66Jetstar

Hello everyone, I have a 1966 Oldsmobile Jetstar 88 and I have a couple questions on what some of my numbers might mean. First off, it has a 425 swapped in and has B heads. How good are B heads? Also, it came with a 2bbl Rochester so I bought a 4bbl intake and a 600cfm carburetor off Summit racing for it (uninstalled). Should be a good combo right? And finally, I'm trying to figure out what the gear ratio of the rear end is. Two codes on the rear end are either G286 (maybe C286) and 9783383. The last code was pretty hard to make out so it could be wrong. Thanks!

Oldsmaniac

Your rear if original should have a 2 letter code stamped on the passenger side axle housing. I am guessing it is around a 323 gear. B heads are standard 66 BB heads and are good heads. Your 425 would like a turbo 400 bolted to it, what trans do you have?

66Jetstar

I looked all over the axle but couldn't find any codes besides the two codes I found on the differential. I know they're supposed to be on the passenger's side of the axle but there was nothing, I'll go look again though. Not sure what it's tranny is, how could I check?

Oldsmaniac

The Jetstar 88 came with a small block 330 engine and most likely a 2 spd trans. The turbo 400 was an option. Your shift indicator wiith the 330 would read PRNDL while the 400 would be PRNDSL. The turbo 400 is a 3spd you would feel 2 shifts when accelerating and would have the xtra detent in the shifter. Yes there is a rear in my 67 cutlass that I cant find the letter stamp on.

66Jetstar

I'm pretty sure it just has the two-speed left in it. Would that be called the "jetaway" transmission? Is it going to make much of a difference, I know that chevy's 2- speed powerglide transmission is used for some drag cars. So 3:23 gears along with that 425 should be enough to light em up right? And finally do you think the 600 cfm carb is a good choice? Sorry for pelting you with questions, I'm really excited about this car and never get to talk to people who know anything about it

66Jetstar

I just checked and actually it is the 3-speed. I suppose its possible that the rear end could've been swapped out too?

Oldsmaniac

Yes the 2spd is a Jetaway but no relation to the chevy powerglide. Generally the 2spd is bolted to a 330 but beefier versions were used in 65 and 66 in the 442 BB. They were never used behind the larger 425 from Gm. I had used a double pumper Holley spreadbore on a 425 for years...it was great. The 600 will be fine but could be a tad larger...

66Jetstar

I'm kinda thinking about returning it for a 750

Oldsmaniac

I would say a 650 would be ideal for a relatively stock engine. The one I used had mechanical secondaries which worked fine for a smaller carb on a larger engine. Mechanical secondaries can cause bogging in an oversized carb on a small engine. If you dont already have dual exhaust on that car you need it.

66Jetstar

Yup, I'm putting dual exhaust on it in the spring. I guess I'll just stick with the 600 then

mrolds88

To check your gear ratio, block the front wheels and jack up one of the rear tires. Put the car in neutral. If the car does not have a posi, you should be able to turn the wheel. Put a jackstand under the rear axle. Now slide under and mark the inside if the tire and the pinion yoke. Now turn the wheel two revolutions and count the number of times that the yoke turns. If it turns about 3 and a quarter times, it's 3.23. I have a 64 J88 and it had 3.08's in it. I have since swapped in a 3.23 posi big car rear. Next round will be 4.10's.

66Jetstar

Thanks, I knew there was technique like that but wasn't sure exactly what to do. I'll give it a shot tomorrow

Kennybill

As I recall and this is just my opinion, the Jetstar has a different housing than the Delta/Dynamic/Starfire/98's. It's an A-body rear end but the housing is unique to just the Jetstar. The 1966 regular 88/98's use the Pontiac rear end in 1965 & 1966. Oldsmobile made their own starting in 1967. The control arms on both frame & rear end on the Jetstar are different so the other 88/98 housings won't bolt in. Around 2000 a Jetstar owner called me up looking for a complete housing. He told me about the difference in the housings and told me the Jetstar's had a bearing problem with their housings. Axle bearing would ruin the housing. This is what happened to his. I had looked and passed on a 65 Jetstar 4-door at $1000. I gave him the phone number but I don't know the outcome. I could be wrong and if I am someone will tell me. If I am right you might want to check/replace your axle bearings. Your car looks very solid. I like the 1966 B-bodies look. I have a solid 66 Dynamic convertible "buried" away in one of my buildings. It's on my bucket list, I think. Hopefully someone knows more about this. Good luck, Ken

66Jetstar

I'm not very familiar with axles and housings but I'll look into it when I get a chance. I really like the look of the 66 88's too. I just happened to find it on craigslist and had to buy it. Good luck with your dynamic 88!