Im in the process of buying a new crate 350 for my 91 RS, and was just wondering what kind of numbers I should be expecting with this swap. The engine is rated at 260 hp and 350 ft/lb torque, and I have a 2400 stall and a mild shift kit, posi, and 3:42 gears.
thanx
Alex

 

Sounds the like the budget, delivery truck, swirl port head motor. If your not changing anything with the motor, is probably not going to be very impressive. Its a good base to add your own heads/cam to. Just going in as-is with TBI on top, I'd estimate 14.8-15.0, its gonna come off the line great w/ your converter and gears - especially if you've got good tires, but petter out as the revs climb and the second half of the track will be where it'll show to be weak. Vortec heads/intake could change everything - but thats another grand from Scoggin/Dickey.

 

Well my 305 has the vortec heads so I will probably put them on the 350, with the heads what time would I be looking at?

 

That'll be a huge difference over those 76cc monsters and the lousy 8.5:1 compression. There are a few different versions of the real basic crate motor, I'm making assumptions based on the $1600 one on SDPC - that has a 195/205* duration w/ .390/.410" lift cam. That motor, with Vortec heads, might be capable of 300hp, maybe 250ish to the wheels. Probably closer to a lower 14 then.

At that point, the crate motor cam becomes the real drawback - if your on a budget SDPC has two different cams that would be a certain improvement over the factory GM cam, either the 204/214* @ .420/.443" cam (coincidently, the cam I have in my 305), or the 214/224* @ .443/.465" cam. Probably would go with the larger of the two, the smaller of the two runs very tame in my 305, I would perfer the 214/224 cam, and you've certainly got the converter for it. Either one should play nice w/ stock lift clearances of vortec heads. I bet you'd be close to 300whp.

With the vortec heads and a decent budget cam, you'd probably be able to crack off some mid 13 passes without too much trouble. I bet you'd be close to 300whp if you have some good TBI intake side components.

Have the vortec heads on your 305 been machined down to make good compression on the 305, or were they left alone? Stock they are good for a street 350, on a 305 they work better if you can get the chambers down a bit - I was curious if that had been the case with your heads. Gonna have quite a bit more compression if they were taken down to 58cc chambers, but still workable with good gas/tuning.

 

The vortec heads on the 305, were actually machined down . However, Im just wondering if I put a cam on the 350 will I have to burn a new chip, for the motor to run correctly or is a new tune required regardless with the swap? Thanx for the responses man!

 

If you want to realize your maximum power potential, you'd want to get retuned regardless. Good heads are a must, and you might as well at least get a decent cam in the motor while its new, out of the car, and easy to do.

 

Thanks for the help man, I really appreciate it.

 

Slow...I would not buy the low po crate motor. Find a 350 to rebuild, get alu heads...you will save money in the LONG run... OR buy the crate motor the way you want it...there are lots of options!

 

The reaso I'm buying this motor is because im on budget. I wish I could afford what I really want, but on this budget I really cant.

 

Then do not mess this motor up...just drop in in as is. Add bolt ons such as exh and gears Tires , glass hood, to pick up a little bit.

 

what about a vortec motor?

 

What do you mean by messing up? Would adding a mild cam hurt the motor instead of helping? As far as the bolt ons, those are the plans for the new motor and already have a fiberglass hood and 3:42 gears.


What is the diffrence of a vortec motor besides being a roller and having of course vortec heads?

 

my stock vortec motor has been 8.6 @83mph in 1/8 on shity 1.98 60ft. running rough tuned carb. all i have done to motor is put summit carb intake and 650dp. around here ill give any stock ls1 car a run for his money.......

 

To me, it sounds like you've got good heads and the matching TBI intake already, that motor would realize huge gain with any cam.

 

you can do a descent rebuild for easy with 1600$.

my dad built a 355 for his vega with 1600$ would be about (2k) if had nothing to start with.

2 bolt main block with .30 over (on car) ( can be found for 150$-200$)
RPM intake (on car) (can be found for 100$)
150$ for clean and honed
100$ for crank .10 turned
400$ for rebuild kit with 9.5-1 pistons, roller rockers, harden pushrods.
200$ for crane cam (.512 lift) and new lifters
500$ for 2.02 heads with 76cc chambers
100$ for rebuilt holly 700dp

dont know numbers. if someone can give me a estimate that would be great.

 

why would u pay $500 for 76cc heads?

 

how much are they worth?

there 2.02 by 1.60 with 76cc chambers

 

sound like smog heads to me. not worth a paper weight to me

 

how do you know that there smog heads?

can you help me out please. im cofused on what SMOG means.

thanks

(dont mean to hi jack this thread)

 

(smog) low compression heads used in the 70s. like 882 and so on... bc with the 9.5 to 1 pistons with 76cc heads ur cr will be atleast down one point so more like 8.5 to 1. sorry to hi jack too. i would of used $500 dollars on vortec heads.

 

Thanx for the help and just a little update, just ordered the engine off jegs and a 214/224* @ .443/.465" cam (thanx atc3434). Man am I excited cant wait to get my car running!!!

 

X2! those stock vortec heads will out flow the the best of the old chevy high performance heads even when the old ones are ported. get the vortec valves clearanced for the higher lift.

 

It should be a good setup with the vortec heads, it should run awesome and still have good manners. Find some place to get well tuned once its done, and it ought to run some good numbers for you - I'll be it'll be a torque monster, its really gonna leap off the line w/ the converter. Get ready to skip the 14's all together and move right on in to the low 13's.

The vortecs shouldn't need any clearancing for that cam. Do you know what the combustion chamber volume is now on the vortecs? As long as they didn't go crazy on them for the 305, it should still be pretty reasonable for the 350, worst case scenario it wants good gas (91+ octane) to get away with reasonable spark advance.