R&R choke plate on 390CFM Holley 0-8007

crs · Apr 1, 2015

How to perform this function:
R&R choke plate on 390CFM Holley- part number 0-8007

Background: During the early testing of my V6, there were a few instances when there was a back fire through the carburetor. On one occasion it was so violent that the choke plate stuck and would not move with finger pressure and some gentle tapping with the butt of a screw driver. The mechanic that was working on the car had to force the plate open and it bent a bit. After that it occasionally stuck and had to be tapped open to function. Then the sticking stopped and I broke in the engine with no issues.

Situation : Now with 1300 miles on the engine, the plate stuck again last week after some really cold weather and had to be tapped open. I surmised that the plate must be replaced and ordered one from Summit racing. The new plate looks like this:

The factory plate is held on with two small screws but the new plate has no holes, just two stamped impressed places. Do I drill holes in the plate depressions or knock out these depressions to form slots? Any help will be appreciated as I do not wish to take the wrong approach and ruin the plate.

pcmenten · Apr 1, 2015

It looks to me like the ridge above the tits and the tits below are meant to locate the choke plate on the shaft. The ridge above and the tits below. Anybody else think so?

sd_pace · Apr 2, 2015

match it to the old one first

crs · May 7, 2015

Holley Carb Mystery solved

After considerable digging on the web and talking to Tim, a friend that owns an auto shop, the following is my understanding of the situation:

The Holley web site has only one choice for the choke plate and shaft for my four barrel carburetor (model 4150, part number 8007) . This is true for web sites that distribute Holley carbs and parts , since they sell the actual Holley parts, not copies or used. The parts are for current Holley carbs do not fit older carbs. Mine was purchased new (must have been rebuilt actually) from Summit Racing during the V6 project.

The current plate and shaft sold by Holley work together, but the shaft is of greater diameter than the original (original = .247 and new = .317 inches). From reading reviews on web sites, I learned that this incompatibility has tripped up many buyers and caused bad ratings. Some sites do mention the diameter of the shaft but say no more about it. Some folks reamed out their original shaft sockets to allow use of the new shaft.

My experienced mechanic friend said this type change is typical of Holley and other manufacturers and he gave me the serial number ranges of the original and newer Holley carburetors so that I can be on the lookout for one with parts that will be compatible with my carb (there are also other differences, so I may just locate and purchase a "parts" carb to keep around.

Meanwhile, I need the car to be useable, so using my workshop vise and hammer and anvil, I flattened the bent plate and filed off rough spots. Then I put one edge of the new plate (which had the bumps on it but is exactly the same OD ) into the slot on the bent shaft and straightened the shaft in the vise. It is all back together now and Tim says it should work fine; if not I will let you know after I install and test it.

Looks pretty good, if I do say so myself!

Now on to other things that will hopefully be easier to solve.

crs · Jun 7, 2015

Finally got around to installing the straightened choke plate in my Holley and it fits perfectly. Starts instantly and fast and slow idle are right on.

Gitnrusty · Jun 7, 2015

Choke plate

A little off topic I'm afraid, but in the photo of your engine compartment is the upper radiator hose that looks like a perfect fit for the 2.8 conversion.
Would you have the brand and part number for that hose?
If you could post same it would save me some parts hunting.
Thanks.

Hillman · Jun 8, 2015

Maybe a dumb question and off topic, but do you need a choke in April in the Republic of Texas? Isn't it in the 60's at least by then?

Here in the frozen north, I drive my (1725) Alpine from about April 1 to November 1 (if the snow is gone or hasn't returned). I haven't bothered to fix the choke (needs new cable). It's easy to start.

My 2.8 V6 has yet to see the road, so we'll see.

crs · Jun 8, 2015

Hillman - in cold weather, the Holley electric choke does work and is beneficial. In summer, it is not needed and the starting idle is slower than the fast idle in winter.

Gitinrusty - I will get the info from the hose next time I pop the hood.

At present, most of my time goes to catching up on farm work now that the monsoons have ended.

crs · Jun 25, 2015

Gitnrusty

In this picture, the hose does look to be a perfect fit and it is a good fit:

So I took another picture for you and saw that it is crimped a bit where it connects to the engine:

I now remember that the mechanic cut a flexible straight hose to fit; it seems it may need a bit removed at the engine end, but the motor runs at thermostat temperature so sufficient water is flowing through it.
The same solution should work for you. Good luck with you conversion.