Carb Questions

[Hooker]

I have a 69 Chevy C10 with pretty stock 350 in it... i have a 670 cfm Street avenger on it now and i think my engine can not handle the cfm... i am looking at getting a new carb... what is the best out of the box carb for my engine?

Also do you think my mechanical stock fuel pump provides enough fuel to the current carb? i am having trouble with it dyeing when i am idled down or at a stop light...

thanks

[60ratrod]

well i don't think that it's too big for the motor. the stock q-jets were actually alot larger than that. i would check your timing. but if you are still thinking of swapping carbs i would go with an edelbrock 1405(manual choke) or 1406(electric choke). both are 600 cfm. they are easy to tune and should run just fine right out of the box.

[ChevLoRay]

I have an Edelbrock Q-Jet (750cfm) on my stock-block 350. It has had no issues with that size carb. Smaller primaries are the key to that issue. I don't think that the CFM ratings are necessarily met as we have them installed. Engines are just air pumps. Getting the air to move involves several factors, from reducing the intake restrictions to relieving the backpressure and making sure the air can move through the intake and exhaust.

[Jcentsr6]

I have an electric choke q-jet
(xtra) if you want to try it? It work fine...just bought a new carb...I will sell it for cheap if you need it..

[Hooker]

I have had this carb for a few months and it is a learning exper. for me... i know nothing about carbs... got this one from a friend cheap.... Any help will be appreciated! THANKS

[whitelightenin69]

have you tried to adjust the ideal mixture screws, on my 750 it will die if the screws are set in to lean.

[webfoot]

Why not just jet it down a few sizes if ya think its too big, those guys are only $5 as opposed to a new carb. Did you adjust your idle mixture and floats when you put the new carb on? What is your timing set at?

[Hooker]

timing is just right of the timing light center... i have been trying to adjust the idle screws.... i am kinda new to all this and learning about it.... any good referneces to setting timing and all?

[webfoot]

Originally Posted by Hooker

timing is just right of the timing light center... i have been trying to adjust the idle screws.... i am kinda new to all this and learning about it.... any good referneces to setting timing and all?

Turn your idle screws all the way in and then adjust back out 1.5 turns. Then fine tune for best idle/highest vacuum.

Also, your timing is slightly retarded. If your cam is stock try for 2-4 degrees btdc initial. (vac advance plugged) Get your timing squared away before adjusting the idle mixture screws BTW.

[60ratrod]

Originally Posted by webfoot

Turn your idle screws all the way in and then adjust back out 1.5 turns. Then fine tune for best idle/highest vacuum.

Also, your timing is slightly retarded. If your cam is stock try for 2-4 degrees btdc initial. (vac advance plugged) Get your timing squared away before adjusting the idle mixture screws BTW.

timing is everything. i would set it at about 4-6 degrees advanced. then with your mix screws and idle screw. i had a truck that wouldn't run cause it was so far out of timing

[Billla]

Originally Posted by webfoot

If your cam is stock try for 2-4 degrees btdc initial. (vac advance plugged)

Huh? What SBC on the planet runs with 2-4 degrees advance? 10-12 is a good starting point, then adjust per my .sig FAQ.

[webfoot]

Originally Posted by Billla

Huh? What SBC on the planet runs with 2-4 degrees advance? 10-12 is a good starting point, then adjust per my .sig FAQ.

Well, he said it was a basically stock motor, these things arent exactly built to be HP mongers. My chevelle is around 18 but it isn't made for towing or hauling. Except hauling a$$.

[Billla]

Originally Posted by Hooker

I have a 69 Chevy C10 with pretty stock 350 in it... i have a 670 cfm Street avenger on it now and i think my engine can not handle the cfm... i am looking at getting a new carb... what is the best out of the box carb for my engine?

Also do you think my mechanical stock fuel pump provides enough fuel to the current carb? i am having trouble with it dyeing when i am idled down or at a stop light...

thanks

CFM = ((CI x RPM)/3456) x VE

Stock engine, figure 75% VE, your engine needs only 646 CFM @ 8500 RPM...your carb sizing is fine The Street Avenger is a perfect street carb for your engine, but likely some time spent tuning your timing curve (see my FAQ list in my sig) followed by some vacuum secondary tuning will take care of any issues you're having.

Your stock fuel pump is providing 60+ GPH to about 5500 RPM - PLENTY for your engine. If the engine is dying at idle look for a vacuum leak, incorrect timing or a poor idle setting (mixture or RPM) including an incorrectly adjusted choke.

Bottom line is that you don't need any new parts - just some time getting everything set right

[VetteVet]

Check here and you will see some excellent pics and info to help you.

http://www.jegs.com/InstallationInst...10-0-80670.pdf

[69C10@16]

well my 2 cents worth is to pickup a cheapo mr gasket co. fuel pressure guage and some fittings and put it in yur fuel line. I did it on my new Edelbrock 1450 600CFM (man choke) carb. I dunno bout holley but the edel's say not more than 6 ur maybe 6.5 psi or you'll flood it out. So to make sure i was good i put that in and had a fuel pressure reg. sittin there too. I was able to take the reg back cuz i didnt need it. But yeah. I'd be checkin pressure 2 c wut i had. Just sumthin else to eliminate as cause. Ive never been a big holley fan anyways. I have a 307 with a Holley intake and edel carb and i think my intake is limiting me a LOT. not sre though. Anyways, long post to say somthing simple so i'll quit now. lol. Good luck in yur quest.

[Billla]

Originally Posted by 69C10@16

I have a 307 with a Holley intake and edel carb and i think my intake is limiting me a LOT.

IMHO, pretty unlikely if you're making less than 1.2 HP/CID (368 HP)

[68C15]

Holley has a big well known name, that's it. they have nothing more that that for the average guy. they have their place and it is not on a daily driven stock engine. I know Chevy used to sell HP cars with them but think about why they stopped and had Rochester Qjets from the late 60s until the late 80s.
I for one can make a Holley run like a scalded dog but it takes a butt-load of time and money to make it reliable on a DD. (I could go into depth about my 80 K20 with my HIGHLY modified holley that got 17MPG and made killer torque but that's another subject)
for the average guy with a daily driver and especially a stock engine it is hard to beat a well chosen Q-jet or properly set up Edelbrock.

[Billla]

Originally Posted by 68C15

they have nothing more that that for the average guy. they have their place and it is not on a daily driven stock engine.

especially a stock engine it is hard to beat a well chosen Q-jet or properly set up Edelbrock.

I agree completely with the performance aftermarket Holley carbs, but the Street/Truck Avenger line is jetted for daily-driver engines and like the Edelbrock they're pretty darn close out of the box and easily adjustable.

The QJet is still the all-around champ for driveability, and I've recently become a big Edelbrock fan as well...but I would consider the Edelbrock Performer and the Street/Truck Avengers to be equal.

[68Stepbed]

Best out of box for stock 350:
-570 Street Avenger
-500 Holley 2-barrel
-500 Edelbrock manual choke

It's always better to figure smaller is better. I've seen alot of people put too big of a carb on too small of an engine and have lots of problems. I've never had any luck with carbs bigger than 600 cfm on stock 350's. The only good Edelbrock I ever had was a 500 manual choke. That engine ran better than any stock 350 I've ever driven.

The 670 you have is a great carb and can be adjusted alot cheaper than buying a new carb. Here's what I did. Buy books on Holley carbs!! I knew nothing about them at first like you, but once I got started working on them, they're actually pretty simple and easy to work on. The only hard part was learning the right combination to get all parts to work right together. Also, call Holley. 1-800-HOLLEY1 Ask for tech support and tell them you have a Street Avenger carb. They will send you to the guru that designed the SA line. He helped me alot when I had trouble with mine. They have great customer support that will help you any way possible.

Edit-I also noticed you're in KY. Holley is in Bowling Green. What part of KY are you in?

[BigDaddyDave]

I have the avenger on my stock 350,and i could not be more pleased.I think it was almost perfect out of the box,i have never turned a single setting on it!

[69halfton]

about yuor fuel pump.

if its dying at an idle, the fuel pump isn't a problem. a good stock pump should EASILY be able to keep up at an idle.

if it was bogging at 6000 rpm, that might be a different story.

[68C15]

Originally Posted by 69halfton

about yuor fuel pump.

if its dying at an idle, the fuel pump isn't a problem. a good stock pump should EASILY be able to keep up at an idle.

if it was bogging at 6000 rpm, that might be a different story.

a mechanical fuel pump CAN fail the other way. they CAN put out too much fuel. I wouldn't have believed it myself but mine did that last winter. it was spewing out the bowl vents at idle. I thought I had a sunk/stuck float so I did a carb kit and float. still did it until I changed the 2 year old pump.

[68Stepbed]

Hooker, what is your exact setup? What kind of intake, dist., wires, plugs, etc.? There could be lots of factors causing the problem. Let us know what you have and we'll try to help you more with better info. It's vary hard to diagnose a problem just by telling us you have a stock 350 with a 670 Holley. It could be something simple(it usually is).

[Hooker]

It is a mid 70s (i think) 350 with 350 tranny.... stock intake and street avenger 670 cfm..... barry white HEI with oreilly wires and bosch plugs

[SchreinerM]

If your cam is stock try for 2-4 degrees btdc initial. (vac advance plugged)

I'm new to carb tuning as well. Is that typically to set timing with the vacuum advance plugged? Is this true of the vacuum on the carb as well?