Cascade Crew

[91RSVert]

So, since this is the first carb Ive ever messed with, I have no effing clue whats going on here.

At idle, this thing purs good, can rev the piss out it w/o a studder. You put it in gear and even move the peddle about 1/2 inch, it studders and stalls.

[Twilightoptics]

Sounds lean.

First you need to adjust the timing and tune the idle and idle mixture with the trans in gear.

[91RSVert]

we did timing, guessed an rpm(no tach), mixture with it in park. Should all of that been done in gear?

:edit: I have never heard of setting timing in gear. But other stuff, since its carb, I have no clue.

[Quasi-Traction]

what PV are you using on the primary side? What size is your "Squirter" on the primary side? Also have to consider with a DP, they're a lot less forgiving for sudden vacuum loss.

Are you running the tube from the dizzy from port or manifold advance? maybe I'm behind the curve (no pun intended)...

[91RSVert]

I have a pair of 56, and a pair of 61 jet sizes. after searching on the post I have made here, and truck board. Whichever is smaller, I would have put that on primary.

I think I installed the 8.5pv pri, and 6.5pv sec. But from the way I understand they work, I cant even put my foot in it enough to activate them.

Other thing your asking I dont understand. If it has to do with the vac advance on the dizzy. I have it hooked up to a port on the carb, not the port on the base intake.

[91RSVert]

Ive got two thoughts I want some feedback on.

1. Maybe I should have put the larger jets in primary, and smaller on second?

2. P.O. had the timing set WAY hi, like totally off the bolt on gauge. We have it set at 8. We were told this motor was built and suppose to be a beast. So likely has a cam in it?

[aaron_sK]

In your last topic on this issue my humble opinion was twofold:

1) Sell the DP and buy a VS carb. This is a truck with an automatic, not a strip car with a stick.

2) The larger jets should have been put in the primary.

I stand by those opinions.

On the vacuum advance front, there are ported and manifold vacuum ports on the carburetor. On a Holley the ported port is up high and the manifold ports are in the base plate. You should run off manifold vacuum, ported vacuum was an attempt at emissions reduction.

[91RSVert]

I'm not spending money on another damn carb. If this doesnt work, its going fuel injected of some nature. I "thought" staying carb would be simple and cheap to get it running. I could have EASLY bought FI stuff by now and had it running well enough to get around.

I'll take a pic of all the hoses and post it as I have no clue wtf your talking about on the ports.

Next, I got a message back from Holley themselfs and they said there is no electronic choke for this carb. Just effing great. Another reason to go FI.

[91RSVert]

https://sphotos-a.xx.fbcdn.net/hphotos-ash4/206733_10151201427298030_1037144285_n.jpg

All the hoses connected to the carb. I do have another vac line that goes from a port on the manifold, to the transmission.

[aaron_sK]

Looksl ike they have some sort of dashpot hooked up to the ported vacuum.

Distributor vacuum looks like it's in the right place.

Electric chokes suck. They always come back on too soon. Mechanical is far superior IMHO. Plus it keeps stupid people from borrowing your truck.

I don't know how it is down there but around here I can get runable 4V vac/sec Holleys for $75~200 all day long. You're not going to EFI swap for that cheap.

[91RSVert]

Ive never looked at carb prices locally. I do know where I can get a complete drop in 5.3l with ecm n harness for 500.

Ive spent well over that on 2 freakin parts on this.

[Twilightoptics]

Aaron wtf. Primary jets are smaller. Stop trying to confuse the poor guy with random backyard customization.



His issue hasnt even gotten into the jet circuit yet.



You should put the vacuum advance line on a manifold vacuum source.


Do you have a dial back light? You should be closer to 12 with the advance disconnected and 20 with it connected Depending on how
much the pod pulls.

Adjust thr mixture evenly to achieve thr highest vacuum. Get a cheap gauge and tee it into the manifold vacuum youve put the advance on.


Does it sound like it has a cam? If its a nasty motor carb tuning for that is a whole other level if you are not experienced.

[aaron_sK]

[chevymad]

Make sure your timing mark is actually at tdc. It's very common to have either slipped or have the wrong timing mark for the balancer. 90% of carb problems will be ignition.

[Twilightoptics]

[aaron_sK]

He is running a PV on both the primary and the secondary.

I will freely admit that my experience with secondary PV's has been discovering they were in there and then immediately plugging, but it seems to me that if you were running one you would lower the secondary jets significantly.

[chevymad]

What's the list# of this carb?

[91RSVert]

holley 6772

I put an in cab vac gauge on it today, but have not started it or drove it.

we just have a normal timing light, nothing fancy. We are setting timing with the vac source dx'd and plugged. We have it at 8.

From my experience, this does not sound like it has a super radical cam, but maybe a mild one. Im not experienced for tuning a carb period!!

When we had the motor apart, the timing mark seemed to be on, or very close (maybe 1-2 out).

[izcain]

I would be capping off the rear PV one less thing to scew with

Also if it has a few mild things done to it I think the jetting is on the light side.

Post up vacuum readings when the stumble happens!

Also here is the identification number description for the carb for anyone wanting it

6772 0 model# 4165 Direct street replacement for all Quadra-Jet carbs on 1972 350,402, 454 C.I.D. engs. Mechanical secondaries, spread bore, doublepump, 650 c.f.m., emission carb.

[izcain]

Also what color pump shot cam do you have on it? and how is the stumble...... Just when holding the throttle steady or as your accelerating and get to 1/2 inch throttle?