Don Terrill’s Speed-Talk

You may want more converter stall torque ratio.

This is most certainly what this combination needs, the original thought was to "cheat" and gain a little extra TQ for testing...

Thank you all for your insight, will be catching up with other thoughts and hopefully posting a graph when I return.

What does comp cams say about it?

That cam has too much duration. Put a 283-300 @050 in it with as much lift as you can stand and it will wake up, especially with that tight of a convertor.

I was thinking he should pull around 20 degrees duration out of the cam. Give Mike Jones a call.

JoePorting wrote: ↑Tue Oct 23, 2018 8:55 pm I was thinking he should pull around 20 degrees duration out of the cam. Give Mike Jones a call.

Wow.. are you serious?

Edit. .."clueless"

That cam has too much duration. Put a 283-300 @050 in it with as much lift as you can stand and it will wake up, especially with that tight of a convertor.

The above duration @ .050" is more in line with what I had thought before deciding Comp new better than me. The conversation with Comp that determined using their grind was the vehicle weight being 1950 lbs and the ability to run on methanol.

What does comp cams say about it?

Did not inquire with Comp. My past experience with any manufacture of aftermarket performance components has been, "any use beyond suggested parameters is not suggested"...

Mesik Motorsports wrote: ↑Fri Oct 26, 2018 9:07 am

That cam has too much duration. Put a 283-300 @050 in it with as much lift as you can stand and it will wake up, especially with that tight of a convertor.

The above duration @ .050" is more in line with what I had thought before deciding Comp new better than me. The conversation with Comp that determined using their grind was the vehicle weight being 1950 lbs and the ability to run on methanol.

And I've heard a lot of "cam" guys at various companies say similar stuff in regards to duration and vehicle weight. And it used to make sense to me kinda, not so much anymore. But more duration, because of vehicle weight implies that giving up torque with the extra duration wont be noticed, and that the extra duration will always yield dividends at the top of the rpm range which is no guarantee whatsoever, a cam that's too big can get spanked by a smaller cam from beginning to end, seen that more than once.

The same thought process behind the methanol, methanol fills the hole in the torque curve created by the cam being too big then its supposed to make more power at the top....again something that's no guarantee whatsoever. I think vehicle weight gets too much credit in the cam department personally.

An image of the car and the graph produced during another run. The video of the car taken at the same time of the posted graph shows a "dead hook" with zero tire spin. Note the hook in driveshaft speed as well as the RPM drop. Thoughts?

And I've heard a lot of "cam" guys at various companies say similar stuff in regards to duration and vehicle weight.

This being my first spread port build I became a victim of the "experts" rather than being the "askwhore" on forums

Mesik Motorsports wrote: ↑Fri Oct 19, 2018 10:55 am I am looking to gain as much low end TQ on a 580 BBC with 12 degree spreadport heads to help with the 60' times. Running a Comp Cam custom solid roller that calls for I-.024" & E-.026" lash. Rockers are: Int 1.8 and Ex 1.7 ratio. How loose can I "safely" run this setup to find more lower RPM TQ without hammering the cam or valve train to a point of damaging it? I will be checking back as time allows to answer any questions that maybe required to get your answers. Thanks in advance for any real world feedback, Walt

To give an answer for this title:
Opening the valve lash until you are at the very end of the "lash ramp" on that cam profile is a much as you should go.
Saying that, you NEED to know the lash ramp specs of the camshaft you are using.

It is hard to tell from looking at the graph. What RPM did you shift at and what RPM did you cross the line at? Also what is your convertor slippage at the finish line?

Stan

Mesik Motorsports wrote: ↑Fri Oct 26, 2018 9:40 am



An image of the car and the graph produced during another run. The video of the car taken at the same time of the posted graph shows a "dead hook" with zero tire spin. Note the hook in driveshaft speed as well as the RPM drop. Thoughts?

Simple.
Take your 60ft time, go back and look at your graph.

Looks like converter to me

What RPM did you shift at and what RPM did you cross the line at? Also what is your convertor slippage at the finish line?

Stan, the shift is occurring @ 7500, crossing the finish line (1/8th mile) is @ 7247 RPM, driveshaft ratio is 1.17.

Since this thread has deviated from the original question, I will stick with my original plan to re-stall the converter rather than trying to tune more TQ into it for test purposes. If y'all have any further input, I would be glad to hear your thoughts. For now, its time call Abruzzi and get the converter loosened up. Thanks for your time

I have loosened up the lash by .004 for a couple of runs to get a baseline with no ill effects. A 1.7 rocker on the intake will also help the 60 ft but I don't know if it will hurt overall. I have played with rocker ratio both ways, larger and smaller, sometimes it hurts, sometimes it helps, sometimes no difference.

I would try the intake side first, them maybe both.