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Oldsmobile FAQ's

The majority of the questions I get are from people who want to know which Heads, Blocks and Crankshafts are the best candidates for a performance/race engine. I will try to answer the most Frequently Asked Questions I have been asked below.


The Best Big Block Heads:

Batten heads are the best all out racing heads that you could put on a production or NASCAR block Oldsmobile. The stage 3 heads are the best, you can tell a stage 3 from the previous versions by looking at the rocker mounts, stage 3 has a solid pad and the others don't. Finding Batten heads and Edelbrock intake is almost impossible nowadays.

Wensler heads designed by John Stolpa at are almost as good as the 40 year old Batten heads. They are basically a small block ford windsor head on the intake side and an Oldsmobile head on the exhaust side. Requires a specific intake made by RRP. The best part about the Wensler heads and intake, they are available and ready for shipping.

Edelbrock Performer RPM heads are a great head for the street and can be ported for all out racing. The redesigned exhaust ports has eliminated the dead spot found in Oldsmobile's production heads by raising the exhaust ports floor. But in stock form these heads only flow slightly better than a stock factory C head which has disappointed a lot customers. But after extensive porting these heads can be made to make massive HP and torque figures. Edelbrock is now doing limited runs on their heads without the pushrod holes, so you can move them outward to eliminate the pinch area in the ports, which allows experienced head porters to widen the port and pick up some cfm. Contact aftermarket Oldsmobile suppliers if you are interested.

The best Oldsmobile production heads for racing are the C, D, E, F, G and Ga Heads because of their high nickel content. The D heads are probably the best but C heads are the most popular and plentiful as the D heads are rare and sell for as much as the Eldebrock heads.

The Best Small Block Heads:

The best heads for a Small Block race motor is the same as the Big Block. Batten followed by Wensler and then Edelbrock Performer RPM heads and then the C, D, E, F, G and Ga heads. Then comes the small block heads #1 through #7a. You can have the larger valves installed and you can even open up the intake ports on the small blcok heads to just as large as the Big block heads for increased flow but it will take alot of time and effort to do so.

The Best Big Block Blocks:

1968-1972 455 Blocks cast #396021F which is located in front of the intake manifold and right behind the oil filler tube. The F Block are the most desirable blocks and the one's with F1 & F2 are great substitutes. To locate the F1 & F2 casting numbers look under the transmission flange at the back of the block behind the flex plate or flywheel. These blocks have a high nickel content and thick cylinder walls and some will go .125 over. Sonic test all 68-72 blocks if boring more than .060 over.

65-67 425 Blocks are good blocks too. Most came with 39 degree lifter bank angle and .921" diameter lifter bores. Some of 1967 425 Blocks were produced with the .841 diameter lifter bore and 39 degree lifter bank angle, but most of the 39 degree lifter bank 425's came with the .921" diameter lifter bores which requires a harder to find lifter but have advantages over the smaller diameter lifter bore engines.

The Best Small Block Blocks:

Back when Oldsmobile was competing in NASCAR they basically made a few changes to the D block casting molds and did a limited run on what known as the NASCAR block. They featured 2.5 inch diameter mains and they also had the the preferred .841 diameter lifter bores. Finding one of these blocks is very unlikely.

The 80-81 D block and 1981-1984 350DX Diesel Blocks is the best foundation for an all out competition small block Oldsmobile. These blocks can be bored to 4.250 with sonic testing. With aftermarket crankshafts by Moldex and few others you can achieve up to 450 cubic inches. This is the block you want to use if your want to build a 950HP Nitrous or 1500 HP turbo small block Oldsmobile.

1968-1973 Blocks cast #395558 which is located in front of the intake manifold and just behind the oil filler tube. These are the most desirable of all the gas small blocks because they have a high nickel content and can be bored to 4.185" with sonic testing. These blocks have a solid main web unlike the windowed mains found on the 1976 and later 350's and 403 blocks but not as solid as the diesel and NASCAR blocks.

The Best Big Block Crankshafts:

Crankshaft manufactured by Moldex or Callie are the Ultimate Cranks to use in a max effort all out race motor. But unfortunately these cranks are Ultra expensive, so unless you have a sponsor with deep pockets lets look at what crankshafts you can use that Oldsmobile manufactured.

1968 Forged steel crankshaft, they came in 68 Toranodo's and 69 Hurst/olds and even in some 68-69  2 bbl 455's. They are easy to spot by the wide forging mark on the front throw or look for the crank forging # 400943 which is located on rear throw.

1965-1967 425 Forged steel crankshafts with forging number #384722 are a great substitutes for the ultra rare forged steel 455 cranks. You can use it as is with it's 3.975" strokE and build a stout 425 or .030 over 430ci or a .0125 over 452 Big Block. But if you want you can have this cranks journals welded up and then off set ground to a 4.25" stroke and presto you'll have a forged steel 455 crank. But of course you'll have to use the 425/330 flex plate or flywheel.

1969-1972 Nodular Iron crank is the next best crank to use. It's casting number is # 397363 and are easy to spot with that big N stamped on the front throw. These cranks have proven to be good to 6000 plus rpm's and are just fine for anything short of a full on competition motor. Avoid the cranks with the same casting number #397363 but lack the N on the front counterweight.

The Best Small Block Crankshafts:

As mentioned before crankshafts manufactured by Moldex or Callie would be the Ultimate in a max effort all out small block race motor.

1965-67 Forged steel 330 crankshafts. Easy to spot this crank with the wide forging mark on the front counterweight. You'll have to use the early 425/330 flex plate or flywheel. You could have the journals off set ground for over a 3 1/2 inch stroke and with a block that can be bored up to a 4.125 that gives you alot of options as far the different piston and rod combos that could be used to make one stout stroker small block.

1968-1972 Nodular Iron crankshafts. These too are easy to spot with the big N cast onto the front counterweight. These cranks if properly prepped can take alot of abuse.


Copyright 9/06/2000 by Bruce Cissell. All Right Reserved


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