"GA" heads...
August 19th, 2018, 12:40 PM
#5
Just an Olds Guy
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G heads are 455 heads produced for 1971 Oldsmobile
GA heads are 455 heads produced for 1972 Oldsmobile
The main difference is the 71 heads have just the exhaust valve seats induction hardened, while the 72 heads have both the intake and exhaust valve seats hardened.
August 20th, 2018, 06:39 AM
#6
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After you cut for a valve job, it’s a moot point for induction hardening. If you’re really concerned about sinking valves, which you shouldn’t be on an Olds, you should cut for steel inserts
August 20th, 2018, 07:48 AM
#7
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August 20th, 2018, 08:15 AM
#8
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Not necessarily so. I had a 67 400E that my son and I drove over 70,000 miles. Tore it down for another reason and there was absolutely no valve recession. Unless you are going to drive long trips at sustained higher RPM, hardened seats are not needed. Flame at me away now.
August 26th, 2018, 11:43 AM
#9
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My #5 small block head exhaust seats look fine after who knows how many miles with California gas. The exhaust valve margins however were almost gone
Meanwhile I had a set of Chevy heads sitting in my garage with exhaust valves buried 1/8” into the exhaust seats.
Meanwhile I had a set of Chevy heads sitting in my garage with exhaust valves buried 1/8” into the exhaust seats.
January 10th, 2021, 08:18 AM
#12
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January 14th, 2021, 01:03 PM
#15
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Specifications of Olds F G Ga H J heads.
six digit number = casting #,
cc = combustion chamber
*F 404438 80cc Intake 2.072", Exhaust 1.625", 1970 455's with W-30. Large valves, 2.072 and 1.625". Maybe have hardened exhaust seats. Valve rotators on all valves, therefore deep spring seats. One center exhaust port blocked off from the intake heat crossover port for better power. 'Improved port configuration for better flow"- according to Supercars Unltd. book 442 by the Numbers. Very rare and valuable. *THE* head to get, if cost is no object, or for an investment. Watch out for an E ground to look like an F; check the 6-digit casting number and the 3 digits on the underside as well (should not be 686). Always look for the two raised ribs on the end of the head that are nearly impossible to duplicate, even with JB weld. Only F heads had these ribs, never E's.
G 409100 80cc Intake 2.000, 2.072", Exhaust 1.625" 1971 455's, except W-30 [see H]. Valves commonly 2.000 and 1.625", but Toronado and 442 heads had the larger 2.072" intakes. Common heads use valve rotators on all valves, but 442 [and Toro?] heads used rotators on exhaust valves only- according to 442 by the Numbers. Wherever rotators are used, the thick rotator/retainer required the use of a deep spring seat. Maybe hard exhaust seats. The A is like 'A'. Some are large, some are small in size.
Ga 409100 [same number as G head] 80cc Intake 2.000, 2.072", Exhaust 1.625, 1.685" 1972 455's, including W-30. Valves almost universally 2.000 and 1.625", even 442's had small intakes, if auto trans models. Even the Toronados were relegated to small intake valves this year. Only 442's with W-30 or MT had the larger 2.072" intakes. No way to tell valve size without measuring a valve. Strange combinations of exhaust valve sizes and angles, depending on application. Weird combination of valve sizes and seat angles that no other heads matched. This might make finding valves more fun, should you need them. Exhaust valve with a unique 1.685" diameter and 30 degree face. All Ga heads use valve rotators on all valves, therefore have all deep spring seats. Hard exhaust seats.
*H 409160 80cc Intake 2.072", Exhaust 1.625" 1971 455's with W-30. Large valves, 2.072 and 1.625". Valve rotators on all valves, therefore deep spring seats. Maybe have hardened exhaust seats. One center exhaust port blocked off from the intake heat crossover port for better power. 'Improved port configuration for better flow"- according to Supercars Unltd. book 442 by the Numbers. Improved *over what* they don't say. Very rare and valuable.
J 411783 80, 82cc Intake 2.000" exhaust 1.625" 1973-76 455 "smog" motors. Standard [small] valves: 2.000 and 1.625", even Toronado, 442, etc. [presumably]. Exhaust port is choked off to about 1" diameter just under the valve. No blocked heat crossover. Rotators, deep spring seats, hardened exhaust seats. Very common. Avoid.
six digit number = casting #,
cc = combustion chamber
*F 404438 80cc Intake 2.072", Exhaust 1.625", 1970 455's with W-30. Large valves, 2.072 and 1.625". Maybe have hardened exhaust seats. Valve rotators on all valves, therefore deep spring seats. One center exhaust port blocked off from the intake heat crossover port for better power. 'Improved port configuration for better flow"- according to Supercars Unltd. book 442 by the Numbers. Very rare and valuable. *THE* head to get, if cost is no object, or for an investment. Watch out for an E ground to look like an F; check the 6-digit casting number and the 3 digits on the underside as well (should not be 686). Always look for the two raised ribs on the end of the head that are nearly impossible to duplicate, even with JB weld. Only F heads had these ribs, never E's.
G 409100 80cc Intake 2.000, 2.072", Exhaust 1.625" 1971 455's, except W-30 [see H]. Valves commonly 2.000 and 1.625", but Toronado and 442 heads had the larger 2.072" intakes. Common heads use valve rotators on all valves, but 442 [and Toro?] heads used rotators on exhaust valves only- according to 442 by the Numbers. Wherever rotators are used, the thick rotator/retainer required the use of a deep spring seat. Maybe hard exhaust seats. The A is like 'A'. Some are large, some are small in size.
Ga 409100 [same number as G head] 80cc Intake 2.000, 2.072", Exhaust 1.625, 1.685" 1972 455's, including W-30. Valves almost universally 2.000 and 1.625", even 442's had small intakes, if auto trans models. Even the Toronados were relegated to small intake valves this year. Only 442's with W-30 or MT had the larger 2.072" intakes. No way to tell valve size without measuring a valve. Strange combinations of exhaust valve sizes and angles, depending on application. Weird combination of valve sizes and seat angles that no other heads matched. This might make finding valves more fun, should you need them. Exhaust valve with a unique 1.685" diameter and 30 degree face. All Ga heads use valve rotators on all valves, therefore have all deep spring seats. Hard exhaust seats.
*H 409160 80cc Intake 2.072", Exhaust 1.625" 1971 455's with W-30. Large valves, 2.072 and 1.625". Valve rotators on all valves, therefore deep spring seats. Maybe have hardened exhaust seats. One center exhaust port blocked off from the intake heat crossover port for better power. 'Improved port configuration for better flow"- according to Supercars Unltd. book 442 by the Numbers. Improved *over what* they don't say. Very rare and valuable.
J 411783 80, 82cc Intake 2.000" exhaust 1.625" 1973-76 455 "smog" motors. Standard [small] valves: 2.000 and 1.625", even Toronado, 442, etc. [presumably]. Exhaust port is choked off to about 1" diameter just under the valve. No blocked heat crossover. Rotators, deep spring seats, hardened exhaust seats. Very common. Avoid.
Last edited by oldsmobilejim; January 14th, 2021 at 01:27 PM.
January 14th, 2021, 04:24 PM
#16
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Dave - I believe you've received some excellent information, and I have followed your threads for 2+ years. Some information I recall some I'd have to research. But, let me know if I'm incorrect.
It's my understanding your car was at one time set up for the strip by a PO. If I'm not mistaken you have said your car has an over-bore, I believe your car has a modified camshaft, and I believe your car has a tricked-out (non-stock, non-OEM) rear-end, if I'm not mistaken. It doesn't matter if your car is a "U" car. That's going to tell you absolutely nothing about the size of the valves currently inside your car. The only way you're going to tell what size valves are inside your current engine is to pull the heads. So, as a follow-up to your statement/question:
It matters none. You either pull the heads to confirm or you will never know what size valves are inside your current engine. "If" your car was tricked-out for the strip, has a modified camshaft, and was bored-over - it may very well have non-stock, non-OEM valves. How bad you want to know?
It's my understanding your car was at one time set up for the strip by a PO. If I'm not mistaken you have said your car has an over-bore, I believe your car has a modified camshaft, and I believe your car has a tricked-out (non-stock, non-OEM) rear-end, if I'm not mistaken. It doesn't matter if your car is a "U" car. That's going to tell you absolutely nothing about the size of the valves currently inside your car. The only way you're going to tell what size valves are inside your current engine is to pull the heads. So, as a follow-up to your statement/question:
It matters none. You either pull the heads to confirm or you will never know what size valves are inside your current engine. "If" your car was tricked-out for the strip, has a modified camshaft, and was bored-over - it may very well have non-stock, non-OEM valves. How bad you want to know?
January 14th, 2021, 07:23 PM
#17
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I don't know what you mean by this. There are no VIN numbers on either of those, so you can't say they are "number matching" to any particular vehicle. The only parts that are "numbers matching" are the block and transmission if their VIN derivative stampings match the vehicle VIN.
January 14th, 2021, 07:56 PM
#18
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January 15th, 2021, 02:03 AM
#19
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I don't know what you mean by this. There are no VIN numbers on either of those, so you can't say they are "number matching" to any particular vehicle. The only parts that are "numbers matching" are the block and transmission if their VIN derivative stampings match the vehicle VIN.
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