19cutlass71supreme

Hello all, it's been a while since I've been on here. Last time I was working on something, I was trying to build a high performance 350. Well between getting screwed by the machine shop, deployments and transition back to the civilian world, I'm finally ready to start working on my project again.

This time, I got a 77-80 olds 350, complete as in straight out of the car. I also still have my 71 block and heads.

I'm using my gi bill now to go to auto tech school so I'll be using this engine set up to work on. I'm not trying to build a serious high performance engine this time but I want to beef this one up as I build it. I'm thinking to maybe get it bored and definitely new cam and valve train, intake and carb

My question is, can u use the 71 heads on the later model engine? Or is it best, to transfer the internals to the 71 block and work on the top end? Another questions I have, or more like a problem of understanding is, I want to put the best cam possible without going so far that I need to do extra machine work to the heads. Can anyone tell me what the best cam would be? I'm hoping to pull 300+ hp just the motor alone using stock internals with the exception of maybe new flat top pistons. And also, what valves, Springs roller rocker arms etc would go best with the cam.

Any help is much appreciated, years back, a member named copper cutlass helped me a whole bunch but this time I have a different approach. I'd like it to be as fast as possible but I don't have the funds to do it all as in better Trans, rear end etc, so I'll just start with the motor first

Thanks all

oddball

Cam recommendation is a fine art. Folks will want to know your entire driveline - rear end type and ratio, type of tires, transmission, what it's going into, and what you want to do with it (daily driver, street/strip, brag at shows, etc)

Take all the parts to the machine shop (hopefully a new one) and let them pick the best. The older heads are almost certainly better. I'd let the machinist pick the block, crank and rods.

If I was doing it all over again (been through 3 major builds and ~6 minor builds in the past 15 years), here's my priority list for a 350 driver with an auto going into a heavy car with 2.73 gears. Note that everyone's list is different. Just stop when the money runs out:

Good rebuild components, including true roller timing chain, neoprene rear seal, 350 diesel oil pan gasket, multi-layer alum exhaust gaskets
Good carb
Bore and pistons if necessary, just stick with regular stock replacement
Cam(*)/lifters/custom length pushrods/Comp roller-tip rocker kit (throw away the comp pushrods!!!)
Valve springs, retainers, locks
Grind out exhaust AIR bump
Balance rotating assembly
zero deck block (can be higher or lower on the list, depending on where the pistons actually end up in the hole)
Performer RPM intake
2.5" dual exhaust
headers
fill heat crossover


For the cam, there's tons of choices and they're mostly personal. I'd say stick with something in the 205 to 215 duration on intake and 215 to 225 on exhaust. Olds heads don't flow terribly well, so they tend to benefit from more exhaust duration. I have a personal vendetta against Comp, but several folks really like them. My current preference is Lunati and I'm running a Voodoo grind. Cutlassefi is an Erson dealer and will offer up some ideas for different grinds. Shop around and look for the grinds that are street/strip, 1500 to 5000 RPM range style.

19cutlass71supreme

That's some awesome advice, thank you. For now, I'm gonna put the set up in an 84 cutlass then when money comes in, I'm gonna put performance heads and swap it into a 71. The 71 is waiting for parts and body work. The 84 is 100% stock with the 307. I going to build up the rear with limited slip and 3.56 or 3.73 and another thing I forgot to mention, I'd like to stick with the stock overdrive Trans because it's been rebuilt recently with new torque converter but if I have to use my 350trans with better converter for the new cam, I will

joe_padavano

Yes, the early heads will bolt to the later block, but you'll need to open up the head bolt holes as the early blocks have 7/16" head bolts and the later ones use 1/2". Of course, the 71 block is a solid main web and the later one is a lightweight windowed main web, so I'd use the early block.

19cutlass71supreme

Thanks for the tip, can I use the crank and rods from the 77-80 block in the 71 block?

19cutlass71supreme

Thanks for the tip, can I use the crank and rods from the 77-80 block in the 71 block?

Fun71

Be aware that "regular stock replacement" means huge 24cc dishes and .020" or more short on compression height, which will likely result in high 7.xx:1 compression ratio. Great for a DD with an extremely mild cam running 87 octane fuel, but nowhere near what will be needed for this:
And about those "performance heads" - the only ones out there are aluminum heads made for big blocks, so if that is really in your future you need to ensure the engine build will accommodate them.

If you are looking for performance, i would recommend you do your homework and plan the build to have around 9-9.5:1 compression ratio with the heads you will end up with. If you aren't going all-out, the 71 heads should be OK and can be made much better with larger valves and slight machine work.

joe_padavano

Yes, but see the post above about CR.

olds 307 and 403

If they are factory original parts and the 71 block isn't worn out, you will gain some compression. I would buy the .028" head gaskets from Rocket Racing, will put you around 8.6 to 1 or slightly less. This allows for a nice cam upgrade from Cutlassefi, use the Cloyes 9 way billet timing set and consider degreeing it in.

19cutlass71supreme

Thank you, I will definitely look into that

oddball

Joe, good point on the head bolts, I forgot about that late year change. Thankfully it's an easy fix and pretty obvious when doing assembly.

Also good point on the pistons. I was thinking the "stock-style" flat tops or shallow dish. Really just focusing on a common availability, cheap piston like a speed pro cast for this type of build - not a custom or fancy piece that is more expensive, but appropriate for a different type of build.

OP, with a 3.X rear gear, you can go a little more aggressive on the cam. In my experience, it gets difficult to keep a tame low RPM idle with more than 215/220 degree duration (@0.050") cam in a 350. YMMV.

1BOSS83

I started with similar build goals and was on a tight budget. Some thoughts:
- I always get right to the point and ask this but what is your budget?
-Replace the pistons if only for the fact that you have so many more options and speed pros are 400 bucks to your front door.
-Get a customer ground cam. As stated Mark R can get you the best overall performing piece. By the time I learned that I had already ordered the comp (for the record I've had no performance issues with comp).
-Begin with the end in mind in terms of the total build. Don't build the motor with what you current situation is w/ trans, gear etc. It's more economical to build the motor for what your eventual gear changes may be IMO.


Thank you for your service,

80 Rocket

pm me