Got my combo running,355 sbc,10:1 brodix ik180 aluminum heads,650 dp blow thru with vent extensions, gt45 turbo,intercooler and snow performance water/meth.I got this running wot a air/fuel 11:4 with water meth injection. Ignition is 6al2, boost timing master,hvc2 coil timing is 14 initial plus 21 mechanical total of 35, pulling 2 degrees per psi starting at 1psi for a reduction og 15 degrees to 20 degrees at full boost. I am currently running 5 to 6psi truck seems to lay overat 5000. I am wondering why it does not want to pull by 5000 rpm? Also fuel system is aeromotive a1000 with aeromotive. Boost referenced regulator.

 

what cam specs.
Might try adding timing and see if it pulls higher.

 

Cam is a 268h xe .224 .230 at .50. .477. .480. 110 lobe sep

 

what exhaust housing a/r

 

1.05 a/r. Also truck has 4.10 gears. If I increase timing, how much are you thinking? Snow performance recommends 12.5 air fuel ratio so I am still rich according to them. Also on timing I have the btm set starting at 1 psi to pull 2 degrees per psi, base timing is set at 35 so at 5 psi I would be at 25 on timing.

 

If you have another ignition you can try, that would be worth a shot. MSD has been crap for the last several years and that sounds like what one if mine did when it laid down.

 

lock the distributor. set timing to 36ish. pull 1 degree of timing per lb of boost. you are pulling way to much timing

 

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Change out them extended tip plugs while your at it

 

What plug and heat range do you suggest?

 

Valve springs?

 

I ran NGK 6s in my turbo 267...with your compression you might go to 7s. I do not know the part numbers offhand

 

ngk 7's.

 

you are pulling too much timing. i don't care what the plugs say.

my combo
355 sbc
9.5:1
15lbs boost
timing locked at 38
pulling 15 degrees timing
i pull 1 to 1 starting immediately

best time of 10.09 @131
csu carb e85 no intercooler

 

Generally the gen 1's like timing, but telling someone to add timing, and ignore the plugs is a bad idea. Swap the plugs, get a good read on them, and then you could try to add a degree or two, and see if it helps, but watch the plugs. I also wouldn't rule out springs as Chuck posted above.

 

Plugs are your best witness to whats going on in the combustion chamber.

Ignoring them is like not looking at the evidence in a murder case

 

Valve springs are 90 on the seat and 290 open with 1.770 installed height good for .525 lift

 

Don't think that will "cut it".
A comparo w/ the turbo Buicks Those engines usually operate in the 5-5500 rpm range. Those values look to be what the stock Buick had. It operated in the 12-18psi range, when stock. They didn't work well, after some minor mods/miles. I stepped up to 120/370. No more issues @ 20+psi, [alky Control, pump gas.]
As mentioned, plug reading is essential. "Sneak up" on the tune!

 

I would suspect springs as well, anything less than 100# on the seat isn't much of a spring, especially with boost, and what I assume are 2.02/1.6 valves. I would have guessed the ik heads would have come with more spring than that.

 

I'm sticking with MSD problems. I swapped a MSD distributor out for a guy today that had less than 100 miles on it that had took a crap.