I'd remove them and try again with them outta the system, certainly easier and quicker than pulling heads .
 
Re: 21 stud head gasket fitment

Could it be something as simple as an air pocket trapped below the thermostat... ie, no water/coolant in there because the T/S won't let water flow?
I had this happen once on a fresh engine, and boy, did that thing heat up fast. I put bleed holes in the T/S, and got rid of problem.
Just a thought. JMO
 
Re: 21 stud head gasket fitment

Bob I already have bleed holes in the stats ;)

Hehe Walt it aint hard - my first thought went to the stats (they were almost new and working fine before the swap) but after testing them both in a saucepan - they fully open once the water is brought up to a slow boil.

And they close when cooled off.

Still cant see any difference b/w the coolant holes on the head gasket regardless of whether the gasket is flipped end for end on the same side.

Ted it cant be the timing can it? Its a fixed helmet dist what was simply removed and reinstalled. Its a NOS fibre gear that has done no work.

Ill remove the T stats just to eliminate them even though they open/close - short of that I what else it could be ?

Stumped.

BFD
 
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Timing, I'd have thought you need less timing with your higher compression ratio. Late timing normally gets hotter than correct timing for sure, but getting ttiming right would help track a problem. Trying to lessen the variables. I'm sure the 21 stud gaskets I got have the slightly different size holes front to back, but I can't check for a couple of days, I'm in a different part of the country to them.
Just a quick question, are these The heads you ran stock, and then had cut? Head gaskets, how do the ones your using now compare to the ones you took off? Did you reuse them, or fit different ones?
Martin
 
Martin, the head are the stock cat iron heads that have been shaved .050 ie: the same heads that were on the engine.

The timing in the dist cannot be changed like an 8BA (it was simply removed/refitted) and as far as I know, the dist can only go on one way.

Upon multiple inspections of the replacement gaskets the holes at each end are the same diameter/location - no holes are blocked. All holes line up correctly with those on the block and deck. They appear to be the same as the ones that were on the engine before the heads were removed.but of copper/sandwich construction.

As an aside, when replacing the cam, the gear was pressed onto the cam so that the mark on the cam lined up with the mark on the gear. When installed with the #1 piston at TDC firing and both valves seated, the cam and crank gears lined up perfectly. I assume this is correct?

Kinda stumped here
 
Kind of odd, but I had a pump on my 36 stop turning. The rust inside caught the impeller, and the pulley started slipping on the stationary shaft. I doubt this is your problem unless it sat for a while, but thought I should offer it up.
 
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