Expected tire spin 426-S

Nate S · Apr 24, 2020

Just rebuilt a 426-S for my '64 Sport Fury. Stockish with factory exhaust and manifolds, '68 magnum cam, CH4B, Holley 3310, 9.25:1 compression (properly cc'd and calculated) using 1975 -975 heads, Chrysler electronic ignition, 36° total ~ 14° at idle. 235/60-16 tires, 727 with stock 11-3/4" converter, 3.23 sure grip

Runs nicely. Pulls well. Floor it from a dead stop and there's no bog but also no tire spin. Memories get foggy but I remember having a '67 charger about 30 years ago with a dead stock 440 magnum and simply stomping it from a dead stop would easily light up the tires. Granted those were narrower but not greatly. Does this sound right? No tach at the moment so I can't check the stall speed of the converter yet, should be ~1850 rpm. Wondering if I have something a little wrong or have my memory a little wrong. Add some brake and it'll smoke 'em but that's not what I'm asking.

Thanks for any help.

Lefty71 · Apr 24, 2020

Beautiful car.... I'd bet a double pumper would light 'em up! If everything is properly tuned now, maybe a well adjusted 3310 would too (maybe 50cc pump on it).

R413 · Apr 24, 2020

Are they sticky tires or just radials? That should lite up the tires easily.

With the stock cam and lower compression you don’t need a 50cc pump.

Nate S · Apr 24, 2020

Lefty71 said:
Beautiful car.... I'd bet a double pumper would light 'em up! If everything is properly tuned now, maybe a well adjusted 3310 would too (maybe 50cc pump on it).

It's pretty well adjusted. Mucked around with the jets a little, mostly to compensate for 10% ethanol. Helped a bit. Not sure I want a double pumper at this point. I seem to remember good performance from the 3310. This one behaves well.

Nate S · Apr 24, 2020

R413 said:
Are they sticky tires or just radials? That should lite up the tires easily.

With the stock cam and lower compression you don’t need a 50cc pump.

Just regular radials. What you're saying is what I'm thinking. Agreed on the 50cc, not needed. At the moment the only thing I can think of is the converter has an issue and is tight / not multiplying as it should. Once it gets rolling the pull is about as good as I expect.

oldkimmer · Apr 24, 2020

The converter stall speed seems way to low for ur motor. A 383 magnum type converter with a factory stall of 2250 or so will liven it up like u won’t believe. Ofcourse if u have a 19 spline tranny u will need to have 1 built. Or change parts in the front of the tranny. U can have ur cake and eat it to if u call a good converter company such as Ultimate,Dynamic, PTC and be honest about ur build. The converter will be very street friendly and cruise like totally stock. Kim

R413 · Apr 24, 2020

Did you degree the cam, is the cam retarded?
Is the ignition timing retarded?

Those will only stall to about 1200, but should still boil the tires. That’s the same converter a 67 440 magnum had from factory.

Nate S · Apr 24, 2020

oldkimmer said:
The converter stall speed seems way to low for ur motor. A 383 magnum type converter with a factory stall of 2250 or so will liven it up like u won’t believe. Ofcourse if u have a 19 spline tranny u will need to have 1 built. Or change parts in the front of the tranny. U can have ur cake and eat it to if u call a good converter company such as Ultimate,Dynsmic, PTC and be honest about ur build. The converter will be very street friendly and cruise like totally stock. Kim

I think Hughes makes one for 19 spline. The 440 / 426 / 413 all used the bigger/tighter one. Certainly on my list of possibilities. Wondering if even this one is behaving as it should. Gonna hook up a tach and see.

Nate S · Apr 24, 2020

R413 said:
Did you degree the cam, is the cam retarded?
Is the ignition timing retarded?

Those will only stall to about 1200, but should still boil the tires. That’s the same converter a 67 440 magnum had from factory.

Cam is using stock timing set. Nice and tight, should be within a degree or two. However, being that I have confirmation this is not expected performance maybe I'll pop off a valve cover and confirm. Certainly not off by a tooth though. Ignition timing is 14° at idle (no vac) and 36° at a couple grand. Factory light spring, heavy spring removed.

Don Frelier · Apr 24, 2020

If you didn't degree the cam, then all bets are off. It could be 6-8 degrees retarded.
Does it pull harder at high RPM? Then that could be your issue.
Does the carb open FULLY when pressed to the floor? Sometimes people forget to check that.
Just a couple ideas.

Nate S · Apr 24, 2020

Another thought. Engine has about 250 miles on it. Doesn't seem like that should matter. Figured I'd add it to the mix.

Nate S · Apr 24, 2020

Don Frelier said:
If you didn't degree the cam, then all bets are off. It could be 6-8 degrees retarded.
Does it pull harder at high RPM? Then that could be your issue.
Does the carb open FULLY when pressed to the floor? Sometimes people forget to check that.
Just a couple ideas.

I'm all in on checking cam timing. Will do that and report. It does pull well at higher RPM. Throttle definitely opens all the way, checked that.

Don Frelier · Apr 24, 2020

You do want to keep the Revs down a bit til you drive it a bit more.
But you can accelerate hard for brief periods.

qkcuda · Apr 24, 2020

I considered something similar to the factory magnum cam myself when trying to figure out cam selection, but remembered that they hcame with higher stall convertors and better exhaust than the earlier stuff. I think a convertor will probably solve your problem.

Don Frelier · Apr 24, 2020

Sorry, but I doubt it's the converter. My Charger had the original converter for 12 years or so which had a pretty low stall.
It would rip from a standing start. .455 cam not way different from what he has.

steve340 · Apr 24, 2020

It is hard to say sitting here but you could be right saying torque converter assuming the engine has some low down punch.
I do not buy off the shelf converters from Hughes, B&M or any others.
I have a company make a custom converter to the engine combo and with yours maybe go for 2500 stall?
So long as it can fully lock at cruising speed. A simple calculation is all that is needed for that.
Surprisingly the cost is only a little more than the B&M and other shelf options.

Nate S · Apr 24, 2020

Don Frelier said:
Sorry, but I doubt it's the converter. My Charger had the original converter for 12 years or so which had a pretty low stall.
It would rip from a standing start. .455 cam not way different from what he has.

Sounds right. Unless there's something wrong with it, unlikely the size / model is the issue. Cam timing sounds like the prime candidate at the moment. Now to see if I can find my degree wheel. Interestingly I had the same cam (like this very physical stick of steel) in a 361 for a couple months and it seemed a little soft off the line too. Only things in common were the cam and converter. By the way, when I swapped it the wear pattern was perfect so no, I didn't wipe it out.

theman440 · Apr 24, 2020

Converter too tight.

steve340 · Apr 24, 2020

I assume the CH4B is the intake? If it is a single plane it will be a bit less responsive down low and may well need a looser converter.

Nate S · Apr 24, 2020

theman440 said:
Converter too tight.

Not doubting that at all. The initial question holds though, when stock it would have had this converter too and I believe it should have roasted the tires. Converter may help but if it won't roast them there must be something else.

Expected tire spin 426-S

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