Carburetor Choice Advice...

[engine24355]

Okay guys, as I am collecting the parts needed to change my dual carb setup to a single, I need some advice on a new carb. I have been reading about the Summit line which is pretty much a Holley, but would like your advice. I think a 600 cfm will be pleanty. Let me know what you think.

Thanks!

 

[donsrods]

600 cfm is just about perfect on a 350-ish motor IMO. I'm partial to Edelbrocks but have to admit a Holley looks better sitting up there, fills the top of the intake up a little more.


Don

 

[Wild Mango]

Yep 600cfm is spot on for a 350. You might want to buy the adjustable secondary jet kit, which is another metering plate and two fuel tubes. Then you can change the jetting in the secondaries as well, really make your baby cha cha!!!
That 350 will go better too........................................

 

[Coupefreak]

I have a Barry Grant Road Demon, took a bit to get it "tuned" to my set-up, but has been trouble free since
625 cfm, 4-corner idle adjustment, Holley based.

Vance

 

[rooster57]

My neighbor has a Holley avenger and swears by it on his vette

 

[Noob]

I'm not a fan of the Edelbrock because of the lag getting into the secondaries. The only way I've been able to get rid of it is to take the counterwieghts out and file them down until you get a smooth transition into the secondaries. Or the other fix is to throw it in the trash and bolt on a Holley.

 

[rooster57]

Noob when you throw that elde carb away let me know where, so i can go and dig it out.

 

[Screaming Metal]

Yep 600cfm is spot on for a 350. You might want to buy the adjustable secondary jet kit, which is another metering plate and two fuel tubes. Then you can change the jetting in the secondaries as well, really make your baby cha cha!!!
That 350 will go better too........................................

yep....600....do like Mango said....then you can tune it nicely.

Its best to go small on the carb.......nothing hurts like too much in that department. Its best to be a little too small than a little too big.......

Ted has told many folks.....you'll be happier having a small tame engine in a bucket....because its so small and light, a stock 350will really haul it! True.....power to weight ratio is really there in the buckets........it don't take alot of engine to motivate these things down the road...........

 

[donsrods]

Noob when you throw that elde carb away let me know where, so i can go and dig it out.

Yep, if he doesn't grab it, I will.

Don

 

[FastEddie59]

Here's my two cents worth, if the motor has been upgraded at all I think a 600 will be too small. Keep in mind that a Q-jet like came on stock motors was 625 cfm. If it has 9.5 to 10 to 1 compression, a bigger or more radical than stock cam, better flowing as in hi-perf heads and I guess your running headers, all of this will increase the ability to flow and burn more fuel. I take it this motor has more power than the previous one and it would take two 600's. I looked at the Summit carbs and if it was me with the limited info I know about your new motor I would lean towards the 750 vacuum, if you go with a holley I would choose the 670 street avenger. They also had a 4150 street carb that was 650 cfm that sounded good. Well thats my two cents worth and for my personal preference I like the mechanical secondary carbs because they are so much more tunable and you can make them do exactly what you want without vacuum being a factor. Good luck and hope you can get it to scream when your done, Eddie

 

[GT63]

To determine what CFM you need use this formula:

Engine Displacment * Max RPM / 3456 = CFM @ 100% Volume Efficiency

I running two Edelbrock 1405s on my blown 355 and they run great. Tried a set of Demons made for blowers and they ran like crap and the tech line wasn't all that friendly either.

 

[Screaming Metal]

Here's my two cents worth, if the motor has been upgraded at all I think a 600 will be too small. Keep in mind that a Q-jet like came on stock motors was 625 cfm. If it has 9.5 to 10 to 1 compression, a bigger or more radical than stock cam, better flowing as in hi-perf heads and I guess your running headers, all of this will increase the ability to flow and burn more fuel. I take it this motor has more power than the previous one and it would take two 600's. I looked at the Summit carbs and if it was me with the limited info I know about your new motor I would lean towards the 750 vacuum, if you go with a holley I would choose the 670 street avenger. They also had a 4150 street carb that was 650 cfm that sounded good. Well thats my two cents worth and for my personal preference I like the mechanical secondary carbs because they are so much more tunable and you can make them do exactly what you want without vacuum being a factor. Good luck and hope you can get it to scream when your done, Eddie

Yea....I believe he's got a bone stock 305.........now if he had a cam......withgears over 3..73's or 4.11's........and a decent set of heads......a 650 doublepumper would be the ticket

Mango.....have we covered this before?????????????????:bed::lol:

 

[Screaming Metal]

To determine what CFM you need use this formula:

Engine Displacment * Max RPM / 3456 = CFM @ 100% Volume Efficiency

I running two Edelbrock 1405s on my blown 355 and they run great. Tried a set of Demons made for blowers and they ran like crap and the tech line wasn't all that friendly either.

You Da Man!!!!!!!!!!!!!!!!!:razz::razz:

 

[engine24355]

The new motor is a 355. Below are the main specs for your consideration. Thanks for the advice!

Top End:
1. 882 Cylinder Heads
2. Stainless Steel Valves (stock diameter & length)
3. Screw in studs & guide plates
4. High lift Z-28 valve springs (stock diameter
5. 10 degree locks & retainers
6. Aluminum roller rocker arms
7. Hardened push rods (stock length)
Bottom End:
1. GM steel crank
2. GM X rods
3. ARP rod bolts
4. Speed-Pro Hypereutectic pistons (LT-1 style)
5. GM block, 2 bolt main bored .30 over and decked
6. Melling 55a oil pump
Camshaft:
Int / Exh
1. Adv Dur: 296 / 305
2. Dur @ 0.50: 246 / 253
3. Valve lift: .510 / .507
4. Lobe Sep: 108.0

 

[rooster57]

Yesterday i got in a 20 MPH roling start race with that 52 chevy in the video. He has a 383 stroker and my little ole 305 just walked away from him that was a smile getter Fo -Sho. So Ted you are right a streetable motor is by far the way to go.But what do i know you know how small a roosters brain is .

 

[Rick]

See?Everyone who ever drove one of these little rockets knows that off the line not much can beat them.AND!! if you keep your foot on the happy pedal long enough you will have to go home and change your shorts.(You dont want them nasty skid marks):bed::lol::lol:

 

[jmr122848]

OK my nickle (inflation)
That mill is a bit more than stock 350. Your VE is going to be a bit higher. 600 cfm will feed about 300-325 horses easy, you may be looking for a bit more with that cam (I'm assuming you have the compression for it.) I think maybe 650 to 700? Back in the day the hot factory small blocks used carbs in this range ( the DZ z28 302 motor used a 780 vac secondary carb, same as a 427).
like I said, I just read a lot and remember a little.

 

[Rick]

650/700 will be fine with that set up.

 

[RPM]

Back when we had a Super Flow flow bench and a dyno. We found that 2 cfm of air will make about 1 HP. That was just a general rule of thumb.

Something else we found on the dyno, I'll share. 93 octane makes less power in a low compression motor that the 87 octane. So unless you have a higher compression motor don't waste your money on 93 octane.

 

[Screaming Metal]

The new motor is a 355. Below are the main specs for your consideration. Thanks for the advice!

Top End:
1.882 Cylinder Heads
2.Stainless Steel Valves (stock diameter & length)
3.Screw in studs & guide plates
4.High lift Z-28 valve springs (stock diameter
5.10 degree locks & retainers
6.Aluminum roller rocker arms
7.Hardened push rods (stock length)
Bottom End:
1.GM steel crank
2.GM X rods
3.ARP rod bolts
4.Speed-Pro Hypereutectic pistons (LT-1 style)
5.GM block, 2 bolt main bored .30 over and decked
6.Melling 55a oil pump
Camshaft:
Int / Exh
1.Adv Dur: 296 / 305
2.Dur @ 0.50: 246 / 253
3.Valve lift: .510 / .507
4.Lobe Sep: 108.0

Hey Engine.....sorry....... I thought about Roosters Engine......305......yours a 355.....Yep......go with a dual feed, Vacc. secondary 650 Holley.......and tune the stew outta it!!!!!!