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View Full Version : Chevy head id?


godtool
05-31-2006, 08:59 PM
The head# is 462624. How can a person tell the size of the valves without taking the head off? Maybe they are 2.02\1.6" valves? The engine block is "txb" which is a mid 70's 350. The guy built the engine, but how do I know if its a good engine? I'm doin a compression test on it this week, 150 psi all around is best right?

sparky
05-31-2006, 09:02 PM
they are 1.94/1.50 heads nothing special and yes 150 psi is good reading to have....[cheers]

pumpkin
05-31-2006, 09:15 PM
Being 462's they could be either or I have a set of 462's with 2.02's and a set with 1.96's. As far as comresion preasure you want it even. A good engine with , say 90 psi might just have a big ass cam. 150 psi is the number that the auto wreckers have come up with as the mint number.[cheers]

sparky
05-31-2006, 09:23 PM
ur 2.02 must have been 1.94 then hogged out to 2.02s......:confused:

and i have a cam in my smc with a 488 lift and i have 140 all the way across and i or does i have to do with the overlap and duration #s too.....???????

caveman
05-31-2006, 09:47 PM
when people say they have 462 or 461 etc they are ref. to the last 3 digits.

caveman
05-31-2006, 09:55 PM
casting# 462624 1975 - 1986, 76cc, this casting was used for the following
1.72/1.5 or 1.94/1.5 and 2.02/1.6 so it could have any of these combos.

pumpkin
05-31-2006, 10:04 PM
ur 2.02 must have been 1.94 then hogged out to 2.02s......:confused:

and i have a cam in my smc with a 488 lift and i have 140 all the way across and i or does i have to do with the overlap and duration #s too.....???????

Duration and overlap is the main factor in cranking cylinder compresion. Since a compresoin test is done at a slow rpm the actual psi can give you an idea of the cam profile. !80 psi would be lotsa bottom end, while the other end I've had a new stock car engine that had 80 psi, and didn't do shit till 5000 rpm.

kootenaycat
05-31-2006, 10:56 PM
Weren't those really prone to cracking? 624 sounds familiar. If it doesn't overheat, then don't worry about it, but if it does, have a block test done.

Truckstuff
06-01-2006, 04:45 AM
Engine Block TXB = 1975 - 1977, 350, Conv. Cab, LS9, 165Hp, 4bbl, C20 to 3500.

Head 462624 = 1979 - 1985, 350, 1.94/1.5

godtool
06-01-2006, 06:53 AM
Thanks for all the info.:D

kootenaycat
06-01-2006, 09:30 PM
http://www.mortec.com/

Pretty good source for GM casting numbers SB and BB

godtool
06-02-2006, 06:22 AM
Did test yesterday. All plugs black so I guess valve seals gone. All cylinders 75 psi except 3, and 5 that seem to be around 65. Better to fix my 305 that has a low #8 cylinder rather re&re both engines, then try to use this low compression 350. Would a 350 with this type of compression pass air care? This 350 is probably ready for a rebuild that I can't afford right today. I guess I could offer the guy $50 for it?

My 305 in my truck right now has good compression except for #8 that has 50 psi. Maybe my time is better spent pulling the head. I'll continue to look for another 350.

caveman
06-02-2006, 05:15 PM
did you do a wet test on the dead cyl on your 305?

kootenaycat
06-02-2006, 09:57 PM
Did test yesterday. All plugs black so I guess valve seals gone. All cylinders 75 psi except 3, and 5 that seem to be around 65. Better to fix my 305 that has a low #8 cylinder rather re&re both engines, then try to use this low compression 350. Would a 350 with this type of compression pass air care? This 350 is probably ready for a rebuild that I can't afford right today. I guess I could offer the guy $50 for it?

My 305 in my truck right now has good compression except for #8 that has 50 psi. Maybe my time is better spent pulling the head. I'll continue to look for another 350.

Black plugs with no fouling may be just running rich. If they are carbon fouled, then I'd say it's burning oil. 75psi? Not too good! Did you hear it running? If not, I'd check your tester, even a worn 350 should have 100psi.

As for the 305, do a wet test as Caveman said, then do a leak down to see where it's going. Could be a cracked ring (doubtful) or a burnt or too tight valve.

shockless
06-02-2006, 10:01 PM
yep wet test, or leakdown if you can, you can tell how an engine is inside nowadays wuithout even pulling it apart

Cadillacburb
06-04-2006, 02:22 PM
yep wet test, or leakdown if you can, you can tell how an engine is inside nowadays wuithout even pulling it apart


:confused: :confused: :confused: NOWADAYS???

godtool
06-07-2006, 02:47 PM
Wet test asap, be nice if its just too tight a valve. Hope to do it soon.

As for the 350, it ran ok, 20 hg when I vacuum tested it. The needle on the "snap-on" vacuum gauge did not move a hair. It held a very steady 20 hg at idle. Maybe I'll try another compression tester.