Has anyone built a 350 oldsmobile approx 300-350hp?

[drifter]

I have a customer that wants to build his 350 olds up he wants it for a street car with the stock #7 cast iron heads & to run on pump gas.It also has power brakes and he is trying to get close to 350hp i see these are real low comp engines what pistons are you guys using to get around 9-1 he is also using a 650 holley carb & headers

[Wolfplace]

I have a customer that wants to build his 350 olds up he wants it for a street car with the stock #7 cast iron heads & to run on pump gas.It also has power brakes and he is trying to get close to 350hp i see these are real low comp engines what pistons are you guys using to get around 9-1 he is also using a 650 holley carb & headers

=
Probe has a very nice flat top for these, just did one but it was not dynoed.
If you are not a Probe dealer I would be happy to help you.

[FEnut]

I am not sure if these are available at this time, but here goes. SpeedPro L2321F dished piston for ~ 9.5:1 compression ratio with 64 cc head. SpeedPro L2320F flat top piston just over 10:1 compression w/ 64cc head. Both rated with a .025" deck clearance.
That #7 head was available with small and large valves, depending on the application. 1.880"/ 2.000" intake and 1.567"/ 1.625" exhaust. I believe W-31 engines had the larger valve option.The SBO castings are quite choked up as cast, but respond well with bowl /SSR work , some reshaping and a real valve seat profile.
Hope this helps.

[Baprace]

I have done a couple of 403 Olds engines that ran quite well with the lower compression pistons, cam was a little tricky as the fulcrums on the rockers are not really set up for High Perf, it did repond very well to opening up a stock Qjet carb intake, I made it a double plane but removed the material from one bore to another.

[gmrocket]

I am not sure if these are available at this time, but here goes. SpeedPro L2321F dished piston for ~ 9.5:1 compression ratio with 64 cc head. SpeedPro L2320F flat top piston just over 10:1 compression w/ 64cc head. Both rated with a .025" deck clearance.
That #7 head was available with small and large valves, depending on the application. 1.880"/ 2.000" intake and 1.567"/ 1.625" exhaust. I believe W-31 engines had the larger valve option.The SBO castings are quite choked up as cast, but respond well with bowl /SSR work , some reshaping and a real valve seat profile.
Hope this helps.

the #7 head only came with one of two size intakes,,early 71(#7)&72(#7a(thats small "a") heads got the 1.875&the the late #7A, 1985 got a 1.750.
the early heads with the 1.875 intake and 9.5:1 is an easy 350 hp with the right cam&performer rpm. cast pistons are fine for this, just make sure you get the comp ratio correct as the comp heights can be shorter than the factory spec.

[racerguy]

Bob dennis =shorter alabama super stock #1 Qualifer most of the time all olds motor guy

[drifter]

has anyone built one using cast dish pistons and get around 350 hp can you just zero deck the block and take some off of the heads or would it take to much milling

[Chris29]

i've built a few,probe does have a nice piston for them that works well,mondello stocks them as well.The speed pro piston is getting hard to get thats why we switched to probe.

[ClassicComp]

I had built a 403 and used 6.125 sbc rods and milled the piston deck to achieve a 0 deck w/no dish.
The crank journals had to be ground to fit the sbc rod.

[drifter]

Has anyone tried a 455 piston would it stick out past the deck i found one thats a 1.720 ch

[Wolfplace]

Has anyone tried a 455 piston would it stick out past the deck i found one thats a 1.720 ch

.100 taller,, yea I think it might be a little proud
Nominal deck is 9.330, rod is 6", stroke is 3.385
If you did not deck it at all you would be about 80 thou out

I don't understand why you are making this difficult,, it a pretty straight forward build with a very nice reasonably priced forged piston.

[Keith Morganstein]

I don't understand why you are making this difficult,, it a pretty straight forward build with a very nice reasonably priced forged piston.

Looking for a cast or hyper piston perhaps?

Pontiac 428 piston would fit the general parameters. STD would be .063" over. Not sure about the valve reliefs though.

[drifter]

The owner just wants a mild street engine if possible i don't think he needs a forged set of pistons to make 325-350hp but if there is no other way to get the comp around 9 1/4-1 without milling the heck out of the block & heads we will have to go that route

[Dodge Freak]

Really the 403 block is the way to go, only thing needs to be done to use the much better old 350 heads is to drill the head bolt holes out to 1/2 inch.

It look just like a 350 motor but have 50 CI more.

I was in to those Olds motors at one time and my shop teacher did that to his Olds Cutlass car. Work very nice and he had 350 stickers on the air cleaner

[Baprace]

drifter , the Olds 403 is still a small block in all dimensions and all of the brackets will fit. that would be my first choice. Give Johnny a call , he can tell you what we did and it was pretty fast in my opinion, some porkchop with a Corvette in the other lane at the 1/4 didn't think so