I pulled the motor out of my 91 Z and the 350 needs to be rebuilt. I have a LT4 Hot Cam for it already and a set of fresh L98 heads off a Corvette. I am debating to jump into a 383 conversion. I will be spraying a 150 shot of nitrous on it also. I will port the factory intake, runners and plenum. I would love to run a 13.3 in the quarter off the bottle. Do I need a 383 to do it or can I get it with the 350. I am trying to justify the 383. I will one day put a mini-ram on the car. If any one has the recipe for running 13.3 or better let me know. I should have bought better heads but I am stuck with these. Where is the cheapest place to buy a rebuild kit for this motor. Is there a such thing as an internal balance 383 crank? Thanks, BranT

 

You can easily run 13.3 with a 350 and 150hp shot of nitrous. you'll need about 350hp to do that on street tires. I'd recomend spending that extra cheese on something else. That is unless you already need a new crank or it needs to be cut down because you can find them for not to much more then a new 350 crank.

 

Well, a 383 gives you torque and power through out the powerband by fact of its greater displacement. With the cheaper 1 piece seal cranks out there now, it is a viable alternative IMO.

If you will primarily drive the car on the street, stroking allows you to use your new found power and improve driveability. With a 350, you generally have to put in a bigger cam to attain the same power levels as a 383, but often at the expense of low end torque and driveability. Lastly, a 383's larger displacement makes a cam that is a bit "wild" on a 350 appear more docile due again to the 383's larger displacement.

GM thought the 383 "idea" was so good, that they even offer a 383 crate motor for "truck replacements".

 

Just get a good nitrous kit like the nos #5151 plate kit not a p.o.s. single fogger nozzle kit. Than just hook-up the car and you can run very high 11s with the 350 or faster with the 383.

My 12.4 run is on a factory stock 100k old motor that has never had the intake base or valve covers off with a #5151 kit.

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92 Z28 5.7 TPI AUTO 105k factory motor and trans.

SLP headers and runners, B&M 2400 stall, shift kit,LCA brackets, EBACH spring kit, NITTO'S, NOS

best 60ft 1.87 1/4 12.48 @ 110.81

 

If you want cost effectiveness, there is no way to bear a 350 rebuild. You can do it sometimes for under $600, including machine work. However, I'm very sold on the 383 concept, especially when teamed up with a good breathing intake, heads, and cam. If your even thinking about keeping the stock intake, your 383 will be a blast to drive from 1200RPM-3800RPM, but it will lay down after about 4200RPM. A miniram 383 would be impressive. Most people here do not like the edelbrock performer RPM cam I ntoiced, because of it's old design and large duration, but none the less, you should be able to find a similar roller cam (With even more lift perhaps), which would allow you to produce massive power from about 4k-6.5K on a 350, or 3.7k-6.3k on a 383. Also, your other alternative might be a long rod 350? Just a thought.

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86 IROC-Z, Retired for winter, weird oil leak (drains out in about 3 minutes), new 355 other than that, TPI, 700R4, edelbrock headers, removed AC/Air pump, heater plate conversion - no heater (loL). 14.8@90MPH

Next project (think I'm going to scrap the IROC)- mid 80's monte carlo, 383, edelbrock performer RPM intake, cam, holley double pumper carb, sportsman 2 heads, NOS. Hoping mid/high 12's on motor, mid 11's on spray.

 

IMO I would perfer the 377. Its a 400 block with a 350 crank. If you know where to go you can usually pick up the 400 bare block pretty cheap. 100 - 200 dollars. You can use all the parts off your 350 for the rebuild. All you need is bearing spacers to fit the crank in. Its probally a lot cheaper than going the 383 route because of the machine work needed to make the 400 crank clear the 350 block. Plus the 377 will wind up a lot faster. But this is just IMO

 

first off, a 377 is a great motor for a lighter car (my friend has one in a 65 nova runs mid-low 11's easily). Problem is we are running 3500lb cars so it needs the torque to get it going. That's where a 383 comes in. If all you want is a n/a 13.3, don't waste the money on the 383. My 350 went 13.2's in 100 degree heat at 1300 feet elevation with crappy heads in a 3695lb car. building a 383 with the stock intake and unported heads won't help you. You'll need a better intake and have the heads ported. I read somewhere that a 383 truly needs a minimum of a 2.08 intake valve to reach full potential but I don't see many people doing that so I'm not sure what is the truth. I personally am awaiting the funds to get a set of ported 210 AFR's and install a superram to my 383. I will then save for upgraded injectors, FP performance DFI and a big spray but that could be many years down the road. right now I have too many other projects to make that happen so my 383 is being starved for air, not to mention the tranny blew so I'm running a weak tranny and just drive the car every couple months to keep everything going. I'd suggest using your 350, buy a good crank, lightweight rods, SRP flat top pistons, ported intake and plenum with high flow runners, injectors and fuel pump and run the heads and cam you have. You should run 13 flats with no problem and probably near the 11's with spray. don't skimp on pistons with spray. My friend had been running TRW's in his 78 trans am since it was new and would burn a piston about twice a year. He switched to Ross pistons a couple years ago and hasn't replaced a piston because of nitrous burn since. Wiseco, SRP, and Ross make some very good pistons and I'm sure there are a couple others out there I can't think of off the top of my head. make sure and have the engine internally balanced and use a lightweight balancer. This will not only increase power but add life to the engine. have fun

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Kyle Osterholt
Okarche, Oklahoma
ASE Master Certified
86 T/A 383 TPI
89 TTA #1002 T-top/Leather
89 TTA #1358 Hardtop/Leather
80 T/A Pace Car
73 Opel GT