My Hemi is running rich on cylinders 1, 2, 3, and 4. The front carb has stock jets and rods. The idle mixture screws are 1 1/4 turns out. I checked the float levels and the float drop is right at 3/4". The stock float height is 7/32". Mine are at about 3/8". I wouldn't think that the floats sitting lower would not cause the rich running issue. The timing is set at 20 initial and 35 total.

Are my thoughts correct that the front cylinders are fed off of the front carb? Any suggestions?

Thanks.

Stan

What intake are you using ? I'm not well versed on stock Hemis so

It is a stock '68 Street Hemi intake.

Stan

If you are using the stock progressive linkage the front carb doesn't do much of anything until you are almost half open on the rear or main carb. Both carbs feed all 8 cylinders. The only mixture screws are on the rear carb

I've got the stock progressive linkage on the carbs. There are idle adjustment screws on the front carb which I think were covered with lead plugs from the factory. The lead plugs in mine had been removed years ago.

Here's a question: When the engine is idling, should it be idling off of just the rear carb or should it also be using the idle circuit on the forward carb as well? I would assume that both carbs are poviding the idle mixture.

Stan

If the linkage is progressive the engine will idle off the rear carb only. So probably the front idle mixture screws should be turned all the way in, but I yield to a Hemi expert.
R.

Your front carb should not be in the circuit until you are about half throttle thats what the progressive linkage does. Shut down the idle screws and close the butterflys all the way. Then readjust the idle off the primary carb. Also look in the carb while its running at about 1/4 throttle and see if any gas is flowing into the secondary carb. Sometimes the floats will ride a little high and let gas gurgle into the engine. However, at part throttle usually the air flow will even out the mixture, it'll be rich all over.

Ok. Good information. A while back I had the front screws all the way in but I noticed a very harsh transition from one carb to both carbs. Once I backed out the front idle mixture screws a bit, the transition was much smoother.

Next question: Do you folks think that the rich condition on the front four cylinders could be casued by having the idle screws turned out a bit or could it be something else?

As crazy as this sounds, I am driving this car 5 hours to Carlisle early tomorrow morning. I may just turn the screws in all the way on the front carb and let it roll. I've got a fresh set of plugs and some tools so I can check it once I arrive.

Stan

That's what I would do! I'm hopping on a jet in the morning going to Carlisle

Well, I turned the idle screws all the way in and adjusted everything so it is running off of the rear carb at idle. I can't take it for a test drive because it is raining cats and dogs right now.

I guess my test drive will be my trip to Carlisle early tomorrow morning!

Stan

Don't forget to close the throttle plates if it has an adjustment screw on the carb. With them open even a little it really makes setting the rear carb up hard.

The front carb idle circuit is designed to function until the throttle linkage starts to open the front carb. Otherwise it wouldn't have an idle circuit would it?
Yes, make sure the return spring pulls the front carb all the way closed and set the front idle mixture as well as the rear idle mixture. Adjust the connector linkage so both carbs reach WOT at the same time.
And are you sure the plugs are fuel fouled and not oil fouled?

Sheldon

Thanks for all of the responses. I just finished driving it back from Carlisle a few minutes ago. I pulled a couple of plugs once I got there on Thursday and they looked pretty decent. I still have a bunch of tuning to do but right now I am going to put it in the garage and take a break!

Stan