pcard

I was working on the car last week, moving it in and out of a work bay once a day for five days. No other driving, so the engine really never even warmed up.
On the last day I took the air cleaner off in order to make an adjustment to the hot air pipe, and I noticed that the carburetor seals (see red arrows in photos) were soaked with fuel.

Background:
this is a 1970 455, carb 7040251 rebuilt in April 2012
car was driven 2500 miles in July 2012 with no carb issues other than sticky accelerator pump
carb accelerator pump was replaced October 2012 with a new NAPA kit
carb was removed from car for this repair
car has not been driven other than a quick test since accelerator pump replaced
no other issues with carb
carb bolts and scews are firm
engine starts and runs well
hot air pipe is about 0.2" long resulting in the air cleaner riding a bit high on passenger side

I am now home and have no access to the car.

Can anyone suggest what may be causing these seals to be soaked in fuel?

As always - I appreciate your input.

Thanks, Peter

Rickman48

Unless you've a Crap kit with JUNK gaskets, I'd just remove the carb and tighten ALL the screws as tight as possible. Snug isn't enough!
There are also screws on the bottom - don't miss those!
If that doesn't do it, get a rebuild kit, and replace the gaskets - they might have fallen apart with age, being fuel soaked.
Todays "fuel" has so much garbage in it, it may have eaten the gaskets - most new kits are made to accomodate that.

joe_padavano

Some wicking of fuel from the float bowl into the paper gasket on the air horn is normal, but this looks like more than that. Check the float level and the fuel pressure. If the fuel level in the float bowl is too high (which could be caused by either float level or fuel pressure), that could cause the problem.

BILL DEMMER

over-tightening the screws is not going to fix anything, but will likely distort/strip parts.

check your fuel pressure, first!
get back to us after you have a fuel pressure number.


bill

pcard

Will do - it won't be until April I afraid.
I have a feeling it is in some way related to the replacement of the accelerator pump. I followed the torquing sequnce for the reassembly, and the screws are firm. But I wonder if the new pump I put in is not sealing properly.
I will not know until I can play with it some more.

Lady72nRob71

when you can, take the thinnest feeler gauge you have and try to insert it between the metal and the gaskets. I have seen where the metal is warped due to screw overtightening in the past, or over tightening the air cleaner nut.

pcard

You know your thread has hit the big time when Lady come to the party! Hey Rob

I hope it is not a case of warping the horn. This condition did not exist before I replaced the accelerator pump, and I tried really hard to follow the torquing sequence specified and not over tighten the screws.

I wanted to ask a question about checking the fuel pressure. The Service Manual says to test the pressure with the engine at slow idle, running on fuel in the carb.
To do this the engine must be warned up, or else the choke will keep it at high idle.
I feel a bit apprehensive about warming the engine up and then disconnecting the fuel line, letting fuel spill on the intake while it is hot, in order to put the pressure gauge on.
Any hints or suggestions on how to do this safely? I have scowered youtube but cannot find anyone testing fuel pressure on a 455.

Cheers, Peter

TripDeuces

What Joe said, float level and/or fuel pressure

ROCKET VAPOR

Just thinking out loud here, but could an ethanol blended gas factor into this gasket issue at all?

The reason I bring this up is I have been hearing about some issues with this blended fuel in our older cars lately.

BILL DEMMER

does the accelerator pump shoot 2 strong, solid streams of gas into the primary bores when you snap the throttle wide open? does gas come shooting up and out of the carb. when you do this? if you get 2 strong, solid streams of gas shooting in to the primary bores, and no gas shooting up and out of the carb; you've verified that the accelerator pump is not the problem.

can you expand on the "sticky accelerator pump" issue?

with the amount of gunk over by the vacuum break bracket, i think it's been having problems longer than you think.


bill

pcard

Hey Bill - I will be checking the pump oeration first off to see if there is any fuel seeping out.
The "sticky pump" was a result of the shaft binding in the fully extened position and in effect no longer being spring loaded. On acceleration the shaft would force the plunger into the fully seated postion and then stop, in essence removing the function of the duration spring. The shaft was a cheap reproduction with bad tolerances. THe replacement works as designed.
I note the comment about the dirt around the break bracket.
From suggestions above the sequence of investigation will be:
- observe operation with air filter removed to determine if fuel leak is visible
- assuming nothing observed then
- check fuel pump pressure
- pressure ok then
- remove carb
- remove air horn
- verify/adjust float level
- replace horn gasket
- install carb
- if fuel pressure high then
- replace fuel pump

Thanks, Peter