Since the renowned Harold Brookshire has passed, does anyone have any thoughts on what the old Crane 274H06(or Elgin 1785) 218’/218’ @ .050”, .450”/.450”, tight 106’ LSA cam would be equivalent when changing over to a hydraulic roller cam & valvetrain instead of a flat tappet?

Street use carb’d L31. Sofa will flame me for a single pattern, if it works for David Vizard, have a low restriction exhaust system for those weak Vortec exh ports, AND I’m not going to RPM the thing.....

Single pattern Lunati Voodoo custom 211/211 @ .050”, 262/262, .515”/.515”, on 106’ LSA?

Vortec heads prepped for lift & springs.
‘88 IROC 5 spd, 3:08, otherwise stock L31 long block, #6210 list Holley.
Thanks

 

Any thoughts?

 

I found a couple of single pattern Erson Hyd Roller cams for you.

 

Here is 8 more from Summit: https://www.summitracing.com/search/...24-int-224-exh

I seriously doubt you will find a "street" camshaft ground on 106 centers. You would need to explore the RACE and CIRCLE TRACK camshafts.

Crower has this one ground on 108: https://www.crower.com/camshafts/che...t-steel-7.html

 

Or COMP will grind whatever you want. That's the route I went at one time. Went into their Master Lobe Profile Catalogue and picked what I wanted and had it ground on whatever LSA and ICL I preferred.
And since you mention Vizard, isn't his spec for a 350 typically based on a 108 LSA when using a traditional 2.02 valve?
He uses this formula: LCA = 128 - (CID/# of Cylinders/In Valve dia. in inches x 0.91).
LCA= 128-(350/8/1.94 x 0.91)
= 107.47 (in the case of the smaller valved Vortec head)..
106 is in 383 territory.
You may find the attached paper by Vizard of interest.

 

Skinny, thanks for linking the Vizard document.

 

Happy to.
Apparently his observations and recommendations aren't all that well received around here or some other places. Not sure what it is but the tight LSA thing puts people on edge and I've listened to and read all sorts of arguments railing against it. Of course there's more to spec'ing a cam that the LSA but his approach is very understandable (from my perspective anyway) and I will move along those lines when the 383 is ready.

 

Yes, and remember............. the earth was FLAT................ until it wasn't.

 

Look what I found - Lunati has cams based on Vizard's formulas:
http://www.motortecmagazine.net/a-ne...ms-speed-spec/
http://www.motortecmagazine.net/esho...nddevelopment/

 

Thank you all for the help & replies.

Skinny-
You’re absolutely correct about the Vizard-spec’d 108 LSA for a 350.

Although everything I’ve read, researched, conversed w/owners etc about the old Crane 274H06 F/T cam with it’s tight 106 LSA & minimal 218’/218’@.050” was that it works great in low compression 350’s without being greatly negatively affected with a lot of overlap due to the relatively short duration figures.

No huge penalty other than slightly lower vacuum reading at idle of course.

​​​​​​​Reasoning for that particular type of cam is.....
In my 6th decade, and as a purely impractical, youth-deferred guilty pleasure, just wanted to finally be able to enjoy a manual trans vehicle with a choppy idle without an emissions issue.

 

His last book on budget building SBCs has those lists as well. Something I've been going through and will probably use that information for my own spec later. Something along the lines of his 290/290 106 LSA 102 ICL .605" offering.
Thanks for the Vizard article link too. I like reading his stuff.

 

I say go for it. And post your results.
FWIW, DV tends to have an established LSA for the head and CID. Then he goes to the overlap spec to determine the RPM range target. The duration falls into place with those values.
I trust you've considered your static compression ratio (SCR) and the dynamic compression ratio (DCR) that would result from your cam selection.
Do you have the cam card for the grind you're interested in? Namely I'm looking for the advertised duration, LSA (listed as 106) and ICL.
And what would your low compression 350 have for an SCR?

 

I got the elgin one in my C3 350 stock dish pistons and sportsman II 64cc in the vid. The 200cc runner heads, low comp, exh manifolds, stock 1500 converter and 3:42 gear make it picky on the tune. An open spacer makes it a bog a matic, the air gap intake(dual plane) prob doesn't help it's street manners either LOL! Still I like the cam, idles bout 14 vac at 800ish rpm I think, only probs with the brakes are the stupid factory calipers LOL gotta install my aftermarket brakes kits on it someday.

idk if I'd get a custom grind but if I found a sim roller I'd prob give it a shot in another build.

 

As Skinny mentioned, in Vizard’s ‘09 book How to build Chevy Small Blocks on a Budget, the cam section, (pg 108 ironically)lists what appear to be the Lunati Voodoo profiles he designed, with Vizard’s lobe combinations & cam part numbers.

The two cam choices I was considering were the

#DV262-06HRH, 262/211, single pattern Lunati profile VHR10/VHR10, 4’ advanced, .338” lobe lift, .507” valve lift w/a 1.5 rr, or,

#DV270-06HRH, 270/219, single pattern Lunati profile VHR-12/VHR-12, 4’ advanced, .343” lobe lift, .514”. valve lift.

270adv + 270adv=540/4=135-106LSA=29X2= 58’ overlap, I think?

Reasonable for a street weekend 5 speed 3:08, stock new 9:0-1 L31, list #6210 Holley, 350 c.i. compression ratio?

A 262/262 106LSA with only 50’ overlap would probably less belligerent?

Not intending to overthink this, this is not a moon shot lol, just would like your opinions.


I had found this posting in a Chevelles.com forum some time ago. Someone wanted to do something similar, also to using the old Crane 274H06, but using Comp or someone instead.


UDHarold
A VooDoo 262 intake lobe ground as a single-pattern cam on 106 LSA would be closer to the Crane 274H06, but better, just because of the lift curve. Crane does not list the 274H or several others in that family in their catalog of lobe profiles, so I do not know the .200 duration for it.
The VooDoo 262 is closer to, but better than, the old original 268 High Energy cam. In each case, we are talking more assymetrical, faster opening rates, more high-lift area, etc. UDHarold PS---I have no control over the supply of VooDoo cams.

Thanks again.

 

#DV262-06HRH with 9:1 SCR yields a 7.8:1 DCR. 50° overlap.
#DV270-06HRH, the DCR drops to 7.6. Overlap is 58°.
I prefer the smaller of the two.
I think that either of those cams wouldn't necessarily have a choppy idle. By way of =13pxcomparison, my Vortec headed 350 (of old) with 10:1 made good use of COMPs XR276HR. (276/282 110LSA 106 ICL). DCR was over 8:1. And with only 58° of overlap, idled very well with vacuum better than 14".
FWIW, given the limited lifts of the DV cams in question, you would benefit from a 1.6 ratio rocker.

 

I have been using single pattern, tight LSA grinds in 305s and TBI head engines for some time now. Great driveability from them. My 99 Tahoe had a L30 305 Vortec with a Lunati High Efficiency 268 cam. I ended up putting Rhoads lifters in it. Had the bottem end torque and smooth idle of a stock Vortec cam but pulled like the ~220 @ 0.50 cam it was at higher rpm. The Lunati cam was 218/218 @ 0.050 on a 110 LSA. .457/.457 lift. I used it with 1.6 rockers making it more like 221/221 @ 0.050 and .487/.487 lift. Dual pattern cams really only help over 4,500 rpm and actually tend to reduce off-idle and low speed torque. With a single pattern cam you can run a smaller exhaust lobe and tighten the LSA giving more low-midrange torque for a given overlap.
​

 

Thank you Skinny & Fast.

I have heard a few videos of the old Crane 274H06 F/T in a 350 smogger, & even stronger 350 builds that sure did have a nice enough entertaining “chop” to make my bucket list.

Thanks to your help, I think the DV270-06HRH will be a close duration hyd roller match to the Crane F/T 274H06 & the answer to a compromise of my superficial need for sound AND off idle driveability.

 

Found a couple cams that should be similar Howards 180305-8 & Elgin E-1135-P