[Print Dad]

Hello All,
Our Mach 1 351C - has been having trouble with a new Holley and today's gas.
The gas was percolating out into the throat. The carb would get so hot, you could barely touch the front bowl.
Today I installed a 1" phenolic spacer and the carb is running cool.

My advice is that we all will need carb spacers or heat shields of some sort especially if they keep changing the gas.

I would not use an aluminum spacer as this will just transfer heat.

A quick tip if you are wondering if a spacer will fit under the hood.
Take a mound of PLay-dough and place it on the air cleaner. Close the hood and if it squishes the play-dough measure the thickness. That will tell you the amount of space between the top of air cleaner and the hood.

Just something I am hearing more and more lately with carbs running hot.

Print Dad

[Jonk67]

I installed a 1/2" phenolic spacer as it was all I could fit, still made a big difference. Couldn't hardly touch the carb before, can put my hand on it after spacer. I took readings with a cheap IR temp. gun but forgot to write them down.
I put a telescoping pencil magnet on my intake next to my air cleaner and closed the hood, it pushed the rod down to the height of the hood closed, then I measured that height. I didn't have any playDoh handy, Ok...I had eaten it all after I sniffed the elmers.
Jon

[Print Dad]

Hello Jonk67,
Nice tip about the telescoping magnet.....however...if you keep the play-do on 5 minutes per side....Mmmmmm ,.., a tasty toasty treat.

No I kid of course but a good idea with the magnet. Print Dad

[6t6gt]

DID YOU JUST BOLT CARB ON TO ENGINE DOYOU KNOW WHAT JETS ARE IN THIS SOUNDS LIKE A LEAN CONDITION, ALTHOUGH TOUGH TO GO ON YET WITH OUT MORE INFO, FUEL DOESNT BOIL LIKE THAT FOR NO REASON, YOU ARE JUST PUTTING A BAND AID ON AND MASKING THE REAL PROBLEM, FUEL IS ALSO NEEDED TO COOL THE ENGINE, BETTER PULL CARB OFF AND CHECK JETS , JETS SHOULD BE ALITTLE LARGER TO THE REAR OF ENGINE, DOES THIS CARB HAVE FOUR CORNER IDLING

[Print Dad]

Hello 6t6gt,
Let me explain a bit.
The carb is a new 4160 series with (get this) no float adjustment and no sight bowl.
So it has only the front metering block with idle mixture screws.

I put the carb on (with gaskets of course) and tried her out.
I ma running a stock fuel pump and 2 inline (clear filters) . One before the pump and one before the carb. (I know a little overkill).

The car had sat for 23 years in the garage till I finally got her going again.
I did all the prep work and compression numbers look good.

I changed all the ignition parts (cap rotor, condensor, plugs wires etc. etc.

Correct gap on the plugs and dwell is right on.

The car runs hot but not to the boiling point.

The reason I say percollation is that is what Holley told me. I called them and talked for quite some time.
When you shut off the car and pull the air cleaner you see puffs of smoke in the throat area. This to me indicates, fuel going into the intake. If the carb had bowl adjustments I would assume the front bowl is too high, but I have no way of checking

To be sure it wasn't fuel pressure I put in a fuel pressure regulator ( I know kinda overkill as the stock pump should put out 4-6), but I put it in anyway.

Bottom line...Holley is replacing the carb and I'll see.
When I get the new carb I plan to re-check all the timing etc vac etc.

All of these things have been checked and re-checked.

My only other possible issue is this Clev has a dual port vac advance (1970).
Right now I have blocked the retrad portion on just running the advance portion.

I should mention the original problem with the car is she doesn't want to "Coast" with the carb set normal (1.5 out from seated). She wants to run pretty good at a bout 3/4 out from a gentl seat, but you can still smell the gas in the exhaust.

The spacer was suggested to me by Holley.

Thanks for your comments and I would appreciate any and all further help..... Print Dad