8BA with single holley 94 running rich

pauldeborr

pauldeborr

Member
I have a '50 8BA that has a single holley 94 that starts to run rich after it warms up. Never has this problem before. Carb has been gone through twice in the last few months and the mech fuel pump was rebuilt with a kit.

It was running fine till I stopped driving it for a while because I'm getting the seat redone. Could letting it sit too long cause a problem? It's only sat for about a month and it still starts and idle's beutifully. It's just at higher rpm's that it starts to run rich with some black smoke out of the pipes.

I don't run a fuel filter, I was told the sediment bowl was good enough...any opinions on that?

Thanks for the help
 
sounds like a float problem or maybe a needle and seat problem, float to high or the needle and seat are leaking, check fuel pressure at the carb, should not be more than #2 1/2, might be a leaking power valve give ken ct a shout, hes the expert on those carbs, he posts on here alot
 
First of all, you definitely need a fuel filter on there, whoever told you that you didn't need one must like to see their friends stuck on the side of the road. However, I don't think that's your issue. (yet...)

Probably not a needle/seat/pressure issue if it idles fine. Check to make sure the choke isn't closing up, or not opening all the way. Check your timing, make sure the dist is advancing correctly as the rpm increases. Are you sure it's black and not blue smoke?

pauldeborr said:
I have a '50 8BA that has a single holley 94 that starts to run rich after it warms up. Never has this problem before. Carb has been gone through twice in the last few months and the mech fuel pump was rebuilt with a kit.

It was running fine till I stopped driving it for a while because I'm getting the seat redone. Could letting it sit too long cause a problem? It's only sat for about a month and it still starts and idle's beutifully. It's just at higher rpm's that it starts to run rich with some black smoke out of the pipes.

I don't run a fuel filter, I was told the sediment bowl was good enough...any opinions on that?

Thanks for the help
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The sediment bowl has to be fitted with a filter of some kind,stone or paper micron filter, Only the paper are still avalible. I think the carb should be gone through again by someone competent to do them right with the correct parts. Most China kits sold today contain many inferior and incorrect parts.The screen in the bowl only stops pebbeles fron getting in the carb.Have it done right. ken ct. Leaving for a week in Hershey,pa. meet tonite. ken ct. 1-203-260-5945 cell.
 
Definately black smoke, but not a lot, only when I rev it hard. If I recall correctly, the fuel pump does have a metal screen, it was part of the pump before I rebuilt it and I put it back. The distributor is the Mallory dual point with no vacume advance. Also have a manual choke that does stay open this is why it's confusing me. I'm guessing that I still need to put a fuel filter on, maybe I got something clogging a jet or something? Seems like it would be starving of fuel if that was the case. The carb is not overflowing or leaking like it has a bad needle seat.
 
Your mallory has mechanical advance, check with a timing light to make sure it's working properly. I don't think this problem is related to your lack of a fuel filter, but you need one regardless. You'd know if a jet was plugged, it would be running like crap. What do the plugs look like?
 
Or the wrong # PV. Most kits have ones with too hi a #. Dumps loads of fuel right away. You need to slow the opening of a lower # PV like a #5.5 or 4.5/ Most installed from kits are 7.5. They open too quick. ken ct.
 
bobscogin said:
I'd suspect a leaking power valve.

Bob
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But then it would be running very rich at idle... It's almost hard to believe that a single 94 would provide too much fuel at high rpm. That is, unless there's something else wrong with the engine's tune and it's just not burning it...
 
I haven't checked the plugs yet, maybe they are fouled. I might not have noticed the rich condition before because the plugs were not fouled yet. I only have about 100 miles on the engine. I certainly didn't think a single carb set up would run that rich either. It's always purred like a kitten till now.

I did have a point's issue in the beginning which caused the engine to cut out at high rpm and finally resolved it with new points and condenser and some pain staking setting of proper gaps. Forgive me cause I am new to the flathead world, but I love em !!!!!!
 
As I said above, I'm not convinced you have a carb problem here... But, for peace of mind, it's probably not a bad idea to take Ken ct's advice and have a reputable rebuilder who's familiar with 94's go over it with a GOOD quality kit and a PV that actually fits.

Recheck your point gap and dwell settings, I don't know what points you used in it, but anything other than NOS ones in my Mallory simply will not hold adjustment longer than a few days. Also, do check to see that the inital timing is set correctly and the dist is advancing properly, as that is a condition that will affect the engine's efficiency at higher RPM only... right where you're noticing an issue! If the spark is way retarded you're going to be blowing excess unburnt mixture out the exhaust valve, hence... black smoke. Good luck.
 
I took Ken's advice over a year ago about changing the Power Valve. I got a 5.5 from him, and my flathead runs better than it has in 13 years. I was running 7.5 PVs from rebuild kits, and they dumped too early. Also, as Ken has pointed out before, the ones in the rebuild kits do not seal properly. The one I got from him was perfect. Also changed the jets to a lower number instead of the stock .51's.
 
thunderbirdesq said:
Check to make sure the choke isn't closing up, or not opening all the way.
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Thanks for the simple solution! I was all worried about power valves and leaking floats. The cable stretched a little on the choke and caused the problem. I didn't check this for a while because I wasn't driving the truck but now she is running perfectly.

I love these trucks because they can be so simple in a lot of ways, like no emissions controls or sensors or computers......YES! no computers...goto love it!!!!:)
 
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