Stall on decel

[Mercury Mike]

So I rebuilt my holley 1940 today. Runs tip top. My timing was a bit off as well. I got it from going thump thump thump to vrooooooooooooOOOOOOOOM. When she's in park, she idles great, sometimes I have to pinch myself to make sure she's still running. =) In drive, she idles good while just sitting there, but if I accelerate, and then try to slow down, even realllllly slowly, she stalls. This doesn't happen in reverse, no matter how fast I go in reverse and hit the brakes. How can I get rid of this problem?

 

[wallaka]

Probably the anti-stall dashpot. It's on the side of the carb. Tried to find a picture but couldn't...oh well.

 

[Mercury Mike]

I didn't think there was an anti-stall dashpot on my carb.

 

[wallaka]

Interesting. This the original carb/tranny? All of the auto tranny cars I've seen had a carb with the dashpot.

Adjusting your idle a little higher might help, but could cause problems in other areas.

It is a little strange that it doesn't do anything in reverse, though.

 

[Mercury Mike]

Yeah, no dashpot (me and my grandpa have looked for one), and yeah, original tranny and carb (holley 1940 1bbl and early C4). I set the idle reallllly high to see if that would help my problem, and it stalled, just not on decel, it waited to come to a complete stop just about. Lasted longer. I'm confused about the whole reverse thing too. I think I'm going to call Ford tomorrow and see if they know anything about this happening on any other 1940 before. The tranny shifts GREAT and real smooth, the acceleration is unbelievable, sounds great, no exhaust leak, everything's just really smooth, and if not for this problem, it would even put my grandpa's '65 to shame in performance. =) I'll figure it out and post my findings, in case anyone else runs into this problem.

 

[JackFish]

If you think the carb is OK, then perhaps it could be debris in the fuel lines.

 

[Mercury Mike]

Hmmmm. Is there a really good additive that I can put in there so that I can clean that out?

 

[Mercury Mike]

So I got home from work, had a buddy pick me up and drop me off, and I went to check the float level. Float level was wrong, fixed it, and then when I put the top of the carb back onto the rest of the carburetor, 3 of the screws that hold it down were stripped. Unfathomable. It wasn't leaking at all and they all seated perfectly last night, and now 3 of them are stripped. Car won't run for longer than a second, and then I went out to check it, and there was fuel all over my intake. I got it all cleaned up, put the air cleaner back on it, and came inside. I guess it's time for a new carburetor.

 

[ludwig]

Wrap teflon tape around the screws for many turns. This will give some bite and you can see if the float fixed the prob or not. Just make sure you don't get any teflon scraps in the the well (like have the cover all the way in place first).

 

[Mercury Mike]

Great idea! I will grab some tape tomorrow. Yeah the float was a bit high and not closing all the way. Thanks for the tip. I will jump on that as soon as possible. So I wrap teflon around the whole screw and just start screwing it in? Sounds like a plan. I hope it did! Is it safe to helicoil carburetors?

 

[addo]

Yes, helicoil if there is the meat for it. Can't upsize - are they 8-32 screws?

 

[Mercury Mike]

Yeah, they're small little dudes. I wish they sold a hardware kit for it, it'd help alot. What size of a helicoil should I use? One other thing... I accidentally soaked my spark control valve in carb cleaner for about an hour, I meant not to set it in the solution, but I wasn't thinking clearly or something and set it in there. Could this affect what's going on?

 

[addo]

Dunno about the SCV! I suppose if it's still airtight where intended, should be OK.

A helicoil style kit to restore the original size fasteners would be best. Only step up a gauge if that option is exhausted.

 

[Mercury Mike]

Rebuilt an Autolite 1100, got it on the car, started it up, and chug chug chug she started running. Not like a sewing machine, or even close, but she starts, which is the first step. =) I am going to idle it and time it tomorrow, and I will post back to let you all know the results. Thanks for all your help guys!

 

[Mercury Mike]

So I got it timed real nice, and idling great. Real great. Only one problem now and it's got me a bit stumped. I was thinking it might've been the acceleration pump, but the rebuild kit on the 1100 said specifically not to remove it, and it didn't come with a plunger, so maybe it's not that. The problem is that when I hit the gas right away it's got a major flat spot. If it doesn't stall, it revs right up and sounds great (however something sounds like a bit of metal getting thrashed around in the valve cover or right inside of the carburetor. It's a weird sound but doesn't sound like anything came apart, and it's only there evvvvvvery once in awhile). How can I get rid of this flat spot? It feels like there's a bunch of air getting sucked in or something, there's a quick hiss, and then if it doesn't stall, it revs up. I can get it to rev in park and neutral real easy. But only once from drive did it go from a flat spot and start moving without me giving it a little gas in neutral and then shifting it into drive. I only did this once because I didn't like the idea of having to do it over and over. The idle is great, and the flat spot is there real quick when I start the car too. If I floor the gas pedal when I start it, it's not really noticeable. What could this be? Thanks guys.