1970 olds 350 questions

[supkylesup]

Alright so my 19th birthday is coming up and I plan on taking all my birthday money and putting it towards an engine for my 1984 cutlass
One of my dads friends said he has an 1970 olds 350 for $400 bucks. Now im told its a complete engine minus the trans but its been sitting for a couple years in his garage and will most likely need somewhat of a rebuild.
So I have a couple questions about it.

1st is $400 a good price or should I take my money elsewhere?

2nd I know I read on here somewhere that the early 70's blocks are more desirable because the blocks are stronger or the compression is better but im not sure so if anyone could tell me that one that'd be great

3rd what kind of trannys will fit on the 70's 350s?

4th was the 1970's olds 350 considered a 350 rocket?

5th if it is the rocket and if it is a 70's block it should be gold and not mettalic blue or gm blue right?

That's just about everything I need to know ill probably get the casting number off it in a couple days just to make sure.
Oh and please keep in mind when answering these questions this will be my first engine swap ever. So my knowledge about it is slim but still slightly there.

Thanks -Kyle

 

[dogsht]

1. IMO $400 is probably all that its worth at least in this area. Although great lil engine in its day & generally a nice match for these cars. Certain casting numbers may make it worth more.
2. I will refer you to www.oldspower.com for correct answers and great experience/advice. 70 head & piston combo probably provided the best factory compression.
3. Several but at least th350, th400, 200-4R which would probably be your most desireable, 700-R4 which would probably take a little more work with driveshaft etc but it does provide an overdrive.
4. They were all considered a rocket by Oldsmobile. It was just a marketing term used over many years.

 

[dan2286]

I think the price is a little high. I paid $400 for a running 70 Olds 350 and a 350 trans. I might pay $2-300 at the most depending on how complete it is, like if it comes with a carb and all accessory brackets.

 

[joe_padavano]

1. IMO $400 is probably all that its worth at least in this area. Although great lil engine in its day & generally a nice match for these cars. Certain casting numbers may make it worth more.

I agree that $400 is the high end for a rebuildable core. I bought a complete, running but rusty 71 Cutlass with a 350 4bbl motor for $100. As for casting numbers, all 1969-1976 350 blocks use the same casting number. Heads vary by year, but the same casting number was used on all 350s within a given year. Even the W-31 motors used the same head castings as low compression 2bbl motors, just the valves were larger. You can machine the heads to accept the largest big block Olds valves, which is a good idea. Until the mid 1970s, Olds varied the compression ratio by changing the size of the dish in the piston. The chambers in the heads were all the same size - about 64 cc.

2. The 68-76 blocks are stronger. The 77-80 blocks have the lightweight windowed main webs. Frankly, for a moderate street motor it really doesn't matter.

3. All 1964-1990 Olds motors have the standard BOP bellhousing bolt pattern and will bolt to an trans with that pattern, which is pretty much ANY GM trans except the 700R4 or the 4L80E.

4. As noted, "rocket" was a marketing term that meant nothing. The W-31 was the high output 350 built 1968-1970. If you have to ask, it's almost certainly not a W-31.[/quote]

5. All Olds small block motors from 1964 to 1975 were gold from the factory. Corporate blue was used after that, until the 307s, which were black. Metallic blue was only used on the 1970-1974 455 motors. Of course, the motor could have been painted any color at any time by a previous owner, so paint is pretty much meaningless.

 

[dogsht]

Good info Joe. W-31 was what I was thinking. I assumed they might have a different number. Werent the W-31s like 325HP & good torque for a smallblock?

 

[joe_padavano]

Good info Joe. W-31 was what I was thinking. I assumed they might have a different number. Werent the W-31s like 325HP & good torque for a smallblock?

Yep, exactly. Same head and block castings, but big-block-sized valves and flattop pistons for 10.5:1 CR. Also a 308/308 degree cam that had previously been used in the 66-67 W-30 big block cars.

 

[bigdan]

those w31 were definitely underated ......
I had one , and was way faster then my rallye 350 rated at 325hp also ......

olds always had some pretty good cams in their HP engines .

 

[joe_padavano]

those w31 were definitely underated ......
I had one , and was way faster then my rallye 350 rated at 325hp also ......

That would be because the Rallye 350 didn't come with a 325 HP motor. There are rumors of a handful of Rallye 350 cars built with the W-31 motor (the only 325 HP small block ever built by Olds), but I've never seen proof of one. The engine in the Rallye 350 was the 310 HP 4bbl motor from the Cutlass Supreme.

The reality is that the Rallye 350 was the first "musclecar" to prioritize show over go - the relatively low HP motor in a flashy body was intended to get around the then-mounting insurance burdens of true musclecars. This is what led to screaming chicken Trans Ams and the infamous King Cobra Mustang II.

 

[bigdan]

I had the 70 rallye 350 brand new from dealer and it was rated at 325hp because of the ram air induction.the regular rocket
4 V cutlass was rated at 310 HP......

but like I said even then if it would have been 310 hp my 325 HP rated W31 was way faster .....
at least 1 second of in the 1/4 mile

with the 308 dur/ over 230 [email protected] valve lift .... compared to the regular around 190 dur @.050

no doubt that the w31 was underated at 325 HP it must have been around 360 ....

when I use to race my W30 ,nhra rated the 70 W30 at 425 HP .....for the same reasons ( insurance )

 

[joe_padavano]

I had the 70 rallye 350 brand new from dealer and it was rated at 325hp because of the ram air induction.

Funny, that would be news to anyone else who owns a Rallye 350. It would also be news to Oldsmobile.