fuel/air woes
 

I have a sputter and slight popping if I try to drive right away after starting the car. If I let it warm up a few minutes the idle gets settled down and I run smoothly without any popping when slowing down in gear. Even after it's warmed up I get a sputter at the high end of the rpm band under WOT.

My setup is: 347 with T trim Vortech at 12# boost; a racing C4 by PA with 4000 stall and transbrake; an 80 mm blow through mass air with 42 lb injectors; a Kirban adjustable fuel pressure regulator; COBRA intake; Edlebrock 1.90 aluminum heads(ported);BBK 13/4 long tubes; off road h-pipe; dynomax 2 1/2 exhaust.

On the recommend of my mechanic I am getting a Cartech billet fmu to make adjustments at WOT. Do you think that will do the trick or is there something else that is making the car run rough when cold and sputter at WOT?

Hope u can help.

I know this sounds a little strange considering the 42 pound injectors but it sounds like it's leaning out. What fuel pressure are you running? (by the way, I have no idea what it should be, I haven't figured out my own pressure yet) I've seen both of mine do this.Once when the fuel filter started to plug off and when the fuel pump (on a different car) got weak enough to light the "check engine" light which signaled a lean condition on the computer.

The pressure on my pillar fuel pressure gauge reads about 34 lbs. My mechanic says the WOT fuel pressure is what counts. He is going to tune the mixture based on fuel air readings on my newly installed fuel/air ratio gauge when he installs the adjustable cartech billet fmu. This unit is supposed to be so adjustable it can even anticipate when WOT is about to occur and increase fuel delivery.

I hope that fixes the problem. All I have to worry about then is when blowby will become excessive because I get a little oil in the breather cap on the valve cover after I nail the gas. Still you have to consider the Coast High short block has over 30k miles of hard motoring.

Thanks for the info

Ignition setup...
 

What's your ignition setup and your fuel delivery(i.e. your in-line pump)? I saw that you have a 255 in tank, what do you have in-line? Are you using the stock distributor/TFI module? How old is it? ....
also, I think(?) FMU's generally make you run a little on the rich side. I'll check...

Not knowing squat about blown engines I have to rely on the written word but everything I've been reading on fuel pressure lately says you are in the "zone" at 38. Even so, what you describe is much like the problems we were having prior to installing a new fuel pump on the 89. Rich conditions would generally cause an engine to run really well when cold and get worse as it warmed up. What you are describing gets better after warmup making me think it is running too lean. I'd be real interested to see what cures the problem as the boys are planning blowers for both cars in the next few months.

chip?
 

Have you considered a chip? That is what I am going with in lieu of a FMU. I have been told by everyone worth their salt that a custom chip burned to your specs/setup is the absolute best way to go.
Just my .02.
You live in Fla too so if you want you can call Tony Gonyan at Hocus Pocus motorsports. He is the owner and will help you out.
904-282-7272