six pak bog-need help

[etoyman]

To the six pak experts
i'm running a 6 pak on my '70 440 (.030) eddy 84cc heads
4 speed car
I like to visit the local track 4-5 times a year ..after my best pass last year the car developed a bog that I can't seem to get rid of
I've experimented with pump cams, different squirters, timing etc- no luck
Any advice appreciated
regads
Enzo

 

[69 Runner]

more info. what cam? are your carbs set up vacuum or (god help us all) mechanical? Where is the bog? What rpm?

 

[etoyman]

Bob Karakashian camshaft-(lift and duration are N/A) vacuum
Bog is off the line -as soon a i put my foot into it -lays down and then does respond but by that time I've lost a lot of momentum
I've tried launching at 3000 which does help a bit
but launching at an idle doesn't work

 

[69 Runner]

I know Bob and have used his cams. Are you sure you're getting a good shot from the accelerator pump? Have you checked your vacuum and timing lately?

 

[Meep-Meep]

What's the vacuum at idle? (will give idea of what kind of cam). What diaphragm springs are installed? ARE there springs installed?? Secondary metering plate main restrictions restricted?

 

[etoyman]

six pack bog

Vacuum at idle 17"
QFT metering plates 68 jets centre carbs...79-81 staggered outboards
timing 10 deg initial- 36 total
was running the black springs ..changed to the white with little or no difference
On the pump cams I have experimented on 4 occasions.. going a little more aggressive each time ...but still no cure

 

[Max Weg]

Hi,

Change your pump to a 50cc and I will check what squirter size I use. A bog off the line is all squirter to get past the transition, jetting plays no part. I run a 69 RR 440 6-barrel 3.55 gear 29" tire with auto and had similair problems, it runs low 12's at 112 to 114 mph on pump gas and closed exhaust. Use purple springs in the outboard carbs.

Max Weg

 

[dantrap]

Hi, I believe Max Weg has hit the answer on the head. I used to run a similar 6pak setup and had the bog. Went to a 50cc pump and stepped up in shooter size. I also used the light clear or uncoated springs and raised the carbs using a 1" thick spacer under each one. The change did not cost much and the car worked fine. Good luck, let us know how you make out. dan

 

[69 Runner]

Bet if you call Bob (who has run 12.0's with his red car) he'll tell you you don't need a 50cc pump. I'm pretty sure he doesn't run one, and neither did I running 110.6mph

 

[etoyman]

Hi Gentlemen
thanks for the advice-I'm currently running a 30CC pump cam with a .035 squirter-no luck
What puzzles me -my best run was with the stock pump cam and .028 squirter
What did you guys do with the adjustable ports on the outboard bases
thanks again for your input

 

[69 Runner]

didn't touch them

 

[dantrap]

I had Ray Murry at R&M Comp. fuel systems, Carbs set mine up at the time the set-up was freshened. Never touched them after that and they worked great. He not to far away from you (Buffalo NY) and is a Mopar guy as well as a Holley expert. He has a shop that is as clean or cleaner as a 10k industral clean room. You can call him at (716)-649-1636 he can help you out. He does Alky carbs, E-85 conversions and all kinds of neat carb stuff. He can even re-anodize or have your setup powder coated. Tell him Big Dan sent ya.

 

[Meep-Meep]

I agree, 30 cc pump should be fine (at least in my experience). You want as little accel pump as you can get away with. White cam, position 1 and a .028" squirter should be enough for a 4 spd. About a 64 main jet should be about right.

I've adjusted the idle mixture on the secondary carbs to get a good idle. These are necessary to get a good idle because the secondary butterflies are cracked ever so slightly so they don't stick in the bores. A good basic adjustment is to remove the carbs and back off the idle stop screw to seat the butterflies, then run it up until the lever just keeps the shaft from sticking. You should have about the same amount of light showing in each barrel, and if not, then loosen the butterfly screws to allow them to float in the bores and tap with the screw driver handle until they seat tight. Tighten shaft screws and repeat adjustment. You can pull plug wires out of the cap while it's idling to check mixture strength for each cylinder - very effective. Pull out of the cap so you are not holding a live wire looking for ground!

I'm starting to wonder if you have a timing curve issue. Do you have a vacuum advance hooked up? is it connected to the ported port on the carb or manifold vacuum? You said you have a 70 engine. Are you running the dual diaphragm advance? Make sure you are getting a smooth advance curve as the RPM increases.

 

[Max Weg]

Hi,

Screwing with the pump cams are for setting the squirt timing and will have little or no effect on your bog. Check your vacumm and put in the right power valve 66 jets on the center carb. adjust your float levels approx. 2/3 the way up the opening so it is high, ensure you have high enough bowl vents if not put on vent extensions. If you are street driving a 30cc pump will suffice as the tire spin will make up for the transition but at the track there will not be spin therefore it needs fuel for the transition. Playing with your idle circuit will as well not provide a stumble free transition. Listen to people who have done there homework.

 

[etoyman]

Hi Fellas
sorry for the long delay in responding
Finally got tot the track on July 18 weekend-first pass 15 deg initial- 38deg total- outboard carb 3/4 turn- (new drag radial T/a's) still a bog 1st & 2nd pass
Changed to # 32 squirter-68 jets to 66- better et's but still hesitation
Run 4 and 5 stll hesitating- missing on top end
Changed clear springs to purple- stll a bog
run # 8 changed pump cam from orange to pink pos. # 1 stll hesitation
Run #9 no changes -car responded
(Phord running after me oiled the track -done for the day)
hoping to get to the track this weekend if weather co-operates
let you know
thanks for all your input
Enzo

 

[Meep-Meep]

Try making a pass with the outboard carbs disconnected - unless you know for sure the center carb is working properly. Also, is the bleed port in the vacuum signal passage plugged causing too fast opening of the outboard carbs?? I wonder if teeing in a vacuum gauge in the outboard carb actuator circuit would provide some useful info?? You said it was basically fine then developed a bog. Hmmmm.

 

[Max Weg]

Did you install a 50 cc pump? The squirt needs to be long enough otherwise it will bog.

 

[69 Runner]

Shouldn't need a 50cc pump

 

[Max Weg]

Yes your right if you run a small shooter and drive on the street you don't need a 50cc shooter. If you have a heavy car not a lot of gear you need to give it a bigger shot to get past the transition. Changing the pump is 4 screws and took me 10 minutes and solved my problems. Before that I would have a pass here and there that the car worked okay. With my current set up I can drive to the track swap on slicks and leave the hood on and race all day and then drive home. Just my 2 cents

 

[69 Runner]

I'm just sayin. My Challenger was 3960 pounds, ran [email protected] on Polyglas tires, and didn't bog. Don't think it would have with stickies either, since the numbers figured out to (I think it was) about 419 to the ground