Hi, new member here. I'm doing an S10 ext cab 2WD pickup, not an F-body, but came here because this board is one of the few that I've read that everyone doesn't automatically slam the 5 liter engine. I also have a Firebird TPI available for use, so I may have a little F-body blood in my truck when it's done. I did search the board for 302 vs 305 info, but the posts didn't answer my questions. I hate 350s, so won't even consider one since they have horrible mileage and not much more power than a 305 does, in street form. If I want bad mileage I'd just build a 400, at least I'd get some fun for my money then.

My overall goal for the truck is to have a high speed cruiser that can net 30MPG or better on the highway, but still be impressive at the track. 10 second quarters would be outstanding, but I'll be happy with 14.x quarter miles on engine only, so long as I meet the mileage goal. If the power winds up not being there, a small turbo might find its way under the hood.

I'm kinda leaning towards the 302 even though it'll cost a little more. Main reason for this is, parts availability for the 4 inch bore. For about 3000 I can have a 302 built up using a standard 350 block, L99 4.3L V8 crank, 6.125 connecting rods and pistons that'll put on 11.0 to 1 compression. I'd be putting a set of AFR 195 heads on top, and can go either TBI or TPI. I have a complete TPI minus the computer and injectors in a box at home right now. Cam would be a Comp 258 roller cam. DD2000 projects this combo should put out a nice, broad torque curve of around 400HP up to the redline, and make about 350/400HP. With the long rods, should also be able to run 87 octane without detonation at full timing, but I'm not 100 percent on this.

I've not actually done the work on a 305, but off just a basic rebuild for an El Camino I used to have I was able to get 20MPG with a carb and a turbo 350, and it was pretty snappy on the road. With an actual build I figure I should be able to get the 305 up there, but parts are hard to find for a 305 bore. To run high compression on 87 octane I also need aluminum heads, which aren't easy to find for the 305 either. I'm also not sure how well a 305 bore would work with a longer rod, need to go a half inch or better more in length to take advantage of the TDC dwell time that allows you to run high compression with lower octane.

The only thing that really concerns me about doing a 302 is everywhere I read also calls them a high rev engine. So, my question is has anyone ever built or seen a 302 that was not built as a 10,000RPM rev monster but as a 5000-6000RPM street runner? How well did it work out?

Comments welcome, other than recommendations to run something with more cubic inches. The only thing larger than a 5 liter I'm considering for this project would be a 327. I've also already considered and decided against an LSx based engine due to the frame work required, because my ultimate goal is to see how well the 4.5L turbodiesels coming out in 2009 work. If they are as good as the 6.6L Duramax, whatever goes in next spring will eventually be replaced with a diesel, and with that I'll be looking for 12 second quarters and 40+MPG . Thanks in advance.

 

High rev engine as in it can easily see 8000 rpm with proper internal parts. By today's standards, that doesn't mean very much because if you have a camshaft that stops building power at 6000 rpm then you have no reason to go to 8000.

My 540 BBC has a camshaft that floats the valves at 7800 rpm and I go through the traps at 7200. It's got a lot more stoke and heavier internal parts than the biggest factory SBC.

It'll cost you more to build a 302 than a 350 because it's just not that common and won't use the cheaper off the shelf parts.

Fuel mileage has very little relation to displacement. My old 4x4 with a 350 got 10 MPG. My daily driver 454SS pickup gets 11 MPG. There are also 4 cylinder engines that get worse mileage than larger 4 cylinder or V6 engines so don't get hung up on displacement.

The Isuzu diesel is junk

 

Agreed... its an oddball combination for a SBC - making all the necessary 302-specific parts substantially more expensive than the exact same parts for something like a 305 or 350, or even a 383 actually. You can buy an aftermarket 302 crank, but its gonna cost a hell of alot more than any 350 or 383 crank or similar quality will. Same goes for the pistons. I know - I've priced all this stuff out a couple years back when I was going to build a 302 myself. I went 350 instead and was better off for doing it.

Also agreed... the 350 in my '83 gets around 6mpg in the city, and around 10mpg on the highway out to the race track - and its still a perfectly streetable, pump gas build.

BUT - the LT1 in my '97 daily driver gets around 16mpg in the city, and close to 30mpg on the highway. Both cars weigh about the same, both cars are driven the same way (race track use aside), and both have been daily drivers, both have 10.5:1 CR and both are run only on 91 octane. An LS1 would be even better than my LT1 is, and its also a 350 (well, 346ci actually, but who's counting?)

Fuel mileage is all in the parts combination and build quality. My '97 vs '83 is proof enough of that for me.

 

A 302 was a 327 block with a 283 crank...so what do you mean an aftermarket 302 crank? Why cant you buy a aftermarket 283 crank and stuff it in a 327? Am I missing something here?

 

The 283 uses small journals for the rods. The small journal rods are weak and are not used on 327+ engines. If you were able to find a small journal 283 crank, you would need the special small journal rods. The original 302's had large journals.

It's not impossible to build one, just a lot more expensive than just building a 350.

 

A reman 307 crank is less than 200 bucks. It will turn a 350 block into a 327 on the cheap. That's with large journals. The last of the 327s ran this crank in 68 and they were large journal 327s.

I don't think you will see any gas mileage difference between a 302 and a 350.

My two cents.

Isuzu diesels DO NOT suck.

 

Telco, welcome to thirdgen.org.

Let's see, you come in asking about something that is not for a 3rd gen. Then you make statements and express biases that are basically totally off-base. As if that wasn't enough, your topic itself is the type of flame-bait that we see all too often around here (hate 350's, 302 was the best engine ever made, ).

Not to make you feel unwelcome (your compliments to thirdgen.org were as close to a true statement as you came), but I can't in good conscience let this keep going.