[PLAY400]

Originally Posted by Ron H

What are the specs for the cam are you running?

Last time valve springs were checked and installed pressures, seat and open?

What rpm are you shifting at?

If your engine is lacking power the converter will also slip. Though I am sure you will find a fair chunk of performance switching to a quality converter.

It's a custom Comp Cam 260/265 dur. @ .050" lift .370"/.375" lobe lift on a
110 lobe sep. Springs have a couple dozen runs on them but were checked by my machinist when we tore the motor apart last year for an inspection. Shifting anywhere from 5000-5500. Majority of my runs had a 1.5~ 60'er but times were slower due to my errors. Only had the car out once last year so I spent the time enjoying the rides and didn't change the tune at all. Running 36 locked advance

[71 Ventura II]

Originally Posted by PLAY400

It's a custom Comp Cam 260/265 dur. @ .050" lift .370"/.375" lobe lift on a
110 lobe sep. Springs have a couple dozen runs on them but were checked by my machinist when we tore the motor apart last year for an inspection. Shifting anywhere from 5000-5500. Majority of my runs had a 1.5~ 60'er but times were slower due to my errors. Only had the car out once last year so I spent the time enjoying the rides and didn't change the tune at all. Running 36 locked advance

Based on the limited cam specs above and accounting for the "5" cams I tried in my 400, I'd stick a 4000-4400 converter in it and get a fresh set of stickies. Also, short shifting your combo might work for bracket racing but the combo will live at or above 6300+ rpm's. I ran the Crower #60311, which is a smaller cam than yours, one Summer and it didn't run the numbers unless I shifted at 6500 rpm's. With your dual carb setup, big cam, and gear it's gonna love RPM as long as the heads can support it.

Throw an ATI "Tree Master" in it or call PTC to get a flash stall in the 4200-4500 rpm range. Hook it and let it breath and you'll be amazed. Good Luck! JD

[Cliff R]

Here is a good formula to determine what RPM you should/would be running with no converter slip:

GEAR RATIO x MPH x 336 divided by TIRE DIAMETER.

For my combo using a Continental 10" (Jim Hand model), 3.42 x 120 x 336 divided by 28". The calculator shows 4924rpm's, we go thru right at 5100rpms, or about 175rpm's slippage in high gear.

That works out to 3.5 percent slippage if I did my math right.

I don't know the exact diameter of your tires, but it looks like trap rpms should be around 5100rpms with no slippage (30" tires). 900rpm's is quite a bit of slippage.

You can have your cake and eat it too with converters, it just doesn't come cheap.....Cliff

[mchell]

Originally Posted by PLAY400

It's a custom Comp Cam 260/265 dur. @ .050" lift .370"/.375" lobe lift on a
110 lobe sep. Springs have a couple dozen runs on them but were checked by my machinist when we tore the motor apart last year for an inspection. Shifting anywhere from 5000-5500. Majority of my runs had a 1.5~ 60'er but times were slower due to my errors. Only had the car out once last year so I spent the time enjoying the rides and didn't change the tune at all. Running 36 locked advance

curious.....whats the cubes and compression ratio?....race only or street/strip?

agree with others that you are probably pushing thru your converter.....a tight converter may cause you to lose some 60...depending on motor........could just be too much gear and converter combined for motor charictaristics....

[PLAY400]

Originally Posted by mchell

curious.....whats the cubes and compression ratio?....race only or street/strip?

agree with others that you are probably pushing thru your converter.....a tight converter may cause you to lose some 60...depending on motor........could just be too much gear and converter combined for motor charictaristics....

[email protected] A little higher than I wanted. I was told I had enough compression to run the cam and it should pull to 6k with my heads. Only running it at the track as its a heat score on the street.

But this brings up another question after I did some reading. I'm running 660 center squirters. They do not come with a power valve and and apparently it is recommended to only change the jet up or down 1 size. Running 72s. From what I read without a pw Holleys tend run rich at top end. Fact or fiction??

[71 Ventura II]

Originally Posted by PLAY400

[email protected] A little higher than I wanted. I was told I had enough compression to run the cam and it should pull to 6k with my heads. Only running it at the track as its a heat score on the street.

But this brings up another question after I did some reading. I'm running 660 center squirters. They do not come with a power valve and and apparently it is recommended to only change the jet up or down 1 size. Running 72s. From what I read without a pw Holleys tend run rich at top end. Fact or fiction??

Sorry my bad, I misunderstood your combo! I should have asked first, your 462 is a way different animal than my 400. Ooops It moves the power band down the scale. I'd still stick with the ATI Tree Master based on your cam, intake, gear, and CID. All you need to do is compare 455+ cid combos running the Comp 290b cam to yours. Running low 11's high 10's if the heads are right. JD