Hi All,

I have what I hope is a simple plan to take a stock Iroc and upgrade it for better performance / keeping up with my friend's Impreza.

The basic plan is to pull the stock 305 TPI and put in the exact same engine set up as described in the following link:

http://www.popularhotrodding.com/eng...ons/index.html

The result is a cheap, drivable, reliable, car that has 350-400HP (depending on if I do the cam modification. I am actually leaning away from the cam mod initially to intentionally keep the HP down due to concerns over how much the T-5 tranny can handle.

My question is... Will this work? Are there any special considerations considering I would be putting some very old school technology into a mid 80's car? In particular I am worried about wiring and mating the engine to the transmission

Thanks for the input!
--Kev--

 

it'll work - kinda. does your state have inspections or emissions? that's going to be a big hurdle to pass if you're trying to go carbed. technically not a legal swap, but that's not my area of expertise. Wiring won't be too bad, you'll need to rewire the fuel pump relay and put in a return-style fuel pressure regulator to keep the fuel at a carb-friendly pressure. also will need to swap to a hei distributor. didn't read the whole artical, but there may not be enough clearance for the intake manifold they used (underhood's pretty tight)

 

I have no idea on costs - I'm broke and so I don't look.

But I thought it very interesting that the LSx's are getting carbed now. PH did an article using an LS1 motor, swapped to a carb intake and 750 carb along with a MSD/Edelbrock control box for the coilpacks, and got the same 400+hp as the stock efi system. After a cam and springs swap, they got over 500hp and 450tq numbers from an otherwise stock LS1. Anyway, LS1 engines ought to be showing up in the JY's by now - might be something to look at. I know there's quite alot of posts at LS1tech.com about carbed LSx motors as well.

Again, your T5 will have to be babied until funds available for a T56 swap, but the JY LSx platform might save a considerable amount of cash over a "crate" anything.

 

Rather than the 290 HP crate, of which you'll be throwing away the heads, cam, lifters, pushrods, and rockers, why not start with the L31 shortblock? http://sdparts.com/details/gm-factor...parts/12556121

You'll have a better block that will accommodate factory roller lifters, and a one-piece rear main seal crank. Then you can add the heads & cam of your choice.

 

Why not just find an L98 long block with the heads already on it, and just throw all your intake and wiring on top of it and be done? The TPI intake is the same whether it's a 305 or 350, so why go through the hassle of removing all the TPI and wiring when you can simply swap out long blocks?

 

Carbs are sooooo old school, and I had drivabilty issues when there were large temp changes between day and night.
I had a carbed 86 Trans Am 5 speed and decided on converting it to TPI.




http://www.youtube.com/watch?v=nGTLJ9nS2aI

going the other way is much much easier.

All you need is a vacuum advanced distributor, either use a multiport fuel pressure regulator to drop the PSI from 40+ to 6psi, or remove the pump in the tank and replace the pump with fuel line and put a pump on the side of the block and move the fuel lines in the engine bay to the pass side

 

I would also say "keep the TPI", but don't know the year of the TPI. With that cam, you'd want to go with SD, I'd think. And, all of the TPI hardware (base, runners, plenum, injectors) would need to be upgraded to handle the rest of the build.

Regardless, I'd say build around the TPI, rather than converting to carb.

 

Thanks for all the posts! Lots of good thoughts here...

My state does not have emissions testing so I am OK there

Based on the pics of the carb'd TA it looks like clearance should be ok. I have seen a lot of other carb'd Camaro's that seem to fit under the standard good.

That short block seems to be a more straightforward approach (ie. it eliminates unnecessary leftover parts which I like). Thanks for the link!

The reason I liked that article so much was that they addressed my primary concerns of reliability, drive ability, and good HP without getting too technical.
I am pretty much going to assume that any camaro I purchase will have been driven pretty hard plus have 80K + miles on it. That being said the idea of a new engine sounds great.

I have read a few articles on this page about "building around the TPI" and I am apparently too dense to see a clear path to get 350-400HP without deep diving into a lot of different things.

Seems like I should aim for a non TPI camaro (with the t-5) for the easiest swap (ie carb to carb).

I like the idea of doing the swap, but not upgrading the cam, until I can get a better tranny. That will keep the power down to about 350HP which will help me baby the stock T-5

 

A common misconception. The laws and regulations are Federal. Not having state or local emissions testing and/or inspection does not exempt you from complying with them.

No more difficult than converting to carb.

Not necessarily.

Babying the T5 is a matter of not doing high-RPM clutch dumps and not trying to speed shift. Whether 350 or 425 HP won't make that much difference to the transmission if you avoid those two things.

 

HP doesn't kill the T5, it's the Torque.

 

Shock is the real T5 killer.

 

I just recently converted my 89 Iroc to carb when my TPI motor threw a rod. I got my engine from phoenixengine.com A 350 330hp motor that runs great. I want to upgrade to bigger motor eventually. I am using the fuel pump in the fuel tank still. I have a FP regulator with a return on it. I got rid of so much wiring to really clean my engine bay up. I had to get som wiring diagrams and some help from friends and on here. Well worth it. I love my carb setup. Let me know if you need some help. I did have to get a custom y-pipe made to fit around the bigger oil pan. Im still working on the car. I bought it for 800 bucks and she has come a long way. Ill post some pics if you want.

 

Mavcar38 - Good to hear a success story! Also good to hear you love your car with the carb set up. Pictures would be great if you have time to post some.

What was the biggest challenge during the conversion? Obviously the FP regulator is an issue but I hadn't heart about the need for a custom Y-Pipe.

I am also wondering if it will be a pain to retain things like A/C?

@ everyone else - I'll be gentle on the T-5 until I can put in a proper transmission to handle the extra power. I think I am a boring gear head in that my first concerns are making sure the car is very reliable and smooth to drive

 

New Idea...

Basically the same story of buying a new short block... adding decent heads and a hotter cam.... but topping it off with the EZ EFI instead of a carb or the TPI system. This would accomplish my goals of an easy upgrade, still drivable, and good HP (I think this combo would get me 350+)

 

I agree with you, and am not debating that shock is the biggest enemy to the drivetrain. But many T5's have broken 3rd gear under power, that's not uncommon at all. 3rd gear is always the weakest

P.S. to the OP... Not to hijack your thread, but I have a Mallory 4309 regulator for sale, along with SS braided hose, fuel filter, and correct AN fittings to connect to your metal fuel lines in the engine bay, if you're interested. So you can have it set up without using any rubber hose. P.M. me if you're interested, sorry for cluttering your thread. Carry on

 

Spev, I tried posting some pics, but for some reason it wont take. I can pm them or email them to you if you want.

 

MavCar- Please send the pics to Spevinator@gmail.com

Thank you very much! I look forward to seeing them. I'll respond to this thread once I see the pics.

 

Spev Im sending you the pics now. Let me know if you get them. Thanks

 

Ok, I must be an idiot. How do you upload multiple pics on here?

 

Mavcar - I got the pics! Thank you very much. These will be helpful when I start my build.

I'll be sure to send any follow up questions your way when the time comes.

Take care,
--Kev--

 

I also have a 305, 5 speed GTA that I want to convert to a 350. I have gone prothane everything, full subframe connectors, 3 point strut tower, even gone so far as to through a moderate cam in my 305 with flowmasters cat back and still getting crushed at the track. How hard of a conversion is this and will any L98 block work with my TPI equipment? I hate working with carbs and dread going back 20 years in technology.

I was also thinking Vortec heads? Any thoughts?

 

Or almost any 4 bolt 350 would work? Be nice to start with one that is already .030 over