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10-30-2020, 11:09 AM | #1 |
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Join Date: Sep 2019
Location: Savannah, Ga
Posts: 225
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Holly 94 issues
I have a 1951 Ford Victoria which I have completed a frame off 8 year restoration. The engine was rebuilt including boring, reground cam and crank, a 3 angle valve job with adjustable lifters and rotator type valve spring retainers and correct valve springs, proper installed height, and adjusted spring pressure of 50 pounds. The carburetor is an "all new" 94 from Mac's. The engine runs well but has two issues: 1. difficult starting after sitting for a few days, and 2. When driving and coming to a stop with the transmission in OD, and the engine free wheeling, the engine frequently stalls unless the choke is partly engaged. The timing appears to be correct and the dwell is 33. I have tried to adjust the the idle needles from their initial setting of 1-1/2 turns to 2-3 turns with no apparent change in the engine idle/rpm. When the choke is pulled out slightly, the engine idles smoothly. At 600 rpm with this choke setting, the manifold vacuum reading Is fairly steady at 18-20. Any advice, or suggested solutions, would be greatly appreciated.
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10-30-2020, 11:41 AM | #2 |
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Join Date: Jun 2014
Location: Williamsburg, VA
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Re: Holly 94 issues
Difficulty starting after a few days is symptomatic of no fuel in the float bowl, requiring extended cranking to get enough gas to the carb. The 94 is notorious for power valves not seating properly and leaking down. Absent that problem, the float bowl should not evaporate down for weeks.
Stalling at idle can be several things. You noted that opening the idle mixture screws does not affect the rpm. If you slowly close one, does the rpm drop at some point? It should do that for both jets. If not the engine is idling on fuel from another source, like the main jets, or leakage from the power valve. Another thing to think about is a newly rebuild engine can be a little tight. You may need to crank up the idle rpm to 600+ until it is broken in, - like over 1000 miles. |
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10-30-2020, 11:50 AM | #3 |
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Join Date: May 2010
Location: N.W. Iowa
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Re: Holly 94 issues
If the car is in OD when you are on the road and you slow down to a round 27 mph the OD should drop out of OD and it will then free wheel. If the OD does not drop out and it stays in OD the car will not go into reverse!
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10-30-2020, 12:19 PM | #4 |
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Join Date: Sep 2019
Location: Savannah, Ga
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Re: Holly 94 issues
I when the idle screws are turned to nearly closed the engine begins to stumble. As I mentioned, turning the screws to open seems to have little effect on engine rpm. The OD is functioning normally. (See my previous posts on its problems) I mentioned the fact that I have the car in OD because the freewheeling features prevents "" popping the clutch to restart the engine.
I have wondered about the power valve but wasn't sure whether a replacement would work with this "all new" Mac's carburetor. |
10-30-2020, 12:33 PM | #5 |
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Location: Savannah, Ga
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Re: Holly 94 issues
I hope this is a clearer picture.
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10-30-2020, 02:01 PM | #6 |
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Location: Minnesota, Florida Keys
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Re: Holly 94 issues
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This precludes you from using the car for this period, which can be a major drawback where you are, but it works for me in Minnesota in the fall and winter. The new power valves are so "iffy", that I do this test on every one I rebuild. |
10-30-2020, 03:09 PM | #7 | |
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Re: Holly 94 issues
Quote:
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10-30-2020, 05:08 PM | #8 |
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Location: Detroit suburb, MI
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Re: Holly 94 issues
A leaking power valve doesn't make sense to be the problem, if closing the choke slightly cures the problem. The leaking power valve would do about the same thing as closing the choke a little bit.
Sal |
10-30-2020, 05:49 PM | #9 |
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Join Date: Jun 2014
Location: Williamsburg, VA
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Re: Holly 94 issues
i thought the same thing, but then figured that the "open slightly" was probably just the idle increase, not choke, that keeps it running.
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11-03-2020, 12:13 PM | #10 |
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Join Date: Sep 2019
Location: Savannah, Ga
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Re: Holly 94 issues
I found this while searching the internet. Is this likely the cause of the stalling when coming to a stop from cursing speed? Incidentally, I have checked for vacuum leaks but found none.
"One or Both Idle Mixtures Screws Doesn't Change Anything Most likely there is a plugged passage. Check the venturi's closely. The holes are small and easily plugged. If the engine has been sitting for a period of time, then the gas may have turned and varnished the inside of the carburetor" |
11-03-2020, 04:21 PM | #11 | |
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Join Date: Jun 2014
Location: Williamsburg, VA
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Re: Holly 94 issues
Quote:
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11-03-2020, 04:32 PM | #12 |
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Join Date: Jul 2010
Location: 36 miles north of Albany NY
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Re: Holly 94 issues
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11-03-2020, 06:13 PM | #13 |
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Join Date: Oct 2015
Location: Socal
Posts: 795
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Re: Holly 94 issues
Come out to California and see how long fuel stays in a float bowl....
Depends upon where the OP lives. If they have real gasoline, and fuel doesn't hang in the float bowl for a week, then you definitely have a float bowl leaking down. |
11-04-2020, 07:01 AM | #14 |
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Join Date: Sep 2019
Location: Savannah, Ga
Posts: 225
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Re: Holly 94 issues
I am actually sending the Holly 94 ( an original 94) to Charlie today. I am in Savannah Ga and we have easy availability to non ethanol fuel because of marine use. That is all that I have used in the car since its restoration. Thanks for the advice and information. Incidentally, I am a former L.A. resident.
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11-21-2020, 11:51 AM | #15 |
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Location: Savannah, Ga
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Re: Holly 94 issues
First a correction then a follow up to my original post. The carburetor that I was having issues with was in fact, an original Holly 94. I had another '51 Ford convertible which I have since sold on which the "all new" carburetor was fitted. (senior moment) The current carburetor was rebuilt by a major parts house a number of years ago. While it looked fantastic, no amount of fiddling with it resulted in a smooth idle or corrected the stalling when coming to a stop. Very frustrating.
I recently sent this carburetor to CharlieNY for his evaluation. The following is an email I sent to Charlie after he returned the repaired carburetor. Charlie, You probably don't need any more positive feedback, but I must tell you that my engine ran perfectly (right out of the box) with the carburetor that you recently rebuilt for me. The idle is spot on and there is no more stalling when coming to a stop. As I mentioned previously, I had sent my original carburetor to .... for a rebuild. While it looked amazing when it was returned, no amount of "adjusting" resulted in a smooth idle or correction of the stalling issues. If it isn't too much trouble, would you let me know what was required to restore the proper function? Thank you for your excellent service. |
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