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foamypirate · 09-13-2012, 01:45 PM

My honest opinion would be to do the 350. I just did a TBI 305 conversion on my 84' that has 3.08s. I would call it adequate for a truck that doesn't tow, but I would hate life with a 4.3L. The 305 has a hard enough time passing or overtaking as is. I don't think the mileage is that different between them either. I pulled down about 17.5mpg highway in my 87' with 3.08s (the truck the 305 in the 84' came out of) over about 300 miles. I can't see a 4.3L doing much better. You'd probably be waaaay under-geared.

09-13-2012, 01:45 PM	#2
foamypirate Registered User Join Date: Apr 2009 Location: Pflugerville, TX Posts: 594	Re: 4.3l vs. 5.7l in a commuter truck My honest opinion would be to do the 350. I just did a TBI 305 conversion on my 84' that has 3.08s. I would call it adequate for a truck that doesn't tow, but I would hate life with a 4.3L. The 305 has a hard enough time passing or overtaking as is. I don't think the mileage is that different between them either. I pulled down about 17.5mpg highway in my 87' with 3.08s (the truck the 305 in the 84' came out of) over about 300 miles. I can't see a 4.3L doing much better. You'd probably be waaaay under-geared.