What is this Cam?

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nismou20
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What is this Cam?

Post by nismou20 » Fri May 03, 2019 2:17 pm

Can anyone tell me by these numbers given to me by American Cams where this Cam stands in relation to B and C? Would a head need some modding to accept, bump in CR as well? Thanks,
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Gregs672000
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Re: What is this Cam?

Post by Gregs672000 » Fri May 03, 2019 3:48 pm

This would be my take based on what I've learned and experienced over the years from reading and trial and error:

Not sure how they calculated out a 214 at 50 thousands duration from an "advertised" 300 duration cam. I wonder if they meant 264. A B cam is 280 advertised duration, about 240 or so at 50 is my understanding, with a rpm onset of about 3200-3400 rpms in my experience. Lift on the cam in question is closer to 476 lift as the rockers are actually slightly less than 1.4, not 1.5, and per Dean's site is between a B and a C, with 460 and 480 lift respectively.

If it's indeed a 300 duration, and a B is 280 and a C is 296, it will come on later in the rpm range and have a similar lift to the C... pretty much a C cam if we can trust the numbers. The Isky cam I intend to run is 246 duration at 50thou, 531 lift (which may be too much as the valve was hitting the block). I specifically chose the lower duration to keep it more streetable. There's generally no bad outcome from running more lift except when it coil binds the springs, hits something, or creates too steep a ramp for the spring to control the weight/movement of the valve, causing erratic valve movement and accelerated rocker and cam wear. I'm able to get away with this because I have lighter valves installed. More lift slightly increases the duration effect.

If they just measured this cam, I would call them up to ask questions about the lift at 50, as that is the most critical value when determining where the cam will start to make power in the rpm range. If it turns out to have this low 214 at 50thou duration, it would probably be a high torque engine but would run out of breath much earlier. Many years ago I was told of an auto crossed U20 that ran a torque cam and it was reportedly a monster on the course.

I'm no expert so I welcome other opinions!
Last edited by Gregs672000 on Fri May 03, 2019 4:09 pm, edited 1 time in total.
Greg Burrows
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nismou20
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Re: What is this Cam?

Post by nismou20 » Fri May 03, 2019 4:01 pm

Appreciate the input Greg, probably too much Cam for the street for me. I’ll most likely post up for sale soon.

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Solex68
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Re: What is this Cam?

Post by Solex68 » Fri May 03, 2019 5:56 pm

My 2 cents...Looks like an Americam Cut #071. It will be fast on the freeway but not great for day to day driving.
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spyder
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Re: What is this Cam?

Post by spyder » Sat May 04, 2019 2:24 am

Gregs672000 wrote:
Fri May 03, 2019 3:48 pm
The Isky cam I intend to run is 246 duration at 50thou, 531 lift (which may be too much as the valve was hitting the block). I specifically chose the lower duration to keep it more streetable.
Which Isky grind is this? Perhaps the 246 is actually 264? The Z-196 has the 264 duration at .050 with .530 lift.

I run this cam without any valve / block issues.
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Gregs672000
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Re: What is this Cam?

Post by Gregs672000 » Sat May 04, 2019 1:47 pm

Hey Spyder's, good to hear from you. This is actually Isky grind # 197, and according to Isky duration is 246 at 50thou, lift is .499. Delta cam profiled this cam and confirmed the 246 duration but had a cam lift of .384, or .536 with our rocker ratio of 1.396. I specifically chose this cam over the Z-196 because the duration was less and I wanted the power band lower.

Regarding your cam card numbers, I don't know how they get to a .530 valve lift from .386 cam lift, since 1.396x.386 = .538, not .530. Their site says the same thing; .530 lift, but isn't that final number based in rocker ratio? So this is confusing to me. Bottom line as far as I can tell, is that we have about the same lift but mine has less duration. Regarding my valves hitting the block, I think this has more to do with the larger valves in my head vs the cam lift per se. In comparison, the Racer Brown cam Delta profiled for me had a 248 duration at 50thou with a cam lift of .336 for a total of .469, so similar duration but less lift (and no hits to the block). When I was comparing the two blocks I have, I did wonder if the original block had been surfaced some, perhaps enough to make a difference, but I really think it's the valve width that is the main factor. I think this is the absolute limit to lift using stock springs, as any more and it will coil bind for sure. Also, the 197 cam will be harder on the valve train due to having less duration but similar lift, as the ramp is steeper and the drop faster, causing possible "ski-jumping" if the spring can not control the valve and rocker. I believe I am "safe" with the lighter valves I am running so the stock springs can keep up without having to use a higher pressure spring and thus causing more potential wear.

At this point, my new block is being bored. After that we will see what needs to be done with the valve reliefs and whether they can be cut deep enough to accommodate for the valve and lift without cutting so far that it exposes the ring (Again! Had to get another block! Also note that these are Arias pistons, so the ring position could be slightly different from stock). If not, my choices will be running Dean's thicker head gasket to gain some space, or to give up on the Isky cam and run the Racer Brown. The new machine shop I'm working with has some detonation concerns with the thicker gasket despite the fact that it would drop my already high compression a bit, as in their experience such a gasket can result in more detonation when we're close to the limit... why, I don't know, but these guys do build race engines, mainly V8s though. We'll see!
Greg Burrows
'67 2000 #588
Tacoma, WA