i recently got my hands on an 87(since 86 causes yelling not that it matters a 350 is a 350 from 86 and up) iroc motor its a 350 TPI.
im gonna rebuild it and wanted a few suggestions heres what ive decided on so far and refuse to go another way on.
im keeping the TPI set up! despite its downfalls i like it.
im gonna port and polish the heads and do a 3 angle valve job.
i dont really want it to go to extreme with it but i would like to hit somewhere in the range of 400 ft lbs of torque.
as for horsepower i could really care less.
im planning on headers but im not to familar with whats good.
im also thinking about lighter weight pistons.
im also on a fairly limited budget say maybe 500 bucks or so i might be able to get more but right now it seems that probably happen.
im just looking for suggestions i may have not left too much room for ideas but nevertheless im still interested in the imput.
the motor will be going in my 91 RS.
i know about what to change as far as computer and other parts go im just looking for motor imput here.

thanks

 

Working on the heads seems like a good idea to me, but you won't see all of the potential there until you free up the breathing a bit, probably with a set of runners - but by then you've used up most of your $500 budget...

You might be able to get somewhat close to your goal with a well-chosen cam that works with the stock TPI - but the stock runners/base will hold you back a bit... Of course, you might be able to find used runners and/or base manifold on ebay/the CZ28 "for sale" boards/etc. Good luck, whichever way you go.

 

the runners in the link you posted look identical to the ones that i got.
ill check more closely in the morning though.
thanks.

 

Just for your info there was NO 350 TPI motor in 1986 in ANY 3rd gen car. What someone did was sell you a 305 TPI claiming it was a 350. Common switch, big mistake claiming it was from a 1986 and you for beliving him. Check the block numbers to verify what it is.

 

maybe the motor is from a vett?

 

Check his quote "86 iroc motor its a 350 TPI".
Where is a vett mentioned??? Are you reading something I missed. More 305's claimed to be 350's then GM Sold stock in 3rd Gen cars.

 

That was my first thought as well when reading this. If you have the motor out of the car look right next to the distributer hole and the block size should be stamped there. It will read 5.7 or 5.0. Good luck hopefully you were not ripped off.

 

*** hat it is indeed a 350 since i did check the casting number the junkyard sold it to me as an lb9 motor when it was an l98 so no i wasnt cheated. and yes there were 50 thirdgens with a 350 tpi motor in it built wheter or not they made it to people is another story and since teh car it came out of was suposedly an 86 iroc ill refer to the motor as an 86 350 regardless since this block casting was used from 86 and up.

 

can we get back to the point of the topic please im looking for suggestion on building it up.
not a debate on whether it is or isnt a 350.
i dont mean to be rude but i dont like being insulted directly or indirectly.
and since i bought the motor thinking it was a 305 the knowledge that it is a 350 is a thrill to me.

 

I know it was mentioned about not getting the full potential of the heads or cam since you need the intake to breath a bit more. If you cant afford the runners, you can try this mod. http://www.gmtips.com/3rd-degree/dox...-port/port.htm Its info on how to free up some air flow in the plenum. When GM designed it, they made restrictive blocks on the interior, blocking up airflow. There is another article here,
http://www.ws6transam.org/efi.html
that describes how to siamese the plenum and runners, giving you even more of an airflow. Finally, if you dont have it, look into getting a Holley Throttle Body, or a TPI Air foil for the throttlebody.

 

i would definately look into going retro roller hydraulic cam, the horse power gains and valve train life will be worth it.

 

good point thanks! i didnt think of that.

 

theres too much you can do

Headers and exhaust is a must on that 350. A 3" y pipe is ideal. I prefer a set of headers like the hookers because they have a 3" collector the slp's that came on my car have some tiny *** collector which i fail to understand.

And the head work combined with the exhaust should put you probably just shy of 300 hp 400 ft lbs.

Your next mod i would reccomend is to get the SLP siamesed intake runners, and then port them as per i think theres a tech article on tgo about how to do it.

If you add a cam to that combo im guessing youre gonna hit around 375 hp 450 ft lbs. Youre at the point where youre risking cracking a cylinder wall, and your stock transmission and rear end have long since been blown to smitherines.

EDIT: in retrospect at 375 hp your motor will probably stay intact, the torque shouldnt crack the block and i think its around 450+ hp that the l98 falls apart.

 

the rearend maybe its a 2.73 week *** rear axle. but the 700 will hold up to somehwere in the 500 to 600 hp from what ive heard.
thanks for the info.

 

I had an amazing laugh at your expense until i read your other thread. Thought you wanted to put the stock slush box behind the car and from personal experience ive already blown one of those up with full exhaust and ported heads on my 350.

And just for knowledge the rear isnt weak because you have 2.73's as opposed to the 3.23's or 3.42's, its weak because the physical size of the gear is 7 1/2" (assuming you have a 10 bolt, the 9 bolt is a bit stronger) and with 400 ft lbs if you drive it hard your stock 10 bolt is eventually gonna be toast. Got about 4 months out of mine but again i drive my car like i stole it.

EDIT: and because i was bored heres a link to the slp intake runners. The person who posted after you opened this thread had a link to some runners on thunder racing. The siamesed version they offer looks really really good, however at almost twice the price id go with the slp's and siamese them yourself.
http://www.slponline.com/view_product.asp?P=20002

and heres the article on tgo about how to siamese the slp's
http://www.thirdgen.org/newdesign/te...meseport.shtml