holley 1940 carb with SCV?

LaGrasta

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I'm running a 1940 carb but found out it doesn't have the SCV for my LOM dizzy. Does anyone know the Holley 1940 carb name that HAS SCV? I think it might be 1945 or 1946. Where do I get one?
 
LaGrasta, there are Holley/Autolite 1940 carbs with an "SCV"; I own one. I believe that the SCV diaphragm on mine may be shot; and I have tried to locate someone who sells the 'SCV diaphragm', but have not found anyone yet. I installed the 1940 carb on a 200cid engine back in the early 80's when I was having trouble with my Autolite 1100 carb at the time. It was a replacement carb for the 1100 at the time. It seems that some people do not like this carb for some reason, but I had good success with it. James
 
James, this is good news to hear. I'd just get a 1940 with an SCV however you also tell me you can't find one. I may be looking at installing an Autolite 110 after all. Let me know if you happen to find one.
 
I've got a spare (new) scv in my 1100 kit parts collection...James either you or Lagrasta are welcome to it if you need it, no charge. Like I mentioned this came from an 1100 kit, but would think they would be the same for holley, but not sure...let me know if either of y'all need it, or want to give it a try.
 
FrankenStang, I appreciate the offer. I will let LaGrasta have first shot at the SCV diaphragm 'if' he thinks he can use it (?); since he started the post on the Holley 1940 carb. If he does not want it, let me know the best way to contact you so I can give you my address. Thanks, James
 
Nice to finally see and know for certain what the SCV looks like. I don't believe that will screw into my Holley 1940 will it?
 
LaGrasta":bz6ph6de said:
I don't believe that will screw into my Holley 1940 will it?

I wouldn't guess so without the correct opening.

I drew a pic around the opening where I think it would go :unsure:: (pic is from pony carbs)


Looks about right (hard to tell) according to this diagram (#48 in diagram) <<<if diagram is correct for y'alls models
http://allfordmustangs.com/forums/attac ... 201940.pdf

It looks like the ebay carb you posted has the same opening, but maybe James can confirm that.

If either of you decide you'd like to give this one a try just shoot me a pm with address, and I'll snail mail it to you. Just be glad to see it go to some use...I've already got another new spare I'm hanging on to for my 1100.
 
Frankenstang,
I'LL TAKE IT!
Now that I know what an SCV looks like and where it belongs on the 1940, I looked at my carb. It had a screw-in plug in this exact location. I unscrewed it and it looks correct for the valve. Please send me your extra SCV and I'll give it a shot. What do I owe you?

25726 Demeter Way
Mission Viejo, CA
92691

Thank you,
Anthony LaGrasta
 
LaGrasta":paiqxtok said:
Please send me your extra SCV and I'll give it a shot. What do I owe you?

Anthony,
I'll send it out tomorrow...should go via first class mail. Don't worry about the cost...after all the help I've received from this forum, lets just call it one of those 'pay it forward' deals ;)

It will be cool if it gets your advance working again.
 
LaGrasta & FrankenStang, the picture that you posted (FrankenStang) that is circled in 'red' is indeed where the SCV diaphragm goes. LaGrasta, if your carb has threads inside of that chamber (that FrankenStang circled), it might possibly work; I am not sure about the difference between the diaphragms for the 1100 carb versus the 1940 carb?? I am pretty sure that the 'Non-SCV' 1940 carbs do not have any threads inside that 'chamber' for the diaphragm to screw into; just a blank hollow chamber. Hope it works. James
 
james singleton":3qxu34sy said:
I am not sure about the difference between the diaphragms for the 1100 carb versus the 1940 carb??...Hope it works. James

That makes two of us. Hopefully there is no diff in tap/thread pitch, but Anthony should be able to let us know in a few days, it's on it's way. James, if it fits his I'll let you know if I can drum up another (might be used) from my assorted parts collection. I've got at least 3 varying types of scv 1100's for cannibalizing parts.
 
Unlike the picture, mine actually had a plug threaded into the location. Once removed, I can see passages, etc. I really think it might work.

Once installed, it just operates and that's it, no other hook-ups? I know how to test it; attach the timing light, rev the engine and watch for the timing mark to advance…
 
LaGrasta":2490x757 said:
Once installed, it just operates and that's it, no other hook-ups?

Nope, just plug and play. Spring on the scv is 'calibrated' to close the valve when manifold vacuum drops momentarily under acceleration...allowing dizzy to p/u increasing venturi vacuum.

You might want to spray some chemtool/carb cleaner up into the scv passages on the carb just to make sure they're clear...you should be able to do this with carb on the car, but I would allow it to dry completely before threading in new scv, as carb cleaner is too harsh on rubber diaphragms like that of scv. Otherwise just thread it in and go...difference should be immediately noticeable under acceleration.
 
It worked!
I spent a great deal of time on my car these past few days. I installed the SCV and the timing now advances when revving the motor. I retimed everything and have yet to take it on a long drive to really test the overheat situation. It makes sense that it will correct the overheat situation as the car will now have the correct timing at freeway speeds. I'll update again after I get a 20 mile drive in.
 
Glad to hear it! I've been so busy it totally slipped my mind that I was supposed to get that carb for you, sorry buddy!

But yeah, well done. Update me on the overheat.
 
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