340camshaft with stock conveter?

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joshua dewitt

joshua dewitt

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Purple Shaft Hydraulic Camshaft & Lifter Kit•Chrysler 273, 318, 340, 360
•Advertised Duration: 268°/276°
•Centerline: 114°
•Lift: .429"/.444"
•RPM Range: Idle to 5800

More info on Mopar Performance P4452782AE
this is the cam I have, here is my drivetrain combination... built 318 302 heads, matching m/p springs ,,, 9.5:1 -9.8- etc.. compression... 3:55 gears, 28" tall tires.. a998? or a904? from 78-79 passenger car with hydraulic lock up for freeway rpm use... now, question... is the cam too much for the converter? will I need a stall converter.. runs awesome but at idle and in gear with foot on brake vacuum reading drops from 20" idle to 7-10" then car dies.. only in gear sitting still, fine driving... so I was thinking I might have to go back to the original a904 with a 2200 stall converter..? thoughts?
 
Sounds like a tuning issue that cam came from the factory in cars with stock converters. What's the ignition advance like?
 
More idle advance is the standard answer, but at 20 inches of idle vacuum,You are probably running enough. Still 20* is a good target.And for sure do not hook the Vcan to manifold vacuum. Check the T-port sync. You may have to close the primaries some and crack the secondaries instead.Jus a wee bit atta time, till it works.
Don't forget to limit your power timing.
And most importantly Be sure the power valve isn't dumping, as the vacuum drops.
That cam with proper tuning should idle just fine in gear at 650 to 700. Or should I say 700 to 650. With a lil luck and a loose engine I think even 600 might be doable
Typically loc-up TCs are a lil looser anyway, cuz, you know, they lock up at hiway speed, so they can be looser, down low.See what I did there? I legalized a run-on sentence with,um,lotsa,um,commas,lol.
 
Another vote for carb/tuning issues, not the converter. Step 1: I would have someone in the car with the brakes on and then put it in gear idling, while you look at the timing and see if the timing drops way back as this is going on. What are the idle RPM's in neutral?
 
well according to carb book I am on ported vacuum, did it with vacuum can disconnected too.... I added a timing tape to a replacement balancer, and was reading around 18-20 idling in park, would need to get another person to help with the in gear thing, I believe it is vacuum leak maybe with the booster, everything new except the brake booster, and master cylinder, when brakes applied 3/4 to full apply to hold rear tires still in gear is when idle drops down to near nothing and dies. pop up into neutral or park ok. , will chase down for a leak later, car is too loud to hear it... will sue the old school methods. as for advance, stock electronic distributor with the large loop spring removed and a lighter one replaced for better advance curve, the other regular standard spring still intact. according to what i read this was how to just go up from a stock design curve....????
 
Acting the same way at idle with the vacuum advance disconnected is a good sign that you are on ported vacuum. What are the RPM's in park/neutral? This will give some indication if you are even possibly up on the mechanical advance in neutral idling, or not.

It is indeed possible to have a TC problem too. But I would not conclude that until the timing and tuning have been wrung out and you know exactly what you have there.

Eliminating a booster leak is easy; just pinch it or disconnect and plug the line.
 
joshua dewitt said:
well according to carb book I am on ported vacuum, did it with vacuum can disconnected too.... I added a timing tape to a replacement balancer, and was reading around 18-20 idling in park, would need to get another person to help with the in gear thing, I believe it is vacuum leak maybe with the booster, everything new except the brake booster, and master cylinder, when brakes applied 3/4 to full apply to hold rear tires still in gear is when idle drops down to near nothing and dies. pop up into neutral or park ok. , will chase down for a leak later, car is too loud to hear it... will sue the old school methods. as for advance, stock electronic distributor with the large loop spring removed and a lighter one replaced for better advance curve, the other regular standard spring still intact. according to what i read this was how to just go up from a stock design curve....????
Click to expand...

Try putting on the parking brake and shifting into gear with your foot off the pedal. If it idles fine you might have a bad booster.
 
also agree the cam just doesn't seem too big for a stock converter. good advice ^^^
 
I have run basically the same engine combo with stock converters without an issue a few times in years gone by. I never had any issues.

You might want to pull up against a tree or use the parking brake(if it will hold the car back) to see how it idles without the brakes applied. A bad booster is a possibility.
 
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