http://store.summitracing.com/partdetail.asp?autofilter=1&part=HLY%2D0%2D3310S&N=700+0&autoview=sku

And if so did you/do you recommend changing the rear metering block with the plate for jets?

The 3310 is a great carb, if its running lean @ WOT yes you need to change it and install a metering block. The first change I like the best is the quick change spring kit.

Dave

it's true that the block makes it easier to change jets but the truth is that if the carb is anywhere near the right size for the engine they probably won't need changing anyway. Same with secondary spring thing, leave it alone unless a genuine need becomes apparent after driving/racing. buy it, take it out of the box and install it. leave the float levels alone unless it is demonstrated that there is an issue.

Most of the crummy Holleys out there were trashed by their owners making 3 or 4 changes to the carb before they even install it. then they fire it up and runs bad. Next thing heard is some whining about effin junk Holleys. Then he starts making more changes to fix the problems caused by the first changes. Next stop: swap meet. Buy it, leave it alone and run it. The car will tell you if it needs a tweak.

Best practice: get a quality fuel filter and install it close to the carb. blow out all the lines and fittings between the filter and the carb even if they're new.

Tom is right about people going nuts with jets etc. I will get a carb into my shop the jets have been changed and they are right out to lunch. I put the carb back to stock and they think, OMG what did you do to repair this thing its awesome. I usually tell them I put it back to stock. Holley does a great job jetting them right out of the box. The 3310 I like installing the purple spring its one looser than the plain stock spring. Using the light yellow or white spring usually causes a bog.

Dave

I appreciate the input.

My current Holley is one of the chokeless street hp ones, and I thought of selling it and going with the 3310, especially since I hear the chokeless Holleys flows no better than a typical Holley with a choke tower.

My street HP is a 4150 and in order to reuse the Holley dual feed line I'd need to swap the rear metering block out on the 3310 to make it into a 4150.

Now I am thinking if I got a 3310 I'd need to make some changes before I ran it....for example the vacuum reading on my 402 is only about 7-8 hg so I'd guess I'd need a 4.5 power valve or it would be running pig rich at idle?

I tried a 3.5 and the car didn't want to run. 4.5 and it does run.

I seem to recall the optimum jetting for my engine was something like a 74/80 or maybe a 76/80, can't remember. But otherwise I'd put it on the intake and go.

as always, the power valve has no effect on the idle. I'm beginning to think this magazine BS will never die.

leave the PV alone, leave the jets alone. the jets needed by some other carb have nothing to do with what this one needs.

Really, try to restrain yourself. You'll be much happier in the long run.

what's wrong with your old carb?

as always, the power valve has no effect on the idle.

So if the power was open at idle it wouldn't richen the fuel/air mixture?

No. It will only richen the idle if it's blown.

Funny this is brought up. I just rebuilt a 80508 (same as a3310, just has a shiny finish and electric choke). I tried it instead on the 870 Street Avenger just for kicks. Guess what, it lacks the punch that the 870 has. It does however idle better and seem to be a little crisper. The 3310's IMO, just seem lean for a stout BB. The metering plate in the 3310's are equivalent to 75's I think. Most people are jetted in the rear 80 to 84's.

no, the PV adds fuel to the main wells, same as the main jet. the idle system feeds off this well, but the amount of fuel used is tiny compared to what's available, with or without the PV.