273 guys..Heads up!!!!

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They didnt run 3.63 size dia gaskets. the chamber is 3.91 on the head thats where i f#$%ed up & figured id be ok with bore dia gaskets made the ones that were on my motor when i tore it down were 3.91 bore made by fitzjarold (spelled that wrong im sure) i figured thet were aftermarket & ordered smaller. The fitz fire ring was @ the 3.91 not 4.140 like the cometics. see what i mean now?
 
2 darts, yes they are the same small bolt (5/16) intake cyl heads. there even withen 3 cc's of each other. I ran thease heads cuz they were already done new guides,valve job & all.
 
Sounds like a surface issue..even if the gasket is exposed it should be able to take the combustion pressure .
On Vic's 273 before I did any combustion chamber work I scribed the bore on the cyl head as to not make the chamber too large..
With that being said even if the gasket was exposed it shouldn't fail unless the combustion gasses are getting inbetween the head and block or there is a whole bunch of exposed gasket like .250 ..
It's definitely a head scratcher, but the first place I'd look is the surfaces.
That little 273 that was built for Vic has 175 lbs cranking pressure and goes to almost 7000 rpm and he's been trying to murder that engine for years now.
No issues,not even a valve adjustment yet..that little 273 makes some serious onions...
 
Ok guys got some awnsers now.... in short the headgasket did not fail @ all so i thuoght WTF!?! is gone on here???? well i figured it out bleave it or not one of the exhaust crossover block off plates i had made to block the cross over completely is my offender! after finding it missing from where i let it i grabbed my plyers & started folding out the bits of steel out flat & suer enoph thats my culprit!!!!!:cussing: I have not a clue how in the world it managed to go past the exhaust valve scott free not so much as even tutching the valve or seat in any way then go for a ride until i removed it from the cyl. & bleave it or not cly looks great chamber looks great the olny thing that took any kinda damage was top of the piston a little. So now im looken for so intake gaskets that already have block off built in. heres a pic of block of plate.
 

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What will you use for the head gasket this time? Hopefully more available.

You lucked out! That is just amazing nothing more happened.
 
I called cometic there gonna send me one new head gasket for 30 bucks cheaper to help a guy out! gooooood poeple man i will recomed them for sure! heres a few more pics.
 

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66fs,Sweet! thanks as long as it will work with my small bolt intake heads that would be perfect! i would have never guessed that the block off plate got in there! ive had them for years in my old 340 without ever an issue & beat that motor twice as hard as i ever would this one!
 
That's good news! The plate is soft enough it shouldn't do big damage. tmm
 
10-4 toolman! i need a cold one & should go buy a lottery ticket now before my luck is gone! lol!
 
I'll have one with ya!
 

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Man there rare to even find,let alone use em. If i could have found them i wouldnt have thought twice about it.
 
Hipo65 said:
66fs,Sweet! thanks as long as it will work with my small bolt intake heads that would be perfect! ...
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They are on the same centers and smaller, Pretty sure they'll work. I do not think intake gaskets are different for 64-65, but it has been quite a while since I used my 64 heads. I sold them years ago.
 
Yeah, I didn't think it was a piece of head gasket.
 
Thanks guys! & i honeslty couldnt think of anything else "steel" that woulda got in there other than the gasket. id never have guessed my home brew blocker would ever end up in any cyl! ive had the same ones in my ols 340 for 6+ years & never an issue & i built that engine to take the severe abuse i dished out @ it until i sold the car last summer. This was the last ting i thought would wind up in a cyl!!!!
 
OK so the factory chambers are bigger than the bore so the fire ring is outside the chamber putting it way past the bore, right? All LA head gaskets are 4.060 right? No on makes a embossed gasket anymore I assume. I think most if us have a ring if nothing around our bores.
 
From what ive found with my own 273 is the dia of the stock head gasket is right @ 3.91 the same size as the chamber in the cylender head. usen a gasket thats matches the bore is ok (mls gasket) & yer good to go.
 
I would not worry about blocking the heat riser. You gain very little form it really, AND, it makes it hard for the engine to warm up. I mean the intake is goin to warm up eventually anyway. The heat riser is there to make some vapors out of the fuel when the engine is cold. After the heat riser thermostat in the exhaust (if you have one) open up the heat riser has little effect on the intake manifold. You waste a lot of fuel by blocking the heat riser and cause some oil wash in the cylinder walls. I know everyone does it and I have done this in the past but now I have changed my mind on this after careful thought.
 
I didn't notice were you running headers ,stock exhaust manifold with the heat riser ,if it has the heat riser in it. will continue to burn a hole through gasket because the exhaust is pushed through the intake and out the other side. until warm up. you could block it open.
 
Stock manafolds with the heat riser gone from the passenger side manafold & holes taped & plugged. & i dont really drive when its colder out any how. i know it makes them kinda cold blooded so da speak but is sure helps with hot weather operation & hot soak too.
 
Hipo65 said:
i know it makes them kinda cold blooded so da speak but is sure helps with hot weather operation & hot soak too.
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Right on. Just to compare notes, I've made block-off out of pieces of annealed copper pipe. The process leaves the metal a little more malleable for being flattened and shaped. What were you using as a start point for this block-off so I can avoid this kind of result?
 
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