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chuck here 50 sumtin year old from san jose california
own two 79 trans am with 403 olds
73 cutlas with rocket 350 POP O was original owner from stratford CT my high school car which smoked many mustangs and camaros in my neighborhood
Ive heard that w31 crank can be used for 403 can anyone verify this rumor as urban legend or reality?
I want it to be true in my head because both olds small blocks .... but cant seem to find specs on w31 crank i.e journal size(main and rod),stroke etc. other than its forged crank
Thanks
Last edited by silverbird; August 15th, 2019 at 05:47 PM.
All small block olds (260, 307, 330, 350, 403) have the same stroke (3.385").
The issue that you would run into is that you would need to have the crank balanced, and a W31crank is iron just like the 403.
If you want a better crank you need to find a 330 crank and flex plate (different bolt pattern) as they are steel vs iron.
Every single small block gasoline-powered Olds motor uses the same 3.385" stroke and the same main and rod bearing diameters. All small block cranks from 1964 to 1990 interchange, other than balancing for different piston weights. The problem is that there is no real difference between a "W31" crank and the one already in your 403. Both are cast. In fact, there is no difference between the cranks used in the W31 motors and the cranks used in any other 350 Olds motor. Now, if you get the crank from a 1964-1967 Olds 330, that is forged. It still drops into a 403 (again, assuming you balance it for the 403 pistons and rods). Note the the 64-67 motors used a different crank flange bolt pattern, so you would need a flywheel that matches the crank.
I merged your identical threads. It is neither necessary nor in your best interest to post the same question in multiple forums. You'll get a better answer more quickly if all responses are kept in the same thread. This way, if incorrect info is posted, it can be caught and corrected.
I merged your identical threads. It is neither necessary nor in your best interest to post the same question in multiple forums. You'll get a better answer more quickly if all responses are kept in the same thread. This way, if incorrect info is posted, it can be caught and corrected.
I wondered why you responded a day later with the same information. Now it all becomes clear.
it was the same day?
i posted first then read closer that the newbie thread was for introductions so posted where i THOUGHT it should go but guess i was wrong.....but the show must go on ....i have found an aftermarket flywheel that fits both bolt patterns with adjustable weights but
still hunting for the perfect balancer
Last edited by silverbird; August 19th, 2019 at 09:56 PM.
well 1,300 views but no answers? I went with a dual pattern billet flexplate from junior at olds rocket parts which has moveable weights and allowed for zero balance as we are doing an internal balance spreading the weight from just the ends of the crank . https://oldsrocketparts.com/index.ph...03400425455-2/ . it does both bolt patters for oldsmobile 150 buck..... but for china a REALLY nice piece as i couldnt find anything else
Last edited by silverbird; August 25th, 2019 at 12:15 PM.
now for you 1300 lurkers.... who knows about the balancers? mine has deteriorated and the ring is loose choice #1 not sure if external balance is going to fly with machinist?
choice #2
removable weights allows for zero balance but I dont know the brand
No matter what balancer and flexplate you get, you still have to get the entire reciprocating assembly balanced. The 403 pistons and rods have different weights than the 330 parts.
yes i understand balancing the motor is the best scenario but when doing an internally balanced rotating assembly it is best to use zero balanced flex/fly wheel and harmonic balancer so that the balance is internal(lobes of the crank.....tungsten plug weights i believe) as opposed to externally balanced(flexplate/harmonic balancer). my question is does any one have experience with these brands? or know of a better choice
the rumor is you have to add weight to the 330 crank in this setup so the less weight at the ends of the crank would help in that effort
thanks
Last edited by silverbird; August 25th, 2019 at 12:51 PM.
Err.... an internally balanced setup, specifically, has neutral balanced flexplate/flywheel and balancer. Which means a balancer with a weight can't be used for an internal balance setup. Well, at least not without machining away the entire weight.
The Professional Products balancer is a decent part and has a removable weight. The base part number (non-SFI) is what I used previously. Moving up to an ATI Super Damper is always a good idea, but quite expensive.
You *can* balance a stock crankshaft for internal, but it requires quite a bit of mallory, so it'll be expensive. IMO it's not worth it on stock parts for anything near a stock build. A good standard balance is just fine.
Oh, and if you're shopping for parts, post in the parts wanted forum. The guys that stockpile (and occasionally sell) stuff will catch it there - not here.
August 6th, 2019, 07:27 PM
