Timing Cont'd

[72demon340]

I'm not sure the exact specs on my cam...not sure how to find out..I know its one of the purple shaft cams...from the way it runs i'd say it has a fairly high lift and duration...I don't know what it idles like as I an't get what I would call an Idle...about 1250 rpms....below that she dies...I think part of that is cam timing...I have a 4 degree offset crank key I am going to try....I cant do much with the base timing...more than 2 degrees or so either direction and she won't even start...not even try!
It's driveble only because the 3200 stall conv doesn't even surge at that rpm (maybe a little) AS for the rest of the motor...
340 .010 over, 10.5:1, edelbrock performer intake, eb carb 650, beat up set of hooker headers(waiting for the boss(read wife) to understand why I need 600$ headers (TTI) for my otherwise budget playtoy). I do have electronic ignition...but have not upgraded the box...considering going the msd6a route instead.
The carb will be getting tunes per Cudas wonderful instructions as soon as I can get the rest of this stuff straight....
SO, am I headed in the right direction?
Paris
72 demon 340
02 dodge dakota quad cab
02 trans am ws-6 6spd
65 jeep
67 kaiser army ambulance
99 vulcan drifter 1500

[451Mopar]

When you go to degree the cam in, measure the lobe lift, and the cam duration at 0.006" tappet lift (opening and closing) and again at 0.050" (opening and closing) to figure out what size the cam is. If you do the same on the exhause you can calculate the lobe seperation angle and overlap. Usually the cams should be installed with about a 106 to 108 centerline (to the crank) on the intake lobe (rember the second lobe is the intake, the first lobe is the exhaust.)
Double check clearances, piston to valve, retainer to valve guide and coil bind.

[71383bee]

This seems to be a more and more common problem, but if you can't get an idle below 1250 RPM I would have to suggest that maybe you have a vacum leak. Take a can of carb claener and spray around the gasket surfaces (intake and Carb) and see if the RPM's go up. If so you have a vacum leak.

[451Mopar]

If the cam is fairly radical, you may have the throttle blades opened up into the transistion circuit. It's usually obvious because the idle mixture screws will have little effect. This is usually when you need to drill the throttl blades so you can get the required airflow and be able to close the throttle blades back down a bit so the idle circuit functions.

This is IF you have no vacuum leaks and the cam is installed correctly.

[72demon340]

I checked the obvious stuff first...right after I got the car home...mostly due to car's many quirks...
Yours truly took delivery of the car w/ only 500 miles on a freshly rebuilt 340. The work was verified by reciepts and the machine work done at a reputable shop, but....
She doesn't like to start after sitting for more than a day w/o running. Starts easy warm...won't start hot...starts easy day after she's been run a little. Nothing out of the norm thats easy to find...NO leaks...plugs all show a generally satisfactory condition...overall not to lean or rich...but I have not tried Cudas method yet(see 4 corner carb sticky) She does run very hot 240-250 w/ 160 thermostat in...unless ambient temp is under 70 ( which doesn't happen often in NC summers ) Thus the reason she is down at the moment...radiator gave up the ghost....Any more Ideas?

[cuda66273]

Ass-uming that the internals and basics are correct as 451 described I would do the following....

1. Pull the distributor/box and have it checked and curved. 25* at idle and all in at 2200-2500 to a max of about 38*

2. Have that Eddy carb checked and rebuilt or chuck it and get a real performance carb for that performance engine.

3. Check the dampner to be sure it hasn't spun on the hub, it should idle from 10-30* of timing without stalling so something is going on there.

4. Check lifter preload...are they hydraulic or solids? You could have a tight valve or two, does this engine have any vacuum at idle???

You've got some things to work on for now let us know how you make out.

[cuda66273]

One more thought...who told you it wa a 650 Eddy carb????...there is no such thing?

500, 600, 750, 800 and I believe years ago they made a 625 in what was called a performance series, they had a black tag on the front with a Horse logo of somekind.....

Why don't you call the machine shop that did all the work and get a build sheet or copy of the bill??

[72demon340]

Sorry that was my typo...carb is an eb 600...puchased new when motor was built last year...found some of the reciepts today...
cam is purpleshaft 284. .484 lift on intake and exhaust
Thanks so much for the help...the distributor is old...I don't know what the acceptable amount of play on the shaft is, but I think that this one's shot....will probably replace it very shortly...any suggestions. I have seen alot of negative comments about botht the MSD and the MP dist's.
On the subject of the damper...that may well be part of the problem....base timing seems to jump around alot and I had wondered if the elastomer had started to seperate....will know friday when I get it off the car to swap in the crank key...
Any suggestions on Dampers?