frightening day
 

O.K. so I get the idle circuit working almost. Far from what it was months ago but o.k.- just a bit of backfire and no spitting. So it's time to drive some distance and see how things work on the main circuit. For various reasons I have only driven the car up the street and back so it's mostly been idle circuit. So... warm up drive about three city blocks and it's almost fine( encouraged!) come back and do it again. This time, on return, I notice a bit of heat on the one side-i.e boiling fuel. Not much but some. So... off for the third run. I might also mention that I'm punching it here and appreciate the response. I'm really pleased at how fast the engine revs and how fast the car is.... BUT about half way out all hell breaks loose. I have smoke billowing from the hood. Stop and open the hood to see flames.( I got to test my extinguisher)Nothing destroyed so I try to restart. Every time I restart I see fuel spurting from the hole between the jets( I have the small screen off now). Needless to say not a good situation. I take the top off two carbs and the floats don't seem to be sticking. I'm just getting too much fuel pushed through on the main circuit.
Here is what I have and would appreciate any help. I noticed in the most recent posts that fuel/heat sink problems come with these carbs but I really have an unsafe situation at this point-
Engine- 306
Carbs- 48IDA
Main.... F11 Emul tube
155 main jet
200 air corrector jet
Idle......60 idle jet
1.0 holder
exhaust valve 50
choke 37
needle valve 200
Most of this/and changes are from conversation with Jim Ingelese but I thought I'd start here before asking him for help.
Any and all ideas will be greatly appreciated. If' I wasn't scared to death at this point I'd just be depressed with what happened today:CRY:. Thanks Jon

Sounds like your fuel pressure is too high

Hi Jon,

A few things to check are:

Are all the floats levels correct as per IDA procedures?

Were the fuel lines flushed are assembly PRIOR to fitting to the carbs?

Fuel line debris could be preventing a needle and seat from closing correctly.

What fuel pump are you using?

Do you have a fuel pressure regulator?

What pressure do you have it set at?

In answer to questions-
1-yes, did set the floats twice and I think they are o.k.
2-Didn't flush lines but did check and blow out jet openings to check for a prior problem. I did do some clean up to the ends of my lines .I'm using cloth bound lines for the period look but with the teflon liners. Debris from that might be the culprit.
3-120 gal mechanical pump with a Holly pressure reg. right behind it set to just under 3#.

I'm over the total frustration at this point and will open up all the carbs today. I can only assume that this has to do with the main circuit but , as you said, Gaz64, something is keeping the needle valve open-debris or just sticking. I'll report back about what I find. Thanks, Jon

btw- have many of you had success with the spacers under the carbs to cool them a bit? I seem to read spotty reports here on the forum.

from reading your post I can't tell if all the carbs are overflowing, or those on one side, or just one.

In any case it does sound like an overpressure and/or no sealing at the needle valve situation.

By the way, I had a small fire in December, and the heat damaged one of the floats. The strap that is part of the float needle tang had gotten hot and was drooping in such a way that it was keeping the float needle from closing, So be sure to recheck all the float settings, especially on the carbs that were on fire.

Z.

webers do take sometime to get sorted out, but totally worth it.
2.5 lbs of fuel pressure
make sure voltage regulator is working right (electric fuel pump)
clean out jets
38 degs full advance on timing
call Jim
trash in the line is common with a new build. Phenolic adapters didn't do much
on mine. Getting the timing right cooled things down.
call Jim

Note to self-do not use a heat gun to smooth out the fuzzies on the end of cloth covered fuel lines. Yes, I found dirt.Probably the result of my taking the lines apart to make them look neater. I've only done two of the carbs but there is more stuff in the bottom of the float bowls and at the bottom of the jet seats than I want. Now I need to figure out how to flush out the lines from the pump before I put them back on.
The rear off side shows the most destruction from this event- heater is toast and some relays on the fire wall may be lost but I feel pretty lucky. My problem could have been much worse. Jon

Yes, that could have been MUCH worse!

A couple of things, what filters are you using? I have a 100 micron before the pump and a 10 micron before the carbs. Clean fuel is a must.

Secondly, if you had that much fuel pouring down your intake, change your oil. It doesn't take much gas in your oil to damage your internals.

Many of the weber guys use an electric fuel pump and shut it off a block or two before they stop to help reduce the amount of fuel in the carbs to reduce boil over.

i use the spacers on my webers ,my floats are set just a little low,run 2.5 and 38deg. all in 2200 rpm , carter fuel pump with a holley reg. no return line.has not boiled over sence i set up this way.

Actually I think I had more gas spurting out over the engine than getting into the oil but I will probably change it just in case. I;m pleased that I actually acted quickly enough to reduce damages. Opening the hood to that picture of flames was not something I ever want to see again.
I have a Fram filter back at the tank but no other filters. Except those little cylinders in the carbs. I think they are there to collect small rocks. I might add the 10 micron in line as suggested and I'm going to replace the fuel pressure gauge. I want to make sure I don't have too much and what is there now is a cheap Jegs liquid filled. It was set to a little under 3#. Also going to very carefully recheck timing. As suggested that may help with the boiling issue. I think I need to address that as much as the line debris.That's why I was asking about the success with spacers. Thanks for all the input. Jon