Hi,
I've got an '89 formula with the TBI'd 305.
I'm looking for a few extra horses when I swap my cam for an LT4 hot cam, a single plane manifold, and a few other TBI related mods.
Now, I know the stock TBI (swirl port) heads flat out suck, so I'm looking to upgrade them. I figure there's no point going with a high lift cam, if my heads can't flow it.
I can find 305 TPI heads for fairly cheap, and I'm wondering if they can be polished to be decent performers for my 305 TBI. There's a discussion going on on the TBI boards about head possibilties, and if you guys could add some info concerning flow numbers (ported or non ported, whatever you have), common things to change (bigger valves, etc) for your stock 305 TPI heads, your lo-po brothers would be very appreciative.

 

btt

 

Apples to apples

tpi 305 heads would need to be ported for you to even feel the gain, and if you do manage to feel it I imagine you'd still be disapointed.

There's a decent variety of heads in the $500-$700 range

Some S/R torquers
maybe ZZ4/ alum L98's

either would do you good

 

Tpi_roc: I'm pretty sure that the TBI heads are way worse. They're the "swirl port" design, with the big bump in the intake tract.

I'm going to make my question a little more specific.
Because I'm going with the LT4 hot cam, I'm wondering what the flow would be at close to half inch lift. Probably ported.

I don't want to keep the 305 for too long, and heads are one of the few pieces that won't overchange to a 350. In other words, I don't want to pump a lot of money into aftermarket heads that I'll only use for a year or so.
Thanks for the responses.

 

Help!
btt

 

If you;re not going to swap these heads after, then stick with the TPI heads! You'll also find that the 416 pre-86 casting is found on the LG4 cars too....