340 cam

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green1

green1

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A long story. My old timers disease can't remember buying this engine, 70 340. I must have bought it in the 70's, when I had 2 A bodies. Last drove it in 1980, put it on jackstands in '87.
It actually fired up several months ago, burning no oil. Borrowed a 780 to start it, so of course it is rich. (unknown carb- put 4.5 power valve in; have 6 at idle). It wont idle below 30 initial. Replaced the balancer with a SPI- 1 degree difference.
Pulling of the left rocker shaft, putting a dial indicator on it, torquing it back- bolt snapped. Fixed.
Now, putting it back together, the manifold bolt on the other head stripped before 30 lbs. So, back apart again.
The cam read .430 lift, so it must be DC 260. The springs are red, not factory. If I pull it back apart again, I might as well replace the cam and chain, which is tight.
The heads are J, with 2.02; the pistons are above the deck, 10.25. 727, manual, 3200 stall .4.88 spool 4 link narrowed Dana, full tubs.
What cam for street/ strip?
 
Hey green1!

Are you running power brakes? What's your tolerance in regards to lumpy cams?
 
No power brakes, just want streetable. Got a 4.5 power valve now.
Never done this before, with a 3200 converter, and a 4.88, which I wish was a 4.11.
 
Dunno, don't really want to do a bunch of machine work; being laid off.
Where are you headed with this?
 
Well, more power is almost always guaranteed with a roller vs. flat tappet, but that gets really pricey really fast.

I would suggest the Lunati 60403 http://www.lunatipower.com/Product.aspx?id=1545&gid=287

It would be definitely streetable in your present set up and and the only machine work required would be for the recommended dual valve springs. Those valve springs would need to be changed out anyway. Needless to say, retainer to guide clearance should be checked too, but this cam doesn't have crazy high lifts which your head may not be able to use efficiently anyway.

You could also go as big as the 60404 with your gearing and torque converter, but streetablity will suffer a bit.

I hope this helps. :)
 
Either cam would work nicely with those x heads and some basic porting. :)

Sorry to hear of the impending lay-off. I was laid off last March. Good luck to you.
 
The Lunati's do work real good. I have the 60404 in my 360 and like it alot although it is pretty lumpy idling. The 60403 or 60404 are great suggestions. But of course to run the dual springs that either require will mean machining the valve spring pockets.

Green1 if their the original 1970 340 heads they might be X's. If their 1970 J's their still big valves so their isn't a hairs diff. between them and the X's.
 
Thanks guys, I have a set of x's and j's. They look the same. Been laid off since Dec, if the economy ever comes back...
 
Hey Green1 What size tire is on the car now?

Are the heads ported and to what level if they are?

If well ported, I like this Huges as seen from the Manciniracing web site. It should give a nice lope and the stall of the cobverter would seem to work with it and the rear gears;

L.A. Small Block Camshaft
Flat Tappet Hydraulic 108º LSA+3

Strip. 3400rpm stall. 4.10:1 gear. Single plane or 2x4 intake. Headers required. Stage II HP ported heads. 180psi suggested cylinder pressure. Hot street for stroker engines.

Intake Valve Lift 1.5 .569" Exhaust Valve Lift 1.5 .576"

Intake Valve Lift 1.6 .606" Exhaust Valve Lift 1.6 .614"

Intake Duration @.050 246 Exhaust Duration @.050 250

Lobe Separation Angle 108

Sweet Spot RPM 2800-6100
$160.00
HEH4650AL

Or this Comp extreme 284/296 with less lift for stock or mild prep worked heads;

RPM RANGE 2300-6500

ADV. DURATION 284/296

DURATION @ .050 240/246

VALVE LIFT .507/.510

LOBE CENTER 110
 
Stock heads, 150psi at cranking, No tires yet, still on jackstands.
Plan on 32" tall; have narrowed Dana, 4.88 spool, 4 link. ld4b manifold, matched to head ports.
 
Still trying to figure out why it won't idle below 30 degrees. Mallory mech, 24 degrees advance; new sfi damper. 3200 stall
 
Is the cam chain timing retarded? Sometimes on those multi keyway timing sets you can get it on the wrong one. Don't ask me how I know and I won't lie. lol
 
I have the comp cam extreme 284/296 in my 340. Idles at 900 and I have the intial set at 20*/34* total. Pretty lumpy but I like it.
 
The cam is installed straight up, but I don't know what it is, only know .430 lift on both.
 
fishy68 said:
Sorry Joe I first overlooked you mentioning the machining for dual springs. Just noticed it. Didn't mean to be repetitive.
Click to expand...

No problem at all. :)

mygwenevere66, he said he was pulling 6" at idle in his first post. :)

Green1, it sounds as though that cam has a ton of duration. Have you tried cracking the secondaries open a touch with the set screw under the carb? Also, even though it was installed straight up, some older cams show up retarded when degreeing the cam.
 
sorry,i missed that.i have to agree with some of the others,it does sound like the cam is retarded.or like mentioned above it has tons of duration,or both.didnt mopar make a "cheater" cam with near stock lift,but alot of duration?
 
mygwenevere66 said:
sorry,i missed that.i have to agree with some of the others,it does sound like the cam is retarded.or like mentioned above it has tons of duration,or both.didnt mopar make a "cheater" cam with near stock lift,but alot of duration?
Click to expand...

This was my thought too. A super stock cam of some sort. It would also explain his low cranking compression with a 10.25:1 static comp ratio.
 
Dunno. bought this engine in the 70's, it was my wife's driver. Never saw that 30 degrees, and I had to have timed it. Dammit, I had the timing cover off, due to a leak last month- chain was tight, put it back together, not knowing about the timing. Have a degree wheel 5 ' away.
It is a cam installed in the 70's. Installing the newer trans next week; after getting drive shaft made, off the stands, and find out how it runs on the street, I guess.
 
Well, we will find out- I thought a bolt on the intake other head had stripped; yep, water kept going down. A gallon of antifreeze in the bottom of the pan.
I'll re-pull the timing cover and put the wheel on it.
Damn, keep going backwards.
 
More backwards- got the intake off, granted ,not run in a month, but the lifters on the good head- 4 have 3'32" play. Do the lifters bleed down, and pump back up fast? I had no valve noise.
And I had more interior water leaks than that one stripped bolt. The Felcro's , that said use no sealer, have evidence of leaking in torqued bolts.
There will be sealer when it goes back together.
 
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