2.8 head on 3.1 block

[lampy]

Will the heads on my carburated 2.8 fit on a 3.1 block? Or can I put a 3.1 crank in my 2.8? Looking to get more cubes/ more power.Any sugestions welcome.
Thanks Rick

[rx191]

iron head or allumium, what is it in

[Arns85GT]

Nope

Your carb intake manifold is set up for the iron heads. No, the 3.1 aluminum heads will not work.

As for the 3.1 crank, there is a kit out for that stroker mod. It is not cheap. You need quite a few parts to make it a stroker. The stock 3.1 rod/piston combo will not do the job for you. Essentially you are much better off just buying a 3.4 short block and bolting on your heads and manifolds at this point.

Arn

[86euro]

If you're FWD, a 3.1 longblock from a u-van will work with your carb/intake

[lampy]

They are iron heads on a 2.8 from an "85 S10 pickup. I want to get more cubes by putting those heads, intake and carb on a 3.1 short block if that will work. I am going this route for now because I think I can get a 3.1 cheap. Not ready for F.I. yet.... So will Iron 2.8 Heads bolt up to a 3.1 block?
Thanks

[Arns85GT]

yes

The heads bolt up, but you don't want them. The S10 heads have smaller valves and you'll be disappointed with the performance. Try a set of Fiero heads and port them before you install. That will get more out of the 3.1

[lampy]

Thanks Arn, been doin some more reading, now I'm looking at a 3.4 swap. Guess I need to do more research befor I jump into this project. the 2.8 I have now is in a Mazda B2000 P.U. It was a fun swap came out pretty clean too.

[Guest]

OMG Misinformation runs rampant in this thread....

The S-10 from '85+ use the same size valves until the demise of the genI 660 used as a 3.4 in the F-bodies in '95. So any genI 660 head used OEM after '85 has the large valves, S-10, Fiero, F-body, etc.

Stroking a 2.8 to a 3.1 is super easy. You need 7 parts: One 3.1 (3.31" stroke) crank, and six 3.1 pistons. The bore is the same between the 2.8 and 3.1. If you are looking for more than about 3.2L then the 3.4 block would be a better start. The only way this doesn't work is if yo start with an older small journal block which was used up to mid '85. All blocks up to the introduction of the 3500 used the same size "large" main journals, which BTW are larger than SBC main journals, the actual difference eludes me at this point and would have to look it up.

The 3.4 swap is a good one.

If your goals are just a bit more power (160ish HP and 200ish ft/lbs) the stock 3.4 would be the way to go. If you want more, look into a "hybrid" using the genIII top end, which would benefit most from a conversion to EFI.

[86euro]

I thought the s-10 didn't get the large valves until tbi came in around '87?

[ezrollin]

Thanks Raven,save me fom having to make a long post. People, please check your facts before posting!

[Blue89rs]

You need to be careful with 60V6's in the 85-87 year range. I have an 87 S10 with an externally balanced crank. Seems like chevy decided to use up all stock of the old parts so there was no definite cutoff date. ALWAYS make sure to measure your parts!

[lampy]

Thanks for the info Raven, looks like I'm back to putting 2.8 heads on the 3.1 block. Cool cause thats what I wanted in the first place.I'm not looking to make killer horse power yet, just playing around. So if I have this straight I can bolt my 2.8 heads and intake to a 3.1 short block or put 3.1 crank and pistons in a 2.8 block. I may do the stroker thing as I have a line on a 2.8 core just have to check the crank to make sure its the larger journals. I'm sure I can find the 3.1 internals no problem, have a friend who owns a wrecking yard. It's good to have friends in low places. Thanks everyone! I'm sure I will visit this site often with more questions.
Later, Rick

[Arns85GT]

Don't mean to be disagreeable....

My understanding is that we are talking about an '85 S10 set of heads.

Excuse me if I'm wrong, but the S10 did not get the HO heads until 1986 when they got EFI.

The '85 S10 was rated at 110 hp and the Fiero at 140 hp.

The '85 S10 heads will give about 20 hp less than using Fiero heads.

Just to clarify this, and hope this steers you right.

Arn

[ignoreance]

Are the heads off Put a set of dial calibers on it and check them... you can tell the difference of .12 of an inch on both valves... best way to check...

1.60 vs 1.72 on intake
1.30 vs 1.42 exhaust

You need to be careful with 60V6's in the 85-87 year range. I have an 87 S10 with an externally balanced crank. Seems like chevy decided to use up all stock of the old parts so there was no definite cutoff date. ALWAYS make sure to measure your parts!

Another like mind

Damn some of you guys work the hard way thats the only way you can truely tell.... Don't guess your in automotive MEASURE get used to it if you don't want to measure then take it to a qualified pro cus your only going to botch it up. Besides seems like at the beging of the year there was about 40 3.1 reman engines or pulls going from 300-900. The crank is alway on ebay about 190 or so. I think this is the guys website hdmaddog.com he may not have the part listed on the website there but he has it. Don't know about pistons call him he probably has them too.

If you do go to the 3.1 Crank it is balanced so no need to worry about the external balance; but could bring up issues with your current flywheel which more than likely has external balance on it. In which case you have to buy that or have the flywheel rebalanced.



Now go measure the valves in your heads and then you will know if you need to buy a set or not. Don't take what people say for fact... always double check. Alot of the guys hear do know what they are talking about. But you never know maybe your engine had a rebuild on it... and the jackass that put it back together wanted to keep your heads and slapped some older ones on there with smaller valves its happend.

So is there anything I missed???

[geoffinbc]

I have a 3.1L Crank for sale.