I have a holley 4160 600 cfm on my 355. Specs as follows.

355
9:1
.420 .442 summit k103 i think
ported and milled 882's
Weiand Xcelerator intake
Hooker 2460's and y
3" hooker catback.


Should i purchase a bigger carb or does anyone want to trade.

My car is alright quick, plenty of torque and holds out well in the higher rpms, but it definitely feels choked with the small y-pipe (2.5" outlet) and small carb.

How much power could be gained from switching up to a larger carb as well as modding the y-pipe to 3" outlet.

Also how much bigger of a cam could i go with without loosing to much bottom end grunt?

 

doubt you'll need to go much bigger on a 882 headed mill, I would look locally for a 650 or 750 double pumper and tune from there. The cam is on the small side but the heads aren't performance heads either. Bigger cams will want bigger rear gears, etc

 

600 CFM isn't hurting you with that combo. The type might be a little bit - I certainly wouldn't recommend getting another vacuum secondary carb.

 

I can tell you that we have pretty close to the same setup , Hooker shorties, y-pipe, hooker cat back, Summit TPI cam kit,except I have a performer intake and an edelbrock 600 carb. It feeds my 305 real good. Now I know there is a difference in the 305 and 350 but you can probably put a metering block on the back of the carb and put some bigger jets in it to fatten it up. Have you had the car on a Dyno to check the A/F ?

 

a 600 is a little on the small side.. i just got rid of mine for a 650.. definatly go with mechanical secondaries.. did i mention i have a 305. lol

 

Haven't dynoed it yet, it runs real good no stumbles or hesitation just get up and go. So tuning wise it should be darn close. I just want more power thats all.

 

A bigger carb won't give that combo more power.

The way to make more power, is to identify the ONE THING most limiting to its power output now; and upgrade it in a manner consistent with the rest of the combo.

It is not to simply un-bolt and re-bolt the big, shiny, easy-to-get-to things that are right up top and out in the open where everybody can see them. Not even if "everybody" thinks you should, or if so-and-so has a fast car with one on it, or the ad copy looks good, or whatever.

The way to improve the power out of that combo would be to get rid of those heads. THAT'S the weak link.

The cam you have is pretty well suited to those heads, and the low compression; that's what it was originally designed for. If the heads go, the cam should too. That's a pitiful cam for making "power"; it's a "torque" cam, commonly referred to as "the RV cam".

The one thing I see that kind of sticks out as a mismatch, is the single-plane racing intake manifold. A manifold that shows no power advantage over a dual-plane until 6000 RPM is not a good match for a cam that limits the motor's useful RPM range to below 4500 ROM or so. A dual-plane would suit the low RPM characteristics of the rest of the motor FAR better. A Performer would be better; certainly nothing beyond a Performer RPM. That would be the smart thing to spend money on, if you're looking for an upgrade. That would give you more bottom-end pep, with no sacrifice whatsoever at the actual top end that the combo is capable of.

Improving the exhaust is a good idea, no matter what. But with a cam that peters out by 4500 RPM, it probably won't make a HUGE difference; maybe no noticeable difference at all.

 

I agree with Sofa that spending the money on a performance dual plane intake will give you better results than a bigger carb will at this point.

Summit house brand intakes are available cheap and they're good designs- they are all re-badged Weiand intakes, not Chinese knock-offs.

Here's one that's the equivalent of an Edelbrock Performer EPS (the new design base Performer intake but with better computer-designed runners):

http://store.summitracing.com/partde...w=1&N=700+150+

And here's the equivalent of a Performer RPM:

http://store.summitracing.com/partde...4&autoview=sku

And lastly, here's the equivalent of a Performer RPM Air-Gap:

http://store.summitracing.com/partde...0&autoview=sku

 

You guys have basicly reassured what i've already known,as you can see i tried to match the cam to the heads and i'm glad i did a good job. and i've been kicking around the idea of a new manifold, i will be getting that for myself for christmas.

Thanks for the advice guys.

 

If youre combo is restricted, badly, you will greatly benefit from a bigger carb and 3" y-pipe.

However, like mentioned above, everything seems to match everything else, you may benefit slightly from a 650-750 cfm carb depending on the model.

My 355 in my bird was restricted with a stock 80's intake manifold and a cc-q-jet. I can usually tune the q-jets to run well but the cc-q-jets just have a certain amount of.... "sucks" to them. My cam is either a 110 LSA or a 112 LSA with about a 0.5 lift. 11:1 TRW pistons and 76cc heads. So the headers, and 750 dp holley made a huge difference for me.

Is your y-pipe a factory one? If so, you would benefit from even a mandrel bent 2.5".

However, for the price of upgrading a carb, your y-pipe and possibly intake, the power gain for your combo wouldnt be worth it in my opinion. Start with the cam.

Or, i would also recommend getting a non-cc q-jet from the 70's era, and see if your car likes the bigger cfm. Those things are dirt cheap, easy to tune, and can sustain quite a bit of power.