I just picked up a holley 650 double pumper real cheap but it is only 650 cfm. Is this too small for a 340? It has a comp xe268 cam, ld340, ported 2.02 J heads and hooker headers. Car is going to be mostly driven on the street with a few trips to the strip.

Have good low end but the higher end will suffer.

Good carb for that combo.

I think you would be happier with a 750-800 c.f.m.

650 will be fine unless you plan to rev over 6k.

650 is perfect in my opinion! Most people make the mistake of over carburating.

Double pump, on a 4speed--GO FOR IT.

Do the cfm math, I bet you'd really have to wind that little sucker up before the carb would be holding you back.

650 DP should work very well . Did you ever race that Subaru ?

It will run fine, have great response but will suffer on the top end compared to a 750-800cfm carb.

When I swapped from a 625cfm Carter to a 850 TQ on my old Duster with a built 340 I could really FEEL THE DIFFERENCE when I tromped hard on the gas pedal while cruising.

Bigger secondaries are nice to have!

Currently working on a 650vac sec carb on a 340.Good low speed response but little lacking on high end 650 dbl pumpers are just about perfect on a street 340 I have several and overall hard to beat over all. I like a 750 on a light car the 650 on heavier. I have just built another 800 dbl pumper and its great on high end and ok at low speed due to the 4.56 gears on my 340 Duster. I have not track tested it to see what the 60fts and 330 are like, your combo a 650 dbl pumper might be a little small but it will out perform most any other carb

should be ok... if you need more mph you can always bump up the rear jets.

How much will this 650 hold me back up top. Will it be enough to worry about or only a little bit.

The carb will work fine with your mild combo,it won't hold you back if it's properly set up. Someone suggested bigger jets to help the top end power,very poor advice. Set it up to stock specs and it will work very well.

Adding jet doesn't make the carb act BIGGER or faster if its correct as is.If it's correct adding jet will slow it down.

My 650 Holley DP seems to be perfect for my combo. XE274 cam, AirGap, stock X heads, 3.91 gears, 3,500# car runs high 12's with the 650.

Everyone said it would run quicker with a Holley 750, we put one on and the car slowed down 3 tenths, even with tuning. Swapped the 650 back on and the car jumped right back.

Well...you can have a street set-up and a track set-up. I have found that some of MY vehicles enjoyed more timing and bigger secondary jetting at the track. All were run w/o air cleaner assemblies w/ fresh air hoods while racing. I also uncapped the exhaust. Adding a few gallons of 110 didn't hurt either.