fire ring diameters of various head gaskets

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volaredon

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I know that over the years people have gone wild with modifying these engines, with bore jobs of 0.060 and more being common.
I am not planning a very "wild" build for mine, just a little more grunt and motivation for a truck. but I am experimenting with head porting and I "think" I might have gone just a little too far in grinding out one of my chambers to where the HG that I have on hand (older Fel Pro's before "Print-O-seal" came along) I bought a pile of /6 parts from another member here, and within that pile was 7-8 of these head gaskets. I haven't done em all yet, (work in progress) but I have played around with the chamber around the valves to "unshroud" them a bit, mostly on cyl #1.... and the new edge of the chamber cuts into the fire ring on this model HG a bit.... oops.... I ground it out a bit here because I want to run the OS valves in it.
does anyone have measurements of fire ring diameter on different brands of head gaskets? Print-o-seal? ROL? Detroit? Victor Reinz? or anyone else that makes head gaskets for a slant? I'm done with this head for now until I find out what I can do for a HG, I hope I didn't turn the time spent on this head into "practice"..... I do have 2 more that I can port out, I just stripped out one of them today, gonna spend much of tomorrow in the garage making metal dust..... (I want to clean up this 2nd head a bit anyways, as if I have not wrecked the 1st head, my son also has a slant powered pickup, that I want to do up a head for)
 
Can you put the head on a bare block? Look through the bores with a light and see where you are. You could spray the chambers with machinist dye and scribe around the top of the bore. Take the head off and lay the gasket on there.
 
I get what youre saying/// but if I see that I'm into the fire ring with the gasket laying on top of the head what more am I gonna see by bolting the head to the block and looking at that? The bore size on the engine I am looking to use this head on is 20-over (3.420) the fire ring ID on the gasket I laid up there measures out 3.540 with a dial caliper. so Im already .120-over the size of the bore?
I have 2 more slant heads here that I set the same head gasket on, (untouched/unported) and the fire ring is right tight against the edge of the chamber on both of them. 1 "peanut" head taht is new enough for the AIR tube hole at the back of the head, and a drool tube head. I have since stripped the 2nd peanut head, and started carving on it. I'd like to use a peanut head because it leaves less chance for leaks... no drool tube seals to worry about.
Im thinking the original head "might" still be OK as I am hoping to shave it at least 0.060. I might go a bit more, as any head gasket that I use is gonna wind up at least 2x as thick as the original steel shim gasket. so to even stay "status quo" on original CR I am gonna have to shave the head at least 20-thou, so that means 20-thou more than I would have otherwise wanted to shave either it, the block, or both....
this other peanut head has never been apart but it already has a couple spots that look like my original head that I started with near about half of the valves.... but the head gasket I have "just" makes the ring around the combustion chamber w/o hanging over...... I would not have thought that a stock, untouched combustion chamber would already be bigger than an original, unbored cylinder bore..... I have not stripped the drool tube head, I might have to bolt that to the block and flip it over and see how the chamber lines up with the bore, once I get the block back......
 
The Print-o-seals are as removed from My K6 2.0; slightly ovaled at 3.515x3.520", & .039" compressed thickness. Aussiespeed makes large-bore Slanty HG's. The Guys at .org were doing some group buys of MLS & some other type(copper?) units. Check there as well.
 
Yeah the Aussie head gaskets are up around 3.6". Pretty big. I could use one right now that's thicker than .040.
 
RustyRatRod said:
Yeah the Aussie head gaskets are up around 3.6". Pretty big. I could use one right now that's thicker than .040.
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yeah me too, but I wouldnt want one any thicker than what a Print O seal one would be..... I found a ROL brand one on Feebay for a better than reasonable price, that (by the pix in the Ebay ad) looks to have less space between cylinder bores though pix can be decieving I know... but thinner between the fire rings means bigger diameter fire rings...
What ever happened to ROL anyway? They came on teh scene out of nowhere, were around for a while then poof... gone.
 
volaredon said:
yeah me too, but I wouldnt want one any thicker than what a Print O seal one would be..... I found a ROL brand one on Feebay for a better than reasonable price, that (by the pix in the Ebay ad) looks to have less space between cylinder bores though pix can be decieving I know... but thinner between the fire rings means bigger diameter fire rings...
What ever happened to ROL anyway? They came on teh scene out of nowhere, were around for a while then poof... gone.
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ROL I believe was bought out and cheaped out by Mahle. Do they not make the Print O Seal anymore?
 
yeah they do make the Print O seal, that is the current Fel Pro offering/ but comparing printed specs online about the print O seal, vs my measurements of the previous generation Fel Pro /6 head gasket, ("SB" suffix rather than "PT" suffix on PN) the Print o seal is 20 thou smaller inner diameter than the old version Fel Pro I have on hand already....
 
If this ROL works out it'll be an easy $13 solution to this issue..... (price I paid on Ebay including shipping) If not I aint out much.... I've "wasted" way more than that before.
 
Well that ROL HG was a bust. The listing was for a slant 6 HG but he sent me an AMC inline 6 gasket by mistake, I think he sent mine to the AMC guyi got it refunded, just ordered a ROL from someone else.
There is a seller that has an Aussie version on the bay, same seller has a single and a lot of 3. But from what I am seeing they are 0.060 compressed, thicker than I wanted. I guess I could have them take a little deeper shave off the block to compensate.
 
It's a shame if you have gone into the fire ring area, but the bore size always dictates how far into the chamber you open it up, and not the diameter of the gasket, and it should never be used as a guide. It's possible that it could be salvaged by using the head on a larger bore size that doesn't exceed the fire ring diameter. But again, even if the chamber overhangs the blocks deck, you have really created a poor breathing head because of this issue, and air entering the bore will get blocked and trapped by the overhanging chamber. You will be better suited to start with another head.
 
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I have already done that.
I have 3 here in all, 2 peanut and 1 drool tube (which is the original one from the engine that I have)
I don't think that any of them had been touched since they left the factory, and all 3 have a couple of chambers that are jagged around the valves, and I was just trying to smooth out the jagged-ness on one of those, and I was gonna try to equal them all out in the end. The head I'm worried about being into the fire ring is a peanut head, no AIR provisions. And the one I have the most time into.
I started on peanut head#2, it has the hole for the AIR tube in back but no holes in the exhaust ports like pix I have seen of heads that do.i have that one roughed out, haven't hit it yet with the sandpaper rolls to smooth it. I wasn't wanting to go with the drool tube one because going with the peanut head would eliminate 6 leak possibilities. But I might have to. I have gotten into the original seats bad enough on that 1st head that I'm gonna have no choice but to put it together with OS valves which I planned on from the start. I'm planning on having exhaust seats put in regardless.
I am gonna take both of them in for evaluation once my OS valves get here and see what happens.
Actually the grinding doesn't look square to the deck, and it's getting a shave no matter what if it is savable. I'm thinking that with the shave, I might lose the ground out part that overhangs the fire ring. I'm hoping so anyway.
I'm gonna pull the drool tube head apart and clean it up under the valves at least, just in case I have to go with that one.
 
I measured the old McCord gasket I used on the "for now" motor I just assembled and its fire ring was 3.595". Uncompressed thickness was .060.
 
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OK that's good... and would give me plenty of room to use the original head that I had put all that work into.... as long as they don't hit water trying to put exhaust seats in for me. I think McCord is gone away now too, though I have seen them on EPay.
 
volaredon said:
OK that's good... and would give me plenty of room to use the original head that I had put all that work into.... as long as they don't hit water trying to put exhaust seats in for me. I think McCord is gone away now too, though I have seen them on EPay.
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Yeah and like a stupid idiot I didn't write the part number down either. I do remember I went everywhere looking, and did not find that exact number. It was in my gasket pile along with several other slant six head gaskets.
 
OK....got a ROL and a Detroit/Corteco from Ebay.... one is a little better (not much!) than the old style Fel Pro I have/ the other, um, no. I forget the measurements I got, I can post them later if itll help someone else here.....
but, I met with a guy from the /6.org site for a few small parts I needed that he had// and he had an Aussie head gasket. Gave it to me, just said "replace it with another when I can, no hurry".... that one will definitely work with this head.... IF I didn't ruin it otherwise (anyway) I took both heads I have been carving on into the machine shop 2 days ago, and when he looked at the original head that I started on (and prompted this thread) I got a huge "OH,MY GAWD, what happened to the bowls"? out of him.... I also took him my new O/S valves and springs, and told him what I wanted, and to evaluate it to see if it can be salvaged, or if it was really a "practice" head. We'll see what he says. I have 1 more head here that I can use, if those 2 are beyond hope.... I never claimed to be an expert at head porting. these 2 heads were my 1st 2 honest attempts at doing so..... where I was working on a head that wasn't already deemed scrap, for some other reason.

BUT, another development. I went from "definitely going" to the Indy Cylinder head swap 2 weeks ago,, to "well I'm not sure"// after talking to @68barracuda since then. The guy I met up with yesterday, was my ride down to the ICH meet last year.... and he ain't going either this time. So I was down to "well see what I feel like in the morning", as to whether I make the trip or not..... didn't want to drive all that way to have to possibly wait in line outside for someone to come out so I could go in.... like waiting in a 2 hr line at an amusement park ride, for a 90 sec thrill..... then take something to my truck and have to wait in line again to get back in. I'd heard that as a possibility, with all of this overblown COVID bull$#!t we have going on these days.....

well I ain't going to ICH. . Basically can't be 2 places at once. I found a deal on CL that seems too good to pass up, and about the same distance from home, but in a different direction...... I'll post what I found, if it winds up being what it seems....
 
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well I found a deal that was too good to pass up, a freshly redone (30-ish years ago) peanut head, all new valves, still sticky with what I think is cosmoline, doesn't look as if it was ever shaved (if so it was minimal) a guy had in his basement all wrapped in plastic. looks like it came fresh from the machine shop yesterday.
I'd like to pull a couple of valves to see what was done.... valves don't look sunk.... so that gives me 3 /6 heads that don't have chambers that extend into the fire ring.
 
I guess I'm a little late for this party, but I dug out the head gasket that's going on my truck very soon. It's a Fel Pro from their standard slant full engine kit, the fire ring is 3.520.
 
No not late yet, the head in question is in the machine shop waiting it's turn to see if I over
it bad enough to make it into a door stop.
Is yours a print o seal HG? (Current fel pro) or the older gray fel pro?
 
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