Expected tire spin 426-S

[Nate S]

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.

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.

Yes, the intake. An early RB dual plane. Similar to a '70 cast iron with slightly larger passages.

 

[steve340]

Now that you have modified the engine the goal posts have shifted.
When the engine was original it may have burned the tyres with that converter as you say.
The original camshaft, cylinder heads, intake manifold, compression ratio, carburettor response may have meant it could roast the tyres.
I think the more torque you apply to a converter the lower the stall speed will be.
So your mods may have driven that stall speed down to a point lower than the engine can get busy.
Another thing to check is jetting on the primary side of the carb. It could be a bit rich and the engine has to get rid of that extra fuel before it turns on.

 

[66Satellite47]

A stock 12" converter is not what you want for that engine/car combination. Is it an original early model 727 or later? The '66 & later input shaft and more common converter 10" or 11" would help. The 3310 can work just great for you.

 

[theman440]

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.



I have the same issue with my mostly stock '66 383 4bbl/auto Coronet. It too has a stock 12in converter - it's a pig out of the hole, but once it gets rollin' and the secondaries open up it will break the tires loose. It ran 15.88 at 88mph, shifting automatically at 2100ft with 2 people in it. I wouldn't put a double pumper on an automatic car.

 

[theman440]

Beautiful car BTW - My dad had one similar to yours but with red interior, it had A/C and power windows too. Love the '64's, my first car was a '64 Dodge 330 2-door.

 

[dmoore]

I have the same engine in a 64 Sport Fury convertible. I removed the factory intake/carb and replaced them with an Edelbrock Performer and the new Edelbrock AVS2 650. What a difference! My engine is .020 over with stock compression 10.3.1, stock grind cam from Competion Cams degreed in, stock heads with performance valve work and the original 12" converter. It will light up the repro polyglas at will...their not wide! Since I am about to pull my trans due to kick down band totally gone I ordered a new converter from PTC in Muscle Shoals Alabama and a street/strip rebuild kit from John Cope of Cope Racing Transmissions in Indiana. Nice folks...Told him my setup and he had PTC build me a 2500-3000 stall 11" converter. Once this 64 727 is done I expect it to be waaaay fun on the street.

 

[Cranky]

It's a huge deal to not have a cam in the right place. It can break or make an engine. Let us know where it is when you find out. Btw, I like to advance my cams but not knowing the stats on it, kinda hard to say what to do with it but in many cases, the engine responds well with 4 degrees....

Now that you have modified the engine the goal posts have shifted.
When the engine was original it may have burned the tyres with that converter as you say.
The original camshaft, cylinder heads, intake manifold, compression ratio, carburettor response may have meant it could roast the tyres.
I think the more torque you apply to a converter the lower the stall speed will be.
So your mods may have driven that stall speed down to a point lower than the engine can get busy.
Another thing to check is jetting on the primary side of the carb. It could be a bit rich and the engine has to get rid of that extra fuel before it turns on.

In my experience, an engine with more torque usually raises stall speed.....

 

[Officer Higgins]

First cam i installed had it retarded couple of degrees. When it started it sounded like a top fuel engine. But had no road power , a friend of mine pulled up next to me on highway to shoot it out. He knew the car could beat his but i couldn't catch him. He asked me why i didn't try to get him i said i couldn't . Later found out it was the cam i had installed retarded. Got pissed and put Hughes rv cam in correctly this time and he wouldn't race me lol.

 

[R413]

I think the more torque you apply to a converter the lower the stall speed will be.
So your mods may have driven that stall speed down to a point lower than the engine can get busy.

n.

You are backwards, the more torque you apply the higher the stall speed goes on the same converter.

Chevy boys would get a Vega converter to go racing on the cheap.

 

[Nate S]

It's a huge deal to not have a cam in the right place. It can break or make an engine. Let us know where it is when you find out. Btw, I like to advance my cams but not knowing the stats on it, kinda hard to say what to do with it but in many cases, the engine responds well with 4 degrees....

In my experience, an engine with more torque usually raises stall speed.....

just measured it. Confirmed the harmonic balancer hadn’t slipped first. 114. Stock is 113 . Measurement is probably plus or minus a degree. So it’s not looking like that. Gonna bump the ignition timing 2 degrees (16/38) and do a stall test on the converter. Factory brake stand is 1850. Won’t do that until tomorrow. I greatly appreciate the help.

 

[Nate S]

Drinking my coffee this morning I decided to look a bit more closely at the cam specs. Rather than some web search for “440 magnum cam”, I went and looked up this exact one, melling spd-31. Lo and behold the intake C/L is listed at 111. So now at 114 it’s seeming a bit late. Not that I really want the work but I think I’ll get one of those bushing kits and nudge the cam forward 4.

 

[Cranky]

Even if it was supposed to be 113 and was at 114, I'd would have moved it lol and I'd shoot for at least 109.

 

[66Satellite47]

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.

Just a reminder, 12" converters were used in the low performance cars/engines. 11" higher stall in the HP versions. There's a good reason for that.

 

[Nate S]

Just a reminder, 12" converters were used in the low performance cars/engines. 11" higher stall in the HP versions. There's a good reason for that.

Actually the RB engines all used the 12 except the HEMI. The only B that used the 11 was the 383 roadrunner engine and some 400s in the 70’s.

 

[66Satellite47]

Once again I stand corrected. You are correct.

 

[Nate S]

Now that you have modified the engine the goal posts have shifted.
When the engine was original it may have burned the tyres with that converter as you say.
The original camshaft, cylinder heads, intake manifold, compression ratio, carburettor response may have meant it could roast the tyres.
I think the more torque you apply to a converter the lower the stall speed will be.
So your mods may have driven that stall speed down to a point lower than the engine can get busy.
Another thing to check is jetting on the primary side of the carb. It could be a bit rich and the engine has to get rid of that extra fuel before it turns on.

re-reading your response...

I don’t think I’m too far from stock (for a late 60’s magnum) on this one. Stock cam, wee bit lower compression (stock claim was 10.1:1 but reality was more like 9.75, I’m at an actual 9.25). Intake is very similar to a regular 440, (in fact I have one, tested it and saw no difference), heads are very similar to -906, manifolds are similar and tests show little advantage to the magnums. No windage tray (doesn’t fit with the ‘64 b-body pickup) but that’s more of a higher rpm deal. Holley 3310 is darn near identical to the AVS except more tuneable. Distributor is very close to stock with a bit faster curve. Timing is close to stock.

Good point on the mixture though. I believe I’m in a decent spot. 30cc pump with .025 squirter. Stock jets are 72/76, I went to 75/79 with no change at the bottom end and more pull up high. 2 sizes of that increase is for the 10% ethanol in the gas. Plugs are a nice coffee-with-lots-of-cream color.

 

[Lefty71]

I think the more torque you apply to a converter the lower the stall speed will be.

I would think the exact opposite to be true..... you would need a different viscosity fluid to make this happen, if my thinking is correct. To the OP, certainly a looser converter will help light the tires from a dead or slow start.

 

[qkcuda]

I helped a buddy with his 79 Corvette upgrade the engine. We used a fairly conservative cam and some modern iron heads. That thing pulled like it had an honest 350 horsepower, but he was still disapointed because with the stock convertor, it wouldn't spin the tires.

 

[Nate S]

I helped a buddy with his 79 Corvette upgrade the engine. We used a fairly conservative cam and some modern iron heads. That thing pulled like it had an honest 350 horsepower, but he was still disapointed because with the stock convertor, it wouldn't spin the tires.

Bushing kit, new degree wheel, gaskets are on the way. We’ll see how that goes. Ultimately I got confirmation of expected stock behavior, not really looking for different just want to correct it to align with that. So, like your friend, I like the tire frying ability, in this case stock should do it so I’m just trying to get it right more than trying to get something different.

I’ll post results once I’ve fixed it and have a decent day to test it.

 

[steve340]

I was wrong about the torque lowers the stall speed it does in fact raise it as others have correctly posted.
What may be the case with your engine is you have shifted up the place were your engine makes enough torque to get the wheels spinning easily.
Meaning your engine actually has less torque off idle.
I would be interested to see if shifting the cam timing is the magic bullet.
If you can keep this thread going I am sure others would like to find out what happens.