Guys got to working on my 340 challenger again.. we did a comp test first and then a leakdown.. the engine was cold, but it gives us a baseline to go by.. what I found is quite odd and I am not sure what it all means? Can u look at the following pic and let me know your thoughts! Something is wrong somewhere ,but where? When @ TDC #1 the balancer is at zero or close to it and rotor pointing at #1 also, I get comp not real good ,but good enough, but when i do a leakdown on that cylinder it's basically dead along with 3 others.I only took it to 70 psi to test it with incase anyone wonders, also I could not hear leakage from anywhere ? a little out breathers ,but thats it!,nothing out exh or thru carb, thats why I am baffled!.Also #2 cylinder is very high too!. is it cam timing? or what? Also the car starts and runs not too bad, is responsive and throaty too , but isn't making alot of vacuum like 7-9? Smokes some too off and on.. and has it warms up has a inner knock what sounds like inside the motor somewhere too.. the oil has been checked and filter cut open no bearing stuff!... At this point were going to pull it and have it gone thru. unless u guys see something we don't

 

smokes on and off, does it smoke at start up, then fine driving around town, when you "hit the gas", it smokes up/down steep grades valves and guides i say.. valves are worn seats are not sealing, guides are worn

 

Ok Here is the results from test #2. without the rocker shafts on..piston at top of cylinder. At this point it looks like the pushrods are wrong for the cam.. cam is unknown, also I should point out this motor is new rebuilt according to previous owner was taken apart and reused pistons etc.stock bore supposedly yet too.. So Next question is those two cylinders that tested low # 3 #7 after i tested second time they gained compression.. whats up with that? Also how does one go about measuring for correct pushrods on a shaft mounted system? The ones now are approximately 7 17/32 long.. also their one piece not ball end ones either that came stock on these.. thinking the guy had no idea what cam is in there and used the stock rocker setupand rods?

 

you can use stock push rods and rockers, i have with no problems the bigest cam ive ran was 292 duration 480 lift, not huge but no problems. theres no reason to change puchrod lengths,

 

well cam is unknown at this point. so I don't know how big it is? why after taking off the rockers i get good readings? gotta be something with the geometry.. too long? maybe this cam needs to have a adjustable valvetrain? this a 39 340 with X heads I believe 2.02 Valve?

 

block and heads milled? a cam closed is a cam closed no matter (valve seated) if its a stock cam or 310 duration 620 lift, and you take the readings when the valves are closed, either the valves dont seat/bore is worn or rings are not totally seated yet,
or head and block milled quite a bit = but hydraulic lifters will bleed off enough to give a good reading,

 

suppose to be a stock block, stock bore, etc.. no milling anywhere, if the cam were off a tooth would screw up the valving? ,but then it wouldn't run very good tho? this car starts and runs granted its low on vac, like 9".. but when i did the timing chain it was dead on lined up. runs the sameway it did before the chain install. Something in the cam/ geometry has to be wrong being that once i unbolted the racker shafts i got some pretty good readings.. when it was on TDC #1 it was one of the cylinders that looked bad with rockers in place, so that tells me the heads are fine its something in the valve train area. cause when removed that cylinder at 100 psi test pressure read 94, pretty tight i would say.

 

Whats a good priced stock replacement valve spring for the J head on a 340?

 

Here's some info that may help. Also have you ever used a degree wheel. Sounds to me like things are out of whack between cam and crank.




http://flag.blackened.net/mopar/camchart.html

 

well putting new springs in, these u can push down on with your thumbs and open the damn valve!.. Ordered some melling VS1120 springs .. have to believe thats the problem their so damn weak the valves are hanging open.