iroccopz28

I have an '86 Iroc with the 305 LG4, 5-speed. The engine smokes a little when it first start and then stops. I have been told that the valve seals need to be replaced. Also, I was told that I should find a good set of heads off a 350 and use them instead.

So hears what I am wondering:

Is there any advantage to using 350 heads instead of my stock heads?
If I use 350 heads, will i still be able to keep my emissions (since i need to in order to keep this car legal in PA.)?

When I do this I plan on replacing the cam and timing set and I need to try to keep this as affordable as I can while giving me a little boost if possable.

Any help and suggestions would be great, thanks in advance.

Jim

Apeiron

350 heads would be a downgrade from your current LG4 heads.

five7kid

iTrader: (14)

The LG4 has pretty go heads. As Apeiron said, 350 heads would hurt you.

On the FAQ forum there's a thread about the differences between 305's and performance improvements. Quick recap of the LG4 liabilities: air cleaner, exhaust, cam, intake manifold, valve size, in that order. Dual snorkel air cleaner, headers & full upgraded exhaust, better cam, something like an Edelbrock Performer intake manifold, 1.94" intake valves will all wake the engine up.

The majority of factory 350 heads would slow it down.

iroccopz28

Thanks guys, thats the information tha i was hoping to hear.

Jim

70's iron

I'd have the same question about a LU-5 Crossfire. Sorry, I didn't find the FAQ topic...

Still looking to have decent power from my ex-CFI engine, I planned to buy Edelbrock Performer alloy heads. But, finally, I've been told they wouldn't fit because of the less-than-4inch 305 bore.

Here in France, we don't have much informations, and the mechanics that specialize in F-bodies aren't very straight...

Do someone have a suggestion ?

Thx

five7kid

iTrader: (14)

The LU5 had the same heads as the LG4 and L69.

The Edelbrock Performer heads will fit, they just won't give you all of the power because of the smaller 305 bore. You would drop compression significantly with them, so you might want to just stick with the stock 305 heads.

70's iron

Wow, this is a clear and efficient answer !!!

This also means I can spend the $1700 for the heads in something else.
Well, here gas is about 8 bucks a gallon. So a late-model aftermarket MPFI seems a good idea...

70's iron

Last thinking ( I promise)

How about GMPP Fastburn or Vortec heads ?
They say they fit any 58-00 262-400 SBC. And they're required if I want an Edelbrock pro-flo fuel injection.

Both are cheap. The downside is that alloy Fastburn heads are bare, I don't know what to complete them with...