Going Backwards (going to a smaller carb)

[GASoline71]

So I've always used 3310's for most of my HP engine builds. But this is the first 5,000 pound brick on wheels I've ever built an engine for. I built it for top end power like I always have. So I topped it off with a 750cfm 3310 with a rear metering block and a 4 corner idle circuit.

So my carb guy and I were yakkin the other day and now that the engine is out of the truck awaiting the truck to be rebuilt after I hit a ditch 1.5 years ago... he recommended a smaller carb.

So I now have an 1850 main body with center hung float bowls, that has been bench flowed to about 625cfm with the choke horn milled off, rear metering block, and a 4 corner idle circuit. He said that if I don't like it, he will leave my 3310 main body on the shelf in case I want to swap it back.



I think I'm going to end up really liking this smaller carb. Especially in the heavy truck. The transition from low end TQ to top end should be smoother. While the engine is out I'm also thinking about going to a smaller roller cam since I can achieve a lot of the performance I have now with a bit milder roller setup, instead of the aggressive flat tappet that's in there now.

prostreet-C10, cableguy and MarvD, I was thinking of you three when I was talking with my carb guy... what say you? Anybody else wanna chime in with thoughts as well?

Gary

[prostreetC-10]

I just responded to another guy's post that went the other way (a little bigger) and is having some issues.

I can speak from real world testing. Towards the end of my Holley farting around, I was testing everything I build on a roller 454 in a gutted Camaro. IT's funny how I'd test an 850, which was way too big for the motor and it would run pretty good. Then I'd build a little 600 DP and it would flat out scream but MUCH better throttle response. I've slowed down so much in my BIG CAM, BIG CARB days of old. What very little I might give up on the very upper end RPM, I will gladly take on the driveability in the RPM range that the motor spends 99% of it's time. It's so nice to not fight part throttle issues. Your guy did drill and modify the main body and base plate so it is a true 4 corner right? I don't even know if I'd have gone that far. On everyday-ers, 2 corner is so damn easy to adjust.

Oh yeah.....put a screw in that secondary linkage and you will have a turbo-supercharger-injected-blown carb!!!!!

[OutlawDrifter]

i think the trend is to over carb anymore...600 is good but 750 must be better right?

i will take a smaller carb any day. as prostreet-c10 said, the driveability in the rpm range that most street engines live in. crisp throttle response is better than 15hp up top in my opinion! but i'm not trying to squeeze every tenth out of my rides anymore either.

[GASoline71]

Originally Posted by prostreetC-10

I just responded to another guy's post that went the other way (a little bigger) and is having some issues.

I can speak from real world testing. Towards the end of my Holley farting around, I was testing everything I build on a roller 454 in a gutted Camaro. IT's funny how I'd test an 850, which was way too big for the motor and it would run pretty good. Then I'd build a little 600 DP and it would flat out scream but MUCH better throttle response. I've slowed down so much in my BIG CAM, BIG CARB days of old. What very little I might give up on the very upper end RPM, I will gladly take on the driveability in the RPM range that the motor spends 99% of it's time. It's so nice to not fight part throttle issues. Your guy did drill and modify the main body and base plate so it is a true 4 corner right? I don't even know if I'd have gone that far. On everyday-ers, 2 corner is so damn easy to adjust.

Oh yeah.....put a screw in that secondary linkage and you will have a turbo-supercharger-injected-blown carb!!!!!

He did... the 1850 main body he had and my base plate were already set up that way so I was fine with it since I can tune it. The few times I will get to top end anymore is what made me look to downsize. I too have been slowly weaning myself away from BIG CARB BIG CAM builds. This engine was probably my last of that kind unless I find a drag car to play with.

Originally Posted by OutlawDrifter

i think the trend is to over carb anymore...600 is good but 750 must be better right?

i will take a smaller carb any day. as prostreet-c10 said, the driveability in the rpm range that most street engines live in. crisp throttle response is better than 15hp up top in my opinion! but i'm not trying to squeeze every tenth out of my rides anymore either.

Looking forward to that sweet spot in the throttle response. I knew how to tune my 750's to pretty much work around the typical flat spot on an over carb'd rig. I also have taught myself how to drive with it too. This will be waaaayyyyyy more betterer.

Gary

[prostreetC-10]

Let's face it Gary.......sometimes we just have to be man enough to say "smaller is okay!". LOL

[GASoline71]

HAHAHA!

Gary

[Ironangel]

Originally Posted by prostreetC-10

Oh yeah.....put a screw in that secondary linkage and you will have a turbo-supercharger-injected-blown carb!!!!!

You just described a well tuned mechanically linked secondary Quadrajet! ...Sounds like you guys are getting "older and wiser?" Welcome to the "Jet Set" almost!

[GASoline71]

How much older do I gotta get? I'm pushin' 50 now!

Gary

[cableguy0]

You will probably be surprised at how well it runs. Throttle response will definitely be improved. The velocity of the air moving is more important than the amount a lot of times. The air moving quicker especially off idle and in street situations helps a ton. Same reason sometimes a little smaller runner on a cylinder head will outperform big open runners. You probably took a step forward not backward.

[crazy longhorn]

Even on the track, if you are not revving real tight, the smaller carb will work nicely? My bros S-10, fitted with my old street 383, made the best of 13.1 on the track (my street tune), with a 1407 /750 Eddy. With a quick fuel 650 DP, she went 12.5 @ 106 mph.....rolling through the big end, @ 52-5300 on the tach...longhorn

[cableguy0]

Originally Posted by crazy longhorn

Even on the track, if you are not revving real tight, the smaller carb will work nicely? My bros S-10, fitted with my old street 383, made the best of 13.1 on the track (my street tune), with a 1407 /750 Eddy. With a quick fuel 650 DP, she went 12.5 @ 106 mph.....rolling through the big end, @ 52-5300 on the tach...longhorn

I doubt carb size had much to do with it. It was likely the quick fuel being that much better. Aside from that the quickfuel/preform main bodies flow a lot more than claimed. That 650 is probably moving close to 700cfm.

[crazy longhorn]

Originally Posted by cableguy0

I doubt carb size had much to do with it. It was likely the quick fuel being that much better. Aside from that the quickfuel/preform main bodies flow a lot more than claimed. That 650 is probably moving close to 700cfm.

I can not argue the point....wish I had the 3310 Holley to baseline on? Just the thought, she don't need a big carb unless 7000+ rpms Longhorn

[cableguy0]

Originally Posted by crazy longhorn

I can not argue the point....wish I had the 3310 Holley to baseline on? Just the thought, she don't need a big carb unless 7000+ rpms Longhorn

Don't matter much at this point. That rig hauls @ss now. No point in messing around. A 3310 would be a step back in my opinion. I went from a 3310 to a preform 750 van secondaries and it was a big difference at least in the seat of the pants dyno. Both carbs tuned by me and no change except the carb. Thought I probably wouldn't mess with any carbed anymore If I did it would have a quickfuel or proform carb on it.

[cableguy0]

On a side note. I believe that the only reason Holley released the Ultra series is because quickfuel/proform came out with their pieces and took a good share of the market.

[prostreetC-10]

That and at certain intervals you must release something "new" whether or not it's "improved".

I think getting away from the cast zinc parts is a good idea with all the ethanol we are seeing at the pump. Shiny and anodized also sells.

[cableguy0]

Originally Posted by prostreetC-10

That and at certain intervals you must release something "new" whether or not it's "improved".

I think getting away from the cast zinc parts is a good idea with all the ethanol we are seeing at the pump. Shiny and anodized also sells.

Yup its likely a combination. Anodized just looks more "finished" than the garbage zinc that discolors. My proform looked the same at 5yrs old once the grime was washed off. My 3310 however couldn't be brought back to like new.

[crazy longhorn]

Originally Posted by cableguy0

On a side note. I believe that the only reason Holley released the Ultra series is because quickfuel/proform came out with their pieces and took a good share of the market.

Yup , that Quick fuel, is a nice carb....screw in air bleeds, 4 corner idle ,ect. that said, we have not opened the carb (stock jets, power valve)? Just set the idle speed, & adjusted the 4 corner idle! Little bro walked in & handed me the plugs out of that 383, nice tan color....burn stops right in the apex of the strap on the plug (@ 38 total). My thoughts are , don't mess with it! She runs 20 initial, with 18 in the mechanical, all in around 2600. 3200 stall, foot brake on the line. He pulls her to 2000-2200 on the foot brake, the lets her go on the lite.....easy ride, very little spin & consistant as he!! Longhorn

[ERASER5]

Originally Posted by prostreetC-10

Let's face it Gary.......sometimes we just have to be man enough to say "smaller is okay!". LOL

Yea, some of you wierdos even say "Make my bed a short one."

[crazy longhorn]

I am all for that + 6" on the bed....longhorn

[Ironangel]

Originally Posted by eraser5

yea, some of you wierdos even say "make my bed a short one."

(((crackup!))) lol! PS. "Pushin Fifty" is still a teenager in Southeast Nebraska! GeeWhiz, I'm only Fifty Sixteen!

[GASoline71]

Originally Posted by ERASER5

Yea, some of you wierdos even say "Make my bed a short one."

NEVER!

Gary

[GASoline71]

I wanted to resurrect an old thread and say that I am super happy with my little 600 cfm carb experiment! Off the line it has no stumble and it rips when the secondaries open up. What an awesome little carb. The cool part is... unless you know what to look for, it still looks like a 3310!

Gary

[jjzepplin]

My favorite carb was a dbl pmpr 650 holley. But you have to remember that the exhaust and plugs and vehicle weight all play into the response of your ride. Experiment and find the sweet spot. It truly is sweet when you find it!

[68Gold/white]

These engines came with 750 cfm vac sec quadrajets, which can be made to run as fine as any carb...

A 3310 is a vac sec 750 carb.

Glad to hear your carb choice is working...