I recently pulled the Vortec/SDPC BASE/SLP runner combo off of my van for use on a different project and in my parts inventory had a pair of stock 187s and a stock TPI setup. Here is the end result. It runs great on 87 octane had decent power, TONS of torque and gets very good gas mileage when I am not ******* on it. 20+ MPG in a fullsize G20 Conversion Van. It has a severe lack of power above 4,500 rpm though. This engine is choking over dead right were the old combination was just getting turned on, even though they both have the same shortblock, cam, and exhaust.







http://s243.photobucket.com/albums/f...t=101_1403.flv

http://s243.photobucket.com/albums/f...t=101_1402.flv

http://s243.photobucket.com/albums/f...t=101_1400.flv

I was surprised to see that the TBI heads wanted even less timing than the L30 Vortecs that were on it before. I might add that the Vortec heads were running on 1 point higher compression than the TBI heads as well.

 

I'd bet a dollar to a dime that the heads alone are 80-90% of the difference in power band loss. I have to believe that on a 305 the stock tpi intake is close to good enough.

 

Are these TBI heads stock or ported?

 

They have been lightly worked but nothing major. The short side radius on the exhaust was reworked, the swirl vane trimmed down slightly, and the exhaust bowl cleaned up.