turley68delta88

Wanted to ask a restoration question and then a modification question. I have an automatic and when my car tries to change gears when accelerating it screeches and then slams the gear sometimes even very late just wondering what that could be if anyone could help me out on that??? Also, after I get that fixed I want to start making upgrades as far as performance and thought I'd start with a Holley 4 bbl vacuum secondary single inlet carb, a new summit racing header-back dual exhaust system, and new headers, but not sure which ones I should get. Hedmen Hedders seem to have quality headers for a fair price but any advice would be greatly appreciated and this car would only be for street use I just wanted to add some more horsepower to my Oldsmobile and get it running better

joe_padavano

The first question is, what trans do you have in your 68 - TH400 or Jetaway?

As for the mods, no one makes headers that will fit the 1965-70 Delta 88s. They have a unique rear steer configuration and there isn't room for headers. You won't really be able to run dual exhaust on your 350. These cars require a unique exhaust manifold on the driver's side to clear the steering box and starter. Unfortunately, the 1965-70 D88 was never offered with dual exhaust on the small block. so that manifold (which is available as a repro) was only offered for the big block. I recently installed one on my 67 D88, and the configuration MAY fit an SBO, but no guarantees.

A properly rebuilt Qjet will perform better than any Holley, especially on a heavy car like a D88 with a small block. I wouldn't waste my time or money on a different carb. Start by getting your stock configuration properly tuned up and fix any maintenance issues and THEN worry about mods.

turley68delta88

thanks for the response, I know it has a newly rebuilt trans but I don't know exactly what it is, also currently it does have a dual exhaust system set up and I have had problems with it there was an exhaust leak and I got that fixed but it still makes a clicking noise after driving it for a while, and I did find out that the exhaust had been rubbing on the drive shaft so I'll just go with the single exhaust and have the carb rebuilt, thank you very much!

joe_padavano

I'm curious as to how the driver's side pipe was routed. My 67 had a custom bent dual exhaust system when I got it, using the single exhaust manifold on the driver's side. The pipe was flattened to almost nothing to get it past the starter and steering linkage. That's why I swapped to the correct exhaust manifold and new pipes.

turley68delta88

Mine is custom as well I believe I just looked at it and it goes up and over the the rear axle shaft

oldcutlass

For your shifting problem, check the vacuum line to the modulator for damage and make sure its hooked to manifold vacuum and that vacuum is present at the trans.

turley68delta88

Okay thank you! I'll check that tomorrow when I have time👍

turley68delta88

also I was wondering what a good website I could use to check my vin I've had no luck so far

joe_padavano

I'm talking about where it connects to the exhaust manifold at the engine.

joe_padavano

What do you want to check it for? None of the Carfax-type sites will take a VIN this old that only has 13 digits. If you just want to decode it, post it here. There is very little info in the VIN - it's all what you can see by looking at the car. All it will tell you is that it's an Oldsmobile, the specific model and body style, the year, and the assembly plant.

turley68delta88

What I could see was it goes around my oil filter and under the oil pan and straight up into the manifold and okay I won't get the vin checked then if there's no need thank you👍

turley68delta88

The passenger side exhaust pipe just goes straight up into the manifold

joe_padavano

So the DRIVER'S side exhaust pipe runs under the oil pan and down the PASSENGER side of the car???

turley68delta88

Yeah it does and I thought the engine was a 350 because when I took the car to a mechanic recently I had told him it was a 455 but when he inspected the car he told me it was a 350, but I just called my uncle who's the person that sold the car to me and he said it's the original 455 so that must be why it fits like that

turley68delta88

[QUOTE=turley68delta88;970236]Yeah it does and I thought the engine was a 350 because when I took the car to a mechanic recently I had told him it was a 455 but when he inspected the car he told me it was a 350, but I just called my uncle who's the person that sold the car to me and he said it's the original 455 so that must be why it fits like that[/
I don't know why that mechanic said it was a 350 but my uncle said its the original 455 with the original miles and I did find out it has the original 350 turbo automostic transmission I'm honestly not familiar at all really with transmissions but he said he had recently had it rebuilt before he sold it to me

svnt442

That doesn't make sense. Being a 1968 car it should have a TH400 seeing as the TH350 was not put into cars until 1969. And besides that, GM wouldn't put a TH350 behind a 455 anyhow.

joe_padavano

The block casting number above the water pump will tell you exactly what engine that is with no uncertainty.

turley68delta88

My uncle owned the car before me and he said and so I asked him what the transmission was and he said it was the 350, but wasn't sure so it probably is just the TH400

turley68delta88

Okay thank you very much!👍

turley68delta88

The number is 396021 F

turley68delta88

Wanted to know exactly what engine I have the number is 396021 F

Fun71

That is a 455.

Fun71

That is the block casting number for all 455s from 1968 through 1976.

To know exactly which 455 it is would have to be determined from the application, which in your case (if I remember your posts correctly) is a 1968 Delta 88 455-4bbl dual exhaust.

I don't have ready access to the 1968 engine specs but they are likely the same as 1969 which was 10.25:1 compression ratio, 365 hp @ 4600 RPM and 510 lb-ft @ 3000 RPM.

turley68delta88

Thank you!

turley68delta88

Okay thank you, I don't know for sure though if it is 4 bbl with that high of hp and torque ratings I thought it would be maybe the lowest with 310 hp and 490 lb-ft torque but when the car was running how it should it was suprisingly fast so I don't know

Fun71

I think the 310 / 490 engine is the low compression 2bbl version.

turley68delta88

Yeah I know I think that's what I might have, in my earlier post I just said I was thinking of putting a 4 bbl carb in there if I could but I'm just going to rebuild the carb and worry about regular maintenance for now

GoodOldsGuyDougie

This was a fun read.