71CutlassS MN

I'm rebuilding a 350 rocket for my 71 Cutlass S and was hoping I could get some suggestions on parts... I'm looking for a complete kit pistons, rings, gaskets etc. Who do you guys use (summit, Jegs. etc.) when buying engine parts? Also, I am looking to boost the performance of the 350 a little. After reading a couple posts I am probably going with upgraded cam, intake, headers, carb, and valve job (will do gears too). Do you guys suggest boring out the piston cylinders or is the juice not worth the squeeze?

BillK

Whether you bore or not is going to depend on the conditions of the cylinders when you take the engine apart. Same goes for all of the other parts like grinding the crankshaft etc.

As far as parts go ask your machine shop about getting them for you. I know I can typically meet or even beat Summits prices on most of that stuff and still make a few bucks. Every little bit helps. Plus if you let your machine shop get the parts there is a good chance they will fit properly. You should never buy the parts first. Wait until everything has been checked / machined.

71CutlassS MN

Thanks Bill. Yeah, I wasn't planning on putting the cart before the horse but want to start researching parts... making a wish list. I will definitely take it apart and clean it first. Now, I just need to find a good machine shop.

Fun71

Be aware that the factory pistons for the 1971-1972 350 engines have HUGE 24cc dishes, and the aftermarket replacement pistons (especially what you will find in a "kit") not only have those HUGE dishes but the compression height is shorter as well. The results in super low compression ratio, like 7.xx:1 or so.

If you want to increase performance, you need better pistons than that. There are definitely better pistons out there, but you need to determine what your overall build will be in order to figure out the correct compression ratio.

OLDSter Ralph

Not sure where you are in MN, but you need a good machine shop/engine builder thats familiar with building an Oldsmobile engine. You'll get lots of suggestions how to spend your money. I don't much care how many Chebby or Ford engines they built "for racing". Others will chime in.
.........Just my two cents worth.

71CutlassS MN

Thanks Fun. When determining the overall build what is the order of operations that you take as an approach?

cutlassefi

First the block and heads need to checked for wear, cracks etc.
Next you need to decide what your HP expectations are as well as your available budget now that you have good parts to work with.
Then after that you can determine what oversized piston is needed. That will dictate what’s available to some degree. Once your compression ratio has been considered the appropriate cam can be chosen. After that intake and carb, but most combinations do well with an RPM intake and a 750cfm or so carb.
I've done dozens and dozens of both small and big block Olds builds with most being dynoed to verify the real power level. Let me know if I can be of help.

71CutlassS MN

Good stuff Cutlassefi! What is the max HP do you think I could get for $5000?

cutlassefi

The bulk of your costs of that will be in the heads. You MIGHT be able to squeak 400 out of it if done right.

71CutlassS MN

If the heads are in good shape, should I have them machined or buy aftermarket?

cutlassefi

Maybe this will help.
I did a project engine a couple of years ago. Here’s what was in it;
Mahle 4.100 forged piston set
ARP main bolts
Block was align honed, square decked, bored with BHJ Bor-Tru plate.
#7 Iron Heads had 2.00/1.62 valves, a fair amount of bowl work, center dividers welded, crossovers filled, milled to 65cc. I had $1400 in the heads.
Erson TQ 40 cam on a 108lsa, RPM intake, 750 Brawler carb, Dyno headers. Comp was 9.4:1.
417hp/433tq.
Hope this helps.

Rocket Launcher

^^^^^^^^^^^^^^^^^^^^
Agree 100% with what he said. We have two nationally known NHRA Chevy racers/engine builders in my area (one is long retired now) and I wouldn't give either one any Oldsmobile engine work. Not only from my experience, but the feedback I received from others who (regrettably) had them do their Olds engines.

olds 307 and 403

The Olds 350 is a more forgiving motor to build than the BBO, smaller mains, rods and much lighter parts. One thing to let the shop know who is rebuilding your heads is center exhaust guide clearance. Unless you fill the cross over, the extra needs more clearance, around .0028' I believe. A few have had valves stick in the guides on new motors. As you can imagine, bad things happen like damaged, guides valves and pistons. I picked up a rebuilt set of heads for $400, I measured .003 to .0032 on the guides on this set of #6 heads. I measured 2.05", probably 2.072" intake valves and stock 1.56" exhaust valves with the bowls opened up. Mine also had the guide tops machined for positive oil seals. As said, figure out what bore is needed to clean up the cylinders. CutlassEFI brought an ultra modern 10cc dish forged piston from Mahle that will give perfect low to mid 9's for compression with a super low friction 1mm ring pack. You want 2"/1.625" or 2.072'/1.625" valves with the bowls opened up with a cutter at minimum. The positive seals work better for oil control and matching springs for your cam along with any worn guides replaced. Almost all the builders like slightly different oil clearances, I would think the higher end of the stock recommended clearance is best. My crank has .0025" rods and mains which some consider too tight, we will see when it goes together.

Dave26

I was in the same position as you several years ago. I had just finished the body/paint work, redone the interior, but was stuck driving a nice car with a "tired" motor. I ended up buying this engine from Mark a couple of years ago, and put it in my 72 Supreme. Aside from having twice the horsepower of my factory 350, this engine is unbelievably reliable, easy to start, runs cool, no matter the outdoor temperature, but most of all has put new life into my old car. I would encourage you to read Mark's threads on this forum..........a wealth of olds engine information.

boese1978

hi, I’m in Maplewood and had a retired machine shop guy /,builder do all of this plus head work for my build. If your interested in speaking to him let me know. I can attest to marks help and guidance, totally happy with my build and the pro comp heads. I have rear gears for you if interested.

pherbicide

Chiming in to subscribe to this thread as I am also browsing for a Olds machinist in the area.

BLUZIN

Hi guys! Following!
Also looking for a Olds guy on N.Shore of Boston. Is it worth redoing the tired 73 motor with #8 heads thats in it?? Not the original motor anyway....or grabbing a 350 with #5 heads (69? out there for $800.00 right now.) and drop it off for a complete rebuild then do a swap into a 72 Vert. Then the dual exhaust so I can hear that Olds rumble!
Thoughts?

olds 307 and 403

If you use flat top pistons and get the bowls on the heads cut with a bowl hog cutter, it every bit as good as an early motor. It will probably have a "N" crank as well vs the later light weight iron crankshaft. That 69 is overpriced unless there is receipts or it is running and you can do a compression test and put on a oil pressure gauge to see where everything is at.

BLUZIN

Thanks Olds Bro! My machine shop came across a 72/350 with 7a Heads. Correct for my ride. Looks like I'll have him do that one since its at his shop and matches my year. Just looking to see what I can improve while its on the bench! Time and money,,,,that's all we need! lol
Jack

Fun71

Get some better pistons than the huge 23cc dished ones that were in the 71-72 engines.

Double D

Following, I am in the exact same situation with a 71 Cutlass Supreme with the original 350 with #7 heads. It has just over 100,000 miles on the engine and believe it has never been touched. I am looking at pulling it as it needs gaskets etc. I am also located in the Central MN wondering if anyone has any suggestions of a reputable builder. My Buddy is a great certified mechanic and willing to do the project which I trust completely but I don't think he has a lot of experience with Old's engines. If it was a Chevrolet I would not even think twice about having him do it.

Any suggestions of a reputable builder in Central MN?

I am looking to keep it reliable with some very much needed added HP without spending a ton of cash..

Dave

Sterling71

I also am trying to rebuild my 350 Oldsmobile rocket out of my 71 Olds Cuttless S but I'm having problems finding a master rebuild kit with everything and it suggestions

Sterling71

I also am trying to do a master rebuild on my 71, Oldsmobile Cutlass S having difficulty finding a master rebuild kit with everything in it

Sterling71

need help going through the same thing trying to find a master rebuild kit for my 71 Oldsmobile Cutlass S

olds 307 and 403

It depends do you want the factory 8 to 1 compression or do you want to improve it over stock?

brownbomber77

Honestly, try Rockauto and google for a 5% coupon. Buy things individually, kind of. Factory style pistons and rings are inexpensive there, just replacement Federal Mogul or Speed Pro. Speed Pro I think still makes a flat top forged piston which will still only yield maybe 10:1 compression with replacement head gaskets. This all comes down to what you want to do with the car. Those "master" rebuild kids just come with a lot of stuff and things like pistons and bearings aren't going to be known until the machine work is done.

olds 307 and 403

Speedpro still makes a 6cc dish forged piston as well. They used to have a complete kit with the forged flat top piston. As said, until parts are measured, you won't know things like bearing undersizes. If you want about a 1 to 1 compression increase, the Mahle 10.2cc dish forrged coated 1mm ring pack pistons are a nice upgrade.