fadetoblack

I am currently running a cam that I bought per Comp Cams recommendation. I have been told since that time that the cam is too 'mild'. I would like some of your opinions.

First of all, my setup consists of the following:
>383 cid 'Stroker'
>Vortec heads
>9.5 - 1 Compression Ratio
>GMPP Vortec TBI intake manifold
>Holley 670 cfm w/oem injector pod
>GM 80 lb. injectors (will be replacing with 90 lb. injectors in near future)
>255 l/hr fuel pump
>VAFPR w/ Vaccum Delay Valve
>SLP headers
>GMMG exhaust (near future)
>Pro-Built 700R4 w/2200-2400 rpm stall converter
>3.73 Rear Axle Ratio
>EBL computer (near future)

The specs of the cam that I am currently running are:
>Comp Cams part # 12-262-4
>Grind # CSXE262H-14
>Gross Valve Lift: Intake - 0.464, Exhaust - 0.47
>Duration At 0.006 Tappet Lift: Intake - 262, Exhaust - 270
>Valve Timing At 0.006
Intake: Open - 21, Close - 61
Exhaust: Open - 73, Close - 17
>Duration At 0.050: Intake - 218, Exhaust - 224
>Lobe Lift: Intake - 0.309, Exhaust - 0.313
>Lobe Separation: 114

Okay, what do you guys think? Did Comp Cams sell me something too mild? My goal is to get as close as possible to 400hp.

BTW, I do use the car as a 'semi' daily driver.

As always, thanks in advance for any and all of your help!

Fast355

iTrader: (2)

I would go Extreme Energy 274 if it were my 383. I am assuming this is going into an F-Body.

PS- NO reason to go to the 90# injectors. Crank the pressure on the 80# a little and you will be there. I made somewhere around 375 FWHP @ 6,500 with 68 lb/hr injectors and HIGH fuel pressure.



My old 312 only pulled 12 in/hg of vacuum at idle, but once tuned the EBL was fine with it. Idled with a slightly choppy exhaust note @ a steady 700 RPM

fadetoblack

Thanks for the suggestion.

Yes, BTW, it is going in an F-Body. I have a 1990 Firebird Formula.

I forgot to mention earlier that the reason I was given for the mild recommendation from Comp Cams was a lack of vacuum with anything stronger.

Any more thoughts?

Fast355

iTrader: (2)

That is a lame excuse on their part. You can dial in a bigger cam with EFI, easier than a bigger cam with a carb. I have tuned engines with factory speed density TPI ecms that only pull 5-8 in/hg @ 800 rpm.

BTW, here is the DD2000 estimate for you beast w/ XE274 cam.

fadetoblack

Thanks again Fast355!

Anybody else?

Dominic Sorresso

I agree with Fast about being able to tune a larger cam for better idle vacuum. My motor is a 350 with a CompCams HydRoller. Specs are
218/218 @ .050 with a .528" lift. Even with a 108LCA, it idles at about 46kPa and 875-900rpm

Buccaneer

Fast355...It looks like you are using EBL which is what I'm currently looking at in combination to my 8746 with a Prominator. Is the EBL easy to use? It looks like from what I've seen and read so far, it's an extremely useful tool on a non-stock motor.

I have a 360cid, 2"TBI w/66lbhr injectors @20psi which is flowing about 85lbhr. Using a comp cam custom grind, ceramic headers w/true duals all the way back, X-Ram, Dart Pro1 180cc/64cc heads, 1.6 roller rockers, 2,200 ATI stall and a few other goodies. It's all on a 82 corvette crossfire.

I just want some good feedback on this EBL mod and wonder how much more I can squeeze out of the motor by using it (realistically). Thanks in advance for any info from you or anyone else.

fadetoblack

I really appreciate the people who have already offered their help.

THANK YOU!

Does anyone else have any suggestions? Or, do you agree or disagree with the suggestions provided above? I just want to get as much advice as possible before I spend my money again. The last time, I only listened to one guy's opinion (tech guy at Comp Cams) and apparently he helped me to waste a lot of money.

To the guys above (ESPECIALLY Fast355), please do not be offended. I hope you understand that I'm just a little gun shy about this. I'm sure that you understand that a bunch of people agreeing to the same thing is obviously more reassuring than just one suggestion. Thanks, again!

BMmonteSS

I don't think the guys at comp were too far off, sure you'll make more power with a bigger cam, but I'm not exactly sure it would be worth the expense and hassle of swapping the cam. If that last 10-20HP (at the sacrifice of the same amount of torque) is worth it to you then do it. I personally tend to err on the side of too small, it makes for a better street motor. Your in that "grey" area where a bigger cam will make more power, but not so much that it's a "must have".

You didn't mention how much experience you had tuning, if you've never tuned before it might be a good idea to learn on the mild cam and then step up down the road if you feel the need. Didn't mean to throw a wrench into the fan here, just thought another point of view might help you get an idea of what the cam will and won't do for you.

Fast, care to run the cam he has now through DD? I'd like to see how much of a trade of torque for HP is invovled.

Fast355

iTrader: (2)

The 114* lobe seperation is just too wide. The XE-274 in a 383 will act similar to a 268 in a 350. The 110* lobe seperation will give much more overall power. Around 10 ft/lbs at the very bottem sacrificed for 30 HP up top. The 274 pulls the lead by 3,500 RPM.

There is no funny business in these, they have the same long-block, just the cam is switched. Both are seat-seat specs, straight from comps catalog.

BMmonteSS

Ahhh, cool. Exactly what I was wanting to see, guess my air dyno guestimate was a little off.

fadetoblack

I have asked other places about this, also. Only one person said anything about the 'lack of vacuum' issue. He said that the larger cam may cause a reduction in the responsiveness of the braking system. Any comments on this?

flaming-ford

iTrader: (7)

Which means a slight lack of vaccum. Less vaccum = less brake booster help, in otherwords you won't have power brake if you go to to big. Although i wouldn't worry about it with those cams. + Their are quite a few cheap and easy ways around low vaccum in the brakes category.

Dominic Sorresso

fadetoblack,

I had a CompCams HR264 cam wih bigger numbers than that and no issue with vacuum and brakes.

91RockS

Dominic,

Did you by chance read the recent CHP 383 cam article. I don't have the issue with me, but I think it was the June or July issue. Anyway, they tested 6 cams on a 383. Three were single pattern, three were dual pattern. Comprehensive dyno data was inclded for all six. Each set of cams were increasingly more agressive. I think you will find it very informative. It really boils down to how you want to drive the car. Steet, street/strip, strip only, which will result in tradeoffs between low end torque and high end hp.

Take a look around on the CHP website. If you don't find it, I can scan the article and send it to you.