Comp Cams HYD Roller for 65 327/350HP with PB, A/C and 3.73:1 rear gear. Any Comments

[Joe L.]

Re: Comp Cams HYD Roller for 65 327/350HP with PB, A/C and 3.73:1 rear gear. Any Comm

Hello All,
I forgot to mention one important point!
I am strongly considering Running Trick Flow Aluminum Double-hump Head Copies. Think they are good for the .525 lift the cam I am looking at has. Does this make any Difference to anyone's opinion?
Thanks again,
Bill

Bill------


The Trick Flow heads are good heads. However, the stock heads you have will work fine with the 0.525" valve lift. I would use long slot rocker arms, though.

In general, hydraulic roller cams use somewhat higher rate valve springs than the stock Chevrolet type. Not wildly higher rate----just a little more than the stock springs used with flat tappet cams. I believe this is at least partially due to the higher lift that hydraulic roller cams can provide for a given duration. This is one of the advantages of hydraulic roller cams. With flat tappet cams, lift for a given duration is limited by the ability of a flat tappet lifter to follow the lobe profile. With a roller cam, the roller lifters can follow a much more aggressive lobe profile. So, more lift can be had for a given duration. This results in "free" extra power.

The Federal-Mogul VS 739R springs that Duke mentioned will work fine. These springs are a somewhat higher rate than the stock GM springs. I use the GM #10134358 with small block roller cams but those are now GM-discontinued.

[Leif A.]

Re: Comp Cams HYD Roller for 65 327/350HP with PB, A/C and 3.73:1 rear gear. Any Comm

That Comp Cam is a nice cam. If you are running 2.02" intake valves and 1.6" exhaust valves, it works great. But I still like a Lobe Separation Angle of 114 to 116 degrees for street use. You could even use 1.6 rocker arms in place of the factory 1.5 to boost the lift just a bit more and it would add a couple of degrees to the cam.

The intake and exhaust port volumes on these L79 style heads with 1.94" intake valves and 1.5" exhaust valves are limited and do not allow as much air flow as let's say the 1992-1996 LT1 heads which use a hydraulic roller cam. So you always have to keep that in mind when choosing a replacement cam.

I prefer Isky, Crower, and Comp Cams.

As someone else mentioned in this post, don't forget about the bottom end. You can't do high RPM's with reliability with a cast crank and pistons. So this spec cam should be more than what you need for street use.

My stock "462" heads with 2.02" intake valves and 1.6" exhaust valves.

[Michael L.]

Re: Comp Cams HYD Roller for 65 327/350HP with PB, A/C and 3.73:1 rear gear. Any Comm

Not that I'm adding much with my N=1 but I rebuilt my 69 L-46 a couple of years ago and used the 280 HR the OP listed at the top. After great difficulty getting the thing to run well unrelated to the cam (bad distributor to coil wire and forgot to put the baffle under the carb-duh) I'm super pleased with how it runs. I too have the M-21 and 3.73 and the car idles real nice at like 750, brakes work fine, and it is extremely well behaved when driving around town. It doesn't seem too sluggish down low but I must confess I drive the car like an old lady.

Mike

[Duke W.]

Re: Comp Cams HYD Roller for 65 327/350HP with PB, A/C and 3.73:1 rear gear. Any Comm

Bill------



The Federal-Mogul VS 739R springs that Duke mentioned will work fine. These springs are a somewhat higher rate than the stock GM springs. I use the GM #10134358 with small block roller cams but those are now GM-discontinued.

I've never recommended those springs with any OE equivalent cam. I've always recommended the Sealed Power VS-677 (equivalent to the OE 3911068), but they are apparently, inexplicably out of production despite tens of millions being installed by GM in production small blocks.

Do you specs on the VS739R?

Duke

[William H.]

Re: Comp Cams HYD Roller for 65 327/350HP with PB, A/C and 3.73:1 rear gear. Any Comm

Thanks Mike,
I appreciate the actual experience with the cam in question. That is what I am looking for maybe someone else who has used this cam, can chime in. I am still trying to figure out what Cam was in the car before. I believed it was a Melling L76 cam, but it seems it is not as the lobe lift is about .310 on both intake and exhaust. Here is a picture in case anyone can ID it. Tried the Melling help line with no success yet.
Thanks,
Bill20230826_113928.jpg
uc

[Joe L.]

Re: Comp Cams HYD Roller for 65 327/350HP with PB, A/C and 3.73:1 rear gear. Any Comm

I've never recommended those springs with any OE equivalent cam. I've always recommended the Sealed Power VS-677 (equivalent to the OE 3911068), but they are apparently, inexplicably out of production despite tens of millions being installed by GM in production small blocks.

Do you specs on the VS739R?

Duke

Duke------


739R

dual spring

OD-----1.260"

Free length----2.00"

Wire diameter-----0.192"

Closed pressure-----110 lbs @ 1.70"

Open Pressure------294 lbs @ 1.210"

[Duke W.]

Re: Comp Cams HYD Roller for 65 327/350HP with PB, A/C and 3.73:1 rear gear. Any Comm

Thanks... that's considerably stiffer than OE - 37.5% greater seat force and 40 percent greater spring rate! Given that OE springs will rev above the usable power range for stock heads and are "just right" for massaged heads and most higher flowing aftermarket heads, I would not recommend these springs for any OE cam.

I believe that most flat tappet cam/lifter failures are due to recommendation by cam grinders for greater than OE seat force/spring rates for OE equivalent cams, or the stiff springs recommended for many aftermarket cams by their manufacturers due to their more aggressive dynamics

Duke

[Jack H.]

Re: Comp Cams HYD Roller for 65 327/350HP with PB, A/C and 3.73:1 rear gear. Any Comm

Thanks Mike,
I appreciate the actual experience with the cam in question. That is what I am looking for maybe someone else who has used this cam, can chime in. I am still trying to figure out what Cam was in the car before. I believed it was a Melling L76 cam, but it seems it is not as the lobe lift is about .310 on both intake and exhaust. Here is a picture in case anyone can ID it. Tried the Melling help line with no success yet.
Thanks,
Bill[ATTACH=CONFIG]118371[/ATTACH]
uc

Being a former parts counter guy, the 112 and 187 numbers are familiar. The Federal Mogul/SealedPower/SpeedPro manufacturer used a cam part numbering scheme of "CSxxx". CS112R and CS187 were both valid part numbers of cams available back in the day. Searching those part numbers on Google, it looks like the CS187 was a Pontiac application so that's not a match. CS112R is a Chevy application number and had a cam lobe lift of 0.291 both intake and exhaust which you could compare to your cam to see if its a match.

[William H.]

Re: Comp Cams HYD Roller for 65 327/350HP with PB, A/C and 3.73:1 rear gear. Any Comm

I measured .310"?????

[Joe R.]

Re: Comp Cams HYD Roller for 65 327/350HP with PB, A/C and 3.73:1 rear gear. Any Comm

Hello everyone,
Per Comp Cams Help Line I am looking at Cam 12-430-8 Hydraulic Roller Lifter Cam:

224 durations at .050"
280 Advertised
.525/.525 Lift
110 Degree LSA
2000-6000 powerband
Running stock L2166nf-.030 pistons
Factory intake Carburetor and Exhaust Manifolds Currently factory side pipes but may switch to N11 undercar exhaust.
1965 Coupe PW, Tele, PB, PS and A/C
3.73:1 rear gear 2.20:1 Low M21
Any Comments or suggestions would be appreciated greatly.
Thanks in advance and Bless you all.
Bill

I have that exact cam in a 383 that I built back around 2015. Attached is an article that I wrote for the NCRS Restorer about the roller cam installation considerations.

Like you, I have power brakes, A/C, and a 3.70 rear. The power brakes and A/C make it important that you try to ensure that the effective overlap is not larger than the stock L79. Otherwise you risk insufficient vacuum for the power brakes, and you also risk a big rpm drop when the A/C compressor switches on at idle.

If you want to match the idle characteristic of the L79 while maintaining the L79 .050" duration of 222/222 (the 12-430-8, aka the 280 HR cam, is almost identical at 224/224), the LSA should be similar to the L79 LSA of 114 degrees.

In my case, I was increasing the displacement of the engine to 383 CID, which makes the engine more tolerant of increased overlap. So, I used the off-the-shelf 280 HR with 110 degree LSA. Even with the added displacement of the 383, the idle characteristic is a bit rougher than the L79 cam in a 327. If your engine will be 327 CID with the 280HR cam (110 degree LSA), I think it will have trouble at idle when the A/C compressor switches on and off. You may have to set the idle to about 1000 rpm to prevent the engine from stalling when the A/C compressor turns on.

Other than the slightly rougher idle of my 383 (which tolerates the A/C compressor turning on when the idle is set to 900 rpm), the engine runs great and makes 424 hp at 6000 rpm. This is with pocket ported Dart heads that flow about the same as the Trick Flow DHC heads.

In hindsight, I wish I had held out for a custom cam that had all the 280HR specs but an LSA of 114 degrees. That would have given me a smoother idle characteristic with almost no compromise on high end power.

Another thing that I should mention is that with the Comp Cams 280 HR cam and lifters I purchased in 2015, I had a lot of trouble with excessive noise from hydraulic roller lifters. At that time, many other people were complaining about lifter noise from Comp Cams hydraulic roller cams and lifters. I do not know whether this problem was due to cam, lifters, or both, and I do not know whether the problem has been fixed.

Based on my experience and the experience of others that I have worked with, I would recommend using a Howards Cam and Howards hydraulic roller lifters (I believe that the Howards lifters are made by Morel). The Howards cam/lifter combinations do not seem to have any issues with lifter noise.

Howards has a couple catalog hydraulic roller cams that come close to matching the L79 specs, such as the 111145-14, which has 219/225 duration, .525/.525 lift. and 114 degree LSA. They also have a couple custom cam part numbers that are similar. The key target is to come close to matching the .050 duration of the L79 (222/222), the LSA of the L79 (114 degrees), but with more lift than the .447" lift of the L79 cam. This will give you the L79 idle characteristic and low end torque, but more power at higher rpm.

BTW, you mention the Trick Flow DHC heads, and I think they would be an excellent choice.

[William H.]

Re: Comp Cams HYD Roller for 65 327/350HP with PB, A/C and 3.73:1 rear gear. Any Comm

Hello Joe,
What pistons did you use on this engine and what was your actual compression ratio?
Thanks,
Bill

[Joe R.]

Re: Comp Cams HYD Roller for 65 327/350HP with PB, A/C and 3.73:1 rear gear. Any Comm

Hello Joe,
What pistons did you use on this engine and what was your actual compression ratio?
Thanks,
Bill

Because I'm old-school, I wanted to use forged pistons. For forged pistons, my machinist recommended the Mahle "PowerPak" forged pistons. These pistons have several technical improvements over the OEM forged pistons used in the 1960s.

I set my compression to 10.25, based on the fact that premium pump gas here in Massachusetts is 92 octane and I was using cast iron heads. I might have gone a bit higher if I was using aluminum heads, and a bit lower if I was using California pump gas.

[Gary B.]