3rdgen Fbody with 3500 heads

[Canyonero]

Yeah, I haven't had the justification to rebuild any other engine either. Maybe after I grenade this 3.4L.

I should learn some other things first anyway, maybe do an OBDII conversion and tune a few more horses into my current setup.

[ForcedFirebird]

Yeah, I haven't had the justification to rebuild any other engine either. Maybe after I grenade this 3.4L.

I should learn some other things first anyway, maybe do an OBDII conversion and tune a few more horses into my current setup.

If your current bottom end is in good shape, get some 3500 heads on there.


What are you currently using for tuning? OBD1 is tunable

[Canyonero]

The engine is in a 4x4 and I want to be able to run 89 octane, so I'd have to change my pistons to get lower compression right?

I'm not tuning at all (yet). I think I have an OBD1.5 untunable ECU.

Since nothing was wrong with my old engine, I should have taken my time and built this one up. I thought I was taking some shortcuts, but ended up wasting time and money. I could have built a bad-ass hybrid with dollars and cents I've sprinkled into this truck over the last year and a half. It's been a learning experience for sure. Now that I finally have the bone-stock 3.4L SFI in there and running good, I realize what I should have done different from the beginning.

I'm not dissatisfied with the engine though, it's a big step up from my tired 2.8L as-is.

[ForcedFirebird]

If you can get a way to tune, you can use the stock pistons and 3500 heads (11.5:1SCR) and run on 87 pump gas. Ben built an engine with 12.5:1 and is still running on pump gas.

[IsaacHayes]

You think 11.5CR on 87 is possible in hot summer weather? Or are you thinking lower it with a cam with overlap?

[grandsport3.4]

keep it up very interested in your progress. i just got a spare 3.4 and some free.99 parts(3100 heads and 3400 top end) so im going to start my build

[ForcedFirebird]

You think 11.5CR on 87 is possible in hot summer weather? Or are you thinking lower it with a cam with overlap?

Yep.

No, I already have the cam...





I actually might try a little boost with it as well before I pull the motor to swap to 3400 pistons.


I know two people now with low 11's for compression and are running on pump gas. One has 10psi on his Mustang (iron heads), and the other is running 4psi in a 280zx (aluminum head).

[ForcedFirebird]

Started fabricating the alt mount brackets. Just so you know, the stock RWD 60* brackets will work with some minor modification, but I need room for some turbos...









Not really happy with the placement of the alt. Lower would be better, but the huge engine mounts are gettin gin the way. I made this prototype out of some scrap AL (probably see the extra tooling marks in it, lol). Might move it to get some more room for the headers.

[Guest]

I might be interestted in a alternaotr bracket once you get the final version done. mine would be for a 3500 in a fiero with gen 2 heads. Not sure if the bolts patterns are different between 2 and 3 for the mounting brackts.

[IsaacHayes]

OMG 3500 with gen2 heads? That's so wrong!!!!

[ForcedFirebird]

Enlarge the holes a little on the P/S bracket...







A/C bracket needs one new hole...





The neighbor at the shop re-builds alts and starters, and I asked him today if he has any GM alts layning around. He said yes, but if yours works, I'll rebuild it for free, and it will look "pretty". Let's see what kind of job he does, neighboly love for ya, lol.

[johnnymossville]

Good looking engine Forced. When do you think that you'll get it installed and running?

[ForcedFirebird]

Good looking engine Forced. When do you think that you'll get it installed and running?

Not sure. I wanted it in by now, but I'm forced to take my time having two jobs and four kids, lol.


Got the alt back from the neighbor today. This is the best free rebuild I ever got (if I ever did get one, lol)...

[soultron]

I never post here, but I have to say that this is awesome.

[ForcedFirebird]

I never post here, but I have to say that this is awesome.

Why thank you

Got some more done...







Before cleaning/glass beading....



Close up of the holes enlarged on the iron head coolant neck. This means so far all the stock brackets can be used, but I will have to machine an adapter...




Cose up of the mounting holes moved...

Some new problems arised, though. Now the TB isn't going to work, it's on up-side down in the pics because the black alt bracket and alt is in the way. I may have to swing the alt down a little and fabricate a replacement (for the small black bracket), re-configure the TB, or use another TB. The alt bracket has two bolts and only two contacts on the head, this could be unstable at high RPM's, so need to figure out something to make to hold the bottom bolt hole to the lower boss on the front of the pass side head.



The A/C bracket, I feel comfortable with. It has two bolts to hold it, with opposing contacts on the head for stability, but the new bolt hole is through some thin cast aluminum and I don't want it to break. To remedy this, I plan on using a steel sleeve over the bolt behind the bracket - so it gets "sandwiched" between the bracket and head when torqued down.