I dont know the numbers offhand but you can contact T A Performence. They qwill have the info you need and if the heads are different, they should have the head gaskets to correct the problem. Just look up their web site on the net. Good luck.
just recently got this 71 skylark unfinished project,it came with a rebuilt long block 455 in it,never been fired up, obviously hot tanked and very clean inside. so i finished bolting on all the accessories,before filling with oil,filled the radiator and the heater hoses so the block would be primed with coolant,to avoid cavitation and to check for suprise leaks anywhere,before initial fire up.i had previously did some homework about mismatched heads leaking.so i opened the oil plug and suprise!antifreeze!and just about a cupfull.nothing more.i compared head to block numbers and they are block-1241735 heads-1241860.is this a good match?could i have a water pump corroded,cracked.or misaligned intake gasket?.i used sealer on both sides of the gasket at the coolant passages upon edelbrock intake installation,have been swapping intakes on cars since 1983,is there some thing i missed??
Last edited by 80sguitarcarguy; 11-14-2009 at 12:22 PM.
I dont know the numbers offhand but you can contact T A Performence. They qwill have the info you need and if the heads are different, they should have the head gaskets to correct the problem. Just look up their web site on the net. Good luck.
Do you know what years the head and block are from?
If the block is 73 or later, and the heads are earlier, it could be the problem. The water jackets were changed.
86 GN, all factory options, engine build in progress
72 Skylark Convertible, 462, TH 400
72 GSX Clone 464, TH400, 3:42. 10.71 @126mph best
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yes,aware of the poss of mismatched heads,thats why i did a leak test ,the numbers are confusing to research because,i have to find an accurate source.so far ive read these heads are 73 to 74? and my block is 72 -75?,could my block be early 72?and heads be later 74??? again numbers are.block rear code 1214735 and the heads 1241860.now the front pass side block code stamp starts with 43x10 cant read the last ones. is the 3 for 1973? i love old cars hate picking up where someone left off.details details.this engine seems to be of a quality rebuild,but iv seen crazy hidden motor mistakes in my past exp.anybody know about these numbers??
Last edited by 80sguitarcarguy; 11-15-2009 at 08:38 AM.
well sunday noontime just pulled the intake,yep its seeping coolant between the head to block all around,and down into the lifter valley. now could it be mismatched in years head to block?or wrong head gaskets,sure glad i did not fire this up.im ready to pull this mystery rebuilt long block 455 and have it gone thru for other mistakes. first..anybody know if these head and block numbers are compatible?is there special gaskets to make mismatched years work? any info before i call around monday?.prepairing to pull the heads to see in a few days,have to save my back for my day job.
well my visual inspection i can see a little of the head gaskets and they are blue in color.and so far from numbers research looks like my heads and block are all 1973.have not pulled the heads yet.but could these gaskets be specific for the earlier 1972 heads.and that could be the culprit.wrong gaskets?
I'm pretty sure felpro only makes one gasket for all of the big blocks (400-430-455) any chance the heads were not torqued correctly? did you have the heads checked for cracks?
Bob Gibbs
well this 455 has the heads already on it,and i researched felpro head gaskets which are correct,now i am thinking they did not use sealer around the coolant passages.you need sealer on those passages right?looks like they just used a clean gasket no sealer, no rtv squishing-out telltale signs. could just be incorrect torque?pulling heads off soon.
Head gaskets go on dry with no sealer. try retorqing the heads although if it were me i would disassemble the engine to inspect it. it would be worth the cost of a new gasket set just to know whats inside and make sure it's correct
Bob Gibbs
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