Cam Questions

[Hotrodpaul]

Has anyone run the 2nd design off road chevy solid small block cam? I have an original LT-1 short block and was thinking about using this cam with some mildly worked over 340292 heads for a nice day 2 driver 1969 Z-28. I plan to call it "Project X" Anyway, just looking for some input on driveability, power, vacuum for the brake booster, etc.

I spent yesterday degreeing some popular cams in the LT-1, and here are the results:
note: the solids are adjusted for lash as it reduces the duration and lift specs.

1970 LT-1 Solid: Int Dur @ .006", .050" = 282, 229 deg, Exh Dur @ .006", .050" = 289, 235 deg
LCA = 114 deg, Int/Exh Lift @ 1.5 ratio = .433"/.450"

GM #3965754 2nd design Solid: Int Dur @ .006", .050" = 300, 248 deg, Exh Dur @ .006", .050" = 313, 259 deg
LCA = 112 deg, Int/Exh Lift @ 1.5 ratio = .488"/.505"

1969 Z-28 Solid: Int Dur @ .006", .050" = 304, 239 deg, Exh Dur @ .006", .050" = 304, 239 deg
LCA = 114 deg, Int/Exh Lift @ 1.5 ratio = .459"/.459" (Comp Cam Replacement)

1966 L-79 Hyd: Int Dur @ .006", .050" = 286, 222 deg, Exh Dur @ .006", .050" = 282, 222 deg
LCA = 114 deg, Int/Exh Lift @ 1.5 ratio = .447"/.447" (GM NOS Cam)

Comp 12-223-4 Solid: Int Dur @ .006", .050" = 270, 222 deg, Exh Dur @ .006", .050" = 269, 221 deg
LCA = 110 deg, Int/Exh Lift @ 1.5 ratio = .471"/.471"

For a good all around street cam, the Comp 12-223-4 would be nice, but I want something a little more nasty, that's why I was considering the 2nd design cam.


http://www.yenko.net/ubbthreads/pics/usergals/2016/11/full-2198-52817-img_0020.jpg

Paul

[scuncio]

Would you consider the 140 cam?

[Hotrodpaul]

Yes, I would consider the 140 cam, I just do not have one on hand. I believe some members here have run that cam with the 302 and had good results. Maybe they could chime in.

[napa68]

What is the compression on your short block?

Tim

[Hotrodpaul]

It would be the stock LT-1 10.5 to 11:1 with the 292 Turbo heads.

Paul

[Billohio]

I have the 140 in my 302 and doesn't have much vacuum and been fighting that.4000 and up its a screamer

[KenMaisano]

I have ran the Comp Cams Nostalgia plus 12-673-4 N+30-30S version of the 3965754 2nd design. This was in a 10to1 383 Four speed 373 gears. I used this camshaft to bleed off some cylinder pressure. the car had a Comp 272 224 110 cam and was Very octane sensitive. It did the job well. no more knocking, Lost a ton of low end torque but pulled good on the top end. It sounds bad ass! If your looking for something close to the sound of the 2nd design, but pulls better thought the whole powerband. I would suggest Comp Cams 12-221-5 280B-8 242-250-108 .507 .530 I have used this cam lashed at .024, installed at 104. makes strong torque and power.

P.S. I think I may still have this camshaft at my shop with a pair of matched lifters. If your interested, I can check Monday and its yours for free:)

Ken Maisano

[napa68]

I'm a huge fan of the LT1 cam. While it wont have the thundering idle it sounds like you care looking for, it pulls hard all through the RPM range and will run your power brakes.

Ken has a good point about bleeding off some cylinder pressure for pump gas. It just comes at the expense of low end torque.

11:1 and the LT1 cam.............you will be mixing in some race gas in order to keep the timing where it should be.

Tim

[scuncio]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KenMaisano</div><div class="ubbcode-body">I have ran the Comp Cams Nostalgia plus 12-673-4 N+30-30S version of the 3965754 2nd design. This was in a 10to1 383 Four speed 373 gears. I used this camshaft to bleed off some cylinder pressure. the car had a Comp 272 224 110 cam and was Very octane sensitive. It did the job well. no more knocking, Lost a ton of low end torque but pulled good on the top end. It sounds bad ass! If your looking for something close to the sound of the 2nd design, but pulls better thought the whole powerband. I would suggest Comp Cams 12-221-5 280B-8 242-250-108 .507 .530 I have used this cam lashed at .024, installed at 104. makes strong torque and power.

P.S. I think I may still have this camshaft at my shop with a pair of matched lifters. If your interested, I can check Monday and its yours for free:)

Ken Maisano
</div></div>

What a great offer!!

[Salvatore]

Go with the Comp set up.

[Hotrodpaul]

Yes Ken, I am up with the offer. Just let me know how much shipping would be to Magnolia, TX zip 77355.

Thanks, Paul

[Lynn]

I am running the exact same short block as you, although mine started life as alate 69 L46. Same crank, rods and pistons. It is also in a 69 Z.

Had the same decision to make 4 years ago. You mention &quot;day two driver&quot;. Two things you should strongly consider IMHO: detonation and flat tappet cam wear.

I never saw where you addressed fuel. Being in Houston, I know you have better pump gas avaialable than we do in OKC. Not sure why, but best pump gas here is 91. Seems every time I drive to TX, there is plenty of 92 and 93 avaialable. Right now fuel isn't an issue for me, as I am 1.5 miles from a Municipal airport that sells 100LL to the public at 3.99 per gal. Don't know if you have that luxury.


Get the quench between .035 and 040. No more. No less. Tight quench helps ward off detonation.

Really hard to to beat the LT-1 cam which is what I went with. One of my main considerations was that the LT-1 could be run reliably with the stock valve springs. That minimizes the chance of wiping a cam. Good lubrication is essential, but I am not opening up that can of worms in this thread, as there are PLENTY of those threads.

Back to detonation, if you are stuck with pump gas, I will tell you that I could not run my LT-1 combo with as much timing as I wanted with 91 octane gas. Had to back it off about 4 degrees. Now, with a mix, I can run full advance. If I were stuck with pump gas, I would consider opening up the heads just a bit to lower compression, or if I had the engine apart, an even better solution would be to cut some off the tops of those pistions (that big single dome kills flame travel anyway).

If you are keeping the big domes, and small combustion chambers, bleeding off some static pressure with a bigger cam will probably help, but as mentioned by others, you may be on the edge when it comes to creating enough vac for power brakes. And... now we are back to cam wear, as you are going to need stiffer springs for the bigger cam.

[Hotrodpaul]

Yes, I had those same concerns. The car will probably be driven less than 300 miles per year, only to cruise, and shows, etc. In Houston, 93 octane is available and I may run a booster as well. In the 80's, I had an L-79 Chevy II that I would mix in some 100 LL aviation fuel, worked well.

For lifter wear, I plan to run coolface oiling lifters with .024&quot; drilled or edm hole, and a high zinc additive in the oil to ward off premature lobe wear.

The cam selection is the big one for me, I think the best combo would be a wider lobe angle, 112-114 degrees to help with vacuum and a later intake closing point to bleed cylinder pressure. Keep lift between .480-.520&quot; and spring pressure max at around 280-300 lbs. I am leaning towards the 30-30 or 2nd design cams. Car will have mildly ported 292 Turbo heads, 1.6 roller rockers, Headers, low restriction exhaust, and remaining parts will be 69 Z-28 items, except for the 350 LT-1 short block. The extra cubes will help the idle and vacuum too. From the outside, it will appear to be a relatively stock Z-28, although the angle plugs may give it away. Other driveline items include M-20 trans for stoplight racing, and 3.73 gear with old school traction bars. Should be fun with around 400 Hp on tap.

Paul

[Salvatore]

I run the Crane version of the 146 cam in my 69 Z. Been in there since 2000 when we built the motor. No issues with wiping, vacuum or detonation. Been running 20w-40 Brad Penn for the last several years also. Stock motor built to spec. Original radiator tanks re-cored. No heating problems on even the hottest days around here. 93 octane mixed with a couple gallons of Sunoco 112. Car pulls to 7 grand with ease. Running Holley 25-25 spark plugs.

Original M21 trans and original 4.10 rear. Replaced trans with an M20 box and went to 4.56's. Made everything come alive. 3.73's to me are not enough. SB's need RPM and a low gear.

Would not hesitate to use a Comp Cam kit. NovaBoy Dave has a real nice Comp Cam set-up in his 1967 302 powered nova.