Tyrel B

Noticed the rear carb on my 68 427 tripower is dripping fuel directly onto the throttle plates out of a small hole right above the throttle plate on passenger side of the carb. Not sure if that means the float level is possibly not adjusted right or something else? I adjusted the float level of all three carbs yesterday and thought I had them all set right. On my driveway, which is pretty dang level, I adjusted them all to right at the bottom of the sight screw so fuel would just barley run out. I had all the carbs restored by chicago corvette 4 years ago or so aswell. Im no carb guru so alittle help would be great. Thanks

JBrooke825

Adjust it after it is warmed up so it doesn’t come out of the carb until
You take your knee and shake the car. Try it again.

Tyrel B

I have readjusted the floats, and it did not change the problem at all. Would going through and putting a rebuild kit/gasket kit help the problem?

v2racing

It sounds like the small hole could be the ported vacuum hole. It should not have fuel coming out of it. It probably is a gasket problem. I would just order a gasket set and replace them. Clean the carb up good while your there and inspect the power valve. If it feels stiff or looks like it is developing cracks in the rubber, replace it. If it's got a few years on it, I would replace it just because. I would replace the fuel pump diaphram too just to be safe also.

Mike

MelWff

I think a picture would be best before you do anything further.

Tyrel B

Tyrel B

Your right, pictures always help. I ran the car for not even a minute and it just leaks out of that hole in little "gulps", I guess you could say, when shut off. I have a video but don't know how to attach it, but I think you can gather what's going on.

thecorvette

No expert here, but I would try to close the throttle blades just a bit with the idle speed screw until it "leaking" stops. May need to reset idle speed on center carburetor.

Or, if front one is not "leaking", remove front and rear carburetors and compare.
Looking at the relation between the throttle plate and transition slot (looking up front the bottom of the carburetor), adjust the rear to match the front. Probably will need to reset idle speed.

Or just google "adjust throttle blade in relation to transfer slot".

Keep track of everything you change so you can put it back as it was just in case.

Once again, no expert here.

Tyrel B

I can see the slot on the front carb and it is bone dry. The rear carb leaks alot of fuel out after shut down, you can watch it just run out over the throttle blades. I can look and compare the front and rear carbs to see if there is any difference there.

suprspooky

If float levels are good and no blown PV's this can be caused by leaking Metering Plate Gaskets, try tightening the Float Bowl Screws first. If it still leaks, I'd disassemble and inspect sealing surfaces for corrosion (hopefully not the problem). If needed I can post pics of said corrosion, I ended up replacing Metering Plates on mine as no amount of tightening could stop the leaking.

sug

Sounds like you need three Holley #37-396 carb rebuild kits .

3X2

Is the closing linkage adjusted correctly?

JBrooke825

Tyrel B

I will check the float Bowl screws, and also the closing linkage. What is the proper way to set the closing linkage? Also, how do you know a PV is bad without physically inspecting it? I hear people talk about a blown PV from a backfire, but I'm not 100% sure how to tell.

3X2

I'm going from memory with this. Disconnect front and rear carbs. Engine at operating temperature, timing correct, and idle speed & mixtures screws set. I do this with the air cleaner installed. Bottom out the clevis pin in the slot of the center carb. Adjust the rear carb rod so that it is short of the hole by 1/2 of the rod diameter, then connect the rear carb. Adjust the front carb rod so that the rod just enters the hole in the lever, then connect the rod. Verify all carbs are fully closed.

MelWff

that hole is the idle transfer slot, before tearing things apart, do as others have suggested and make sure the bowl screws are tight. Just be careful when tightening to not strip the screws, they should be just hand tight. A PV leaks on a running engine not an engine that is shut off and it doesnt leak out the idle transfer slot. In addition the front and rear carbs do not have a PV.

Tyrel B

I will check the linkage, but fuel shouldn't come out of the slot after shutdown. The fact that it does would that mean the metering plate isn't tight, like the float bowl screws are loose, or the plate is warped?

Jims66

Also, when you get this all sorted out (which you will) don't forget to change your oil and filter. You've had alot of "wash down" from what I've read above. Good Luck

MelWff

You wont know until you check the screws. If they are loose, tighten them and see if the leak stops. If they are not loose or the leak doesnt stop you will have to disassemble the carburetor and check the metering plate and see if the gasket had shrunk/distorted causing the leak.

suprspooky

If you end up disassembling save yourself some headaches and install the nylon washers for the Bowl Screws, the Holley red or blue Gaskets have great life for Carbs that sit a lot and get opened up occasionally. As one of the other reply's mentioned don't over tighten (spec. is 25-30 inch pounds). You may also want to upgrade the Bowl Inlet Fittings to Holley 26-162, they have a 3/4" Hex instead of the 1" or 13/16" Hex and make leak free servicing easier.