65 327 camshaft

[Byron Martin]

I just purchased a 65 coupe with the original 300 hp 327. It's been sitting in my cousins shop on jack stands for the past 27 years. I have the motor apart for its first ever rebuild and I am looking for advice on selecting a camshaft. I dont want anything to aggressive, just a little more power. I was thinking about the Comp cam 268H (218 deg /.454" lift). Has anyone here run this cam in an otherwise stock 300hp 327. Also, where can I find the specs for the original GM 327 camshafts. Any advice would be appreciated. Thanks, Byron

[Craig S.]

Re: 65 327 camshaft

Byron - you may want to consider the blueprint grinds of the GM L79 cam, it runs sweet, lots of torque and should work well with your other internals. I belive it gets called the 161 cam, for the last three digits of the GM part number. You may want to open the valves up to match on the heads, like the original double hump heads on the L79's. I know both Crane and SpeedPro (Federal Mogul) make a blueprint grind....Craig

[Bob Simard]

Camshaft

A 151 cam with rhodes lifters. Best of both worlds.

[Joe L.]

Re: 65 327 camshaft

Byron----

My recommendation: use a Speed-Pro KS-1070-R retrofit hydraulic roller camshaft kit. This is a bit expensive, but it's a great value and a lot less expensive than other retrofit hydrualic rollers. This kit contains everything you need----camshaft, lifters, push rods, and cam button. I recommend using GM #10134358 valve springs with this cam. Use NO valve springs with greater spring pressure than these. Also, use a Cloyes #9-3100T timing set with roller thrust bearing.

The 1070-R camshaft will produce great power and torque from idle to about 5,500 RPM; exactly the RPM range that your engine was designed for. It will work PERFECTLY with 1.94/1.50 valve heads, too.

[Joe C.]

Re: 65 327 camshaft

Craig:

All 1965 smallblocks used 1.60"/2.02" heads, EXCEPT all 250HP, and 300HP with Powerglide.

Joe

[Steve D.]

Re: 65 327 camshaft

Joe

Is there an on-line Speed Pro catalog location? I have gone to the Federal Mogul site but can't find any product details.

Steve

[Clem Z.]

Re: 65 327 camshaft

what speed pro/ fm cam do you want the specs for?

[Joe L.]

Re: 65 327 camshaft

Steve-----

Not that I know of. For such a big company, the Federal Mogul (including all of their "subsidiaries"/brand names) web site is one of the poorest out there. Real "bush-league"! The specs on the 1070-R cam are as follows:

valve lift (with 1.50:1 rockers)=0.462"--intake; 0.470"--exhaust

duration @ 0.050" lift= 210 degrees intake; 215 degrees exhaust

duration @0.006" lift= 288 degrees intake; 284 degrees exhaust

Lobe centerline= 110 degrees

[Duke W.]

Re: 65 327 camshaft

For the amount of duration I think that cam has too much overlap.

I have yet to find a cam that equals the torque bandwidth of the LT-1 cam. Timing points at .006" lift using the actual rocker ratio of 1.37:1 at the lash point and clearances of .021"/.026" are 26-71/83-29.5; duration 277/292.5; points of Max lift: 110 ABC/122 BTC: angle 116. These numbers are not exactly "centerline" or "lobe center" because the lobes are asymmetrical.

Max valve lift using the above clearances and actual measured rocker ratio of 1.44:1 at maximum lift are: 0.418"/0.438".

These are all actual measured numbers on a real production machined vintage smallblock. In particular the OEM rockers and probaby most aftermarket rockers are not really what is specified and the ration isn't even constant.

Duke

[Joe L.]

Re: 65 327 camshaft

Duke----

I can tell you for certain that the CS-1070-R performs SUPERBLY and is "just what the doctor ordered" for street engines.

[Pete Whelan]

Re: 65 327 camshaft

Byron,
If you want to run a Comp cam, I would recommend the 262H over the 268H. You won't like the 268H with a 3.08 or 3.36 rear axle ratio. The smaller cam will give you more low rpm torque and a smoother idle with nearly the same HP. I also recommend a Crane H-260-2 cam, which has max. valve lift of 0.427I/0.454E with 204/214 degrees duration at 0.050 lift. This cam has a smooth idle and produces maximum torque around 3000 rpm and maximum hp around 5000 rpm (and continues to produce good hp past 5500). Both the Comp and Crane cams require slightly stiffer valve springs (105 lb seat pressure vs. 80) because of increased cam lobe ramp speeds. The following link gives camshaft specifications for Corvette engines.

http://www.geocities.com/MotorCity/Downs/3000/cmspec.html

Good luck,
Pete

[Duke W.]

Re: 65 327 camshaft

Joe-

If you give me the actual timing points or at least one lobe centerline angle I'll run the numbers on DD2000 and report the number relative to the LT-1 cam. The info you've provided is one data point short of characterizing the cam.

Duke

[Clem Z.]

duke i think this is correct

CS 1070R 110 intake CL,advertised dur 284,open@seat BTDC 32, close @ seat ABDC 72, exhaust advertised dur 288, open@seat BBDC 72, closed @ seat ATDC 36, lobe lift .308/.313 lobe seperation 109

[Duke W.]

Re: duke i think this is correct

One of the things this exercise shows is that roller lifters provide a big advantage. DD2000 allows you to choose between hydraulic flat tappet, mechanical flat tappet, and roller for both mechanical or hydraulic. Greater flank acceleration is assumed as you move from hydraulic to mechanical and then roller, which usually shows up as more mid range and top end power for the same timing numbers. The CS 1070R might have a slight advantage in this analysis becasue I multiplied total lobe lift times 1.44 and didn't take out any lift for clearance ramps, though I beleive hydraulic cams they are usually fairly low.

The base reference numbers are for my '63 L-76 that is OEM except for the LT-1 cam, pocket ported/port matched heads and other blueprinting. For reference DD2000 predicts 304 HP for the OEM '63 L-76, and I have dyno sheets on a stock rebuilt '63 L-76 (not mine) that was within a couple of HP of this prediction. Consider all these numbers to be essentially SAE gross.

LT-1 cam:

297 lb-ft @ 2000, 354 lb-ft @ 4500, 346 HP @ 6000, 80% torq b/w 1800-6200

Speed pro CS 1070R Clem's posted specs

280@2000 357@4500, 364HP@6000, 2100-6500 bandwidth

For comparison I ran the LT-1 cam timing with roller lifters:

309@2000, 371@4500, 368HP@6000, 1800-6300 bandwidth

Now the CS 1070R timing with flat tappet mechanical lifters:

271@2000, 342@4500, 344HP@6000, 2000-6500

The CS 1070R's additional overlap hurts low end torque, but helps top end power. The LT-1 cam is excellent because it opens the exhaust valve very early, which is beneficial on the SB because of its relatively restrictive exhaust port.
It looks like the hot setup would be the LT-1 timing points with roller lifters.

Duke

[Clem Z.]

go to www.idavette.net/hib/camcon.htm

for a good comparison between flat hyd tappet and roller hyd tappet cams in corvette engines