I just got done putting my car back together and it seems like it doesn't have as much power as it should. Here is my setup:
350
stock cam Intake Lift-.383" Exhaust Lift-.401"

Intake Duration @ .050"- 194 Exhaust Duration @.050"- 202

Lobe Seperation-112
gm 383 fast burn heads 2" intake 1.55" exhaust with 62cc chambers
Wieand stealth intake manifold
670 street avenger holley carb
right now it has 65/70 jets 35 squiter and blue cam
hei ignition (summit)
1.6 roller rockers
1 5/8" heddman headers LT
2 1/2" dual exhaust with cross over
everything else is standard
I mean I can't even blow the tires off my car, I have 245s on it with spohnn LCA's. It accelerates alright until about 80 mph then the power just dies off. Also, sometimes when I accelerate (WOT) the carb sputters, almost a backfire but not quite. Not sure what to do but after all the work I just put in it I was hoping for a little more. Hope some of you guys have some suggestions.

 

Why are you running a stock cam with that setup? The cam sounds like a big problem. If you were running something more like the comp XE276 it would pull till whenever u let off the pedal.

 

Just to add to it, I know the cam sucks but I think it should still be doing better than it is. I want to change out the cam when I get back to the states because getting stuff in germany is a PITA.

 

You said it stumbles when u hit WOT does it do it when you first floor it or when it accelerating? As far as your combo all of it should work pretty well together except the cam is killing it.

 

it does the sputter mid part through acceleration. Not at first, know what I mean? I know the cam is killing it but I was wondering if maybe I have mistuned something? I just really thought it would put out some more.

 

f355bird, was wondering how that setup is doing for you? What size jets do you run with it? Did you ever try the wieand manifold? Hope I don't have too many questions but I don't see too many people with the 670

 

As for your stumble part way through accelerating im not sure what can cause that. If it was intial i would say carb if it is upper rpm's i would say weak ignition or weak fuel. But in the middle i dont know.


I just got my car running not too long ago and im still tuning. Right now i have 72 jets in the front and whatever is stock in the rear. It runs a little bit rich at idle so we are going to put 70's in the front. As for the rear we are going to jet it up some. The only problem mine is giving me is a stumble when i floor it which is the accelerator pump we are going to increase the pump shot so the stumble goes away. Other than that it runs great.

 

And as for the manifold never tryed the weiand i had a victor jr on before the rpm manifold. And before that i was fuel injected and i have ran 2 different setups fuel injected i ran the stealth ram and the stock TPI.

 

When your talking about the comp 276 which is it? I tried a search on summit and it came up with a hundred types. Wondered if you knew the part number? Some other guys I talked to a while back suggested to get the xe274
Advertised Intake Duration: 274
Advertised Exhaust Duration: 286
Advertised Duration: 274 int./286 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.487
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.490
What do you think, go bigger? Also have to keep in mind I have an older block with the flat tappet, so no roller for me besides the rocker arms.

 

with the manifold I was wondering if switching it up to the air gap or rpm like you have would help out mid range or top end. Right now my low and mid range is alright but top end is ugly. Thats why I jetted up on the secondaries to experiment, not sure if it helped out or not. I went with a lighter spring on the secondaries and it seemed to help with mid range some (purple spring) You could try the larger shooter and blue cam for your accelerator pump, might help out. I got that advice from chickenman

 

oops i was used to looking at roller cams. For your flat tappet setup i would go with the X268 if u wanted a more broad power band or the xe274 if you wanted more mid to high rpm power. The xe274 will make the most power but will give up some lowend.

 

The rpm intake is great if you wanted to step up to the rpm intake i would pick the xe274 and that thing would scream mid to high rpm's. On my carb i am running the lightest secondary spring.

 

I have enough lowend as it is, I think I'll stick with the xe274 though. I keep thinking about the sputter in mid acceleration. I don't understand it. At first I had a problem with a stumble in the beginning so I upped the squirter and changed the cam and it was night and day difference. Then I started having this sputter and I thought maybe it was the choke because it was cool outside. Adjusted it and same thing. So then I thought maybe jet up a little and see, same thing. But I only jetted up on the secondary side not the primary. Do you think the primary would make a difference? Also thought maybe something with timing? I don't know, I have my timing set at 14 intial and 34 at WOT. I think this is about right for my situation. I also have my vac advance hooked up to full vacuum and not port.

 

I might try out a lighter one. I have the yellow and the white left with purple in it now. You're like the first person I heard of running the lightest. Most the guys run the brown or black, but you've a 670 like me. I'll try that out later today and see what happens.

 

now that i think of it thats what my car was doing originally when i would floor it would pop and cutout going up in the rpms. It didnt quit doing that untill i had 70's up front it was leaning out and that making it cutout. I wasnt even thinking about that untill i read u asking about the primaries. Yes jet the primaries up that should solve your problem. When you do it go up in 2 increments.

 

thats pretty funny we are both having the same problems with all of it on the carb.

 

Right on I'll go and do that right now and see what happens. Its cool that we've got the same carbs, makes troubleshooting easier. By the way what squirter and cam are you using on your carb now?

 

whatever is stock i havent touched it.

 

If haven't read any of chickenman's posts then try what I said before, 35 squirter and the blue accelerator pump cam with the screw in the #2 slot. It really helped out my situation because I couldn't even hit the gas and it would almost die.

 

I will give it try later today and see what happens

 

Oh and you were talking about u couldnt spin the tires neither could i before i jetted up. After i richend it up i haze the tires from a roll without any problems if that tells u the difference. And i am running 275-40-17's

 

hey, I'm going to add you to my buddy list. I'll give it a try because that sounds like a huge difference. Maybe my problem right there. I'll pm you with my results. Let me know how the settings on the pump work out for you. Have to go take it easy
and thanks for the help

 

No problem good luck