Need Help Intermittent Stalling L36 Holley 3370

[Neil C.]

On my 66 Vette 427/390 Holley#3370>>>
Car was running fine for year and a half THEN occasional Stalling like Switch to ignition turned off suddenly and at first happened while driving only. When starting and idling it never did this even if idling in garage forv 45 minutes . Only on occasion while moving in gear. Now its getting more frequent and even now on occasion when starting...

New Battery/ Voltage regulator/Fuel Pump/ New Gas Tank/ New Rubber fuel Hoses Front and Rear / New Metal Pump to Carb Line/ New Rotor/New Plugs/ New Spark Plug Wires/New Coil /New Distributor Cap.... ( All either NOS or GM Authorised repos)

Is this Electric or Fuel???

Previously had an accelerator pump gasket diaphram replaced as leaking from gas with 10% ethanol ? Mechanic also epoxied a fuel leak from a carb bowl this spring
Shaking the Ignition Key and jiggling wires does not replicate. .. When car stalls all Lights radio etc remain on. Popping the clutch is worthless and ONLY a Keyed Ignition Restart fires it back up instantly. It ALWAYS restarts whther hot or cold but you never know when its going to QUIT next. Ive also recently had some only on a few occasions backfire loud pops ...Is it The CARB or Bad Coil or Loose wiring or??? Any CLUES as to where to start???? Thanks in advance

[Gene M.]

Re: Need Help Intermittent Stalling L36 Holley 3370

The back fire is a clue. There is raw fuel in the exhaust and then gets ignited............then boom.

Are all plugs firing?

[Bill L.]

Re: Need Help Intermittent Stalling L36 Holley 3370

HI Neil:

Did I read correctly that a mechanic "epoxied a fuel leak from the carb bowl" ???

That is probably NOT the problem but seriously, epoxied parts on a carburetor are not a wise choice.... I would also check the float level and the fuel level in the carb as well --- but a good rebuild should solve that and the expoy problem as well.

Back to the problem --- first I would get the carb rebuilt and get the epoxy out of the equation (regardless) ---

Then --- are you using the correct plugs? i.e. 45XLS I think for a '66 L36 Big block --- and are they gapped correctly? Not oil fouled?

Is the new rotor long enough to make contact vs. the shorter repro ones some shops sell? New plug wires -- have you checked each one to make sure it has continuity and that it is firing? There was a post some time back regarding broken plug wires that were actually new repros... I forget the brand ---

Tune up? i.e. are the points gapped correctly and the timing / advance set appropriately, idle (fast & slow) correct for the car / conditions?

These are just some of the possibilities --- but in any event get that carb squared away and the epoxy out of the way first (in my opinion) ---

Hope this helps---

Regards
Bill

Motor 1.jpg

[Timothy B.]

Re: Need Help Intermittent Stalling L36 Holley 3370

Neil,

Does the car have points or a electronic points conversion?

Is the coil a GM reproduction coil? If it is I would start there and swap in a known good part or go spend 20 for a NAPA IC-12 (I think that's the number) and try it. Repro stuff is junk, my .02 cents is on a electrical issue.

[Neil C.]

Re: Need Help Intermittent Stalling L36 Holley 3370

New Extended Tip Rotor /Correct New Plugs Gapped and correct/ New Correct Spark Plug wires/New correct GM coil /New Distrib cap New/ Fuel Tank Lines etc etc etc etc At first thought a bad ground UT upon reflection as stalling has gotton worse and more frequent over time Im going with crud in the fuel bowls.. Movement also makes it worse... vs idling in garage even acelerating while idling is also fine...... Think its Sloshing of fuel ?? Car RUNS strong in Garage and when running UNTILL it stalls on occasion. As this is getting more and more prevelant Im going with Carb vs Electical as it appears to be a worsenening condition..That doesnt seem to suggest electric to me...Ordered a Original correctly rebuilt Correct Dated 3370 as I did not want a repop even tho half the $$. I feel confident this will fix it but if not then Ill pursue electrical.. Let ya know in a few weeks after install By the way my original 3370 is dated 5 Mo prior to build and I wanted a closer Date so decided to start there...Thanks

[Neil C.]

Re: Need Help Intermittent Stalling L36 Holley 3370

Only Orignal style points no conversion Timing is fine etc Coil is New GM repop.. As I stated it runs Strong untill the occasional stall. As you I thought electric at first but decided upon the Carb to Start with and am sure thats the culprit After a newly Rebuilt original vs repop 3370 is on we shall see if problem is cured... If not then electrical as that will complete all fuel related parts being recently replaced. Thanks Ill post what happend after install...

[Jim T.]

Re: Need Help Intermittent Stalling L36 Holley 3370

Neil you have installed so many new parts. Did the problem start before the installation of all the new parts or after the installation? I once had a dying problem on my 1968 Corvette in 1974. Walked home and got some tools and went back to the 68, but it started right up and I drove it home. I did find a problem with the 68's original coil. The terminal that 12 volts connects to could be twisted in the 68's original coil. Replaced the coil and no more engine quitting problems since 1974.

[Neil C.]

Re: Need Help Intermittent Stalling L36 Holley 3370

OK Vette's Running Perfect// Turned out to be Bad Pink Positive Coil Wire at Solenoid Starter Brace had a previous Bare Wire Fray and would touch and Kill the Motor whenever it felt like it...hit a bump turn a corner or whenever.splicing in a NEW wire and problem of frustration Solved....Thats why popping the clutch would not restart but Cranking it only by the Ignition Switch would... Now alls copacetic in the Vette / Was NOT COIL/Points/Condensor/ Carb/Fuel Pump Ign Switch/ Bulkhead connection as previously thoughtetc etc etc Electrical probs can be either easy or impossiblly difficult when Intermittent.... Now on to other less pressing Items....

[William F.]

Re: Need Help Intermittent Stalling L36 Holley 3370

Firewall electrical connection always a suspect in this kind of problem.

[Neil C.]

Re: Need Help Intermittent Stalling L36 Holley 3370

Not this Time Just a Bad Pink Positive Coil to Starter Solenoid Wire rubbing a frayed wire on the brae JUST enough whenever it bumped it....Competley replace the Pink Wire and Alls GREAT now....