C2:67 3810 Main Body Torture

[Gerard F.]

[Clem Z.]

Re: C2:67 3810 Main Body Torture

you should have machined the surface before dichromate because moisture will attack the unplated zink surface and did you machine the bottom suface also because if it is not flat you will have idle problems.same for the throttle base plate,check it for flatness. you do not need the extra 2 holes tapped because if those screws come loose they can end up in the intake manifold and go thru the engine. i use loc-tite on those screws on carbs that come with them. i think that is why GM left them out of the OEM carbs. you will also need to use a fixture and a press to straighten the metering bodies as they will be warped the same as the main body and will not seal to your new flat main body surface

[Gerard F.]

Re: C2:67 3810 Main Body Torture

Thanks Clem,

I did have the base also surfaced as well as both top and bottom of the throttle plate. As I have to do a few touchups of the dichromate on the body, I'll also dichromate the machined surfaces.

The primary metering block is flat and mates well with the body. But the secondary metering plate (#22)has quite a warp to it in the bottom center inward to the body and the bottom corners sticking out 1/32" on each side.
Is it possible to put the plate in a vise between two flat plates to get the warp out, or should I just get a new one.

On the two extra screws for the throttle plate, I don't see how they could go into the intake with the stock 4 hole intake (327/300) although I can see the problem with a square hole or 327/350 intake.

While I have you here, I have another question. This original 3810 (751) came with #62 main jets and a #65 power valve. My Holley book says that the correct main jets should be #65 and a #65AS power valve. Do you think the #62 jets were original or changed at a later time. Would I be running too lean it I put back the #62 jets for a 4 speed 300HP. I was thinking maybe the #62's were for an automatic.

Also, what color locktite do you use on carbs?

Jerry Fuccillo

[Clem Z.]

Re: C2:67 3810 Main Body Torture

i use loc tite #242 medium strength. the holley manual calls for #65 jets and # 65 power valve and the #22 plate is still available from holley so if you can not flatten the one you have you can get a new one. sometime when you machine both the main body and the throttle plate they may interfer with each other and not seal without using 2 gaskets. set them together without a gasket and see what you have

[Gerard F.]

Re: C2:67 3810 Main Body Torture

Clem,

I put the original 22 metering plate in a vise between two 3/8" plates and shimmed the high spot. It flattened out fairly well although not perfect. With a cork gasket and the thin steel plate it looks pretty good installed.

I scavenged a 22 plate from a later replacement and was going to use it and side by side they looked the same. However, the original metering plate was almost twice as heavy as the replacement, so I opted to use the original.

I can't figure out this 3810. On both the primary side and secondary side, one of the high speed vents has never been drilled. Would this mean that I'd be running on only one main jet on the primary side and half the secondary side, or does the lack of the vent mean that I'd be running rich on acceleration?

I'm going to put this carb back together as I got it with #62 jets, then test it out. I've got a replacement 3810 with all high speed vents open, and #65 jets.
It would be interesting to see what the difference is.

Jerry Fuccillo
#42179

[Clem Z.]

Re: C2:67 3810 Main Body Torture

the air bleeds also act a siphon break and with no hole the the fuel could contine to flow even after the engine has been shut off. i have seen this happen when a air bleed got plugged with dirt. without the air bleed that side of the carb would run rich so maybe that is why someone put in smaller jets