hey guys i'm looking for some 2.8/3.1 aluminum heads and was wondering what years they are? i have a message in the parts wanted... but if you the years, let me know... also if you have a set of 2.8/3.1 aluminum heads for sale that are *cheap*. I need them running... no warps, no cracks... i don't care if they look like crap, as long as they run ok. i'm going to grind on them some and see what i can do... if i mess them up, oh well! i still have the ones i know run good.

edit: i tried searching for aluminum 2.8 heads, but i got no luck so if anyone can point me to a thread, that would be awesome, or just tell me.

also, here is the link to my "parts wanted": https://www.thirdgen.org/forums/engi...2-8-3-1-a.html

 

Sorry to bust your bubble...

All RWD 660 V6's made by GM had iron heads, from the 2.8 to the 3.4. Later, after GenI 660's, they started putting some aluminum heads on FWD vehicles. Now, the problem is, you can't just grab some of those and expect them to work for several reasons:

Intake manifold differences - can't use old intake, new intake won't fit with dizzy
Compression I believe goes way too high with aluminum heads
etc.

I think that the only way you're gonna get aluminum heads in a car with a GenI 660 RWD is to buy yourself a 3100 or 3400 FWD motor, which brings it's own set of problems into play from swapping from FWD to RWD, including these:

Redrilling starter holes
Converting to DIS
Swapping ECM and wiring the beast up
plus more I forget right now...


Finally, I don't see why you want aluminum heads really, the major good thing about them is heat dissipation from combustion, but whatever.... If you only wanna grind on 'em and do some home porting, just grab some iron ones from somewhere and go to town. I'm not sure how much improvement is to be gotten from stock casting heads, I've never heard how bad they are from anyone and mine haven't been off yet... But if there is any gain to be made, it would be easiest to just start with iron heads in the first place...

 

that's what i thought... 2.8 heads were all cast iron. my brother in law said mine were aluminum, but i thought they were cast iron. Thanks

Now, another question... is there any difference from 83-89' cast iron heads? or are they direct bolt on?

 

There's MUCH more to benifit than just the material they are made of.

I don't remember the actual numbers in flow inprovement from genI heads to genII heads, but I do remember tha from genII to genIII there was an 18% flow improvment on intake and 33% flow improvement on exhaust, whihc is quite significant. I'd say that the comparison between the genI and II heads will be someithing similar, due the all the Aluminiun heads using higher ports (intake side anyway), splayed valves, more efficiant combustion chambers using a "heart" shape, among other reasons.

Now, if you're going through this trouble, skip the genII top end and use the genIII top end, more specifically '96+ 3400 or 2000+ 3100. these cited top ends have the "large port" and out flow the '94 to '99 3100 "small port" top ends.

The hardest part is getting a crank trigger, to trigger the DIS ignition. If you start with a 3.4 block, it is not a problem since the 3.4 from the mid '90s F-body used DIS ignition and has provisions for the crank trigger sensor. I made/had made an external crank trigger wheel that mounts between the harmonic balancer and the crank pulley.

Yes, using RWD pistons will put the SCR between 12.5:1 to 14.5 (or so):1, depending o teh displacment, the higher discplament engines with have the higher SCR.

The good news is that the FWD pistons will fit right into the RWD block, you just have to choose the correct piston for your block/crank combo. 2.99 stroke/3.50 bore is a 2.8, 3.31 stroke/3.50 bore is a 3.1/3100, 3.31 stroke/3.62 bore is a 3400, I'm only refering to the aluminium headed FWD engine in thier displacement/designations in the last references. Also selecting the piston to match can vary the SCR by a little bit, if I were to build from scratch again for teh same purpose (Daily driver/tow vehicle), I would use the higher SCR pistons for the newer 3100, instead of the lower SCR pistons of the genII 3.1 (9.6:1 Vs. 8.9:1 respectivly)

ALL FWD engines with the exception of the Lumina APV (mini-van up to '93), had aluminium heads from '87 on. The genII ran from '87 to '94, the genII started in select models in '93 and was FWD platform wide in '95.

I've made several posts concerning the swap, and you should be able to find them quite usefull to build a hybrid.

I started with the SP top end, but had the LP top end to go one with some other upgrades.

 

http://www.engine-parts.com/GMV6/gmv6heads.html

try here, but they are very expensive.

 

HOLY ****! You Aren't kidding.

$359 for a pair of stock heads? WTF?!

 

they have always been exspensive for there parts.ur best bet i sprolly a local junkyard. prolyl pick up a set for 100-150$'s

 

:lol I threw mine out, when I did my build and swap, if I knew they'd bring in that much I would have kept them.

 

lol the 60* store has some pretty steep prices as well,from what i seen it looks liek he buy sall the stuff from board members then turns it back around at a huge increase.

though some of his cnc stuff is nice.

lol btw did u see how much he was getting for head stud kits

 

No, I haven't looked through most of his stuff, since I generally have other sources for what I need.

 

I agree with Dave about some of the prices on 60*V6.

ScottieB, I just got a set of '99 3400 aluminum heads for $25 on e-bay (in fact I was the only bidder). Rebuilders are selling cleaned heads with valve jobs for less than $200.

I am in the process of buying parts to do a hybrid (that's what they call a FWD top on an iron head motor) and going to use .030 over RWD pistons to get the high compression, but to get 11:1 compression aprox. 3cc's of material is goint to have to be removed (W/+.030 pistons).

What I want to know is how thick of head gaskets can we get away with? Stock is .040" compressed height, IIRC.

 

u can get .060 thick head gaskets

 

That means with .030 pistons,.060 gaskets, aluminum heads, and RWD (12cc dish) pistons will yield a 11.19:1 SCR.
So with .060 gaskets and removing 1cc of material will yield a 10.99 SCR. Removing 2cc's would be 10.88:1, and 3cc's would be 10.63.
With the aluminum heads and 11:1 compression, do you think it would run on 93 octane (since the aluminum heads would allow about 1 more point)?

 

In the original post, the guy was looking for GenI aluminum heads... Now I'm not gonna dispute that GenII and GenIII heads do flow better, but that is not because they are aluminum, it is because Gm improved them over time. An exact duplicate of a GenI iron head, but in aluminum, will not flow better, it will just reduce heat buildup in the heads, which can help if running a power adder of some sort or really high compression.

Otherwise, I agree totally with everything

 

Hey man! I always thought that the van heads were a better head... after reading up a little, i think its just the genIII heads. Then why is my 2002 pontiac montana rated at over 200hp when all other 3x00s of the same year are rated under 200?

 

Cam and tune can make a big difference.

 

true... But I guess if its the cam and computer, theres better options out htere then going with factory cam and computer! Thanks for your help!

 

All 3x00 cams are the same.

The difference lies in the fact that they are SAE rated, meaning, they are rated with the actual installed exhaust, actualy intake system (filter, box, and related tubing), along with the ECM. Since exhaust and intake systems differ between vehicles that changes the end result for power.

Internally all 3400s are essentially the same, as far as power production goes. There were some small changes over the years, but were made more for reliablity or customer satisfaction issues.

 

Ok, now im confused. so what makes the Van motors worth 25hp over the exact same motor in a car? If the heads are the same, the cam, all internals... An extra long exhaust cant be worth that, and I know the air cleaner box is a tad smaller then the 3400 in a car. must be a computer tunning thing? But I bet its not as simple as just swapping computers out of my mom's 2002 venture into my brothers 2002 impala, is it......

 

Re-read what Six_Shooter said.

 

Dude, why?
That will give you a terrible quench distance. Tighter quench fights detonation. A tighter quench and more compression is better then large quench and lower compression. Quench is measured from how far in the hole your pistons are at TDC + gasket size.
I know its a completly different application, but my LT1 build I used .13 head gaskets to get my quench around .40
Static Compression of 12.2:1, Dynamic of 9.2:1

Go with the tighter quench and put a cam in that will bleed off some of the compression.......