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I have a 72 cutlass supreme. The motor Rocket 350 has been replaced with a remanufactured long block with #8 heads. Sooooooo What do I really have? A dog?, or a decent combo to build alittle hourse power. Whoever did the swap put a Edelbrock intake (Not sure what type) and Edelbrock carb on it (not sure of the CFM). They also put headers on it. I am doing a full frame off and this is going to be a driver/some show car. I would like to see something better than 200HP....... Am I there?
Any kind of history on heads and other add-on's for these 350's would be good to know.
Well, without knowing what type of pistons were used in the rebuild it is impossible to determine much. #8 heads with flat top pistons would yield a decent compression ratio for a performance platform, but #8 heads with "factory replacement" large dish pistons would be a disaster.
You should be able to determine which intake it is just by reading the molded in name off of it.
Note this one has Performer RPM on the #2 intake runner:
And this one has Performer 350 Olds in front of the carb flange:
Oh, FYI you posted this in the Big Block forum instead of the Small Block forum.
Last edited by Fun71; January 19th, 2016 at 03:44 PM.
It most likely pretty low compression motor. The right pistons could make it better and perhaps different heads. I'm afraid it is what it is. Just enjoy it. It beats having it in hundreds of pieces on the garage floor.
If it were me and had the cash...I would get another engine and build it for your expectations, while keeping the car currently running.
Thanks but this is a big block 350. Or is the big block section for the 455's?
I will be pulling the heads, to replace all the gaskets. I don't trust who ever built it and will see what type of pistons are in it. I'll be seeing if it really has 10,000 miles on it as was told me.
When you get the heads off, if the pistons are dished, measure the diameter and depth of the dishes, trying to be as accurate as possible. With that info we can help determine the dish volume and roughly the compression ratio.
Last edited by Fun71; January 19th, 2016 at 04:06 PM.
X2 350 is small block olds. Chances are it has deep dish pistons of they have been replaced. The #8 heads are not bad but you need flat tops and a thin head gasket to make em work.
I will also say start with another core and build it to suit your needs. keep it on the road then do the swap when its ready.
If someone could move this thread to the small block post it would be most greatfull. I am new to the forum. Thank you for letting me know!
And thanks for the info for what I have....or Don't have. When I pull the heads I'll know more of course......BUT keep the hits coming.
Thanks for moving this thread. So far this forum has treated me very well and the people I have done business with, have been fantastic! I'm looking forward to this restoration and the info I can get here.
FYI, there is no real definition of big block or small block. In the Oldsmobile community, common use among the second-gen V8s refers to the tall deck motors (400, 425, 455) as big blocks and the short deck motors (26-, 307, 330, 350, 403, diesels) as small blocks. The reality is that the first gen Olds V8s actually had three different deck heights, and no one really makes a big/small distinction with those. The big/small split really came from the Chevy-centric world, where there are two completely different engine families with few interchangeable parts. The big/small Olds motors really share the same architecture and just have different deck heights. Yeah, there are detail differences in bearing size, rod length, etc in addition to bore/stroke, but the basic architecture is common - bore spacing, cam design, cam-to-crank centerline distance, head bolt pattern, distributor, oil system etc, etc.
I have a 72 cutlass supreme. The motor Rocket 350 has been replaced with a remanufactured long block with #8 heads. Sooooooo What do I really have? A dog?, or a decent combo to build alittle hourse power. Whoever did the swap put a Edelbrock intake (Not sure what type) and Edelbrock carb on it (not sure of the CFM). They also put headers on it. I am doing a full frame off and this is going to be a driver/some show car. I would like to see something better than 200HP....... Am I there?
Any kind of history on heads and other add-on's for these 350's would be good to know.
A friend of mine bought a "remanufactured HP engine from USA " it was a 350cui, with 8 heads, flat top pistons, mild street cam and a edelbrock performer intake. I runs good but its not a hot engine mostly because the mild cam i think.
I ran 13.86 in the 1/4 mile with a 9 to 1 engine and a towing cam. Mild but reliable and fun .
Would run on 87 octane could get in it and drive anywhere and not worry.
The #8 heads flow shitty in stock form. If bowl work and a bigger intake valve wasn't installed, flow would be poor. There is ridge under the exhaust valve to remove. Other than that, the port on the #8 heads is better than the J, 3A, 4A and 5A on the exhaust side.
Don't they all in stock form? Actually I've read that 7s and 8s have flowed better than the coveted 5s in stock form! It really amazes me how much variation there seems to be with stock Olds heads in big or smallblock forms? It's my theory that the individuals that cast all of the heads over the years knew how to pour the casting right or not at all which caused the flow inconsitantsies. With today's technology this wouldn't happen but this is just my theory.
The biggest issue with the #8 heads is the large combustion chamber. They are 79 CCs. That's the same size as most BB heads. The average for earlier SB heads is 69 CCs. Any head can be ported to flow well, but you would be better off starting with #2 - #7 castings. I really don't know why people say #5s were the best SB heads. The #4 heads have identical ports with the smallest chamber for any Olds head. If you want to learn about improving your heads check out the "Home Porting Techniques" thread here - https://classicoldsmobile.com/forums...echniques.html
My 8 heads were around 77-78cc and others have found the same. With flat top pistons, maybe a .020-.030" cut and opening up the exhaust bowls will make a nice regular octane motor.
I ran 13.86 in the 1/4 mile with a 9 to 1 engine and a towing cam. Mild but reliable and fun .
Would run on 87 octane could get in it and drive anywhere and not worry.
It was a pretty basic combo . But it's all in the details I guess. Like manual steering, electric fans , electric driven water pump , good exhaust. It couldn't break into the 13's with open headers. I got it to run 13.86 once I added the x pipe. It managed that E/T with mufflers .
I am running the Stratus electric fans. Couldn't stand manual steering, probably a few tenths there. How much power does a water pump draw? What weight and what rpm did you shift at? I was auto shifting at 4500 rpm, planning on 5000 to 5500 rpm with the new shifter.
My 72 was all steel minus the interior. So probably 3600 ro 3500 with me in it. Appx. It went 13.71 with fiberglass fenders and hood. I shifted at 5000 rpm engine didn't really pull much over 5300. If I remembered right.
Edit: i may add i still had the stock rockers on this engine.
Last edited by coppercutlass; January 26th, 2016 at 06:16 PM.
Don't they all in stock form? Actually I've read that 7s and 8s have flowed better than the coveted 5s in stock form! It really amazes me how much variation there seems to be with stock Olds heads in big or smallblock forms? It's my theory that the individuals that cast all of the heads over the years knew how to pour the casting right or not at all which caused the flow inconsitantsies. With today's technology this wouldn't happen but this is just my theory.
There are actual casting differences between Olds heads. 64-69 had similar ports, 70-72 had similar ports, and 73-76 had much different ports. I never looked at ports after 76.
There are actual casting differences between Olds heads. 64-69 had similar ports, 70-72 had similar ports, and 73-76 had much different ports. I never looked at ports after 76.
You're not missing much. Copper that is 400 pounds lighter than my combo.
Last edited by olds 307 and 403; January 26th, 2016 at 06:15 PM.
Me too, mine is almost a second slower with 9.5 to 1 and a towing cam with 1.72 to 1 roller rocker arms.
Well mines a stock 72 motor. Gotta decide this winter/early spring what I'm going to. Sell the car and start over or start dropping some serious coin on it. Rebuilding a stock 72 motor to get 330/350hp isn't cost effective. Ancient tech, to get ancient results. The 12/14 mpg isn't exciting either.
That 350 i ran high 13's with was a freshened up 350 i bought from a local olds guy . It was a 73 so it had the 14 cc pistons. Then we put on my 7A 72 heads on there . it had a comp 260h with a performer intake. That engine is now in my dads pontiac bonneville and still runs great.
My advice is to look at the classifieds section and try to find good deals to keep your build cost down.
My current mill is a 355 that is running 12.6's and i spent originally 3500. But a bad cam ate the bearings and i had to replace the cam and the bearings so my total cost was 4k.
I used a swap meet bought short block that ended up being a wash but i broke even and spent the same had i started from scratch. my heads cost me 1455. that was with rockers , studs , pushrods , all that stuff , my intake was used. My short block ran me 1600 .
Exactly, check all the Olds boards, EBay etc for used parts. I picked up ported, milled, big valve #6 heads for $800 shipped. These cars are what they are, Olds was one of the best in their day for reliability and mileage.
Last edited by olds 307 and 403; January 27th, 2016 at 06:09 PM.
What I have is the Performer 350 olds intake. I need to try and find the number to the carb to see what cfm I have. It will be a couple of months before the motor is pulled and on a engine stand.
January 19th, 2016, 03:20 PM
