View Full Version : Holly Carburetor problems
galveston
Apr 24, 2010, 10:12 AM
I have a dual bowl 4v Holly on a Ford 351 cid engine.
The choke is activated or pulled off (?) by electric control.
It seems like it either chokes too much or not enough. It starts fine, but when the engine is partly warmed up, if it dies, it may not restart. When I set the choke richer to correct this problem, it seems to choke too much when the engine is warmed up.
I have rebuilt several Quadrajets successfully, but this is my first experience with a Holly.
TxGreaseMonkey
Apr 24, 2010, 10:54 AM
Personally, I would buy an inexpensive rebuild kit; clean the carburetor in stoddard fluid; blow it out with air; install the new parts and gaskets; and set the choke pull-off, idle mixture screws, float, etc. Ensure the insulator between the carburetor and intake manifold are new. If there's an air leak there, you'll never get it to run right.
KISS
Apr 24, 2010, 12:27 PM
Holley's are a real PITA to set up. Do you know how to do propane enrichment? It's the BEST way to set those pesky things.
See this post in an old thread of mine:
https://www.askmehelpdesk.com/cars-trucks/chevy-305ci-v8-idles-fine-but-stumbles-acceleration-214855.html
cdad
Apr 24, 2010, 12:40 PM
What year is this set up for and what type of air cleaner is on it.
galveston
Apr 26, 2010, 05:23 PM
What year is this set up for and what type of air cleaner is on it.
1985 Ford PU 351 cid with paper element (stock).
Seems to run OK, but often keeps slowing at idle until it dies. Then it can be difficult to start, needs extra choke, especially if it is not completely warmed up.
KISS
Apr 26, 2010, 05:55 PM
The throttle plates may not be positioned in the idle system. The propane enrichment method will ensure that.
If you have a small propane torch and a tach, you can easily see the effects. Just inject some propane in the intake when monitoring the RPM. As you add propane there should be little difference in the idle speed, until the carb can no longer compensate, then it will stop.
It should increase to a max RPM and then start to decline. The MAX RPM probably should be no more than 25-50 RPM over the initial RPM.
To do it right you have to injet it cleanly into a vacuum port and have a means to regulate and turn off the gas independently.
For a test, you can use the air horn.
Typical ways to determine your not in the idle system is rough idle when it's raining.
cdad
Apr 26, 2010, 06:16 PM
1985 Ford PU 351 cid with paper element (stock).
Seems to run ok, but often keeps slowing at idle until it dies. Then it can be difficult to start, needs extra choke, especially if it is not completely warmed up.
Check here for carb and choke adjustment.
Ref:
Rebuilt, now to adjust? - Ford Truck Enthusiasts Forums (http://www.ford-trucks.com/forums/showthread.php?p=8566767#post8566767)
The 4180-c should be the correct carb for your truck.