Long story short...

Wanted to build a twin turbo chevy 229 v6 to make around 250+ wheel with using small mazda cx7 turbos. Nothing radical, just realistic and usable with a dash of never done before and with blow-thru carb.

Well after realizing there is no real reasonable way to control timing i dropped the project and bought a 4.8LS.

The bug has bit back. I do not want an LS swap in this car....too easy and common.

Ive read of the 5-pin mod for HEIs that drops timing, but its one big glob and supposedly weakens the spark too. Im not sure how the early turbo pontiac 301s and carb'd turbo buick regals controlled spark.

ATI wants $1000 for a custom damper with magnets (yikes) for trigger pick up.

What about manipulating the vacuum signal and mechanical advance curves in the HEI??

Due to my low power goals precise control is not required. More like 'good enough'

Any ideas are appreciated. The cheaper and more creative the better!

 

You can set up the mechanical advance to limit the total amount of advance but that will affect the way the motor runs off of boost and that is real bad thing on a powerhouse of a 229.
I've seen some vacuum advance cans that people have modified/adapted to retard timing with boost but it doesn't seem very adjustable.
Seems like a MSD BTM box or some kind of electronic boost retard would be a better way to go.

But you may not to do much of anything with the timing at that power level though now that I think about it. Maybe a little water/meth injection will take care of it as long as you keep the IATs in check.

 

Limit your mech advance so that you can have decent initial, and also limit timing in boost, then run the vacuum advance as is with a check valve so the va never sees boost. I ran this way for a whole season, and it works great for a budget setup.

 

I was hoping for something like this.

Due to the semi odd fire i cannot run a MSD box, like a 6530? That was my original plan

 

Its easy to do, the toughest part is limiting the mech advance. On my Duraspark dist, I just figured how much to shorten the slot, and welded it partially shut. The HEI should be easier than the Ford. I set it up for 10* initial, 22* with mech in, and adjusted the va to add another 18-19* for 40-41 total. The check valve can be built for about $7 at the parts store. I ran it locked at 22* prior to doing this, and it sucked to drive off boost.... neither the engine, or I was happy.

 

What fuel do you plan to run?

What is the reason that a 6530 box wont work?

 

a bit of an oddball setup would be an ms2 with a trigger wheel doing ignition only

 

Initial plan was to try to make it happen with 87 but i do not think it will happen. So i guess 93 octane at 45~ cents more a gallon it is

 

I dont understand why a 6530 box wont work. It just delays spark timing from trigger signal based on the box settings. If your using the stock 229 distributor pickup it will trigger the msd at the proper times. Same thing done with the odd/fire 4.3s .

 

Have you made any progress with this yet?I know the threads a little old . Was just hoping

 

I'd want to call MSD and validate that. The reason I say so is that it could be doing some sort of integral calculus on the signal to establish a time base of which it will fire. By delaying the signal for X time when the engine's spinning at Y RPM it will fire X degrees before the piston rises up. They'd certainly be able to give more insight into it.

Besides that I will point out that the 78 Buick came as a turbo 3.8L and was an odd fire configuration. It may be worth looking into that for options.

 

Please let us know what they say. I have parts to put a nasty odd fire 4.3 together in the future.

 

No i ended up boosting a 267 v8 and that turned out well (went 13.9@97 on 8psi)

Ive already ripped that motor out and in the process of fitting a toyota 1uzfe v8 into the car

I hope to find another chassis to be more drag oriented with and push the 267 further with proper parts