#81  
Old 06-27-2022, 11:08 AM
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Quote:
Originally Posted by ekancler View Post
How many folks use this for cam selection:

http://davidvizardperformanceseminar...oftware.phpolk
Let me first post a Disclaimer. I wrote that software package with David.

The package that is for sell does not include Pontiac. It only does SBC, SBF, and for BBC only HRT.

Yes, I know I posted an output for Pontiac. But the Pontiac option is experimental and less than 6 people in the world have a version of the software where the Pontiac option works.

Stan

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  #82  
Old 06-27-2022, 11:21 AM
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Originally Posted by Stan Weiss View Post
Let me first post a Disclaimer. I wrote that software package with David.

The package that is for sell does not include Pontiac. It only does SBC, SBF, and for BBC only HRT.
No Pontiac?!



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  #83  
Old 06-27-2022, 11:27 AM
ekancler ekancler is offline
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Quote:
Originally Posted by Stan Weiss View Post
Let me first post a Disclaimer. I wrote that software package with David.

The package that is for sell does not include Pontiac. It only does SBC, SBF, and for BBC only HRT.

Yes, I know I posted an output for Pontiac. But the Pontiac option is experimental and less than 6 people in the world have a version of the software where the Pontiac option works.

Stan
I'm reading one of David's books now. Mentions cos cams. Book was written a few years ago. Does this service exist in 2022?

  #84  
Old 06-27-2022, 12:42 PM
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Originally Posted by ekancler View Post
I'm reading one of David's books now. Mentions cos cams. Book was written a few years ago. Does this service exist in 2022?
I have not talked with David about COS Cam in sometime. I believe it is still offered.

Stan

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  #85  
Old 06-29-2022, 02:37 PM
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My concern is 9.0 compression, power steering, power brakes, air-conditioning auto trans and I need to have good vacuum a strong steady idle and it has to be reliable to to take on trips. And the fact that it has RA/HO exhaust manifolds and full exhaust. Doesn't less duration build dynamic compression.

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  #86  
Old 06-29-2022, 02:44 PM
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Originally Posted by Tim Corcoran View Post
My concern is 9.0 compression, power steering, power brakes, air-conditioning auto trans and I need to have good vacuum a strong steady idle and it has to be reliable to to take on trips. And the fact that it has RA/HO exhaust manifolds and full exhaust. Doesn't less duration build dynamic compression.
IMHO you are a little conservative with that Lunati cam. I would bump it up a notch. You are a bit limited with the 2500 rpm stall speed and compression ratio. Years ago I built a 4" stroke 455 topped with 285 cfm RAIV heads, 9.5 compression, factory manifolds and an original intake manifold. I used an aggressive HFT camshaft that was 228/236 540/510 on a 114. It had a smooth idle (sounded like an 068 in a 389) and ran mid 12's around 110. I always thought that would be the minimum cam for that combination.

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  #87  
Old 06-29-2022, 05:19 PM
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Stan
I looked at your analysis you included and it has vacuum at 11.2 hg. I would not be happy at all if with that little vacuum that would be a very weak idle turning all my accessories.

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  #88  
Old 06-29-2022, 11:32 PM
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I am willing to go with a little more duration just concerned about vacuum and idle quality since I only have 9.0:1 static compression auto trans, PS, AC and restricted exhaust. I am not after max power but do want to take advantage of the airflow of the heads. I am considering the cam that Lemans 400 suggested (282/288 adv 230/236 @.050 .510/.521 lift) Butler had it custom ground from the 112 to 114 LSA. How much vacuum do you think I would have at idle with that cam and how radical of an idle would you expect?

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  #89  
Old 06-30-2022, 01:30 AM
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Quote:
Originally Posted by Tim Corcoran View Post
Stan
I looked at your analysis you included and it has vacuum at 11.2 hg. I would not be happy at all if with that little vacuum that would be a very weak idle turning all my accessories.
Tim,
What is the min vacuum you want?

Stan

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  #90  
Old 06-30-2022, 01:45 AM
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Quote:
Originally Posted by Cliff R View Post
...........One of the last 428's I did ............ I used a custom ground Comp Cam with XFI lobes with .361" lift, 236/242 @ .050" with 1.6 ratio Crower Enduro rockers. .............. but you need to put some cam in them as they like to rev............Cliff
What was the LSA on that cam? And installed at what ICL? That's about what I'd like to swap with my current cam.

The 428 in my '66 GTO has a custom cam with cam card attached below, 114 LSA installed at 110 ICL. I have 1.5:1 rockers. Crane made it for me back in 1996 or so. According to 1/4 mile MPH and ET calculators, it makes in the neighborhood of 550HP. And loves to rev. This engine has 72cc E-heads, Doug's headers, and EFI. CR is 11.4:1 and works fine with 91 octane. (with this cam, might be too much with less cam)

As well as this cam performs, it's too much for the street and I'd like to take it down a notch or two. Exhaust stinks with the modern fuel we have now, probably because the exhaust valves open so soon.
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  #91  
Old 06-30-2022, 02:10 AM
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On a 9:1 4” stroke engine I think you would find all the Bulter 230, 236 HR in the 114 version is going to offer versus the 112 version is to make less power, get worse economy, and not change the vacuum or idle very much. Just my 2 cent. 112 would be better, the next size smaller 224, 230 would be ok on 114 if you really after something mild.

I am not crazy about extra lift on the exhaust side of those Bulter cams, I think it hurts more than it helps, and is really no benefit, it is just beating up your valve guides more, even more so with 1.65s.

Would be nice to know the heads flow at different lifts. That has potential to effect the LSA you might want quite a bit also, which is just a guess right now. Big low lift flows tend to make the cam act like the LSA is narrower. Changing a 6x head to 45* intakes from 30* do the opposite, making the cam LSA act wider. Some people manipulate that port flow at low lifts a lot when they port the heads, and don’t really even realize it. That can change the compression your engine can pump before it pings, and the E/I split you might want on your cam. Slowbird 274 XE example is probably a good example of pumping more compression. I think he had 45* valves on that engine judging by how much compression he had on his XE 274 engine. Just my hunch anyway. Sometimes cams will respond better to a smallish aggresive cam when the low lifts are not as high. 45* intake valves generally do that. If vacuum is a concern, that 30*s have less vacuum too. Be nice to know that stuff if you want the get the best cam narrowed down.


Last edited by Jay S; 06-30-2022 at 02:29 AM.
  #92  
Old 06-30-2022, 07:08 AM
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hgerhardt

Your Edelbrock heads flow well past 0.600" valve lift. Your current net valve lift after the indicated .020" valve lash is 0.610". This is a very good match.

If you change from your current cam to the XFI hyd roller lobe 3017 you will be giving up some valuable valve lift. From the 0.610" to 0.579".

Rather than a XFI lobe you might consider Comp QXI lobe 13451 on page 24 here: https://www.compcams.com/lobe-catalog

It is rated with 0.593" valve lift and it has a similar 0.200" duration as the XFI lobe.


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  #93  
Old 06-30-2022, 07:22 AM
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Quote:
Originally Posted by Jay S View Post
On a 9:1 4” stroke engine I think you would find all the Bulter 230, 236 HR in the 114 version is going to offer versus the 112 version is to make less power, get worse economy, and not change the vacuum or idle very much. Just my 2 cent. 112 would be better, the next size smaller 224, 230 would be ok on 114 if you really after something mild.

I am not crazy about extra lift on the exhaust side of those Bulter cams, I think it hurts more than it helps, and is really no benefit, it is just beating up your valve guides more, even more so with 1.65s.

Would be nice to know the heads flow at different lifts. That has potential to effect the LSA you might want quite a bit also, which is just a guess right now. Big low lift flows tend to make the cam act like the LSA is narrower. Changing a 6x head to 45* intakes from 30* do the opposite, making the cam LSA act wider. Some people manipulate that port flow at low lifts a lot when they port the heads, and don’t really even realize it. That can change the compression your engine can pump before it pings, and the E/I split you might want on your cam. Slowbird 274 XE example is probably a good example of pumping more compression. I think he had 45* valves on that engine judging by how much compression he had on his XE 274 engine. Just my hunch anyway. Sometimes cams will respond better to a smallish aggresive cam when the low lifts are not as high. 45* intake valves generally do that. If vacuum is a concern, that 30*s have less vacuum too. Be nice to know that stuff if you want the get the best cam narrowed down.
Yes we did run a 45° seat

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  #94  
Old 06-30-2022, 09:00 AM
Steve C. Steve C. is offline
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hgerhardt, you eluded to a good point in your post...

"CR is 11.4:1 and works fine with 91 octane. (with this cam, might be too much with less cam)"

Your solid roller cam is rated at 0.0205" tappet lift whereas the Comp hydraulic roller cam is rated at 0.006" tappet lift. Therefore the 'advertised' duration for the two cams will not be apples-to-apples.

Here is a conversation that considers the situation:
https://www.forbbodiesonly.com/mopar...arison.205262/

The information provided in that specific thread does not represent any endorsement. It is offered for general interest only. I personally don't know enough about that specific topic, I suspect Jay S would. Maybe he will chime in.




.

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Last edited by Steve C.; 06-30-2022 at 09:29 AM.
  #95  
Old 06-30-2022, 10:08 AM
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Quote:
Originally Posted by Stan Weiss View Post
This shows a 2802 (110 ICL), 2801 (110 ICL), and an OEM 068 (116 ICL) which has more seat duration than either of the other 2.

Stan
I'm reading all this and find it complicated. The comments about seat-to-seat timing being key make sense to me but I'm struggling to see big differences in this chart. Assuming the pink is 068, differences in lift are obvious. Differences in ICL are obvious.

But differences in duration at ~0.010 lift are not obvious to me and I am surprised if differences in duration below 0.010" cause big differences in performance. I can see that the 068 will have longer duration at maybe 0.006" but does that really have a big effect?

All this must be really sensitive!

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  #96  
Old 06-30-2022, 11:54 AM
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Quote:
Originally Posted by Shiny View Post
I'm reading all this and find it complicated. The comments about seat-to-seat timing being key make sense to me but I'm struggling to see big differences in this chart. Assuming the pink is 068, differences in lift are obvious. Differences in ICL are obvious.

But differences in duration at ~0.010 lift are not obvious to me and I am surprised if differences in duration below 0.010" cause big differences in performance. I can see that the 068 will have longer duration at maybe 0.006" but does that really have a big effect?

All this must be really sensitive!

The point was less about performance and that the 068 while being a small cam would have less DCR for the same SCR and require a lower octane.

Stan
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