Help make my 340 run great

[YO7_A66]

"" 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.""

 Some kits have the analog gauges that mount in the car and some have the hand-held module that can also be mounted or unplugged when not in use. The type that you purchase is up to you.
 The analog gauges just show "live" what the A/F ratio is showing. The hand held units show live but they can also record the data for you to download onto a computer at a later time. Once again, the style is up to you. The analog are usually around $160-$230 or so and the hand-held can be twice that amount. It just depends on what you need. If you want something simple and have the room to mount the gauge, then go analog. If you do not want the gauge mounted in the car and you want to download the information, then go with the hand-held units.

 My car is a street car and I wanted the gauges mounted so that I can keep an eye on them all of the time while driving. I just take notes on the A/F readings when I am tuning, or I have a passenger write down the readings.
 
 I would suggest just buying one kit and mount it to the drivers side exhaust. Then after you have done some tuning and have a decent setup, swap the sensor to the other side for piece of mind.

 If you do not have a welder or have someone that can weld the bung into position, I have seen the bungs that strap around the exhaust pipe. All you do is drill the hole and strap on the bung over the hole.
 

[blown motor]

I know it's a bit crude and it's a one shot deal but I've heard of using the emission test equipment to read the exhaust. It's not fine science but it could put you in the ball park. It all depends on what level of precision you want and how much you want to spend.

[cudabob496]

or you could install one new sparkplug, and drive around a little, then
see how it looks.

[moper]

Dave (Y07..) is a great resource for tuning info. I missed if you said you were having a problem - but if guys randomly come up and tell you what's wrong with the car, but you haven't noticed, you might think again about getting into parts changing. Do a lot of reading. The science for carbs and tuning these is decades old. Some basics - always do timing first. Timing affects the carb. The carb will never affect timing. Verify the ignition you have is working to it's potential - whatever type it is. Then look into optimizing it (assuming it's a factory type setup). Once that's done you can get into tuning the carb. Buy the books first. Then decide if what you have can't be worked with. I don't feel a 340 will be starved with a 650 carb. I've seen 351 Fords make great power at 8200rpm with the factory Autolite 4bbl. The factory Carters on 340s were 625s.

[Lbs]

I appreciate all the good info you guys are laying out for me and it seems the best thing I can do first is to get myself better informed which is what I've been doing the last few days but I will certainly be happy to hear any other input that you all send my way. Thanks from California

[jhaag]

LBS, first thing you need to do is find another shop. The guy you are talking to doesn't know what he is talking about. Next you need to educate yourself, so guys like him can't take advantage of you. Tuning carbureted engines can be difficult, but once you have the basics, the learning curve should get easier and quicker. You will get good advice from "most" on this board. This can be a fun hobby, or a pain in butt. It all depends on educating yourself, OR finding a really good mechanic, (you can trust) to help you when you have issues.. Good luck

[cudabob496]

lotta good You-tubes on how to tune a car

[Lbs]

Spent a lot of time researching the carburator issue on line and I'm convinced that my holley 650 should be plenty. The good news is I'm a lot more informed than I was a week ago. Does anybody have a recommendation on a book that covers mopar engines to keep in the garage as a reference. I'll be getting on this project this week and keep you posted on my progress and probably asking for more guidance. Thanks again

[moper]

If it's tuning you need - the get tuning books. HP Books has them on Carters, Holleys, and anything else you might want to run. In terms of general info there are a few good Mopar books that have info on everything. One is P5249704 from mopar themselves.  How to Rebuild the Small-Block Mopar is also very good for small block only. There are other books on building strokers but they tend to be more model specific and can miss some of the general info and tech.

[Lbs]

Think I'm going down the "getting better educated" road. I've watched a lot of holley YouTube videos the last few days so today I started in on actually doing something. Took the carb off the motor and took it apart to see what size jets etc etc were in it. So here are some of the specs that I've come up with, so if anybody has any input I'm open to suggestions and if not I'll just continue on the same track the videos have me on.

So my motor is a 340 with and unknown upgraded cam

Carb is holley 650 CFM   Model 1850-5

Power valve is 6.5

The number on the squirt nozzle is 25

And the jets are 66

When the car is idling at operating temperature the vacuum stays steady at 14

If you go from idle to full throttle it hesitates pretty bad and sometimes backfires

Any opinions are welcome. Thanks, Mike

[moper]

Hard to say just based on the carburetor. What is your timing curve like? What ignition and distributor?

[Lbs]

My initial timing is 15* and the total is 37*. It is all in at 25 or 26 RPM. I'm having trouble with my idle circuit. The idle screws have no effect on the vacuum at all. The throttle plates are closed enough so that the slots are barely visible. I'm wondering if the fuel pressure is too high would that cause the problem? My pressure is about 9 lbs. I have a regulator and gauge on the way.

[Chryco Psycho]

You need 7 lbs max for a Carb , 6 is better , once you have that check the float level , the 25 squirter is the smallest one available , move up to a 30 or so  the hesitation should immediatly improve , you may need different pump cam too

[Lbs]

I don't understand what I am trying to accomplish with the pump cam. I know they open and close the acceleration pump at different speeds and lengths of time, but I don't know what I'm trying to accomplish. :Iclueless. My cam is orange and in the 1 hole. Thanks.

[Oldschool]

I don't understand what I am trying to accomplish with the pump cam. I know they open and close the acceleration pump at different speeds and lengths of time, but I don't know what I'm trying to accomplish. :Iclueless. My cam is orange and in the 1 hole. Thanks.

 I would do like Chryco suggested first and go up in squirter size first before trying to custom tune the squirter curve to your application. Sometimes a larger squirter will fix the whole hesitation issue and no cam change is needed. Just go up in size a bit and see if it helps. If it does, you might want to go up a little more until hopefully it eliminates the stumble. Gas mileage will suffer a tiny bit, but it is worth it...