Help with cam ID / roller or flat tappet?

General engine tech -- Drag Racing to Circle Track

Moderator: Team

HillClimbCamaro89
New Member
New Member
Posts: 10
Joined: Fri Apr 15, 2022 2:25 pm
Location: PA

Help with cam ID / roller or flat tappet?

Post by HillClimbCamaro89 »

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
20220415_135858.jpg
20220415_135855.jpg
20220415_135633.jpg
20220415_135628.jpg
20220411_184420.jpg
You do not have the required permissions to view the files attached to this post.
HillClimbCamaro89
New Member
New Member
Posts: 10
Joined: Fri Apr 15, 2022 2:25 pm
Location: PA

Re: Help with cam ID / roller or flat tappet?

Post by HillClimbCamaro89 »

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.
BillK
Guru
Guru
Posts: 1745
Joined: Wed Aug 26, 2009 8:30 pm
Location: Beautiful Southern Maryland
Contact:

Re: Help with cam ID / roller or flat tappet?

Post by BillK »

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
6.50camaro
HotPass
HotPass
Posts: 594
Joined: Sun Jul 30, 2017 2:24 pm
Location: Summer Shade, Ky

Re: Help with cam ID / roller or flat tappet?

Post by 6.50camaro »

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 .
sjre
Member
Member
Posts: 120
Joined: Sun Nov 23, 2014 9:38 am
Location:

Re: Help with cam ID / roller or flat tappet?

Post by sjre »

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 ?
PackardV8
Guru
Guru
Posts: 7619
Joined: Sun Jul 30, 2006 2:03 pm
Location: Spokane, WA

Re: Help with cam ID / roller or flat tappet?

Post by PackardV8 »

sjre wrote: Fri Apr 15, 2022 4:26 pmWere not the original roller cams just cast cores ?
Yes, back in the day of 250# springs and .300" lobe lift.
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
F-BIRD'88
Guru
Guru
Posts: 9802
Joined: Tue Mar 27, 2007 6:56 pm
Location: Ontario, Canada

Re: Help with cam ID / roller or flat tappet?

Post by F-BIRD'88 »

HiLLbIlLy DIY rOllEr
User avatar
Tom68
HotPass
HotPass
Posts: 2541
Joined: Mon Feb 07, 2022 3:43 am
Location: VIC OZ

Re: Help with cam ID / roller or flat tappet?

Post by Tom68 »

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.
Ignorance leads to confidence more often than knowledge does.
Nah, I'm not leaving myself out of the ignorant brigade....at times.
1980RS
Guru
Guru
Posts: 1636
Joined: Thu Oct 13, 2016 10:03 am
Location:

Re: Help with cam ID / roller or flat tappet?

Post by 1980RS »

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.
HillClimbCamaro89
New Member
New Member
Posts: 10
Joined: Fri Apr 15, 2022 2:25 pm
Location: PA

Re: Help with cam ID / roller or flat tappet?

Post by HillClimbCamaro89 »

BillK wrote: Fri Apr 15, 2022 3:19 pm Any number on the back side ? Can you tell if there is any taper on the lobes ?
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.
HillClimbCamaro89
New Member
New Member
Posts: 10
Joined: Fri Apr 15, 2022 2:25 pm
Location: PA

Re: Help with cam ID / roller or flat tappet?

Post by HillClimbCamaro89 »

:lol:
F-BIRD'88 wrote: Fri Apr 15, 2022 5:17 pm HiLLbIlLy DIY rOllEr
HillClimbCamaro89
New Member
New Member
Posts: 10
Joined: Fri Apr 15, 2022 2:25 pm
Location: PA

Re: Help with cam ID / roller or flat tappet?

Post by HillClimbCamaro89 »

Tom68 wrote: Fri Apr 15, 2022 5:20 pm 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.
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.
HillClimbCamaro89
New Member
New Member
Posts: 10
Joined: Fri Apr 15, 2022 2:25 pm
Location: PA

Re: Help with cam ID / roller or flat tappet?

Post by HillClimbCamaro89 »

1980RS wrote: Fri Apr 15, 2022 6:00 pm 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.
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.
HillClimbCamaro89
New Member
New Member
Posts: 10
Joined: Fri Apr 15, 2022 2:25 pm
Location: PA

Re: Help with cam ID / roller or flat tappet?

Post by HillClimbCamaro89 »

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?
HillClimbCamaro89
New Member
New Member
Posts: 10
Joined: Fri Apr 15, 2022 2:25 pm
Location: PA

Re: Help with cam ID / roller or flat tappet?

Post by HillClimbCamaro89 »

Tom68 wrote: Fri Apr 15, 2022 5:20 pm 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.
Tom do you think you could explain a little bit of area under the lift curve? Would that be because of the ramp differences ?
Post Reply