engine solution

[Justins72]

I have a 340 in my 72 that has just been rebuilt. I is bored 30 over, the heads have been ported and polished and was told flows better then victor jr heads, but not 100 percent sure on that. The heads have bigger valves and new vavles for pump gas, not sure on the CR but my guess would be 10.5 to 1. It has an LD340 manifold with a 750 speed demon carb. Electronic ignition with a mopar performance chrome ecu. Now from what i have been told the cam is a mopar purple shaft not sure on the specs, Now My uncle and grandfather told me that i should change the cam since it might not match all the other components. Now the car is going to be driven on the street and it wont see little to none track since i live in san jose the only track is like
3-4 hours away. So what do you guys sugest on a cam? i want as much power as possible but still street freindly       Thanks

[moper]

How does the car feel to you? is there a problem you noticed?

[Super Blue 72]

How does the car feel to you? is there a problem you noticed?

  My thoughts too.  Is it running well or is there a performance issue or do you just want more power out of this engine? 

[Justins72]

it feels like it has no power at all, not very responisve, and i just cant seem to get it running right.

[Chryco Psycho]

I use a lot of the Engle cams , something like a K 56 or K 58 hyd ,should work perfect for you , do you have a stall converter assuming it is auto trans ?
www.englecams.com

[Super Blue 72]

What condition is the carb in, just curious?  Does the car feel like it's bogging?  I like to shoot at the easy stuff first.  I would much rather rebuild a carb than change a cam. 

Is it old?  Was it messed with as far as jets or what not?  I'm not familiar with Demon carbs.  Someone want to chime in?  Is that 750 too much carb?  I know when I got my car  when I stepped on the gas there was a big bog.  Lots of sound but no action.  No power and not responsive.  I think it had a bad accelerator pump because after I rebuilt the carb it easily spun the tires afterwards.

Am I barking up the wrong tree???   

Has it been tuned up recently?  Right timing/plugs?  Check the basics first.  It won't cost you as much.

[Justins72]

Its a brand new carb, jets were never messed with, The car hesitates when stepped on the gas. I dont know about the stall converter, Could the trans not be putting the power to the wheels? Im pretty sure the trans is time for a rebuild. i have messed with the timming but i have no idea what it should be around.

[MEK-Dangerfield]

Set your timing around 12 BTDC, just for starters. That should be close. It sounds like your new carb isn't playing nice here. How do your spark plugs look? Maybe it is too rich, or too lean? Maybe you need bigger squirters for the accelerator pump, if it is indeed working?


  Mike

[dimples]

I think I would find me a motorhead, (someone here live near you?) to take a look. Unless compression is low, cam is off, or something kinda major, it should make at least the power of a stock 340.............

[PlumCraZRT]

See what settings you have with your accelerator pump.  Bogging or "stumbling" is a sign of a rich condition (gettin too much gas) and popping or backfiring is a sign of a lean condition (not enough gas).  Look to the carb first.  I can almost gaurantee thats where your problem is.  Wouldn't hurt to check the voltage at your coil either.  A new coil and wires would be nice too if they are old.  I actually had issues with my car when i first got it runnin cause way too much voltage was goin to the coil and frying it.  Sometimes my car would run great, other times it would run terrible.  A cam shouldn't make your car feel like it has no power, its just gonna shift your torque curve around (unless the lobes are ground off your cam). I'll try to keep an eye on this thread.  Anyway, attack the carburetor first.  Additionally, i don't wanna be the one to tell you, but you would probably be better off with a 650-675 carb.  Smaller carb is a lot easier to dial in.  Good luck.

[ntstlgl1970]

Are you a member of Mopar Alley car club? They are located in San Jose, the members are pretty nice and I bet would be willing to help you out. When I still lived in SJ, I was in the club and we had more than one post meeting engine tuning session.    It's pretty hard to diagnose a problem via a keyboard.

Monthly Meetings
Round Table Pizza
Corner of Saratoga Avenue and Moorpark
San Jose, California

3rd Saturday of every month
Meeting starts at 6:30pm. EVERYONE is welcome!

www.moparalley.org

[Super Blue 72]

Set your timing around 12 BTDC, just for starters. That should be close. It sounds like your new carb isn't playing nice here. How do your spark plugs look? Maybe it is too rich, or too lean? Maybe you need bigger squirters for the accelerator pump, if it is indeed working?


  Mike

   What do the plugs look like?  Too rich or lean?

[IMNCARN82]

thoughly check the fuel lines for kinks... 

[PlumCraZRT]

I know Edelbrock has said that the "check the plugs" technique is almost a thing of the past.  Modern detergents supposedly make plug diagnosis difficult at best.  I had always liked the thought of that, but from the sounds of things it has become somewhat useless... The plug check technique, although less effective than before should probably still get you in the ballpark of what is reasonable... just my 

[moper]

I would start with educating yourself on timing, and invest in a timing light. You can play all day witha  carb, and then change timing, and then the carb settings are out the window. Always make the timing the first thing. On reading plugs..That's BS. It is only more difficult as you get the burn close. Then the cleaner burning makes it harder to read. But for the vast majority of tuners, the basic approach still works fine providing the engine is in decent working order, and the plugs being read are fresh.