What was the #'s...hard to see it. John may be right, time for a carb!! Im not a pump gas fan, put some good gas in it and put a good tune it and call it a day. There HAS to be more on the table.

 

We made 610 on 10psi with pump gas, you need to tune it on your own. That's why we went carb, i didn't trust anyone to tune "my money". You will hurt things with that low of timing...fact. You will make more power with more timing...fact. Did i see somewhere that your AF was 11.8 at WOT?? If it is, that's too close for pump. Another thing to think about is that not all 93 octane gas is the same. One bad/low octane fill up that you don't know about and your done.

I'd set the boost to 13-14psi, put 19* of timing in it (under boost) and get the AF around 10.5-10.8. Then slowly up the boost and timing. Hell alot of what we did, we never had a intercooler of any kind, so you should have more room to play with.

john

 

What valve springs are you using? In the past (years ago) I built a Chevy motor (Carb'd) with Vic heads that wasnt making as much HP beyond 5500 where it should have made another 100hp from 5500 - 7000. The heads I bought came with Comp springs that were good to .600 lift. I played with the timing and carb till I was blue in the face and every pass I made I was just getting pissed off. The car wouldnt pull beyond 6000 RPM. My father inlaw recommended that I change valve springs so I went with stiffer springs and changed out the pushrods as well. This was a solid lifter flat tappet cam designed to make power between 3000 - 7000.

Changing the valve springs was like night and day difference. Pulled all the way to 7000. Turned out I was experiencing valve float and didnt know it. Solid lifter flat tappet cams are pretty noisy to begin with and I was not very experienced with them. Live and learn.

Not saying this is your problem. But it is an avenue that you can investigate. Lifters, pushrods and valve springs.

Hurst

 

555 and 598 but falls off at 4800RPM.im going to the track thursday and im going to run it with the tune and then put in my pms and see what the diffrence is.if it runs better with the pms then its in the tune

 

i used you as a example and told them you made over 600 and if i remember right you said you had a smaller turbo.as for the timing you are the 2nd person thats told me that low timing can hurt the motor.i took the car to the dyno day yesterday and car made same power and the graph is the same i think the tuner has it set up drop off at 4800RPM because its doing the same thing on 2 diffrent dynos

first dyno


2nd dyno diffrent sop

 

the valve springs are the dual valve springs that came on the victor jr heads.springs are good for .650 list and i have a .550 list.what i dont understand is how its falling off at 4800RPM when a stock 5.0 is about the same if not better

 

What you have to see if they are for roller or non roller. They come both ways but are much different springs. Maybe the springs are done when you hit 4800?? When boost comes into play, things start acting goofy, where you may not experience it with a N/A set-up

The Vr Jr's I have come with the .650 springs, but for a flat tappet cam

 

ill ask spencer on here i got the heads from him.if i remember right he said they were part number 77189 which on summit does not say what springs they are

 

Edelbrock 77189 - Edelbrock Victor Jr. Cylinder Heads - Overview - SummitRacing.com this is the heads
edelbrock say's solid flat tappet or hyd roller http://www.edelbrock.com/automotive_...ictor_jr.shtml

hope this helps.

 

You seem to be focusing on spark, what about your fuel system? Have you done any logs on the dyno of the pumps duty cycle %?
Is your rail pressure holding steady at 5K?