Has anyone used one? $240 with free shipping!! It is calling. I guess what is bothering me is that many parts are similar to the autolite 4100. I frequently work on them, and for my 300 I run .046 primary jets. I see the Summit carb comes with .067 primary jets.

Does anyone want to chime in here? Thoughts?

 

I thought about getting one being as the throttle shaft on my afb is pretty wore out and the manual choke got old really quickly, I assume the tune is setup for a 350 so I'd imagine it'll be pretty rich out of the box.

 

I agree it might be a tad rich as it comes out of the box, but it looks like a great carb to me. The best features of the Autolite 4100 with additional features such as external adjustable floats, clear sight-glass windows, great price, and you are dealing with a new part. I believe it also comes with a tuning manual. Looks good to me. 600 CFM would be my choice. Best of luck with whatever you choose...jack

 

I've been eyeing this carb for quite a while. I'm currently saving up for one.

 

AB: Please keep us posted if you get one. Best wishes,...jack

 

I definitely plan to. My current Holley 600 has a throttle bushing leak. Instead of paying $100+ for a new base plate, I'd rather a little over double it for a new carb, especially since the summit one has some really nice features. And I'm kinda in a hurry since I'm tired of the bogs and lags from the vac leak.

 

IMHO, summit brand carbs- avoid like the plague- design is great mfg QA runs from good to crap because it is a chinese mfg.

 

Thats the entire point behind leaving feedback on a product, I have used a few summit made parts on my truck with no complaints. If one person buys that carb and it performs and holds up well its worth the $240.

 

I've read about this before on line about this exact carb, but the review was very detailed in what to look for as far as issues. However, their warranty is good enough that they'll work with you to get you a good one, if you're patient.

 

I found a vid on youtube of 300 build that the guy used a new Summit carb. It looks as though he has an Offy C, header, DUI dizzy. I don't know if he had head work done.

(copy/paste if the link is not active.)

I know the carb is a copy of the Autolite 4100 and Holley 4010 (iirc). I now run a 4100 and I use .047 jets in the primary. The Summit comes with .067 jets. Certainly it couldn't need that big of a change? Different carb/ different jets.... Yes, it is past time to get a wide band....

 

My Holley 600 had .066 jets stock. I think I have .064s in it right now. The 390 came with .051s. Just matters on how much air is going through it.

 

Thanks AB. I have an Autolite 4100, the big block type, 480 cfm, oe for a 67 tbird with a 390, and I took iit off that car and engine myself. It had .047 pri jets. Different carbs meter differently?

 

You're correct, there's not much correlation across different carb make on jets.

A smaller carb on a big engine is sort of counter-intuitive on jetting because you'd think it would want richer jets. Ditto an 850 cfm (or mechanical secondary 4v) on a small engine - you'd think it would need smaller jets. But it draws so little air you'll probably need to jet it very rich to get any kind of low rpm then it runs too rich at high rpm when airflow increases.

That assumes identical carbs. I think there are internal differences on an Autolite that came on an FE vs SBF?

 

From my experience and reading, jetting has absolutely nothing to do with the engine (aside from maybe one engine liking things to be just a "tad" leaner or richer than another.) It simply comes down to how much air is moving through the carb.

If it has a large capacity for air (higher CFM), it needs more fuel to balance it to the proper AFR.

Then, if you, for example, put a big carb on a small engine, the engine just pulls less air through the big venturis and therefore less fuel out of the big jets. All balances out in the end.

 

"... jetting has absolutely nothing to do with the engine"

Agreed...and that's pretty much why contemplating a jet change before running/driving is not a good idea.