I Have No Power From a Stop

'69 Road Runner, freshly rebuild 383 with small Summit camshaft and 9.0 compression, electronic ignition with original heads and an Edlebrock 650. 4 speed with new Brewster's clutch and a suregrip 3.23.

When I start from a stop it seems like I have to ride the clutch to get the car to start moving, like is has no power. Once the car is moving and the clutch is all the way out it will accelerate fine and seems to have the power it should. The clutch isn't slipping, it just seems like I have no power/torque when I start letting out the clutch.

This is my only 4 speed car so I don't have much to compare it to but this can't be right. What are your thoughts???

are you running a stock type ignition system?
Do you know what you initial timing is set at? S/be ~ 10 degrees BTDC as a starting point wit the vacuum advance disconnected if you have it hooked up..
Are you running a vacuum advance?
If so, is it hooked up to manifold or ported vacuum. Should be ported. but some may argue that.
Also need to know what your mechanical advance is doing ad make sure it is not affecting your initial timing setting.

Any other oddities such as idle, setting mixture, surging issues ?

All good questions.

It has the Summit electronic ignition/dizzy. The timing is about 12 degrees to keep it at ~34 total. Vacuum is hooked up to ported vacuum. No other know issues.

Once it get's going it accelerates OK.

try more initial timing. If that helps, change the curve.

Did you build the motor? If so di you degree that cam in the motor? If yes look elsewhere. If you didn't degree it and use a Cloyes timing set it may have the dor on the cam gear wrong which makes the cam retarded when you align any of the three dots on it without verifying the actual lobe separation angles on that cam in your motor
I've learn that lesson more than once from three different cam grinders
I degree every new cam and timing set now
Retarded cams have no bottom end and very little mid and top end power

TDC mark verified?
Cam degreed?
Clutch adjusted properly?

I rebuilt the engine and I did degree the cam. I had to get an adjustable timing set to get it right.

TDC was verified as well.

I forgot how I did the clutch adjustment, I'll have to go out and check. I know the engagement is all the way at the top of the pedal. It doesn't slip at high rpm's like a bad clutch does.

34 total , that's not enough , bring it up to 38 , listen for pinging .

34 is enough. Stock heads like 33-35 for max power per Mopar Action. My own experience has been 34 is what they like. Certainly that is enough timing to make good power taking off. 38 might’ve been good with old high octane gas at every station, but not these days.

You are not going to be at total timing taking off from a stop on the street, regardless of what you might set it at.

initial timing will have more effect and if the OP's numbers are correct that looks ok.

Double check you have ported vacuum to the distributor, I know you said you did, but it doesn't hurt to double check it.

Check the carb adjustments.

Maybe you need to give it more throttle when letting the clutch out? Not sure how experienced you are driving a stick car? But my 51 Plymouth, which is about 300lbs lighter and 235 hp weaker, has zero issues taking off. I do have 3.91 gears, which helps. But still, you should have more than enough poop to scoot.

I have, and have had, multiple 4 speed vehicles.

I have the oil pan and windage tray off right now fixing an oil pan leak so when I get them back on I'll re-check the timing, the ported vacuum and the clutch adjustment and then advance the initial timing to see what happens.

Thanks

The Road Runner is on the lift so I went out and checked the clutch linkage.

I did not have the 5/32" free play at the end of the clutch fork as recommended by the FSM, I had little to no free play. I don't think the rod was adjusted long enough to put pressure on the fingers/pressure plate that would cause any issues, but stranger things have happened.

This is confusing.

Is it a steel flywheel?

Maybe increase the idle speed.

Try an initial timing of 15 degrees plus your ported vacuum advance.

Sorry, this is my only 4 spd car, I do have three CJ-5's and have had 4 spd trucks but of course they are/were geared lower.

Yep, steel flywheel. I'll push the timing up a bit and see what that does for me.

Thanks.

based on the above statement and your previous one about the clutch engaging at the top is cause for concern . The clutch should start to engage about 1-1.5" or so off the floor and have free play at the top before feeling the resistance of the pressure plate.

This was my concern based on what was posted.

Well, hopefully the linkage adjustment will fix the problem!

I'm not confident that it will, but only because it's never that easy for me

I adjusted the clutch per the FSM. That moved the clutch engagement down about an inch. It's about 4" off the floor now . That didn't do anything for the power off the line. Then I increased the accelerator pump flow, bumped up the idle from 700 to 750 and moved the timing to 19 initial (35 total), that seemed to wake it up a bit. I'm a little surprised it likes that much initial timing, it turned over a little slow when warm but I think it will be OK.

I was at 12 initial with about 29 total. I thought I was at 34 or 35 total when I last adjusted it but evidently I was wrong...

VITC_GTX
I have a 383 with a mild Mopar .474 lift cam. Timing wise, I’m running 24 initial and 36 total with one light and one medium spring to advance faster, plus vacuum advance. I believe you’re solution will be found in dialing in the timing.
Ron

What centerline did you degree the cam to?

What RPM are you at during this “no power” timeframe? A lot of cams don’t make power till about 2000 rpm and if you try to engage the clutch well below that the power just isn’t there yet……..

Thanks. The bump up to 19 really helped it and I'm fairly happy with it now. I'll still try and tune it up a little more in the future.

I don't remember, I'd have to go back in the paperwork and my notes to see what I did. That was over a year ago...

Right off the line (700 - 1200-ish). I realize the cam/engine isn't even close to it's power band but it was noticeably down on power. A '63 Volkswagon Beetle with three heavy guys in it could have beat it off the line.

With the timing bumped up it's much better!

Adding to your initial timing with out limiting the total timing to 34 - 36 degrees will give you too much timing well over 36 degrees. When you hook the vacuum pod up to manifold FBO can explain why you time these cars was way and can help in getting your distributor set up right. vacuum, you will get even more power off idle and just better mileage and performance off idle. vacuum advance

Most Mopars, especially with larger than factory spec cams will need more initial timing. Yours is sounding like its pretty close at 19. You use a vaccuum gauge to find the sweet spot, You are looking for the highest reading. Once you find what your combo need to reach the highest level of vacuum, you now have to shorten the amount of mechanical advance to limit the total timing added to keep that between 34 and 36 degrees.

Another often misunderstood way to increase off idle power is to use manifold, not ported vacuum. You can also fine tune both the range or amount and how much pressure it takes to change the vacuum pods range of motion. manifold vacuum advances the timing at idle and falls away as the throttle is opening to reduce the timing and avoid detonation. This set-up absolutely woke up my Slant six super six.

How tall are the rear tires? That can kill those 3.23 gears. How many miles on this engine?
It will get better when the rings are seated and it gets a few thousand miles on it.

I had a “small summit cam” in a 318, no bottom end power on that one. Like you are saying severely lacking off idle and low rpm.