[Johnny406]

I picked up a Summit 2802 for my T/A to replace the XE274 I'm currently running since I added the centrifical supercharger/belt driven turbo. I chose this cam for a few reasons, mainly because I want this engine and the unported 96 heads on it to go into my red 81 T/A naturally aspirated. I'm going to race it this year in the black 78 T/A with the "air pump."

I learned how to degree in a cam and will do so with this one to verify the cam card. My big question is, should it be installed advanced, backed off, or as recommended (12 o'clock dots) if the cam was ground correctly?

Thank you!!

[Johnny406]

Summit Racing Part Number SUM-2802

Cam Style Hydraulic flat tappet
Basic Operating RPM Range 2,500-5,000
Intake Duration at 050 inch Lift 224
Exhaust Duration at 050 inch Lift 234
Duration at 050 inch Lift 224 int./234 exh.
Advertised Intake Duration 282
Advertised Exhaust Duration 292
Advertised Duration 282 int./292 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.465 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.488 in.
Valve Lift with Factory Rocker Arm Ratio 0.465 int./0.488 exh. lift
Lobe Separation (degrees) 114

[baron_]

I wasn't terribly impressed with the summit 2802 (you probably don't want to hear that)
I've got it in my car now...


About to be replaced with a custom cam

[6D6GOAT]

im running my 2802 straight up for what its worth.

[BruceWilkie]

111.5 degree intake centerline would give you equal intake opening to exhaust closing during overlap. Advancing to 109-110 might help low end some as that closes the intake sooner and gives more degrees in compression. Unfortunately doing so opens the exhaust too early and you lose combustion efficiency. (opens the valve before piston hits peak velocity, and without looking thats usually between 71 and 74 degrees atdc) However that also empty's the cylinder sooner leaving less residual exhaust on the upsweep cutting pumping losses and allows a later opening intake. But then this cam having so much exhaust duration closes the exhaust valve a tid late and the intake opens too early and still closes late. Ok with your centrifugal at higher speeds but I dont like this cam overall for your combo. TOO MUCH SEAT TIME.

I thought you had a 60916 Crower? If so I like it better than the 2802. Its not perfect but a better choice IMO than the Summit. The Comp 268 XFI series or similar in a solid might be a better way to go. It will help replace low end lost to low compression yet still be able to carry powerband rpm further than NA when boosted. The xfi series are asymetrical and ground on 113 LSA with suggested 109 ICL ground in. With different open and close ramps the cam will behave differently than the numbers look. Comp might suggest something slightly different if they have enough info on a custom grind but I suspect it will be close.

IMO the 2802 is not a good cam for a low compression motor that wont see significant boost at low to medium speeds. Its at best a good cam for a 10:1 + compression street motor trying to run on 91 octane fuel. The late intake closing leaves less degrees in compression lowering compression pressure! The 114 LSA cuts overlap helping to tame the idle quality of the big duration split. NA they usually are done making power around 5000 rpm.

Just my 2 cents!

[Johnny406]

Originally Posted by BruceWilkie

111.5 degree intake centerline would give you equal intake opening to exhaust closing during overlap. Advancing to 109-110 might help low end some as that closes the intake sooner and gives more degrees in compression. Unfortunately doing so opens the exhaust too early and you lose combustion efficiency. (opens the valve before piston hits peak velocity, and without looking thats usually between 71 and 74 degrees atdc) However that also empty's the cylinder sooner leaving less residual exhaust on the upsweep cutting pumping losses and allows a later opening intake. But then this cam having so much exhaust duration closes the valve a tid late. Ok with your centrifugal at higher speeds but I dont like this cam overall for your combo. TOO MUCH SEAT TIME.

I thought you had a 60916 Crower? If so I like it better than the 2802. Its not perfect but a better choice IMO than the Summit. The Comp 268 XFI series or similar in a solid might be a better way to go. It will help replace low end lost to low compression yet still be able to carry powerband rpm further than NA when boosted. The xfi series are asymetrical and ground on 113 LSA with suggested 109 ICL ground in. With different open and close ramps the cam will behave differently than the numbers look. Comp might suggest something slightly different if they have enough info on a custom grind but I suspect it will be close.

IMO the 2802 is not a good cam for a low compression motor that wont see significant boost at low to medium speeds. Its at best a good cam for a 10:1 + compression street motor trying to run on 91 octane fuel. NA they usually are done making power around 5000 rpm.

Just my 2 cents!

Thanks you for your input Bruce. I have never owned a Crower cam (yet), I am looking for a cam to replace the XE274 I am currently running.

[baron_]

Bruce describes what I see in my 2802

Not very good for a low compression motor
It works....and works substantially better than a stock, low comp cam...
But there are other options that work much better.....if you're going to be adding a cam

[Johnny406]

Should I just leave the XE 274 in it?

[Johnny406]

What do you guys think of this cam?

INTAKE EXHAUST

DURATION .050: 224 234

LOBE LIFT: .310 .325

LOBE SEPARATION: 107 117

ADVERTISED DURATION: 301 313

GROSS VALVE LIFT: 480 480

[Johnny406]

P-Dude set me straight....THANKS KEN!!

[Tom Vaught]

Originally Posted by Johnny406

P-Dude set me straight....THANKS KEN!!

So what did he whisper in your ear vs supplying the info to everyone on the board?

Tom Vaught

[Johnny406]

Originally Posted by Tom Vaught

So what did he whisper in your ear vs supplying the info to everyone on the board?

Tom Vaught

I called him yesterday and he recommended a Comp grind based off a SBC 268AH-14

Duration: 222/226 @.050 .464 lift w/ 1.5 rockers.

[Tom Vaught]

Did he tell you why?

The lobe separation is 2 degrees more on the Chebby grind. (112 vs 114)

The other camshaft is a slightly higher lift camshaft, (.025" more for the Pontiac cam)

The duration is within 2 degrees at .050 of the exhaust. You have a supercharger, not a turbo so typically you need more exhaust duration vs intake duration to clear out the clyinder for the next event. The first cam gave you that extra duration.

You sure you did not confuse him with your "belt driven Turbo" discription of your supercharger?

Tom Vaught

One other comment on your deal. A company called Powerdyne (run by my buddy Jim Wheeler) for years offered a supercharger with a internal belt step-up vs a gear step-up in the supercharger. The unit was fine up to about 9 psi and then the belt would fail from the S/C drive loads conbined with the heat generated by the system lowering the strength of the belt trapped inside the S/C housing. A 15 degree increase in ambient heat around the belt will lower the belt strength by 30%.

In your case you system has an exposed second "step-up belt" so that is not an issue.

[62fatcat]

jony406,
i have used the crane blueprint of the ra4. 308/320 seat duration with thw 113.9 lobe seperation.
it worked great, ran some 9.75's with it with tthe old p600 blower and a a/a intercooler boost was about 12#.

when my younger brother was wanting to play with a nos kity he gaot wat back when he had a 350 sb chevy. he asked me about what cam so i looked all the old hipo factories, and i think it was the 35ohp 327" cam i recomended because it had the widest lobe seperation. i think it was 113 or something
funny story we were tunning the carb on the road and the tranny lost 2and gear. he was so upset that he was not going to get to use hi new nos kit as it was 2 hours before we went to the track. i got in and it would go from 1-3 gear if you just shifted it quickley. long shory short, we went to the track, car ran 13.95 best all day. last run i told him to hit the button and just pull the gears as fast as possible.(175hpn2o jets)
he gets back to the pits, falls out of the car shaking and said "YOU DIDN'T TELL ME IT WAS GOING TO DO THAT". IT RAN A 11.75 @ with a ton of mph.
he had never driven anything on the track that was quicker than a 13.3 car.
i will never forget, as it was one of the funiest things i had ever seen.