Help with cam ID / roller or flat tappet?
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Help with cam ID / roller or flat tappet?
Hello guys, first time poster and I hope someone more knowledgeable than me can help me out. Long story short is I traded a guy a few years back for his northeast dirt modified. I proceeded to sell the roller and keep the 358 sbc to put in a street stock camaro. I run SCCA hill climb events in northeast PA with it.
I ran it last season at 3 events. This week a friend gave me a gear drive timing set so I was installing that when I said while I'm in here I mind as well see what cam shaft is in it. I was setting lash at 0.018 and 0.020 as a guess.
Now the cam shaft has a grind ID of Comp Cams CS 284BTL-6 which when I look it up is a number for a mechanical flat tappet cam. I find this really weird because the engine has crane solid rollers in it. I don't think it would of ran those events last season without a major failure of the cam if it was a flat tappet cam with rollers. Or am I wrong?
Here is the summit link. https://www.summitracing.com/parts/cca-12-505-5
Here are some pictures of the cam. As far as I can tell the lobes look like roller lobes. Maybe someone had it custom ground with the flat tappet specs? I'm lost here.
Any help would be awesome.
Attached are some pictures
I ran it last season at 3 events. This week a friend gave me a gear drive timing set so I was installing that when I said while I'm in here I mind as well see what cam shaft is in it. I was setting lash at 0.018 and 0.020 as a guess.
Now the cam shaft has a grind ID of Comp Cams CS 284BTL-6 which when I look it up is a number for a mechanical flat tappet cam. I find this really weird because the engine has crane solid rollers in it. I don't think it would of ran those events last season without a major failure of the cam if it was a flat tappet cam with rollers. Or am I wrong?
Here is the summit link. https://www.summitracing.com/parts/cca-12-505-5
Here are some pictures of the cam. As far as I can tell the lobes look like roller lobes. Maybe someone had it custom ground with the flat tappet specs? I'm lost here.
Any help would be awesome.
Attached are some pictures
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Re: Help with cam ID / roller or flat tappet?
Also I should mention that the car wouldn't rev past 5500 RPM when racing. I don't know if that's because of the crappy Chinese HEI distributor or what. Trans is a TH350 that I shift manually.
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Re: Help with cam ID / roller or flat tappet?
Any number on the back side ? Can you tell if there is any taper on the lobes ?
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
www.enginerepairshop.com
Advanced Automotive Machine
Waldorf Md
www.enginerepairshop.com
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Re: Help with cam ID / roller or flat tappet?
It sure looks like a flat tappet to me. The lobe profile, cast core and wear pattern is not what I'd expect to see for a solid roller cam .
Re: Help with cam ID / roller or flat tappet?
Sure looks like a flat tappet . Ive heard of some people actually using rollers on flat tappet cams never heard results but I can only cringe at the thought ! But it actually looks not too bad .Were not the original roller cams just cast cores ?
Re: Help with cam ID / roller or flat tappet?
Yes, back in the day of 250# springs and .300" lobe lift.
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
Studebaker-Packard V8 Limited
Obsolete Engineering
Re: Help with cam ID / roller or flat tappet?
I guess it's lasted because the valve spring rates aren't too high ?
Area under the lift curve would be abysmal. Race cam idle, Race cam lift, but no top end power.
Area under the lift curve would be abysmal. Race cam idle, Race cam lift, but no top end power.
Ignorance leads to confidence more often than knowledge does.
Nah, I'm not leaving myself out of the ignorant brigade....at times.
Nah, I'm not leaving myself out of the ignorant brigade....at times.
Re: Help with cam ID / roller or flat tappet?
That's a flat tappet cam. I would use an Elgin 1090P cam instead of the com cam. Makes explosive power and cost a lot less.
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Re: Help with cam ID / roller or flat tappet?
Thanks for the response. Only number on the back is 284. I measured the lobes with a mic and it does not appear to have any taper. Weird.
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Re: Help with cam ID / roller or flat tappet?
Hi Tom. Yes sounds about right. It sounds nasty at idle but it is kind of a dog. I have a modded ls1 Camaro and it pulls so much harder than the small block. Obviously I didn't expect LS power it is a pretty drastic difference. Also when using a timing light with the distributor locked out it would retard timing as I reved it. Thats what led me to putting the geared timing set in, I thought the chain was stretched.
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Re: Help with cam ID / roller or flat tappet?
Thanks I will look into it. I will most likely go with a solid flat tappet package from summit. I don't have the money for a roller cam right now. Plus if I want to go dirt racing I will be legal.
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Re: Help with cam ID / roller or flat tappet?
Well from what you all have said it seems like my problem with it falling flat at 5500 looks like its from this cam issue. I can't afford a roller cam right now so I will order a cam and lifters and push rods from summit. Has anyone used the CT106K Summit cam?
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Re: Help with cam ID / roller or flat tappet?
Tom do you think you could explain a little bit of area under the lift curve? Would that be because of the ramp differences ?