305 tpi uprade to 350 vortec tpi?
 

Hello there fellow thirdgen enthuses,

I currently own a 1986 Firebird trans am with a 305 tpi motor with an auto trans. I have been wanting to rebuild the motor for a long time, and after lots of reading i've learned that it is a much better idea to replace the 305 with a 350. Well lucky for me i have come into possession of a Vortec 350 for !!FREE!! out of a 1998 Chevy 2500 that had no transmission. So far everything checks out and theres no evidence of any kind of internal damage and the Plan is to freshen the motor up.


Background information out of the way...What modifications would I need in order to place original TPI setup on this 350 Vortec. Yes it would be ideal to replace it with a Stealth TPI system, but at the same time im trying to keep a budget as well as getting the best bang for my buck. Any input is welcome THANKS!:driving:

Re: 305 tpi uprade to 350 vortec tpi?
 

You need a edlebrock or scoggin dickey intake , 22#hr injectors, memcal reprogramed or replaced and a flexplate for a one piec rear main seal engine.

Re: 305 tpi uprade to 350 vortec tpi?
 

Normaly with just switching to a regular 350 tpi you would need the larger injectors and a chip because of the larger displacement, the edlebrock or scoggin dickey intake is because its vortec, and a one piece remain seal flex plate because the engine is a 1998 correct?

Re: 305 tpi uprade to 350 vortec tpi?
 

From 55-86 you have a two piece rear main seal the bolt pattern for crank is different from a one piece rear main seal engine. You can get one for a 87-92 v8 camaro. The intake would be needed to bolt to the l31 heads, injectors are needed because its a larger displacement and will need more fuel, the memcal will control the fueling and spark much better than a 305 memcal.

Incorrect. 1955-1985 SBC cranks were 2-piece rear main seal.

1-piece rear main seal started in 1986.

Re: 305 tpi uprade to 350 vortec tpi?
 

Sorry, I thought 86 was just the beginning of center bolt. Oh well bobs your uncle

Re: 305 tpi uprade to 350 vortec tpi?
 

Any suggestions on a Valve Train setup up with a 350 Vortec TPI? Looking for around the $400 range and with good Top End power.

Understand that "TPI" and "good top end power" do not belong in the same sentence.

At least, not stock TPI. The runners are long and small, which means it works for low-RPM torque, but not high-RPM power. 4800 RPMs is generally considered max power. You can do aftermarket base & runners, and port the plenum, which help, but it'll still be limited on the top end to about 5500 RPMs.

If you are willing/able to go with a Holley/Weiand Stealth Ram, "top end power" is more meaningful. Now you're talking 6000-6500 RPM capability. It will also cost less than the Vortec base and aftermarket runners above will run you.

Have you looked into what it will take to make the heads worthy of more cam?

Re: 305 tpi uprade to 350 vortec tpi?
 

Look into the vortec dual intake bolt pattern heads. i bought a pair a couple of months ago but you can bolt on of either regular intake manifold or vortec



http://www.jegs.com/p/Chevrolet-Perf...55896/10002/-1

Re: 305 tpi uprade to 350 vortec tpi?
 

While you may be able to bolt a conventional intake to them, how well do the ports line up? My understanding is that those heads still use the Vortec style intake port shape, which won't properly align with non-vortec intake ports.

Re: 305 tpi uprade to 350 vortec tpi?
 

I'm off this weekend. I'll see how they line up to my old heads.

Re: 305 tpi uprade to 350 vortec tpi?
 

Hey Sorry i've had a bit of a hideous, but however I am still searching for a Camshaft for this build. If I run the vortec baseplate and the better flowing runners from scoggin and dickey, what would you guys advise? Also would it be a good idea to run a 1.6:1 rocker set up? or would that be a headache modding the vortec heads(cast 062). Im looking to do as less machine work to them being that i live far from any automotive machinist. I do plan to run Comp Beehive springs.

Re: 305 tpi uprade to 350 vortec tpi?
 

If you're picking a cam anyway, just pick one with a little more lift instead of dealing with 1.6 rockers. That said, going with 1.6 rockers isn't difficult. Some said they had to clearance the pushrod holes, but on my heads that wasn't necessary. The 1.6s were a drop-in for me.

Re: 305 tpi uprade to 350 vortec tpi?
 

i have an 1986 trans am and it has perimeter bolt valve covers,isnt this a sign its a two piece rear main seal block?


ive got a spare 1991 LB9 305 on a stand and it has center-bolt valve covers and one piece rmc so i always assumed perimeter bolt valve covers/2 piece rmc,center-bolt valve covers ,1 piece rmc,is this wrong?