Help make my 340 run great

[Lbs]

I am trying to figure out what I need to do to get the most out of my 340. I am not and expert on engines by any stretch of the imagination so if I'm not including enough info please let me know. I've been told by a local shop that my 340 with a 650 holley carb is starving for gas and not to drive it very hard until that is resolved. He was going to look into a 750 double pumper for it. A couple days ago at a car show I was talking to a guy there and he thought the 650 should handle it fine and that it was all about the timing. Said it needed to be at about 12 degrees initial and around 36 advanced timing. Also said that my distributor might not be able to be set that way without pinging and whatnot and otherwise damaging the motor. This is getting out of my league and I'm not sure what's right and what's wrong or which way to go. Any input would be greatly appreciated.

[cudabob496]

starving with a 650 is rediculous.

Just get it a good tune up, and all that that involves.

[GranCuda1970]

340 wants fuel, More top end needed 650 not enough. I starve my 440 with a 750 cfm.

[cudabob496]

340 wants fuel, More top end needed 650 not enough. I starve my 440 with a 750 cfm.

no way, I had a 500+ hp 440 that used a 750 double pumper. Had ported 915 heads and 1 7/8 inch headers.

[cudabob496]

see bottom of page (go to carburetor section first)

https://www.holley.com/support/faq/

[blown motor]

I have a 340 .060 over with a 650 Edelbrock. It runs awesome. I've never felt that it lacked fuel. I would say your car show guy nailed it on timing.

[Cudaragtop]

650 cfm is plenty for a street 340. 
I'm running a Quick Fuel 650 DP on my 418 CI stroked 340. Wideband Air Fuel Gauge says  right foot says 

[YO7_A66]

If you want the most out of YOUR 340, then the next part that you should purchase is a wideband sensor kit!
It will give you information about your current setup and we can help you tune your current combo. These kits are the best learning tool that you can buy for you and your car.

 I have two of them on my stock stroke 340. This is not stock and it has a QF 750 DP Annular carb and this tool has tought me that if a carb has tunable circuits, a wide range of carbs could be tuned on many types of engines once you know what the engine needs. I can see a 600cfm vacuum secondary working on a 340 and I could see a dual quad setup working on a 340 if you have the information from a wideband to help tune the setup.

 Tune what you have and purchase the tool to help you do so!

 

[jhaag]

What exactly are you trying to do? Does it run poorly now? If so what are the symptoms? Has the engine been modified or is it basically stock? A 650 Holley will work on a 340, but it may need some tuning as well. Get on the web and learn all you can about tuning Holley carbs, and ignition advance curves. Answers to above questions will help folks here, help you.

[blown motor]

If you want the most out of YOUR 340, then the next part that you should purchase is a wideband sensor kit!
It will give you information about your current setup and we can help you tune your current combo. These kits are the best learning tool that you can buy for you and your car.

 

What brand and model do you suggest?

[Chryco Psycho]

I agree with the timing 14-16 at idle with 34-36* total si about right .
You will not stave the engine even with a 2bbl , the carb tuned correctly will flow enough fule to match air flow , however 340 cam from the factory with an 800 cfm Thermoquad , so to maximze power I would look at 2 x the ci so 650 -750  is about right but it is all about tuning & the quality of the carb .
 Proform , QF , Holley Hp series  are all great carbs to work with

[YO7_A66]

I use two of the FAST #170634 kits. I bought one and tuned with it and bought the second kit about a year later. They run about $180. Is it the best, no. But they work great for me. Investigate the different types of kits and try to determine how much info you may need for your situation.

[HemiOrange70]

Have 340, 9.5-1 compression, x heads, airgap intake, stock manifolds, 904 trans with shift kit, electronic ignition with a 650 eddy and mopar purple cam-runs great

[Lbs]

Thanks for all of the information and input. I'm real interested in the wideband sensor kit but like I said I am not very well schooled on a lot of this. Is this kit something that is installed in and stays on the car or just a tool used to measure outputs? Also seems to be a very wide range of prices and I'm not sure what you are getting by spending more. Jhaag, you asked about symptoms and the truth of the matter is their aren't any. I took it to a guy recommended to me to have him dial it in and make it run great. He said he did what he could but I shouldn't drive it hard because it was starving for gas and getting on it would do damage to the motor. He was going to do some research to see what carb I should have. That was a few weeks ago and I've been driving it ever since but not getting on it at all. To be honest it's been running great so I don't really have any symptoms except being told, " NO HOTRODDING"     I don't know all of the history on this motor but it has a cam, but I don't know specs. Probably not much help. Looks to be stock heads.

[cudabob496]

fuel pressure gauge would be helpful. Need around 6 psi at carb.
how does he know its starving for fuel?
A simple solution is to increade carburetor jet sizes. Not buy a larger carb.