Holley Insensitive to Secondary Spring Changes
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From: Fowlerville, Michigan
Holley Insensitive to Secondary Spring Changes
Well, ladies and gentleman, children of all ages, I'm back to screwing around with the old 4180-C on the 460.
I keep getting a stumble when the secondaries open. I changed springs starting with the short yellow spring to the heaviest black spring and all springs in between, and no matter what spring I change to, I still get a flat spot/stumble when the secondaries open. The stumble started slowly going away as the spring got heavier, but now I'm running the heaviest secondary spring and it still stumbles.
Just to make sure the stumble wasn't something going on with the primary side of the carb, I pulled the diaphragm post off so the secondaries wouldn't open, and I took the truck out, flat-footed it, and there was no stumble, so something's definitely going on with the secondaries.
Could this stumble be caused by the secondary jets being too small? I'm running 68's in the primary side (stock had 62's), and the secondary plate is the stock '84 Mustang GT spec.
What do I have going on here
???
Thanks in advance for the ideas fellas!
-Crazy Eddie
I keep getting a stumble when the secondaries open. I changed springs starting with the short yellow spring to the heaviest black spring and all springs in between, and no matter what spring I change to, I still get a flat spot/stumble when the secondaries open. The stumble started slowly going away as the spring got heavier, but now I'm running the heaviest secondary spring and it still stumbles.
Just to make sure the stumble wasn't something going on with the primary side of the carb, I pulled the diaphragm post off so the secondaries wouldn't open, and I took the truck out, flat-footed it, and there was no stumble, so something's definitely going on with the secondaries.
Could this stumble be caused by the secondary jets being too small? I'm running 68's in the primary side (stock had 62's), and the secondary plate is the stock '84 Mustang GT spec.
What do I have going on here
???Thanks in advance for the ideas fellas!
-Crazy Eddie
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From: Fowlerville, Michigan
I did the conversion to the metering block with .72 jets and it ran MUCH stronger but the secondaries still slam open. I did some research and found out the 4180-C carbs and few others have a slightly longer diaphragm. The diaphragm I had was only 1/4" shorter than the correct one, but apparently it's enough to make the secondaries open too soon, too fast.
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From: Fowlerville, Michigan
Mission accomplished. Put the right diaphragm in and problem solved. Also went with the secondary spring quick-change kit and got it tuned-in in a half hour. Runs nice finally.
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From: Giggigamba, South Sudan
Eddie,
Went thru sumpthin' similar in the mid '80s on my F370/460ci swap project. Supershops (am dating myself here, eh??) sold me a Holley "Track Pack" tuning kit that was worth it's weight in gold, hookers, etc.
Re their very detailed instructions: "For a heavy vehicle, use a LIGHT secondary spring". (Believe it was color-coded purple). Heck, I mused ....... What's heavier than an F-370 (108" wheelbase) w/ a 10.5 ft camper on top?
Bottom line: we threw it in & never looked back.
Went thru sumpthin' similar in the mid '80s on my F370/460ci swap project. Supershops (am dating myself here, eh??) sold me a Holley "Track Pack" tuning kit that was worth it's weight in gold, hookers, etc.
Re their very detailed instructions: "For a heavy vehicle, use a LIGHT secondary spring". (Believe it was color-coded purple). Heck, I mused ....... What's heavier than an F-370 (108" wheelbase) w/ a 10.5 ft camper on top?
Bottom line: we threw it in & never looked back.
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From: Fowlerville, Michigan
Eddie,
Went thru sumpthin' similar in the mid '80s on my F370/460ci swap project. Supershops (am dating myself here, eh??) sold me a Holley "Track Pack" tuning kit that was worth it's weight in gold, hookers, etc.
Re their very detailed instructions: "For a heavy vehicle, use a LIGHT secondary spring". (Believe it was color-coded purple). Heck, I mused ....... What's heavier than an F-370 (108" wheelbase) w/ a 10.5 ft camper on top?
Bottom line: we threw it in & never looked back.
Went thru sumpthin' similar in the mid '80s on my F370/460ci swap project. Supershops (am dating myself here, eh??) sold me a Holley "Track Pack" tuning kit that was worth it's weight in gold, hookers, etc.
Re their very detailed instructions: "For a heavy vehicle, use a LIGHT secondary spring". (Believe it was color-coded purple). Heck, I mused ....... What's heavier than an F-370 (108" wheelbase) w/ a 10.5 ft camper on top?
Bottom line: we threw it in & never looked back.
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Thread Starter
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Senior User
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From: Fowlerville, Michigan
...I just know too much for my own good. When I threw a Holley on the truck I forced myself into reading the Holley Carbs book on the toilet three times a day. Now after trying three carbs and blowing a few paychecks on different parts and countless hours tuning and tinkering, I think I got the Holley 4150/60 down finally.
I think Holley fried my brain
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