IROC-J28

Ok so my 87 Iroc overheated and blew the pass side head gasket in December... the motor is toast. I had been lookin into an engine swap anyways just because the LG4 was a dog of a motor. No power what so ever even with the Holley Street Dominator carb and manifold. Its was slightly torquey from a dead still launch but other than that, an eco-tech 2.2 could run circles around it. (how embarassing). So Im lookin at the L69 (305 H.O. out of the G-body cars) i believe its got a hotter cam freer and flowing heads. Also lookin into The LM1 (carb'd C/K Truck 350 engine from 70's-80's) i kno those engines were torque monsters for the time. Also lookin into the L05 (TBI 350 in the pre-vortec C/K trucks, tahoes, Suburbans and so on) I want to keep it carb'd because i really hate computerized engines. The Holley manifold and carb should bolt right on to all of those engines and they are all pretty easily accessable for around $200. I just want to kno which engine would make the most power in my Iroc. BTW its the factry 700R4 automatic tranny. I kinda wanted a 350 but whatever is cheap and powerful is the way im goin. Thanx

five7kid

iTrader: (14)

Common misconception, but there was no difference between LG4 and L69 heads. Exhaust, yes. Cam, yes. Pistons, yes (except '85-'87).

Your Street Dominator won't "bolt right on" an LO5. The center two mount bolts on each side are at a different angle. You can get it to work, but it "bolt right on".

If you put a 350 in, or want a 305 to run better, change every piece of exhaust on the car - headers, 3" exhaust, etc.

LM1 stands for "lame one".

Most power, least money would be an LO5. L69 close behind, depending upon what you pay for it, and assuming you upgrade the entire exhaust system.

IROC-J28

my LG4 has a set of summit headers 2.5" hi-flo sumit cat, and 2.5" pipeing all the way back. No muffler but a special f-body mufler delete pipe that sits in a mufflers place. Its runnin 2.5" to make up for the lack of back pressure created by the lack of a true muffler. This set up gave me a good torque gain down low and i plan on keepin it. As far as the L05, the only problem i see is the fact that this is originaly a TBI set up and i want to run carb. i kno theres no provisions for a mechanical fuel pump, and i guess It wont be simple to run my holley manifold. Any solution??? They sell electric in-line fuel pumps at part stores but what about an intake?? I wanna kinda stick to holley (My dad swears by them and so does his dad) Im lookin to start this project soon since i just got laid off (Damn U Circuit City) I have alot of time on my hands.

five7kid

iTrader: (14)

Lack of back pressure - another common misconception. 2.5" exhaust may not "hurt" you with a 305, but it isn't helping you by increasing backpressure. With a decent 350, it will hurt you. Summit headers, if they're the ones I've heard of before, have 1-1/2" primary tubes - good for a stock 305 or low-RPM 350, not good for a healthy 305 or typical passenger car 350.

An '87 should already have an in-tank electric fuel pump.

If you have your Holley intake on an '87 LG4, it'll fit an LO5 (I overlooked that in my original response). But, it won't directly fit an L69.

IROC-J28

Thats what i thought with the manifold problem. I knew they switched it over in 87 and it took holley forever to send me the right intake because summit only had the pre-87 style and in 88 they did away with carb motors all together so it was damn near impossible (u sould try to find a set of 87+ valve covers) i just thought maybe it was a carb to TBI thing. and technically shouldnt the manifold work on an L69 if its out of an 87 modle car?

my '87 LG4 has a mechanical fuel pump. it has a sending unit in the tank but a mechanical fuel pump (that i switched out to a holley unit might i add)

five7kid

iTrader: (14)

87's had both the mechanical on the engine and the electric in the tank.

The '87 G-body L69 probably has the bolt angle change (you hadn't previously mentioned it was from an '87).

But, the G-body L69 < the f-body L69.

IROC-J28

got ya, well i got access to a L05 out of a 1500 pick-up for $150 so i guess ill be droppin that in in the next few weeks. thanx for clearin that up for me bro.