Carb is all stock with 28/28 squiter, out of the box new carb. I have tried all the way from 25 to 37 with zero change, it also has pink cams. No real noticeable puff of smoke either. Idles fine.

engine is a mild 350 with vic jr, 3.43 posi, stock converter, hyd cam.

Thanks for the help guys!

You need to be sure the pumps are adjusted propperly, .015 to .020 and change the pump cams to something with longer shots. What camshaft are you running? What is your timing curve? Your intake with a stock converter will make it a little harder to tune also.

timing is 12 initial and about 32 at 4000, I have to check it again. I know it needs to come in sooner.

It already had the pink cam, I just tried white on both and it seems to be the same.

actually i take that back, I put the white on the front no change and then I put the white on the back and the stumble is about 60% better. I'm going to compare cams to see if I can find one with more duration.

any other ideas to dial it in better???

Hii,
Does your distributor have vacuum advance ?? If not, 12 degrees is not enough initial timing. If you want to do a quick check to see if that is the problem, start the car and bump the initial timing up to about 20 degrees while running. Then try stabbing it...if your problem is gone, you know what you need to do. If you are going to try to run it on the street without vacuum advance, then you need all the timing to be in by about 1600-1800 rpm.

Originally posted by Dragn70:
You need to be sure the pumps are adjusted propperlyChech your float level.

Is there any fleeplay between the pump arm and the cump cam at an idle?

I would install two #330 pink pump cams,they have the most duration of the 30cc cams..

Do you also have the problem when it is at part throttle going to full throttle?

Sometimes an engine will have that same problem when the jetting is too lean.

Originally posted by BillK:
Hii,
Does your distributor have vacuum advance ?? If not, 12 degrees is not enough initial timing. If you want to do a quick check to see if that is the problem, start the car and bump the initial timing up to about 20 degrees while running. Then try stabbing it...if your problem is gone, you know what you need to do.Good advice.
When properly set up Iv'e never had a 650DP that didn't run like a rapped ape :D

Thanks guys,

Bill,
It does have vacuum advance. It's basically a stock kragen reman HEI. It's my friends truck so I didn't know his whole setup and unfortunately neither does he. It's a new combo so he's just getting started with it. I know he needs to recurve the dis. We'll try bumping up the timing.

I think he has about 12 initial and 32 total in by 4000, he also has a four hole spacer on a vic, not sure if this is a good idea. Cam is like 246@.050 .500 lift Clevite, too much I know. He doesn't know the exact part number that's just the info he received from the builder.

Thrasher,

We tried all sizes of squirters with no change and then replaced the pink cam with the white and actually noticed and improvement. So I was thinking about increasing sec squirt again and maybe a jet increase.

how do you know which cam has more duration. To me the white looked like it had more then the pink? :confused:

The lift and duration curve is in a book (Holley Carbs by Dave Emanuel published by SA Designs) I have.

I believe the White #218 cam is the one with the least amount of lift.

Originally posted by hilljack:
Thanks guys,

Bill,
It does have vacuum advance. It's basically a stock kragen reman HEI. It's my friends truck so I didn't know his whole setup and unfortunately neither does he. It's a new combo so he's just getting started with it. I know he needs to recurve the dis. We'll try bumping up the timing.

I think he has about 12 initial and 32 total in by 4000, he also has a four hole spacer on a vic, not sure if this is a good idea. Cam is like 246@.050 .500 lift Clevite, too much I know. He doesn't know the exact part number that's just the info he received from the builder.How much compression does the engine have?

Try taking a cranking compression test.If he has less than 165 pounds get a smaller cam.

With that cam I would set it up with no less than 20 degrees initial (no vacuum advance) with 32-36 total to be dialed in correctly.

How much converter stall and gear does this thing have?

Originally posted by thrasher:
</font><blockquote>quote:</font><hr />Originally posted by hilljack:
Thanks guys,

Bill,
It does have vacuum advance. It's basically a stock kragen reman HEI. It's my friends truck so I didn't know his whole setup and unfortunately neither does he. It's a new combo so he's just getting started with it. I know he needs to recurve the dis. We'll try bumping up the timing.

I think he has about 12 initial and 32 total in by 4000, he also has a four hole spacer on a vic, not sure if this is a good idea. Cam is like 246@.050 .500 lift Clevite, too much I know. He doesn't know the exact part number that's just the info he received from the builder.How much compression does the engine have?

Try taking a cranking compression test.If he has less than 165 pounds get a smaller cam.

With that cam I would set it up with no less than 20 degrees initial (no vacuum advance) with 32-36 total to be dialed in correctly.

How much converter stall and gear does this thing have? </font>[/QUOTE]About 10:1, KB's with 291 fullie heads. It has 3.43 with a stock converter, I know....I know we tried to tell him!!!

why do you say no vacuum advance?

So you think timing is causuing the stumble?


Thanks dude I really appreciate the help. This will help me a lot when I fire up my 406 pretty soon here graemlins/thumbsup.gif

355-Heavy Truck-Victor JR.-3.42's-Tall Tire-Stock Converter-246 at .050 cam graemlins/clonk.gif

I said no vacuum advance because I would get rid of the HEI and get a MSD distributor and run it without one.

Another guess is that he is running a tall tire,probably 28+inches.
This means that his combo should probably have a gear closer to 4.10-4.30.

1 3/4 headers???

That combination will never have a happy ending untill it gets a cam change.

Add,

10inch Stall converter for a 2800-3500 stall speed

Intake
RPM
Air Gap RPM
Holley 300-36
Weiand Stealth

Cam
Comp Cams 280 Magnum
CompCams 276XE
Isky 280Megga

Gear
3.90-4.10 for tall tire

Headers
1 5/8

=
Nuthin but :D

Right now it is really set up to run a cam more like a

Comp Cams XE268
CompCams 270Magnum
Crane Energizer 278H10
Isky 270 Megga

Of course they will also need a
Ebrock RPM
RPM AirGap
Holley 300-36
Weiand Stealth

And headers
1 5/8inch

Add a 11inch 2500-2800 stall and it will run way harder than his combo now.

I agree totally but it's his first engine an you know how that goes. He thinks he has 11:1 with flat tops but I don't want to rain on his parade. The machinist sold him a whole bunch of snake oil he didn't need :( expensive rockers, new steel crank.....etc. He was told zero deck, cam degree, 11:1......etc...etc. He got taken for a ride and it will be awhile before it sinks in.

So you think there is no chance of us getting rid of the bog condition? He did run 14.30 first time out in a 64 chevy fleetside.

the bog can be helped by a couple of things..hook the vacuum advance up to full manifold vacuum..get the timing to come in much sooner...(I assume there is no detonation problem)..raise the float level a touch..check to make sure the transition circuit of the carb isn't uncovered..this can happen by having the Idle adjustment screw to far out(because of crappy vacuum)(because of to big of cam and low CR) Make sure your getting a good squirt from the acc. pump. My 67 fleetside with a 355 goes 12.2 on the motor with a solid cam thats just a hair bigger

bigjimzIII speaks the truth.
Hook the vacuum advance up to full manifold vacuum.There should be a tube on the baseplate (lowest part of the carb) for this.

You and your friend are headed down a
LONG TUFF ROAD!!!
There is no real fix,other than going with a smaller cam or a 10inch stall and a set of 4.30's.
There are way WAY too many mismatched parts.

As bigjimzIII stated make sure the idle transfur slots aren't uncoverd at idle.
Wich I assume they are because he has low vacuum and no stall.That means he had to raise the idle speed to keep it running in gear.

Take the carb off and look in the throttle bores.
You will see two slots that extend upward.Back the idle speed screw off untill they are once again coverd.

From the bottom you will see a small screw that controlls the secondary idle throttle blade position.Give it a full turn in.This will again raise the idle speed without messing up the primary idle mixture.
Re'adjust the idle mixture screws when it is in park.

He will end up needing to put it in neutral when he approaches a stop.
Untill he get's a 10inch converter or a cam with about 270 224 470 110, that is something he will just have to live with untill he comes to his senses :(

Hey guys thanks a lot for the help. The sad part is he built this thing to smoke another guy that had a great combo. A 268XE, rpm manifold, Vortec, 355, 9.5:1, 3.36 and ran 12.90 in a 70 velle. One hell of an every day driver.

Let me see if I'm following you correctly. The manifold vacuum allows more advance at idle, ported comes in later? I know there's pros and cons to ported/unported but don't remember what they are?

Is the 10" converter to help the bog or just to help him ET better? What would the stall be on the 10"?

Originally posted by hilljack:
The sad part is he built this thing to smoke another guy that had a great combo. A 268XE, rpm manifold, Vortec, 355, 9.5:1, 3.36 and ran 12.90 in a 70 velle. One hell of an every day driver.I hope he enjoy's the looks of gleaming red tail lights tongue.gif

Hooking up the vacuum advance up to manifold vacuum will pull harder on the advance can wich will give more timing at an idle.A spark ported connection only gives vacuum at part throttle.

Any time you help a bog you will ET better.

The 10inch converter will help the bog because it will let the engine basically free rev a bit when he punches it from a stop.He will be able to apply the break and add gas bringing the RPM up to a point where the cam want's to make power(3200+).It will be much more responcive to the throttle at a higher RPM.
That cam is a dead player in a 10:1 SB350 under 3500 RPM from a performance standpoint.He truley is LOOSING MASSIVE LOW END AND MIDRANGE POWER :( When it does come up on the cam it still isn't going to accelerate that hard because the cam isn't designed to make torque,wich is what that combo REALLY NEEDS.

The 10inch will also let the engine idle in gear without the need to put it in neutral at a stop because it is looser.

With the stock stall, 3.42's, and tall tire, the engine is being forced to function in an RPM range where it is not happy at all.It will probably tend to load up plugs unless his fuel mixtures are lean.