what is your cam's overlap degree?!

[SilverMachine]

Hey guys, just wanting to know what your cam overlap degree was. my cam that will be installed next week will have around 7 degree @50 and 61 or 62 advertised overlap (they call it SEAT overlap or something similar?)
just wanting to know what to expect with this mild cam....i know its a smaller cam with 223/223@ 50 and 108 LSA w/277 duration...501/501 lift. i want a little rumble to my DD!! haha with flowmaster 10's dumped before the axle hehe

[Jake Wade]

That's not really a mild cam, for the street anyway, and especially if 350 cubes.

It will for sure talk to you.

around 50 degrees overlap is a good target for 350 cubes and good street manners, stock/low stall converter, etc. That's just me, some people can tolerate a lot more.

[53chevyforever]

Originally Posted by Jake Wade

That's not really a mild cam, for the street anyway, and especially if 350 cubes.

It will for sure talk to you.

around 50 degrees overlap is a good target for 350 cubes and good street manners, stock/low stall converter, etc. That's just me, some people can tolerate a lot more.

With that big of a cam you won't have much vacuum...prob around 12 inches at idle...also if your engine is low compression even worse......not good for power brakes...not good for staying running with a stock converter and air conditioning. I would call one of the cam suppliers and pick something a little smaller...

[SilverMachine]

Yeah. I've done a lot to the truck to get it ready for this. 3.73 gears with positraction diff..new torque converter higher stall of course, aluminum heads. The compression will be probably the middle of the road 9:5 or so with 64cc chambers and .0015 felpro 1094 gaskets. I hope this works out! I want it to be beefy but maintain decent performance at the same time!

[SkinnyG]

My cam has 14°@050, 68° calculated off advertised duration. It idles at 8inHg in gear, but still somehow runs brakes adequately. Not really a good "truck" cam, but I love it.

[SilverMachine]

Hey Skinny, I've been wondering..what does your brakes actually feel like if you have less vacuum? Is it supposed to work but you just push down the brake pedal more or what? I don't understand what would be the difference, other than the brakes either working or not working at all.

[DieselSJ]

Originally Posted by SilverMachine

Yeah. I've done a lot to the truck to get it ready for this. 3.73 gears with positraction diff..new torque converter higher stall of course, aluminum heads. The compression will be probably the middle of the road 9:5 or so with 64cc chambers and .0015 felpro 1094 gaskets. I hope this works out! I want it to be beefy but maintain decent performance at the same time!

That cam would do worlds better with about a 10:1 static comp ratio. IMHO, 9.5 is low with aluminum heads also.

[SilverMachine]

Diesel, is there anyway I can up my compression without having to change pistons at this point? And yeah I would like higher compression but where I live the highest octane around is 89 non ethanol. So I try to run that without having to use octane boosters.

[SkinnyG]

I'm at 10.9:1 with iron heads, and it's working on 91 just fine.

You could bump the compression more by milling the heads, but I think you'll be ok for now. If the bottom goes soft, change the pistons at that time.

The cam you picked has an Intake Center line of 104°, which means it's advanced 4°, which is good for low end torque and building cylinder pressure (sort of makes up for the lower compression ratio you have). You'll probably be ok. It has an RPM range of 1700-5700 which is very decent for street/performance/truck. Your 3.73 gears put you right in that cam's happy place. The 108° Lobe Separation Angle gives you a strong but more peaky mid range, at the expense of idle quality and vacuum.

When you don't have enough vacuum to run the power brakes, it just takes MORE pedal effort to slow down. An extreme example: zero vacuum when the engine is off and you're trying to use the brakes.

I've driven some cars where the cam was so big, the power brakes did nothing at a stop light - it took a phenomenal amount of pedal effort just to stay still.

Adding a vacuum canister just increases the volume of available vacuum before you run out at a stop light.

By cam is bigger than yours, and my brakes are certainly adequate - you'll be fine.

[SilverMachine]

OK cool! That makes me feel better thanks! Can't wait till next week haha. Edit: why does this have a red thumbs down before reply haha

[Jay2Cor517]

I run a CompCams Magnum hydraulic-roller (p/n 12-420-8). It has listed specs of 270/215@0.5 lift, 110* Lobe Seperation. I honestly get compliments on the sound everywhere I go. The lower the RPM the better it sounds but I leave idle set at 750-800. I love this thing.

[SkinnyG]

Jay, any comment on the cam's affect on power brakes, and are you using the stock torque converter?

[Jay2Cor517]

Originally Posted by SkinnyG

Jay, any comment on the cam's affect on power brakes, and are you using the stock torque converter?

SkinnyG, I have no power brake problems. It runs right at 15" Hg Mercury (vacuum). It's been a while since I bought the tranny, but I think it has a 2700 stall converter-just a little bit more than stock. The engine is a Gen I SBC 355 with stock iron 487 heads, maybe cleaned up a little. This is a crate motor I bought off eBay.

[Jake Wade]

Originally Posted by Jay2Cor517

I run a CompCams Magnum hydraulic-roller (p/n 12-420-8). It has listed specs of 270/215@0.5 lift, 110* Lobe Seperation. I honestly get compliments on the sound everywhere I go. The lower the RPM the better it sounds but I leave idle set at 750-800. I love this thing.

That is a nice camshaft. Ran one in a 9.5:1 383 with a 700R4 and 3.73's. Good all around. 50º overlap on the button.