the age old question....what cam?

[BLACK71]

need help with picking a cam for my 340...currently it is all stock including manifolds. will be running a mechanical six pack on top and keeping the manifolds. not opposed to a different converter down the road (still running the stock performance 340 converter). will be using 3.91's when i want to have a little more fun as opposed to the 3.23's. i would like to stay away from Lunati;s (personal preferance)

 

[moparleo]

Contact the cam mfgs. They will tell you what to run based on your information.

 

[Chryco Psycho]

Lunatis have some of the better designs tailored for Mopar engines but that is your call .
Crower would be my next choice .
Engle makes some excellent Mopar grinds but changed ownership since I was buying from them .
Hughes has cams to but I have no idea who is grinding them now & they can be very difficult to deal with .

 

[moper]

If you don;t mind me saying - the mechanical 6bbl setup is a bit much for the 340. If you have the option to stay vacuum operated I'd advise that.
Your manifolds won't cost you a ton of power, but any cam choice will need to take them into account. I would dat yon the smaller side. If you don;t mind Comp the XE268 is a great cam for what you want and will run well. Another choice would be the Crane 693801 (H-278-2).

 

[BLACK71]

this is what engle says
NUMBER 1.6 Rockers 1.5 Rockers At Cam @ .008" lift @ .050" @ .200" lift

K-58HYD .549" .514" .343" 276° 230° 148°

 

[BLACK71]

and this is what crower says
31 204 catalog grind 280 HDP

280° intake 292° exhaust
218° intake 227° exhaust
.474 intake .480 exhaust
lobe separation 108
nice performance idle. I mean rough idle. If you want it smooth it out. Will open centers up to 110°
373.15 hp at 5500 RPM
431.64 foot-pounds of torque at 3652 RPM

 

[moper]

Given the two I like the Engle more.

 

[BLACK71]

and i'll definatley check out that comp cam you recommended i just posted those two as those are the two companies i heard from

 

[Chryco Psycho]

Engle is a faster ramp cam , similar duration @ .050 but less advertised so I agree , I have used the K58 lots , nice cam

 

[BLACK71]

Still havent made a choice yet....what about a mechanical cam...this is mainly a street car...see's the track a couple times a year...i dont flogg it too hard as it is the numbers motor...would really love to hit low 14's/high 13's

 

[moparleo]

Stay with a hydraulic grind. Adjustable valve train not required. Valves always in adjustment, no ticking and having to take valve covers off to readjust the clearances. Not to mention the hassle, oily mess and inconvenience.

 

[Chryco Psycho]

I typically choose solid lifter cams over hyd , they require occaisional adjustment but are generally the most reliable , they also require adjustable rockers . Most engine I build use Lunati special grinds designed only for the Mopar wider .906 lifters & I use the PRW stainless rockers .

 

[moparleo]

Says it is the numbers matching engine, for street use, track 1-2 times a year, only looking for 14's at the track. Hydraulics also require adjustable rockers ?

 

[Chryco Psycho]

the adjustable rockers are a more accurate ratio as the stock are more like 1.4 ratio but you can have issues with dropping pushrods as the lifters will bleed down while sitting & drop when you start up while the oil is trying to pump the lifter back up

 

[moparleo]

Guess Iv'e been lucky all these years running small block Mopars with standard rockers. 100's of thousands of miles with no dropped pushrods, but I wasn't racing either. If your lifters are collapsing and bleeding down that much, you have other problems/parts that are worn out. How many vehicles are on the road that run non adjustable valve trains ?

 

[Chryco Psycho]

newer cams use higher spring pressures lifter can bleed down while sitting , most valvetrains now are hyd non adjustable & use rollers with low zinc oil

 

[moper]

you can have issues with dropping pushrods as the lifters will bleed down while sitting & drop when you start up while the oil is trying to pump the lifter back up

Not sure I agree. It never happened to anyone I know. The lifter plunger travel is only about 30% of the lift figure on stock cammed stuff. Plus there's a spring in the hydraulic lifter to maintain a small amount of preload while the engine's not running and the lifter is on the camshaft base circle (valve closed).
If the owner was unlucky enough to have a lifter bore with too much clearance, on a lifter with a broken internal spring, and it happened to land that lifter at the one place where the valve spring pressure could act on it, and then it sat for long enough for gravity to pull the plunger down further beyond when the valve spring closed the valve - the owner should give up on cars because he's the most unlucky SOB that I know...lol

 

[BLACK71]

..now i just need to find a good set of adjustable rockers

 

[Chryco Psycho]

I have been using PRW bronze bushed stainless steel rockers available in different ratios for a reasonable price

 

[BLACK71]

yeah they dont look to shabby! i was considering using a set of 273 ones also