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Hello all,
Im wondering if someone can assist me, the oem casting numbers at the base of the cylinders/jugs, do the numbers vary from year to year? How do I know if they are a matched pair?
Thanks
Put it this way though… even the early 74” jugs are tough. I built a number of 88” 4 3/4 in stock 74 jugs all at north of 11:1 and they held together. Ok maybe they leaked here and there but let’s not speak of that.
Tip: just remove the absolute minimum from the bottom of the jug to ensure they are square. Any meat removed should always come from the top. Keep the base ear tabs as thick as you can. Also be patient and willing to get that fire ring as tight and even as possible to the fire ring spicket roof with a crushed gasket installed. Shovel hemi’s love to build up carbon between lose fire ring to spicket roof gap. This causes hot spots and leads to detonation. Try for (clay it…. A lot) an even 1 to 1.5 thou all the way around when torqued with a crushed gasket. Your chamber will burn a lot cleaner. Last tip… throw the blue paper head gaskets in the trash. Personally I wil ONLY use copper and gasanwitch. No joke, once I stopped all the James fire ring and high end nonsense and went copper, I never blew blew a head gasket again… and I’m talking Ohio to Florida straight through at 12:1 compression… dozens of motors and never a blown head gasket again.
Turn heads and jugs on a lathe.. not a mill. Maybe its voodoo but that too just always worked better for a good seal, I can’t explain why, just that it does.
Last edited by Rains2much; Sep 22, 2024 at 06:53 AM.
Great thanks, do the other identifying numbers change between years? Are any prone to failure more than others? Thanks
The heads have casting dates on the pushrod side between the fins. Easy to read with the tubes out of the way, a bit awkward on a running engine but still possible.
Put it this way though even the early 74 jugs are tough. I built a number of 88 4 3/4 in stock 74 jugs all at north of 11:1 and they held together. Ok maybe they leaked here and there but lets not speak of that.
Tip: just remove the absolute minimum from the bottom of the jug to ensure they are square. Any meat removed should always come from the top. Keep the base ear tabs as thick as you can. Also be patient and willing to get that fire ring as tight and even as possible to the fire ring spicket roof with a crushed gasket installed. Shovel hemis love to build up carbon between lose fire ring to spicket roof gap. This causes hot spots and leads to detonation. Try for (clay it . A lot) an even 1 to 1.5 thou all the way around when torqued with a crushed gasket. Your chamber will burn a lot cleaner. Last tip throw the blue paper head gaskets in the trash. Personally I wil ONLY use copper and gasanwitch. No joke, once I stopped all the James fire ring and high end nonsense and went copper, I never blew blew a head gasket again and Im talking Ohio to Florida straight through at 12:1 compression dozens of motors and never a blown head gasket again.
Turn heads and jugs on a lathe.. not a mill. Maybe its voodoo but that too just always worked better for a good seal, I cant explain why, just that it does.
Except, I never put Anything on Copper head Gaskets... Anneal, and Go..too many times blown the **** Off the Gasket...and Yes..Trued up properly..Quit having Problems, After learned..Nothing, on Head Gasket
Hello all,
Im wondering if someone can assist me, the oem casting numbers at the base of the cylinders/jugs, do the numbers vary from year to year? How do I know if they are a matched pair?
Thanks
To answer your question (not about heads), earlier stuff has casting dates like month and year, the later stuff (70's) has the Julian calendar to date code them and then they may have gone back to month year Im not sure. You didn't mention what year you were working on.
Except, I never put Anything on Copper head Gaskets... Anneal, and Go..too many times blown the **** Off the Gasket...and Yes..Trued up properly..Quit having Problems, After learned..Nothing, on Head Gasket
I didnt have such good fortune. But my builds were always big compression, lots of stroke and lots of rpm.
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