1971 Scamp performance

[dd386]

Well here's the question.
1971 Plymouth 360 Police block holley 4 barrel carburetor 670 cfm dual feed. MSD. Weiand intake. 1987 Police Block 40 over.
New Hank the crank. Lunati 508 lift cam
727 Torqflite shift kit.
8 three quarter rear 373 gears
This dam thing won't do a f#&$,$ burn out from a dead stop I have tried everything timing is 34 degrees.
Power brake no problem roast the tires.
Not enough torque not enough horse power. Carb seems to open all the way.
I'm stumped. I have been doing burnouts for over 40 plus years. Should compression test. Change the timing ?
Neutral Drop it ... power brake it.
Any sane input would be appreciated

 

[junkyardhero]

what stall converter?

what's your compression?

that cam doesn't like to even get out of bed until 3K plus...

 

[dd386]

2800 stall converter
Compression 10.25

 

[vntned]

Cam timing off?

 

[dd386]

It doesn't fall on its face but it seems weak when i smash the pedal to the floor
Then comes on hard after hole shot

 

[vntned]

What heads?

More timing can’t hurt

 

[vntned]

The 318 in my truck acts the same way, but I think it’s lack of converter in mine.

 

[vntned]

Had a buddy with a small cam’d 318 that was soft on the bottom end and it turned out to be the cam was off a tooth.

 

[vntned]

What brand converter?

 

[dd386]

Don't know converter brand. iron heads stock.
How much advance timing ?

 

[remytherat]

That’s not a ton of converter but it shouldn’t be a dog.

Vacuum secondaries or double pumper? If it’s a VS I would try some different springs. It may be a problem of opening too slow or too quick.

 

[TT5.9mag]

Post cranking compression numbers. I’d bet you don’t have 10.25:1 compression. How’d you come up with that number?
What was the cam degreed to?
What’s the curve look like in the distributor? Timing at 34 tells us virtually nothing.

 

[dd386]

Sorry guys that's all the info I can provide for now. I appreciate the expertise.
Hopefully I will get this figured out.
I'm not a shade tree mechanic and don't pretent to be one. That's why I'm here with experts that know Mopars .

 

[70dart340]

Check the accelerator pump?

 

[dd386]

Check the accelerator pump
Adjustment? Or diaphragm if it's stuck ?

 

[crackedback]

Timing at idle? Those largish camshafts usually need a bunch of initial timing to get any kind of respectable power under 2500RPM

 

[skep419]

Timing at idle? Those largish camshafts usually need a bunch of initial timing to get any kind of respectable power under 2500RPM

Crank the initial up to at least 20, if you don't limit the mechanical advance you may get by with 200 octane......

 

[Bewy]

High rpm cam expected to deliver low rpm performance. Try advancing the cam 4*. If it is an improvement, you could advance a further 4*. Check valve to piston clearance FIRST.

 

[Dartsun]

Put a 4spd in it.

 

[middleagecrisis]

Cam is either not degreed correctly or you don't really have 10.5-1 compression. Lack of traction should be your problem with the combination you have. Before you tear into the motor, you need to go get a compression gauge and do a cold compression check. Make sure the throttle is fully open when performing and pull the coil wire. You can rent one at the auto part chain stores. Look on You-Tube if you're not familiar with how to do this test. Report back with numbers for the corresponding cylinders. This will tell the group what you're working with. This is a basically free 1st option. This forum has lots of knowledge, but if you listen to all the suggestions, you'll be paying someone to build you a 408 stroker! Do the simple, free stuff first before you tear into the engine.

 

[dd386]

Holley 670 dual feed vacum secondaries. 10.25 flat top pistons
MSD with 6 box. I will do a compression test next week. I'm looking for minor stuff that may cause no burnout This car should boil the tires from a dead stop.
Murphy is stalking me

 

[dd386]

670 Holley carb. Cam is a lunati #10210302- 507/507 lift avg duration 285/285 w/comp springs and retainers. Lunati timing set. Pistons-10.25 to one flat top floaters .40 over. Heads were milled and have new valves 188/160 reconditioned rods. New cam berings, hardened push rods, adjustable rockers, police motor/ block and heads.

 

[Ricks70Duster340]

Sure sounds like a bad torque converter. I'd look that direction instead of at the engine at this point.

 

[1966Post]

Big cam/tight convertor=soft bottom end

 

[TF360]

Cam's too big and most likely compression not high enough.