Help to ID Holley carb, with unusual modification?

[JohnP]

I shift manually thru the gears almost all the time because, if left in drive, I have to rev the engine up to about 5K rpm before it shifts, it seems to go from low to high gear with a hard tire chirping shift.

Manually shifts make the car more drivable.

Anyway, hoping the double pumper will be ok, won't know for sure til we get some nice weather and can get the car on the road.

thanks

[Astre-mutt]

A manual valve body doesnt rely on any engine input like vacuum, or kick down cable. The manual secondaries on the carb is going to kill your vacuum signal at wide open throttle during low RPM's. So anything that relies on a vacuum signal will be affected. Did I see a vacuum advance on the distribuitor? You probably have a few other things you need to tune other then just the carb. I think there maybe a lot more horse power left in the engine. I have to ask, did the guy that built the motor build the carb too?

[TopNX75]

John,

If the trans still has a vac modulator on it and there is no vac hose connected, this would be the reason for the high rpm/harsh shift.

The reason is that the lack of vacuum to the module makes the trans "think" that you are wide open (no vacuum), so it holds off on the shift for higher rpm, and it increases the line pressure hence the harsh shift (when it finally does.

If you run a vacuum line to the modulator, you will find the trans does a much better job at determining the load and pedal position (kinda).

Don't worry,,, when you put it to the wood (floor it), the trans will act just like it is now, high rpm/hard shift!

Hope this info helps!

Sean

[JohnP]

I'm not sure if the same guy who did the carb did the whole engine, I sure hope not . I have to contact the guy I got the car from and get some specs on the motor, I had it in an email somewhere, but lost it.

I'll have to get under the car and check out the trans, I guess it is not manual. There are no vacum lines runing to the trans, I know that. Though I'm fine just shifting it manually.

The distributor does have a vacum advance on it. I replaced the springs and weights, and replaceed the module, cap, coil of the hei with msd stuff in the summer. Little bushings on the weights were all worn shot. Inside of dizzy was all crudy, and had surface rust , that got all cleaned up too. I tried lighter springs on the weights, but it became harder to start the car. I'm not sure what my total timing is, but I do have some tuningto do there. Just need a new timing light as I melted the cables on the headers.

Could I just cap off the vacum advance on the distributor?

[Astre-mutt]

If you disconnect the vacuum line you won't get the total timing advance. Is the vacuum advance an adjustable one? There maybe a way to use the HEI with the lower vacuum. The vacuum will come back as the RPM's rise. Just something else to play with as you tune the car for acceleration. Driving around on the street it will work just fine.

[JohnP]

I finally drove the Vega today with the Proform bodies double pumper.

Well, I have some kind of stutter. When I accelerate just a bit more then just rolling, the car stutters, like a roughness. Not a stumble. When I slowly give a little more gas it clear and the car will take off fine. I nailed the accelerator when it passed this point and the car really hauled, no bog like with that hillbilly rigged carb I replaced.
In my drive from a stop I hit the gas quickly and the car launches forward without a stumble, enough to break the tires loose. In park, reving the engine throttle by hand, I hear no indication of any stutter or hesatation at all.

Any suggestion what this might be?

For some of the other gaskets and small parts I wanted to replace when doing the main body I got a rebuilt kit. I used the power valve that came in the kit. It was a 4.5, which at the time I thought was really soft. But since it came in the rebuild kit for a 750/800 cfm double pumper I used it. I think this carb originally came with a 6.5.

Other then this initial stutter this carb feels like a big improvement

[BillPappy]

I would look for a small vacum leak 1st.
Not big enuff to hear But a nuff to make it
stutter.

Did you turn the gasget under the carb backwards? would be the 1st thing I would look at.

[Sirshredalot]

Might try a new accelerator pump cam...might want just a little more fuel just a little sooner....
holley and barry grant I believe have a chart that shows the ramp rates of all the pump cams as well as the colors...see which one you have and take it a step up....or the one that offers fuel sooner...
Might be caused because the proform body came with larger pump nozzles...Do they come with nozzles?...also might have just been covered up by the botched work on the old carb.

Ive never heard of putting a base gasket on backwards....unless its a spreadbore carb.

God bless
-Shred

[BillPappy]

I was not really serious about that carb gasket But I am about vacum leaks Yes Holley has larger shooter nozzles.
A studder and not just a bog.
Most the time comes from running out of gas from the accelerator pump. A longer squirt of gas is needed. IF its not just bogging off
the line. A bigger cam might not do it. Just makes a rich/lean.
Smaller shooter nozzles can Help with a longer squirt by compressing the spring. The spring does the squirting long after stop pushing the accelerator. A 50cc Pump is nice to have.

I would still look for vacum leaks

[BillPappy]

I had a 4 barrel 305 intake that someone drilled the plenum. I could only guess trying to make the carb tuneing easyer. All they did was make a internal vacum leak. I could never get
all the stutter out of it. Drove me nuts.
I didin't notice the hole tell I was junking that
old intake.

[JohnP]

will check for vacum leak. squirter on proform body were 31-32's. There was a slight bog when snaping throttle, so I had some 35's and 37's, bog went away with 37's, they are downleg type.

here is holley cam chart
http://www.holley.com/types/Accelerator ... 0Parts.asp

Which cam would you suggest. I cannot tell or understand from this graph which would give me a bit more gas sooner. The one on the carb now is a pink one. I have a set of cams.

[Sirshredalot]

I would try the green or the blue pump cams....the chart is showing how fast and how long the pump is delivering fuel through the travel of the pump arm...with that particular color cam.

If your cam/plenum is rowdy enough you might need the 50cc pump, I recommend it alot in the primaries....Id say that 90% of all bogs and hickups are caused by a need for more fuel.

The two large ramps on that graph are for the dominator/4500 carbs only...They where yellow and brown I think.

How easily does it let you adjust the idle?...If you turn the idle screws in all the way does it die or still stay running?

God bless
-Shred

[JohnP]

Shred,
I'll give the green and blue cams a try. And maybe I'll need a 50cc pump. I'll try different cams first.

It idles pretty easy. I did not try what your sugesting. One thing I did do when I did the main body swap was to drill 3/32 holes in the primary throttle blades to aid idle adjustment.

I got into replacing my rear control arms this weekend, so it will probably take me a week to get back to tuning the carb

Thanks for help
John

[MIKESMONZA]

Do the 3310 and 4150 gasket rebuild kits fit each other????
I noticed the holley site has a hot rod part's of the year,
and that when you click onto the picture you get the info that newer models are called 4150's ???

Just got handed a dichromate "dull silver" finish 3150 with manual choke and Square botom,,

vacumn secondary,dual line bowls,,69 chevelle BB 396 Carb???

Probaly needs some work,, dissasembly, clean,soak in cleaner and reasembled with kit,,,,
by the light carbon bonded to it on the inside and choke horn ,,and secondarys end .,,,
It was on a BB 71 Chevy pu, Mike