I’m trying to dial in the jetting on my carbs. I’ve got a little over 100 miles on the new motor and will be changing the oil and adjusting the valves this weekend.

Below 3000 rpms, I’ve getting a little hesitation when I accelerate, regardless of whether it’s ¼ throttle, WOT or in between. I’m running 55 idle jets. I have a set of 50 idle jets. From what I can gather, the jetting requirements of every motor is a little bit different. Does it make sense to try the 50 idle jets? Should I get some 52s and 57s and try them?

Have you played with your accelerator pumps?

A set of jet reamers will save you money in the long run. Order one new set of jets. Ream your current jets a little at a time and test a lot. If er when you ream them too big, get out your new set and ream them to the setting where your car was running best...At least that's what I did.

Jets are cheap, just buy them. That way the numbers will actually match what they really are.

I'm running.....50 or 55's on my stock 2.0 with FI cam and it runs really good.

You're running a 2056? I would think 55's would be fine.

What's your total set-up?

Idles
Mains
Airs
Emul tubes

They all work in concert with your cam, compression, displacement etc.

I agree with the above statement to check your accelerator pump adjustment as well as thier condition. Cracks in the diaphram will really jose things up.

What dizzy are you running? That makes a big diff as well.

I'm with Root on just getting an assortment of jets. If you get to the point where you just can't get it perfect, one size is close but too lean, and the next size is too rich, then resort to reaming the jets.

Also the actual size of the jet vrs the plug gauge is different, the jets will always be a little smaller than the corresponding plug gauge.

I have the old style accel pumps, so there is no adjustment (that I'm aware of).

My setup is:

2056 w/9050 cam, dizzy is an L-Jet with mechanical advance only, compression is 8.8 to 1.

Weber 40mm
Idle 55
Main 130
Air 200
Emulsion F11

I imagine the best thing is to use a chassis dyno with a handfull of jets and venturis.

AMEN!

Should I buy idle jets on either side of the 55s?

What about the main jets? At 3500 rpms, if I hit the gas, it starts to pull instantly with no hesitation. And so far, it continues to pull thru 5600 rpms.

You're lean in transition. At the very least you need more accel pump, but you may try going up on the idles. Definitely not lower...

You can probably buy a pump jet too! At least with Dell's you can. I wasn't aware there were carbs made without an adjustment on the pump arm...

I'd try a little bigger on the idles.

I think even the early accel pumps can be adjusted? That I don't know.

If you have 57's or even 60's, I'd wager if you run them for a little bit, you'd notice an improvement.

Chris, bigger idles not smaller will help with your hesitation.
If you have time, swing by our shop and pull the idle jets in the driveway.
I'll ream them just a little bit for you.

Thanks for the offer. I may try to swing down there next week.

Once the weather turns colder (Oct-Dec), will I likely have to go up on the idle and main jets due to the change in the A/F mixture?

Due to the increased density of colder air.

Yes, which I assume leans out the fuel mixture.

As there was no way I was going to make it to Chris' shop in trhe next 2 weeks, I ordered some 57 and 60 idle jets. I popped the 57s in this morning and just came back from a drive. It appears the stumble is gone.

Thanks for everyone's advice. The engine seems a little quieter on acceleration now. It feels smooth from 2000 to 5600 rpms.

Btw, 300 miles on the engine so far.