After a rebuild, my 1973 225 with a Holley 1920 runs great except for a significant stumble off idle if I give it anymore than about 1/3 throttle. I have the accelerator pump hooked to the hole nearest the pivot point/inner most, is this the correct spot?
1973 Holley 1920 Accelerator Pump Question - Stumble Off Idle
- Thread starter Lizey93
- Start date
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I cannot picture that one in my mind. If you can post a picture, that would be helpful. Likely though that is correct for the strongest pump shot, but I am not certain, since I cannot see it. Have you actually LOOKED into the carburetor throat to see if it's spraying a good strong stream of fuel and that it sprays IMMEDIATELY when you move the throttle lever?
I suppose a picture is worth a thousand words! This is a stock image off the internet but mine looks identical. Blue arrow is to the linkage just for reference, green arrow is where my accelerator pump is hooked up. When I move the throttle by hand, it appears to be a decent shot and its as immediate as I can tell by the naked eye.
Thanks! I thought maybe that was the one. You said it's in the hole closest to the pivot point, correct? I believe that's right for the longest pump shot. I'm sure someone will correct me if I'm wrong.
I think its correct as well from what Ive read, but wanted to be sure. The stumble is frustrating, besides that it runs awesome. Thanks for replying!
You bet. Have you looked to assure the pump is working?
No, that's what I am talking about. Where do you have the initial timing set?
This may not be your answer to your problem but here is what I found on a slant with a stumble as you are describng. The timing chain was the issue. Take the distributor cap off. Rotate the engine back and forth and see if the timing chain has slack and how much by watching how much movement the crankshaft has before the distributor rotor moves. This could be your problem if it does. I have seen this before. Just something that is an easy check to cross off.
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Innermost hole = SMALLEST pump shot. Outermost hole = largest pump shot. Try moving the link one hole outward (middle hole) and see how it does.
Beyond that: Carburetor operation and repair manuals and links to training movies and carb repair/modification threads (heavy on Holley 1920 material) are posted here, and other tune-up parts and technique suggestions in this post.
Beyond that: Carburetor operation and repair manuals and links to training movies and carb repair/modification threads (heavy on Holley 1920 material) are posted here, and other tune-up parts and technique suggestions in this post.
Well that clears it up. I guess maybe being 90 degrees off from say a Carter or Holley four barrel makes a difference. On those, the hole closest to the pivot gives the largest pump shot.
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