273 guys..Heads up!!!!

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Hipo65

Hipo65

Yeah I'm "That Guy"
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Alrite 273 guys heres some first hand info & results on the head gasket dia debate. I had comitic make me some .030 mls gaskets in 3.700 dia & thet fit the bore perfectly! heres the bad part the cyl head chamber is a little bigger than the bore so there is now some exposed steel gasket not doen anything & i figured it wouldnt be an issue...... Wrong! ive had her runnen about a total of 2 weeks ish & yesterday she started to randomly make a god awfull tick/konck until it droped #5 all together. Pulled spark plug to see strap bent over on it so i got the bore scope to see wtf happened! & found 3 small chunks of thin beat up steel in the hole that im assumeing is the "out in the open" part of the head gasket! See pic. got those chunks out & she runs like she did before!:cheers: i got sooooooo dam lucky it didnt trash the bore or valves just roughed up the top of the piston a little. soooo i guess match the gasket to the head from now on guys just a heads up!
 

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Hipo65 said:
Alrite 273 guys heres some first hand info & results on the head gasket dia debate. I had comitic make me some .030 mls gaskets in 3.700 dia & thet fit the bore perfectly! heres the bad part the cyl head chamber is a little bigger than the bore so there is now some exposed steel gasket not doen anything & i figured it wouldnt be an issue...... Wrong! ive had her runnen about a total of 2 weeks ish & yesterday she started to randomly make a god awfull tick/konck until it droped #5 all together. Pulled spark plug to see strap bent over on it so i got the bore scope to see wtf happened! & found 3 small chunks of thin beat up steel in the hole that im assumeing is the "out in the open" part of the head gasket! See pic. got those chunks out & she runs like she did before!:cheers: i got sooooooo dam lucky it didnt trash the bore or valves just roughed up the top of the piston a little. soooo i guess match the gasket to the head from now on guys just a heads up!
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You didn't mention it but, Are you going to change those head gaskets? The way I see it you got lucky the first time, what about the other 7. Just wondering.

Russ
 
Yes sir you better tear it down now before more damage occurs,if one hole puked that out what do you think will happens in the others?..dont take a chance on it...you may have got lucky but dont push it,that was a warning of whats to come....
 
Yes i am gonna change them for sure! man there was another member on here that did the same thing (with the gasket size) but for the life of me i canna remebmer his name on here,hes got a white 68/69 dart for his pic. im tryen to get this info to him too before it happens to him!
 
Well that sucks. If the other cylinders look ok you should be ok with just a head gasket change. Post some head gasket pics when you can. Which head are you using?
 
toolmanmike said:
Well that sucks. If the other cylinders look ok you should be ok with just a head gasket change. Post some head gasket pics when you can. Which head are you using?
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If the head gasket fits the same, it may just be a matter of time before the others do the same thing. It's best to replace the gaskets to be safe.
 
Hipo65 said:
Yes i am gonna change them for sure! man there was another member on here that did the same thing (with the gasket size) but for the life of me i canna remebmer his name on here,hes got a white 68/69 dart for his pic. im tryen to get this info to him too before it happens to him!
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Do you remember if you posted in that thread? If you did, you may be able to go back in your history and pull that thread back up.
 
I figured out who it was Rob R & i sent him a pm about it. The heads are the o.e. small intake bolt ones that came on the motor. If ya look @ the pics of the gasket close up the actual fire ring that does the sealing is back 1/4 inch from the bore dia. & the cylnder head dia is right @ 3.90 ish i didnt figure it would be a problom........:eek:ops: guess not! sucks popen the heads off a nice shiny pretty motor but @ least nothen got severly damaged! I did a compression test & all holes are rite @ 185 give er take a pound so all is good in #5:prayer:
 
see what i mean. This another members photo but did the same thing i did with gaskets. only they used 2bbl pistons where i used 4bbl pistons.
 

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krazykuda said:
If the head gasket fits the same, it may just be a matter of time before the others do the same thing. It's best to replace the gaskets to be safe.
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Yes I agree. I should have said Head gasket(s).
 
I don't have any 273 heads around to measure but What part of it blew out? You have a photo of the bad gasket? Must be the area next to the valves.
 

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I dont have it apart yet,im assumeing the area before the fire ring thats not really doen any thing? i do have a set o 65 273 heads off another motor in the shed & they are rite @ 3.90 dia.
 
I was assuming there was a spot that the fire ring wasn't sandwiched between the head and deck surfaces like around the intake valve area.
 

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It very well could be man,ill know more tomarrow when i open her up. If the fire ring wasnt holding youd think it wouldnt have squat for cranking compression?
 
It will be interesting to find out what happened.
 
We will all know more tomarrow. It was up on jack stands running cuz i just o/h the tranny goen through the gears & just started to make funny tick/pop noise until it droped #5 all together. Im just soooooo thankful it did it @ home & didnt distroy cyl. wall,valves,rings or piston!:prayer::prayer::prayer: I just dont know what else it could possably be?
 
the gasket is larger than the bore and larger than the chamber. As i said in the thread when we were building our 273 we wanted a stock bore gasket but to none avail. what this means is ALL of your gasket is squished, the reason the big bore gasets suck is you have this nice sharp edge to get hot and a big gap all the way around the bore edge to collect junk like carbon.

Your problem is more than likely you had a ring end gap wrong and you broke the top of the piston off...
 
That's a lot of metal for a little bit of exposed gasket , as you put it. I'd expect that exposed gasket to become a hot spot in the combustion chamber and start to melt away as it's multi layer instead of a solid piece. Guess we will see when it's apart.
 
085moparkid,The piston is fine i can see it plane as day with my bore scope! if it had broken a ring & or piston "ray charles" could see that with a bore scope man! Plus it would run like crap. All cylnders have 185 psi cranking comp. & fyi the ring gaps were twords the lose side of .014 thou. for top & second ring. & the gasket is smaller than the chamber (chamber off of another 65 273 head is right on the money 3.910 accross) The gasket is bore size @ 3.700 & fire ring is right @ 4.060 see photo above.
 
Hipo65 said:
085moparkid,The piston is fine i can see it plane as day with my bore scope! if it had broken a ring & or piston "ray charles" could see that with a bore scope man! Plus it would run like crap. All cylnders have 185 psi cranking comp. & fyi the ring gaps were twords the lose side of .014 thou. for top & second ring. & the gasket is smaller than the chamber (chamber off of another 65 273 head is right on the money 3.910 accross) The gasket is bore size @ 3.700 & fire ring is right @ 4.060 see photo above.
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so you think when they ran stock bore gaskets at 3.63 (I think that was stock bore) they had these failures?
 
Hipo65 said:
I dont have it apart yet,im assumeing the area before the fire ring thats not really doen any thing? i do have a set o 65 273 heads off another motor in the shed & they are rite @ 3.90 dia.
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You have probably already checked to be sure that this other set of 65 273 heads has the same intake bolt angle as the ones that were on the engine.:thumbup: Maybe not. :thumbdow: If they don't match be prepared to use a different intake manifold.
 
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