Ok guys i have a 1987 irocz with a tpi 305, thinking of putting a 350 in it using the 305 tpi heads and intake. Will i have to switch to bigger injectors or upgrade my fuel pump? Any info would be appreciated.

 

22#hr injectors for a mild 350 and a tune is needed.
Why are you using the 081 heads ?

 

was wanting to keep it tpi so figured i would use the tpi heads plus boost compression a little bit. Will do a little port and polish job on them first.

 

FWIW, if you are going to write/burn a PROM you can adjust the injector constant so that 19 lb injectors will run a 350 respectably. I've done a few conversions, and some were 305 TPIs onto older, larger chamber headed 350s from the '70s. Most of those run out of guts at 5,000 RPM anyway, and the flow of a 19 pounder is sufficient for the fuel demand in some cases. There's an example here:

http://www.hotrodders.com/forum/305-...ck-178778.html

On an L98, you may want to go with the 22 lb or larger injectors just to support the potential a little better.

The '87 model may have had '081 heads with 58cc chambers, whereas the 1987 L98 heads ('083) would have had 64cc chambers. The '081 heads are really going to bump compression, however. If your ESC is working you should be O.K. They should take the 9.4-ish static CR very close to 10:1.

However, the increase in compression may not benefit enough to make up for the loss in flow and potential valve shrouding. No doubt that it will run acceptably, but only to a point where the flow becomes restrictive. The benefit is that they are not much worse than the '081s, and a TPI requires velocity at low RPM to make torque. The same weaknesses that make a TPI lose power at RPM are carried over to the heads, so it's no big loss.

If you're going to spend any money on altering either head, just replace them with something better. If you want to watch your budget, choose based on the benefits and penalties.

 

Thanks. I believe that is what i was needing to find out, that was very helpful.