blacknwhitedog

Hi, New to this board, maybe this question has been asked before, but I need some help in deciding whether to use a Summit 1103 cam
(214/224 duration at .050, with .442/.465 lift, intake closes at 34 ABDC, lobe centers of 107/117. Engine is a 350, bored .030 over with 9.1 to 1 compression, patriot vortec heads with 64 cc chambers, flat top pistons, and felpro 1094 head gasket coupled to a TH350 with 3.07 rear gears and stock converter

I am thinking of using the summit cam and installing it at 4 degrees advanced instead of straight up to gain some bottom end torque, or using the tried and true 929 cam straight up. I've used the Summit 1102 in a previous build, which worked very well....is the 1103 too much?

thanks

63mako

I would intall the 1103 straight up. About right for a 9 to 1 build. That said flat top piston, 64 cc chambers and 1094 gasket is generally closer to 10 to 1.

billla

Given the trans and gears, I would look more towards one of the CompCams "4x4" cams with additional advance ground-in.

The Summit (Elgin) cams are an "old skool" lobe design and will make less power than a comperable more agressive lobe profile.

drwet

Sounds like a nice cam for your combination. I would install it straight up as well.

gkull

I usually don't comment on cams. But your higher compression especially if you are using only two valve relief flat tops require more cam to stay out of detonation. I would advise the next larger the 1104. Just for reference the stock L-82 cam was 222/222 with I think 114 lobe centers and it was a very mild cam

Anybody that tell you to buy a Comp Cams cheap pot metal cam is not your friend. Untold numbers of flattened lobes even with the best oils. I'm one of the victims

billla

...and I'm one that's installed literally 100's of them with no issues. The cam failures (of all brands) I've personally seen (vs. just hype and internet stories) were directly attributable to extreme lifts, incorrect oil and/or incorrect valve adjustment. Just one (friendly )guy's experience

blacknwhitedog

Thanks, I'm going to re check the pistons and verify the CR. I purchased the engine kit from PAW over a year ago, and the tech told me they were going to produce around 9:1, but yeah, I had always thought that flat tops were closer to 10:1 as you stated. I'm going to recheck the valve reliefs and deck height....I like 10:1 better.

63mako

If you find your compression is higher than 9 to 1 you need more duration especially if your running modern lobes. That summit cam has slow rams so your intake closing point will be later reducing DCR compared to a modern lobe design. Intake closing point, rod length and static compression are the only factors that determine DCR.
This will help you figure out your desired intake closing point to optimize DCR on any cam. You can use the DCR calculators online and plug in your actual intake closing point then.
http://forums.corvetteforum.com/c3-t...lculation.html

dochorsepower

Don't listen to anyones opinion on what your compression ratio is, calculate it yourself. Also the vortec heads will take less spark advance than you may be accustomed to, start out very conservative. If your budget can stand it go with a hydraulic roller, you'll be glad you did later.

scottyp99

I know this is kind of an old thread, but if you haven't already installed the cam, be advised that the Summit 1103 already has 5 degrees of advance ground into it. Another 4 degrees might be a little too much, especially if it turns out that you are actually running 10:1 SCR. Download a compression calculator that will also compute Dynamic compression ratio, and crunch the numbers.


Keep the shiny side up!
Scott