Technical Car cranks and runs fine, give it gas and it dies - UPDATE

Today at our regular Thursday lunch BS session Gary said he had been fighting with his Comet, he recently rebuilt the 351 and also rebuilt the Holley carburetor, the car fires up and will idle for as long as you let it, give it gas and it dies, the floats seem to be set correctly & it's getting gas but regardless of what he does the car just doesn't want to be driven,

Anyone have a suggestion, we have our club meeting tonight so I would relly like to be able to offer him any suggestions you might care to share. HRP

 

Its running out of fuel or fire? 90% of carb problems are ignition related.

 

Check pump shot might have put bowl gasket in wrong blocking hole

 

From what I gather, the fuel & fire are both working. HRP

 

If that's the case it would run properly. I would inspect igniton. check and clean all grounds . change condenser with a known good one. check the resistor or resistance wire. Not likely but I seen a vacuum advance when it moved short out the points?

 

Had the same problem with my sisters 65 mustang....ended up being the condenser in the distributor. That was after a new to new carburetor exchange.

 

Timing or advance could be an issue. Fuel delivery could too.

 

Check to see if you are getting a squirt of gas when you open the throttle. Best done when the engine is not running if you value your eyebrows (do I hear backfire?).

Charlie Stephens

 

In addition to the suggestions already offered: Cam issue? Either flat lobe(s) or off a tooth? I'd like to see a vacuum gauge reading on that engine...

 

If it has one of those sintered bronze filters , it could be stopped up. Seen this a lot on the old Quadrajets. Good Luck

 

Did it run well before he rebuilt/replaced the carb?

 

All the suggestions above are excellent. Only thing I can add is checking voltage at the coil/dist. Kind of sounds like there isn't enough juice to make the ignition work when under a load. Check it with the engine running and see if it drops or goes away when put under a load. Verify there is a solid ground at the dist. also.

 

Gary, recently rebuilt the engine, new pistons,rings,valves,valve springs & a new cam, he has built a lot of engines over the years, his son rebuilt the carburetor, Ken tunes and builds carburetors for several drag racing teams locally.

The carburetor seemed to be fine before the rebuild. HRP

 

SBF firing order correct for the engine?

 

Excel pump is EZ check,just look in to carb{when not running}an push gas link open too see if it is spraying gas. Other thing if power valve failed{ can only take one back fire or bad out of box},it can make gas mix too rich an stall. One odd thing I ran across years a go,a buddy who had build a few motor with out prob,did one that did this same trick,every one thought he could not of timed the cam wrong,after all he did a few that all ran fine! Turned out he did screw up cam timing,do to gear marks on
New timing set,with 3 sets of marks{ had" + "marks,an "-"also "0",he mixed the dot with the 0 ,so was two teeth out,but run just fine at under 1000rpm, { I didn't know before he did that,one would even run that far off with out bending the valve or back firing !

 

Check the wire from the coil to the points, could have an internal break when the distributor advances.
Quick check is a vacuum pump to the advance unit

 

This...

 

- so, he has already done the break in of motor and ran good then? has not driven since then because of current problem?

 

Coil not working right.

 

Many answers have been defined , my 2 cents are if Holley crab , the bowl gasket is on incorrect or weight under the squirter is stuck , breaker plate could be shorting or broken ground wire as stated .

 

Power valve not working (check gasket to metering block). Check to see if ball fell out of accelerator pump or check to see if soft orange rubber check valve was forgotten and not installed. I'm basing this primarily on the fact the carb was brought up first on this thread.

 

Any follow up here? Lots of great ideas pitched. I’m having a similar issue and interested to hear where Gary’s gremlin was hiding.


Sent from my iPhone using The H.A.M.B. mobile app

 

Sorry, they are not. At least not at the right time.

Ben

 

I had a Weber on a 4cyl spitfire engine that did the exact same thing.
Cleaned emulsion tubes and passages on the carb that had been "professionally rebuilt" and it ran like a top
Chappy

 

I talked with Gary last night at the club meeting and we discussed the problem with the members there, a few of us plan on going to his place Saturday and seeing if some of the suggestions here will help.

What I do know from last night, the Comet has electronic ignition so there is no condenser, with the car not running when you blip the accelerator it does spray gas, the fuel pump seems to be working and it has a new fuel filter that is full of clean gasoline. HRP

 

I'd be curious what the idle vacuum was, and definitely look for vacuum leaks. An easy check of the distributor vacuum canister is to pull it off the ported vacuum and hook it to manifold vacuum, it should speed up. A vacuum pump is nice, if you have one, but I bought my first one this year, its not a necessity for a quick check. Definitely double check the initial timing.
I'd still have to prove to myself the fuel delivery is sufficient to run at a speed above idle. Does the motor not turn up at all, or does it just choke down when you put it in gear?
Good Luck.

 

Thanks! Let us know if it gets worked out. I’m hoping to look at mine this weekend.


Sent from my iPhone using The H.A.M.B. mobile app

 

If it was a new engine, how did he break it in properly if it only idles or did I miss something. Can't do a proper engine break in without revving up the motor. If it dies on revving up than I bet he has wiped out one or more lobes on the cam.

 

What do you mean when you say "give it gas and it dies"? If you gradually increase throttle does instantly die, or does it sputter out and die... like it's getting too much fuel... or does it die the second you hit the throttle... like an ignition problem? Does it do the same when you give it a little gas or a lot of gas?