The end of my cam is stamped: '264s10' and 'VA2676' and has a squiggly curl stamped into it. Does anybody know who might have made this cam as well as the specs?

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Cheers!
Al T

Al,

That may be either Isky or Comp cams. You might give their sites a look or give a call. That Isky 264 is supposed to be pretty nice - www.iskycams.com.

Cheers,

Lou

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Home of Slant6-powered fun machines since 1988

Hey Lou! I looked at the Isky & Crane website's last night but so far have not found anything. I just tried the Comp site but no luck. I'll have to give them a call.

BTW, looks like I got that contract I was working on last week so I just might see you again shortly!

_________________
Cheers!
Al T

Phone is always the best way, IMHO.

Great! I'll see if I can make the car faster before you get back down here... We'll get you that killer salad at Top of the Hill next time too.

Lou

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Home of Slant6-powered fun machines since 1988

I started calling the different cam manufacturers (Crane, Comp, Isky, Melling, Sig Erson, Racer Brown, Ultradyne) and fortunately for me, the 3rd place I called was Comp. The tech guy got a hit on the 264S-10 number for the slant. I redid the search on this site using 'CAM/Overlap/Profile' and got this post by "brent" from the old board specifically referencing what appears to be the same cam.
http://www.slantsix.org/forum/viewtopic ... le+overlap

Lou, we ended up at Top of Hill on Thurs nite and had some excellent food but didn't have the salad. Next time.

_________________
Cheers!
Al T

Cool beans. Glad you found the cam. It may be useable for your blower motor, but might be at the limit of overlap that you could use, at least from my limited knowledge.

See you on your next visit to NC,

Lou

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Home of Slant6-powered fun machines since 1988

With any build, there's always another step and that's where I'm at with Big Red. After seeing the cars run at Clay City, I've got to take the next step.
I believe that the blower is pushing too much of the charge through into the exhaust with my current cam. (Symptoms are: high under hood temps - very hot Dutra duals, poor fuel economy, pressure from blower not building up beyond 5 psi even with the addition of the smaller blower pulley.) I'm now looking for a more appropriate cam.
==================================
Current Comp cam Grind Number: CR6 264S-10

Intake Exhaust
Valve Adjustment .010 .012
Gross Valve Lift .440 .440

Duration AT .020 Tappet Lift 264 264

Valve Timing open close at .020
INT 24 BTDC 60 ABDC
EXH 60 BBDC 24 ATDC

Cam installed at 106 intake center line.

Intake Exhaust
Duration at .50 220 220
Lobe Lift .2933 .2933
Lobe Separation 110
===============================
This gives an valve overlap at 0.020 lift of 48 degrees

Any specific recommendations from the board before I call Comp?

_________________
Cheers!
Al T

Most guys I've talked to have said that 110 is a bare minimum for LSA for a forced-induction cam even with short duration. 112-114 deg is probably better. Mike J mentioned at CC that he runs in that 112 range on his nitrous motors too, but 104 LSA seemed to work best for his purely NA motors.

The Drake's recently talked to a specialist at Comp, who set them up with a very nice low-overlap performance cam with almost 0.500" lift. They said the cam was worth something like 0.2 sec in the 1/4th mile over a MP 244 cam (Tom??), and that's on a high 9 sec 1/4 car!

The other place I might look is the Buick GN websites for specs (www.turbobuick.com, www. turbobuicks.com...), or maybe the Mopar 4 cyl turbo sites?

Lou

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Home of Slant6-powered fun machines since 1988

Your lobe separation is too narrow. Depending on a few things (head flow numbers), you want a cam that favors exhaust duration. Where do you want your powerband? What is your complete setup? Intake, exhaust, head work, compression ratio... What is your spark timing? What is you A/F?

Mitch

I had my turbo cam custom ground by a company that does mostly performance engines, and alot of Marine engines. I had a dual pattern , mild cam with wider lobe seperation than stock. I think it is 112 or 113, but I can check on that. The stock cam is narrower than I had expected, but I don;t remember the exact numbers. Comp cams consistant use of 110 seperation through their entire line seems a little funny to me, and is the one reason I did not put a comp cam in my 360 Dart. I used a 112 seperation Wiend cam in that car, (which I think was actualy provide to them by Isky).

On the turbo slant, I also used bigger exhaust valves. I dialed in the ratio of the rocker arms, and put the higher ratio ones on the exhaust side. This was all operating on the theory that the exhaust of a turbo engine has to be freer than normal both because it is restricted by the turbo, and is not assisted in any way by boost like the intake is. I am sure it is not in the league of your race cars, but it does all seem to work well. I am getting 8 lbs of boost below the throttle blade out of a Buick Grand National turbo. I have not checked the efficiency of the inner cooler by checking the boost and the temperature at the turbo outlet, and comparing that to the same figures at the TB. That would be an interesting piece of data to guide in your design work.

What kind of overlap do you have on your cam?

Tom

Hi Tom. I found the cam card. I am sorry, I had this all worked out when I degreed the cam in, but I will try to get this figured out here. It is a mild cam to start with, so there is less by far than a high RPM cam would have. The cam started as a 1962 225 lobe shape and grind, and he widened the lobe seperation 2 degees to 111. The lift is .398 and .408. The advertized duration is 242, and 254. At .050 it is only 203 and 209. This gives it lots of low rpm torque. The lobe centerline is 105 intake, and 117 exhaust.

The intake opens, -4 BTDC; exhaust closes,-14 ATDC. I guess that works out to 18 degrees overlap, no? Anyway, in practice, it has very mild street maners, and uses the turbo well. It would rev freely to 5K without the turbo, but I haven;t been able to get the clutch to hold well enough to test it above 4K now.

Oh yeah, I did some pretty dramatic bowel work on the head. I completely removed the innner boss from around the valve guide, and took the valve opening all the way back to the seat. I opened the chamber up slightly to un-shroud the valves, and CC'd the chambers to check their uniformity, which was suprisingly good, considering I polished the combustion chambers. This was all done after reading a
British book about head work on small in-line engines. My thinking all along was that if I got the head cleaned up well enough, forced induction would overcome the mild cam, and poor design of the slant head (when compared to modern multi valve, crossflow designs).So far I am pleased with the results.

Tom, I don;t know that I figured what those opening and closing specs mean. If I got it wrong, then my math is meaningless. I remember that when the degree wheel was on the crank sprocket, and I marked all the events on the wheel with tape, it all made wense to me. To finish the specs, In closes, 26 ABDC; EX opens 41, BBDC. Maybe you can clear this up for me and everyone else. I spent a week working this out when I built the engine, which was at least 3 years ago now.

Remember this. If the intake opens before the exhuast closes (as is the case ) then the boost on the intake side is "pushing" the exhuast for as long as it is still open. With a boosted motor you do not want this overlap to be very long otherwise you are pushing good intake air mixture out the exhaust valve.(the higher then boost then less overlap you want) To say that the exhaust is not effected by boost is incorrect. You can help evacuate the cylinder by increasing the overlap but you can also run into the problem described above. There is a very fine line here and you really need a cam manufacture that has experience with boosted applications.

If you call Comp then talk to Derek Scott. He is the person they directed me to when I called with questions about a Turbo application. Also keep in mind that a Supercharger cam and turbo cam will be different in their needs. Since the Supercharged cam does not have any back pressure to deal with in the exhaust (like a turbo) then the requirements will be different.

Now with that said the other factor here is rpm. The MP cam we ran had the power band below 6000rpms. The first cam that Comp supplied us brought the power curve above 6000. That cam would have run faster than any other cam but we were not willing to turn it tighter than 6000. We went back to the MP cam and that is what was in the car at Farmington for the 6.10 run.(1/8 mile) Right before Bristol we had comp grind us another cam that was closer to the MP cam and that is what we had in it at Bristol for the 9.85(1/4) run. We only got 5 runs on this cam but it seem to have its power all below 6000rpms.

Lots of things to consider but in my opinion on a turbo motor you would never go wrong with a stock cam(or mild MP cam specs). It would idle like a pussycat but put the boost to it and 69 camaro's would make you raise the hood to prove it was a slant six!

Tom

Thanks for the info Mitch, Tom, Darth and Lou . . .
Things got a little busy with work so I had to drop the topic but I'm back.

Mitch - my head has stock valves with aggressive head porting and dual springs. Static CR is about 8.2. I've got a convertor with stock stall speed and 2:76 posi rear gearing. Timing is 10' BTDC with 32' advance in at around 2000 rpm. It is fully programmable so I can set that where I want it. My A/F ratio is all over . . . depends on driving habits and rpm range. I'm looking for the power band to be spread across the lower range up until 5000. I'd rather put stress on the componants from higher boost . . . not internal reciprocating/centrifugal and friction forces.

Tom & Lou: thks for the info/contact at Comp. I'll be talking to them as well as Engle. Another respected source mentioned that Engle cams have aggressive ramps which take advantage of the larger diameter Mopar lifter. Everyone seems to agree on LSA of between 114' and 116'.

Also is agreement on the need for blower cams to be different than turbo cams because of the reduced exhaust restriction. Appears that cams for blown engines need even less overlap because the boost is even more effective at purging the exhaust gases out of the cylinder due to the low restriction in the exhaust.

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Cheers!
Al T