Have a 377C with a BIGS 950 Carb, Wiand X-Cellerator, quench heads. I am having some issues with the power band once I bolted up the new carb and intake. I know my cam is a little on the small side, 536/545 lift, but I know there is more power to be had with this combo until I bump the cam.

It seems to run good up and through 4000-4500, flattens out pretty bad, then has a short surge of power again before 5000, again flattens out up to 6000?!? What's the additional short power surge about??

Let me know what you "C" guys think.

Thanks,

Carb is a BIGS 950 HP Stage 5 brand new, jetted at 81-88. Timing is set at 10deg with 38deg total in about 3000.

Funny though, the plugs don't seem look that rich to be overjetting that much, believe me I am no expert on carbs. They are a little rich though...I wanted to put a fresh set of ASF-32's in too.

70coupe, What's your poison when it comes to intakes? others have shown me the light with the strip dom, there are a couple that have had reasonably good luck with the torker.

One thing to look out for with the light springs is if the cam wants to idle over 900 rpm the distributor will try and start the advance curve at that point. Since my motor idles around 1000-1100, I had to put one light spring and one spring that was a touch heavier to get it to stop doing that. It would start to advance the timing, then once the idle slowed down, it would try to die. Blip the throttle, the thing would idle too high, till it slowed down below the advance curve again and it would try to die, rinse and repeat as necassary. I could not figure out why it wouldn't idle. It was very frustrating till I figured out what it was doing.

"With a powervalve in the front it looks like 75/82 and 77/84 were very popular jet combos on my motor".

Should I run the jet sizes square or keep them 7 sizes apart?? I have always read to always have them about 7 apart.

Kid,

I am not sure if you remember, but I am the guy that "must" run the shaker. With the weiand and the correct shaker base (which I now have on the car), I could fit a 1/2" easily, maybe a 3/4"-1". I was thinking about it over the weekend to try that. I remember you and Xerox saying that yours lit up some when you increased the spacer size. I am going to throw some washers in there tonight if I get a chance and see how high I can go before I buy one.

So you have an MSD dist in yours then? Which stop are you running then? the 25deg? If I go by the book the light blue and light silver with a 28deg stop will bring it all in over 3000 (thought we wnated it in by then). For right now I have been just looking at the chart in regards to the advance and rate of it. I haven't had someone help with the gas to actualy see if the charts are correct or not.

I would think any amount of spacer you can get under it would be better, even if it is only 1/2".

It sounds to me like your fuel pump may be starving the carb or your floats are set too low in the carb.

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Rick Austin

Tank to fuel pump is stock line, fuel pump to carb is -8AN to dual feed Barry Grant line.

As a matter of fact, I also had another little problem that wasn't a big deal to me, but when I come up to a stop light the car seems like it wants to stumble a little. I can't remember if this happens after I mash the throttle every time or not. Will this be a float level problem???

Kid, So, 21* stop with 17 deg of initial timing?

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Originally posted by orangemach1:
Kid, So, 21* stop with 17 deg of initial timing?

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You will have to figure out what yours works best with. I currently have mine with the 21* bushing and 20* initial. But my motor likes a lot of timing.

IN yours, I would probably start off with the 25* bushing, 11-13* initial, one light silver spring and one blue spring to start with.

70coupe, what numbers have you ran, jet size?

"As a matter of fact, I also had another little problem that wasn't a big deal to me, but when I come up to a stop light the car seems like it wants to stumble a little. I can't remember if this happens after I mash the throttle every time or not. Will this be a float level problem???"

With more performance upgrades planned for the future, I'd sure think about 1/2 inch line and a good electric pump. The Holley 350 has worked well for KV on alky, but that may be a bit much for a milder setup on gas. Even if fuel delivery isn't the problem now, more performance mods will make it one sometime in the future.

Just my $.02

quote:

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Originally posted by orangemach1:
"As a matter of fact, I also had another little problem that wasn't a big deal to me, but when I come up to a stop light the car seems like it wants to stumble a little. I can't remember if this happens after I mash the throttle every time or not. Will this be a float level problem???"

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Sounds like a low float level to me, but I could be wrong. The only way to know for sure is to check it while's running on flat ground.

That could also be why it has a "flat" spot in the middle of the powerband (like Rick said).

quote:

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Originally posted by Dad Vishus:
With more performance upgrades planned for the future, I'd sure think about 1/2 inch line and a good electric pump.

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Does it have solid or hydraulic lifters? Hydraulic lifters with too much preload (tightened down too far) will cause problems at higher rpm.

If it's a vacuum secondary carb, verify that the secondaries are opening. Personally, I'd do this by installing a double pumper. It doesn't take much to render the vacuum secondaries on a Holley inoperative. The diaphragm can be ripped or leaking. The connection between the vacuum 'pod' and main body can be leaking. (there's a tiny donut gasket between the two) The port where the vacuum acts can be clogged. Etc... Plus, it seems they pretty much NEVER open up all the way. Needless to say, I don't really care for vacuum secondary Holleys.

Good Luck!

Carb is BIGS Holley 950HP and Weiand XCellerator.

valves seem a little loud, I have Hydraulic lifters. Might need a valve adjustment.

Runs extremely better up top. But, I still have that "pull, flatten, pull, flatten, pull" type fo power band up above 4500 to about 6000. What does this mean. It seems to stumble while going through this area of the power band. Down low is a little worse, not much.