Cam recommendations for present build

[Jeff Alton]

Originally Posted by jpgroth

I have a motor finishing up with similar specs. 3.0 big port, 9.5 JEs, 42mm ITBs and the M1 cam. Street car, can't wait to get back into the car

Interested in why you chose this cam for your build.... pretty mild cam considering the rest of your build specs.

Cheers

[Henry Schmidt]

Originally Posted by Jeff Alton

Interested in why you chose this cam for your build.... pretty mild cam considering the rest of your build specs.

Cheers

Hi Jeff, this suggests you know the M1 cam specs....care to share?

[Jeff Alton]

Originally Posted by jpgroth

I have a motor finishing up with similar specs. 3.0 big port, 9.5 JEs, 42mm ITBs and the M1 cam. Street car, can't wait to get back into the car

Interested in why you chose this cam for your build.... pretty mild cam considering the rest of your build specs.

Cheers

[mikedsilva]

Originally Posted by Henry Schmidt

Hi Jeff, this suggests you know the M1 cam specs....care to share?

I think the fact it is designed to work on a stock CIS motor, lends to the idea that perfomance is left on the table, seeing as the owner is using programmable efi and ITBs.

[mikedsilva]

Originally Posted by icarp

Sorry I am sick as a dog
DP is using JE pistons, this opens up the cam choice tremendously .
For a 9:5/1 comp ratio , I think the most fun will come from a Kight Race. 45


Ill get back to you all later

Ian

What is a Knight Race 45 cam?

[Henry Schmidt]

Originally Posted by mikedsilva

I think the fact it is designed to work on a stock CIS motor, lends to the idea that perfomance is left on the table, seeing as the owner is using programmable efi and ITBs.

Given Davids design components and performance requirements, DC30 seems apropos. Nothing crazy but give the parameters, this build should be fun to drive.

[PeteKz]

Back to the M1 cam: I haven't got my car on a dyno yet to do the final tuning, so I don't know what the numbers are. I will post those after I do that. That said, I do know from my measurements as I timed the M1 cam that it uses all the room available for lift and duration on 3.0 and 3.2 engines without the valves hitting the pistons. Therefore, one has to stay very close to the recommended cam timing, because retarding or advancing the timing more than a few degrees, WILL result in cam/piston interference. I measured that. So, yes, "it leaves performance on the table" IF you want higher RPM power, but are willing to give up low-mid RPM torque.

If you choose different pistons with valve pockets, you can choose a more "radical" cam, but you will give up low RPM torque and smoothness. As Henry observed, to a racer, high-RPM power is most important, but a high-RPM engine is a lousy street driving experience.

What the M1 does for a street car is give a wide range of torque. As I noted before, I have retained CIS on my car, and I can floor the gas pedal at just above idle, in the higher gears, and it will pull smoothly all the way to redline. I like that for a street car, especially with the crappy-shifting 915 transmission. I also get close to 30MPG at constant highway speed. Not shabby for an old engine design. Even if I don't get to my desired 230 RWHP @6000RPM in my tuning, I like the driving characteristics enough that I would build another engine with it.

[Old H2S]

I got the fuel distributor back and installed and running but I only have 200 miles on it so I have not gone above 4000 RPM yet and can not tell what the butt dyno says. I did a Kermit clone CIS set up and it starts better loosing the WUR. I have Carillo pistons with big valve cut outs so I could have gone to a much bigger cam than the M1. With no shims under the cylinders I came up with 9.75:1 CR. and 4mm VtoP clearance but the VtoV clearance was VERY close at overlap. Nice and smooth pulls to 4k but that is not saying much yet.. I built this 3.2ss to be a good cruiser going up and I-95 at 28mpg, I optimized Henry's advice on shooting for friction reduction rather that all out power.

[Jeff Alton]

Originally Posted by Henry Schmidt

Hi Jeff, this suggests you know the M1 cam specs....care to share?

For some reason I double posted. But the M1 has SC/Carerra lift with increased duration only....

Cheers

[PeteKz]

Originally Posted by Old H2S

I got the fuel distributor back and installed and running but I only have 200 miles on it so I have not gone above 4000 RPM yet and can not tell what the butt dyno says. I did a Kermit clone CIS set up and it starts better loosing the WUR. I have Carillo pistons with big valve cut outs so I could have gone to a much bigger cam than the M1. With no shims under the cylinders I came up with 9.75:1 CR. and 4mm VtoP clearance but the VtoV clearance was VERY close at overlap. Nice and smooth pulls to 4k but that is not saying much yet.. I built this 3.2ss to be a good cruiser going up and I-95 at 28mpg, I optimized Henry's advice on shooting for friction reduction rather that all out power.

Hell, 200 miles is plenty. Time to start exercising it. See whatcha built.

[Old H2S]

The engine gods have touched me..last night, I'll get right on it today after I change out the rear wheel bearings with 350k on them.

[Henry Schmidt]

Originally Posted by Jeff Alton

For some reason I double posted. But the M1 has SC/Carerra lift with increased duration only....

Cheers

As I've indicated in previous posts, lobe center/overlap is as important to cylinder filling [volumetric efficiency] as any other consideration.
Without a reasonable amount of overlap, performance is always/generally compromised. I added generally because "always" is a trigger for dissension. In this conversation, understanding cams in their simplest terms seems beneficial.

To add perspective as I understand lobe center:
Changing the lobe separation changes the amount of overlap that exists during the time the intake and exhaust valves are both open. On a naturally aspirated engine, the lobe separation angle has an effect on whether the engine reaches peak torque a little earlier or later in the rpm range. Typically, narrower lobe separation develops peak torque at lower rpm and widening the separation tends to build peak torque higher in the rpm range.
If a street car has smaller lift and duration numbers, they might run 106 or 114. Widening their separation angle helps increase upper rpm power output. Alternatively, if you are running a bigger camshaft to gain maximum top-end power, cam makers often suggest reducing the lobe separation angle to recover power lost in the lower rev range.

[dannobee]

To add what Henry stated about LSA. Lower LSA's will make the torque curve more "peaky." Widening the LSA will broaden the torque curve, but the peak torque output will be lower. Lower LSA's will increase torque at lower RPM's, but will also reduce engine vacuum and idle quality (important if you have power brakes). Lower LSA = lower RPM for peak torque, but decreased idle quality. Higher LSA = higher RPM for peak torque (and usually lower peak torque output), but increased idle quality. The higher LSA cam will make more peak HP than the lower LSA cam at the expense of reduced peak torque output.

If it has boost, the turbo/supercharger will forgive a lot of the sins with respect to torque output that the wide LSA cam tends to have. Boost and a wider LSA go hand in hand and tend compliment each other. If you run a really narrow LSA with boost, some of that boost will go right out the exhaust during overlap, wasting fuel and reducing power.

[Henry Schmidt]

Originally Posted by dannobee

To add what Henry stated about LSA. Lower LSA's will make the torque curve more "peaky." Widening the LSA will broaden the torque curve, but the peak torque output will be lower. Lower LSA's will increase torque at lower RPM's, but will also reduce engine vacuum and idle quality (important if you have power brakes). Lower LSA = lower RPM for peak torque, but decreased idle quality. Higher LSA = higher RPM for peak torque (and usually lower peak torque output), but increased idle quality. The higher LSA cam will make more peak HP than the lower LSA cam at the expense of reduced peak torque output.

If it has boost, the turbo/supercharger will forgive a lot of the sins with respect to torque output that the wide LSA cam tends to have. Boost and a wider LSA go hand in hand and tend compliment each other. If you run a really narrow LSA with boost, some of that boost will go right out the exhaust during overlap, wasting fuel and reducing power.

^^^^^^Nice^^^^^^

[G450X]

Originally Posted by Old H2S

I got the fuel distributor back and installed and running but I only have 200 miles on it so I have not gone above 4000 RPM yet and can not tell what the butt dyno says. I did a Kermit clone CIS set up and it starts better loosing the WUR. I have Carillo pistons with big valve cut outs so I could have gone to a much bigger cam than the M1. With no shims under the cylinders I came up with 9.75:1 CR. and 4mm VtoP clearance but the VtoV clearance was VERY close at overlap. Nice and smooth pulls to 4k but that is not saying much yet.. I built this 3.2ss to be a good cruiser going up and I-95 at 28mpg, I optimized Henry's advice on shooting for friction reduction rather that all out power.

Let us know how the M1 performs at higher RPM’s. I had 964 cams for my pending ‘82 SC build, but I picked up M1 cams due to the positive feedback. My stock SC falls flat above 5500 RPM’s, and it drives me crazy. My pending build includes an early high flow CIS setup & heads, Max Moritz P&C’s, SSI’s, etc.. I hope to gain at least a 6800 RPM redline…

[Old H2S]

The only thing I know are '83 CIS cams. 964 cams are good but William says they are still a CIS emissions cam and the M1 is a max cam for CIS pistons, so there are MANY other cams to choose from that are bigger. I have Carillo pistons with lots of P to V clearance could have gone much bigger, instead I could get rid of the under cylinder shims and squeeze 9.75 out of the stock heads. I picked the M1 so it would not tear up a stock valve train because that is where problems start. The only spec I know is the lift comes out to 11.4 mm from setting the valve timing and set it at 2.2mm which is mild. Good, that's what I wanted, my engine had 350k on it and all the cylinders were at 150 PSI static but it was tired. Performance and reliability and diametrically opposed so when we dream up engines it is good we have William, Henry and Neil to ask to help. Henry made an impression on me with the 3.2ss is well sorted and output documented and the way to go was friction reduction, so that was the path I did, very expensive to get all the parts coated but it does spin nice.. the car jumps but is that from 40% reduction in rotating mass or the bump in displacement or the M1 cam? It doesn't hurt that the cam was designed with a chick that was at Ferrari..

[Dpmulvan]

Originally Posted by Old H2S

The only thing I know are '83 CIS cams. 964 cams are good but William says they are still a CIS emissions cam and the M1 is a max cam for CIS pistons, so there are MANY other cams to choose from that are bigger. I have Carillo pistons with lots of P to V clearance could have gone much bigger, instead I could get rid of the under cylinder shims and squeeze 9.75 out of the stock heads. I picked the M1 so it would not tear up a stock valve train because that is where problems start. The only spec I know is the lift comes out to 11.4 mm from setting the valve timing and set it at 2.2mm which is mild. Good, that's what I wanted, my engine had 350k on it and all the cylinders were at 150 PSI static but it was tired. Performance and reliability and diametrically opposed so when we dream up engines it is good we have William, Henry and Neil to ask to help. Henry made an impression on me with the 3.2ss is well sorted and output documented and the way to go was friction reduction, so that was the path I did, very expensive to get all the parts coated but it does spin nice.. the car jumps but is that from 40% reduction in rotating mass or the bump in displacement or the M1 cam? It doesn't hurt that the cam was designed with a chick that was at Ferrari..

I’ve been looking at different products to reduce friction myself. What did you end up going with?? I was looking at some of these https://techlinecoatings.com.au/product/dfl-1-powerkote/

[Old H2S]

I used Industrial Hard Coatings of Denver NC. They do all the NASCAR teams DLC coatings.

[dkirk]

Why not use wide LSA cams and retard timing a few degrees to pick up the top end? Wouldn't this be a good compromise for those running manifold fuel injection systems?

[VFR750]

Originally Posted by Henry Schmidt

Post the cam specs [lift, duration, lobe center] and I'll tell you what I think.
Just off the top, if the cam works well with a CIS injection you are probably leaving performance that the carburetor can provide.
CIS injections can't handle intake pulses so wide lobe centers are required. Carburetor don't haven that issue.
3.0, small port 9.5:1 with 40 Webers and a clean exhaust is a 230+ horse power engine. A CIS compatible cam will hamper that kind of output. Not knowing the M1 specs I can only guess it's performance. I would lean towards DC40 [mod "S"] based on previous experience.

I’m running the DC40 cam, small ports, 3.0, highly modified Zenith TIN carburetor. Excellent combination as Henry points out.

The DC40 is a great match for carbs. Carbs really like overlap.

The stock SC cam is not optimal. I also ran a DC20/19 cam, but that wasn’t much better than the SC. The carbs didn’t tune as easy with these two compared to the DC40

JE pistons needed to have the exhaust valve pocket cut 0.025” deeper to get the minimum acceptable clearance with the DC40.

Getting the pockets cut at a machine shop was easier than I thought. And maybe $150?