Carb issues with a new Holley 94
 

Good day everyone
I have been lurking around the ford barn for a number of months and like what I see. I have a 1946 Ford Coupe that is pretty much original with stock flathead V8. The car was pretty much completely restored when I purchased it. I have had fuel issues with it and have removed and cleaned fuel tank, have electric fuel pump and new lines and filters. I put in a carb kit and float and still wasn't pleased with how it ran. So I purchased a new Holley 94. Made in USA purchased at George Moirs in Canada and its from Dennis Carpenter in the USA. The car now runs pretty decent but I am having trouble with the idle. The engine idles right down when I come to a stop....so low that it almost stalls. Now when you start it up it idles around 700 rpm and when you rev it up and let off the throttle it idles right down to where it barely runs. It does the same thing once warmed up. You can rev it up a number of times and each time it idles down to almost a stall. Then after a few times doing this it goes back to idling at the right rpm. Then you rev it up again and it drops to almost a stall. I have played around with the idle adjustment screws with no luck. Screws are out about 1 1/4 to 1 1/2 turns..... about where they where when I first installed the carp.......
I figured all my problems would be solved once I installed the new carb. it has new spark plugs and wires, complete new fuel system. I also checked throttle linkage for any binding etc. Any help would be greatly appreciated. Thank you

Re: Carb issues with a new Holley 94
 

You should look at throudle plates see if they are loose

Re: Carb issues with a new Holley 94
 

Did you try adjusting the speed screw ? You only mentioned the mixture screws which aren't really for changing the speed, but for trimming the mixture for smoothness.
Besides that, it sounds like the throttle lever is not returning to the same spot every time you return to idle.

Check to make sure the return spring is doing it's job, or for a loose peen where the throttle lever attaches to the throttle shaft.

Also could be loose throttle plates as George/Maine mentioned, although would be unusual.

Sal

Re: Carb issues with a new Holley 94
 

George and Sal have good hints
Might also try tuning with a vacuum gauge to see if idle adj srews are actually working

Re: Carb issues with a new Holley 94
 

Yes I have the idle set at about 700rpms. If I set the idle say at 900rpm or higher ( which is way to high)it does not idle down to almost a stall when I step on the accelerator and then let off, it stays at 900 rpm. In my first post I mentioned that when I let off the accelerator it idles down to almost a stall and takes reving it up a bit a number of times before it gets back to a normal idle. I was just out again and tried it and was able to get it to return to regular idle speed by just slowly increasing rpms a couple time. I tried setting the carb again....I had mixture screws out about 1 1/2 turns. I cranked idle back so it was idling really slow and tried adjusting mixture screws. One screw I was able to turn in all the way and did not stall engine or really changed idle at all. This is a brand new carb and I talked to the company I bought it from and they said they've never had a problem with these carbs right out of the box. I see nothing wrong with the linkage throttle shafts etc. I am going to try tuning with vacuum gauge to see what happens.

Re: Carb issues with a new Holley 94
 

A long shot but is the timing retarding properly when you isle down?

Re: Carb issues with a new Holley 94
 

"I cranked idle back so it was idling really slow and tried adjusting mixture screws. One screw I was able to turn in all the way and did not stall engine or really changed idle at all."

Well, I would think there is a problem of fuel is leaking somewhere if shutting the idle screw off does nothing.

Re: Carb issues with a new Holley 94
 

If one screw is not making any difference, you have a blockage in one of the idling passages. As far as idle speed goes, I had similar problem, installed a spring from the accelerator arm on the carb to the generator so it pulls it back harder and lands in the same spot every time. Worked for me.

Re: Carb issues with a new Holley 94
 

Are you sure the new carburetor was made in the USA ? Or just maybe sold in the USA. If it's one of the Chinese knock offs it's hard to believe they said they never heard of problems with them. Maybe your's is the only one they sold.

Sal

Re: Carb issues with a new Holley 94
 

I saw Carpenter actually making and testing each 94 they made on a flathead during the Charlotte meet in June while going thru their shop. If it actually came from their manufacturing, you should be good to go. One guy at the meet had a bad carb and took a DC 94 and put it on and it ran good.
Don:)

Re: Carb issues with a new Holley 94
 

Make sure your linkage is not binding a little and the return spring is doing it`s job.

Re: Carb issues with a new Holley 94
 

Thanks everyone for your replies. Yes its definitely a Dennis Carpenter carb. There may have been a blockage in one of the idling passages. I removed the screw and lightly took air hose to it. Now I can get some response when adjusting both idle screws. Its still doing the same thing....idling right down to where it barely runs and then slowly over time idles up. This time i set the idle using a vacuum gauge...no change.
I am also finding that after car has been run for a long time and when the car is idling the rpm surge s up and down a lot. I am thinking that Frank Miller may be right about timing not retarding properly. Well now check that out.

Re: Carb issues with a new Holley 94
 

welcome to the 'Barn...got pics of your coupe?....good luck on getting your car running smoothly so you can enjoy it....Mike

Re: Carb issues with a new Holley 94
 

Thanks Mike. Yes I have some pics posted on my profile. Its been very frustrating trying to solve this issue. Would be nice if there was someone in this city that I could take it to that knows something about flat heads.

Re: Carb issues with a new Holley 94
 

I had to change the engine in my 47 and I bent the linkage on fire wall.
When I went to put the linkage on carb the rod was to short. I made a new one longer by putting 2 together. So if you take a measurement from fire wall to rod closest to fire wall .Now remove link from carb and see if you have less clearance to fire wall.
Not a Toyota check the carpet for binding. There are springs in linkage could be broken.

Re: Carb issues with a new Holley 94
 

Hi there, A proven method for fault finding is to connect a vacuum gauge to the intake manifold. Look up a vacuum chart for fault finding and reading guidelines. There is a possibility you have a vacuum leak somewhere on the intake and it may vary in intensity with engine cold and hot. Check all intake manifold bolts and other intake manifold fittings for leaks. Good luck, Regards, Kevin.

Re: Carb issues with a new Holley 94
 

I would also suspect a vacuum leak.

Re: Carb issues with a new Holley 94
 

Agreed on the vacuum leak... similiar issue with my flathead this spring, changed the intake gasket & all is well, no more idle or weird acceleration issues :-)

Re: Carb issues with a new Holley 94
 

I hope some of this helps..

1.Check the fuel filters you installed they may be partially clogged.. I haven't had much luck cleaning fuel tanks.
2. Check the timing and if you have a loadmatic distributor make sure the vacuum lines are connected correctly.
3.Check the fuel pressure on the electric fuel pump. It may be too high.
Even though the carb is new the float level may be incorrect.
It sounds like the engine is flooding.

Re: Carb issues with a new Holley 94
 

Well I tried the propane test and could not find any leaks. I install two new fuel filters, one before the electric fuel pump and one before the carb, when I install new carb as well as new fuel lines and had fuel tank cleaned and sealed. I wondered about fuel pressure cuz I do have electric fuel pump. The old carb was doing the same thing as this one only acceleration was bad and hard starting and ran rich even after a carb kit. When I bought the car it just had electric fuel pump so I thought possibly too much pressure and was causing these issues. So I put the rod back in the stock fuel pump, hooked it up and had electric fuel pump running through stock fuel pump. I had the electric fuel pump on an on/off switch and only used electric when car sat for awhile for better starting. Anyway after all this work the car didnt run any better. Then just before I bought the new carb I noticed fuel leaking out of gasket on stock fuel pump so I said screw it. When I put new carb on I bypassed stock fuel pump again.
I had the top off the old carb at least a dozen times setting the float...infact I almost had the slot wore out on screws. Thats why I finally bought the new carb. The new Denis Carpenter carbs are all run and tested before being sold.....I hear ya about even though its new it still might need float set......I just dont want to get started with that cuz id hate to wear the screw slots out on the new carb

Re: Carb issues with a new Holley 94
 

Have someone follow you and watch the tailpipe for black smoke as you make a quick stop ( ask them to not run into you, either). If it puffs out some black smoke as it almost stalls, likely the float level is too high and fuel is sloshing over during a stop.

Re: Carb issues with a new Holley 94
 

Been there, done that, especially the fuel leaking part. What I did:

1. Timed the engine, new plug wires eliminated a miss

2. Blew out the carb with all parts removed, set float to 5/16", added fuel filter to line at carb

3. Ran OK but had leakage from throttle shaft at shutdown

4. Added fuel pump shims til it ran lean, then removed 1/16" shim

5. Ran great but throttle shaft still leaked at shaft/accel pump area

6. Bought new DC carb and installed. Filled up with ethanol-free gas

7. Runs well (idle not as smooth as before but very acceptable

At that point, done messing with it. My '46 and '50 followed the same pattern.

Re: Carb issues with a new Holley 94
 

I was having problems with my 47 coupe with 8ba would quit running once I got it going made a dash for home. I had a new fuel pump as a spare 94 carb.
I had a small filter before carb. I was having fuel line leaking got that fixed. Wouldn't keep running. Now this was same carb you have new out of box.
What I did was pull the top and remove the float and check the needle, it was made of rubber on seat. I thought I had a all medal needle but wrong part.
So all the did was put the top back on with new filter and the new pump so far so good. The old carb had lot of dirt in side blew out gas line.More bad luck took out 5 teeth on cluster gear. should be back on road soon.

Re: Carb issues with a new Holley 94
 

Well I've found the problem. There is something wrong with the new carb from Dennis Carpenter. I put the old carb back on and it idles okay. You can rev it up and then let off throttle and engine comes back to idling the right rpm. The Dennis Carpenter carb was purchased from George Moir antique parts in Alberta Canada. Try figure this out..... he wants me to wait until they find out from dennis carpenter what is wrong with carb....I told them 3 days after getting it that something was wrong with it. I said why cant you just give me another one. He said he cant.....im like what do you mean dont you have warranty....he says yes we can give you a refund..........hmmmmmm now your not making sense.......you cant give me another new carb but you can give me a refund!!!!! Okay well give me the refund then and I will just turn around and buy another one from you.....he said no I cant do that.........wellllll so much for trying to figure that one out... I told him ......whatever ......the carb is in the mail on its way back to you. Dont know what he wwas smoking this morning

Re: Carb issues with a new Holley 94
 

Back to the problem: rich mixtures above idle, as in cruise, or acceleration, will cause over rich and low idle speed when plates return to idle. Power valve leak, high float level, will contribute. Some carbs mixed air in the main jet wells as it came to the ventury to better atomize mixture. Don't know if the 94s did this. If those air orfices are not there,well it would make rich, and cause low idle from too rich a mixture.
Does this engine return to normal idle speed after its " problem" time of low idle speed? Does it clean up after awhile? I too have a couple of these carbs, not on yet but will be at some time in the near future. Hoping not to have the same issues.

Re: Carb issues with a new Holley 94
 

This is a lot of trouble and expense so you may not want to try it but here is a suggestion.
Install an A/F gauge. This will involve putting a bung in the exhaust and installing an O2 sensor and the gauge. Hopefully you have 12volt neg ground as I don't know it the gauges comes 6 volt.
Ideal A/F is 14.7 at idle. As you drive this will vary but you can see how the carb is doing. If it is rich either the float is incorrect, the fuel pressure is too high, or the jets or power valve are too big. Not necessarily in that order. You can also install a fuel pressure gauge in the fuel line to monitor the pressure.
Like I said a lot of trouble and expense but it should zero in on the problem if it's fuel related.

Re: Carb issues with a new Holley 94
 

Yes the engine comes back to normal idle speed after at least 30 seconds if not more. it just kinda chugs away until it gets up to proper rpm. You can get it back to idle speed by kinda feathering the trottle. The bad thing is that when driving it when you come to a stop it idles down to almost a stall and was always worried it would. The rpms also surge up and down at idle. I honestly dont think there is anything wrong with these carburetors......I think unfortunately I was unlucky and got one with issues. So the problem has been solved. I sent back the carb and asked for a refund. I have my old carb back on which always idled well. It just doesnt accelerate well and fuel is leaking out of throttle shaft.
Thanks everyone for your input. It was greatly appreciated

Re: Carb issues with a new Holley 94
 

What I think your problem is that the valves are leaking, and a loose throdle shaft will cause up and down idle.

Re: Carb issues with a new Holley 94
 

Replacing worn, leaking throttle shafts is no big deal. I have done a couple of them. I got the oversize shafts from Mac's (in retrospect, there are probably better sources). I got a reamer to match off of Amazon. I removed the screws holding the throttle plates and the shafts themselves, reamed the carb base, and installed the oversize shafts.

The only caveat here is that the Mac's shafts have real cheezy arms on them. Luckily, they are held on by screws. I ground the "peened-over" end off of the original shafts, removed the original levers, and installed them on the Mac's shafts, using the Mac's screws and some red Loctite. Carbs run fine with no leaks.

Here is a saying I came up with after spending too much time in the Corvette community : "Real mechanics fix things, wannabees replace parts, and Gold-chainers pay other people to do it".

Re: Carb issues with a new Holley 94
 

Tubman, I love that line, I will use it with your permission, if it's not copyrighted. Lol

Re: Carb issues with a new Holley 94
 

Solved the problem with new holley 94 that Dennis Carpenter manufactures. Sent it back and bought a new Stromberg 97. Car runs awesome! I think I'll keep it now.

Re: Carb issues with a new Holley 94
 

Back to a possible vacuum leak. If it did the same thing with the old carb and you have pieced your way through the entire fuel system then the gremlin is still there.
We may not all admit it, but we have all "chased the gremlin" by replacing lots of parts. That's why we have those boxes of extra parts in the back corner of our garage. Those of us who have done it enough have enough parts to open a parts store when we finally retire. I refer to it as the kids inheritance, along with the reverse mortgage.
Don't get discouraged, you'll get it figured out. Enjoy the adventure!