Carb issues with a new Holley 94

[40 Deluxe]

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.

[46ford]

Originally Posted by yahbut

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

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.

[George/Maine]

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.

[yahbut]

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

[avrotom]

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.

[41LjH]

Sponsored Links (Register now to hide all advertisements)

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.

[yahbut]

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

[George/Maine]

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

[tubman]

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".

[avrotom]

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

[yahbut]

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.

[chap52]

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!