blee49

I recently purchased a 1953 Chevy pickup with a 1970 350 engine with a matching numbers th400 trans. Block casting #385558 2, engine pad #30M372264 , trans 30M372264 and casting #8 on head (don't think the heads are original. What model oldsmobile had that combo ? Check the photos

tru-blue 442

Welcome. I must say I have never heard of a 400 turbo behind a 350.
There are the numbers though, cool. Maybe a motor home? I have never
seen that type of cap for the oil fill either. Others will chime in.

olds 307 and 403

Chances are it is a 73-76 Olds 350. If it was originally mated to the TH400, probably from a big car. That block casting # was used through 76. Good motor but is factory low compression with a tiny cam.

joe_padavano

That's likely not a TH400, but a TH375. Basically it's a light-duty version of the TH400, used behind the small block in heavy cars. The output shaft is the smaller diameter shaft used on the TH350, for example. Probably a long-tail trans. This combo could have come from a Delta 88 or Vista Cruiser. By the way, the VIN derivative proves that the block is from a 1970, not a 73-76 car. If the heads are original, they would be #6 castings.

pherbicide

The '69 350 I picked up a few months ago that came out of a Delta 88 has #8 heads, and I'm 98% sure they're original. It was also matched to a long tail trans.

https://i.imgur.com/gxZDctz.jpg

joe_padavano

No. 8 heads were used for the 1973-1976 model years only. They are absolutely not "original" to a 1969 motor, as they didn't exist in 1969. Either the heads have been swapped on that block, or the whole engine was swapped. The VIN derivative stamp will tell you the model year of the block.

blee49

Just googled GM TH375 trans used in 72-74 cars my vin decodes to a 70 motor ? still a mystery....

joe_padavano

The "mystery" is that you are believing everything you read on Wikipedia.

Olds used the TH375 in heavy cars behind the 350 motor as far back as 1968. If it's a TH375, that will be cast into the tailhousing. Olds also used the TH400 in some of these applications. In any case, your engine and trans is from a heavy car, either a VC or a D88.

blee49

Joe, thanks for your knowledge, will look on tail housing for numbers, I'm identifying the trans by the pan shape.

MDchanic

TH400 & TH375 have the same pan shape and body, but different tail housings, and a few different internals.
The "TH375" will be cast into the tail housing (left side, if I recall).
More obviously (perhaps), the output shaft diameter (and yoke size) will be those of a TH350, and not those of a TH400 - if you've seen a bunch of both, the difference will be glaring.

- Eric

olds 307 and 403

I missed he had the actual year code. Strange someone swapped on #8 heads, unless they were trying to lower compression? Who knows what pistons or cam are in that motor. How does it perform?

blee49

I have not driven it very much being I only bought it 2 weeks ago. the guy I bought it from said it needed a tune up. then I test drove it and I did not get on it. I have never owned an Oldsmobile before so I did not know what to expect from a 350 engine particularly being transplanted in a 1953 Chevy pickup truck only God knows. I'm planning on doing a full tune up, convert the points with pertonix ignitor, new cap and rotor, wires, sparks plugs, and change oil, trans filter, and rear end lube. hopefully it will run better.

joe_padavano

Just so we're all clear (because even I'm getting confused by this thread), there are actually TWO different engines being discussed.

The first engine, belonging to O.P. blee49, is a 1970 Olds short block (per the VIN derivative stamp) and numbers matching TH400 (or TH375) long tail currently installed in a 1953 Chevy pickup. This engine has non-original #8 heads.

The second engine belongs to poster pherbicide and was pulled from a 1969 Delta 88, with the trans. This engine also has #8 heads but we do not yet know the year of the block from the VIN derivative.

I hate to say this, but here's a perfect example of why you are better off starting your own thread instead of hijacking someone else's thread.

pherbicide

Completely understood, I wasn't trying to hijack, I was trying to contribute because I thought I had stock '69 heads on my engine. I wasn't trying to hijack, just contribute.

Octania

Well, embrace that 2% then.
'69 engines came wearing #5 heads; #8 were 73-76 only.


OP: Maybe you misread the heads' "6" as an "8"
try the heads' 6-digit casting number, often around the center lower rocker cover bolt.
6 = 403859
8 = 411929

joe_padavano

I'm thinking not...