black_89_vette

Current cam : Comp Cam
230/230 @ 0.050" , 0.598 with 1.6 rr, 110 LSA
2500-6000 advertised rpm range
http://www.compcams.com/Company/CC/c...?csid=181&sb=0

Cam I am interested in : Doug Herbert
240/240 @ 0.050" , 0.608 with 1.6 rr , 110 LSA
2500-6500 advertised rpm range
http://www.herbertcams.com/sbc-rolle...0lc-2500-6500/


Will this just bump hp up a touch throughout rpm range (608 lift vs. 598 lift) , and give me 500 more usable rpms giving me more hp up top as well?

I have AFR 195 Eliminators and a Pro Systems Racing carb (838 cfm) with an Edelbrock RPM Air Gap intake. The rpm range for the air gap says 1500-6500. Peak hp is currently at 5700 rpm.

I am thinking with the efficiency of the AFR heads (exhaust yielding 75 % of the intake flow) that a single pattern cam would be fine.

Anyone use or hear much about Herbert cams?

black_89_vette

THE 383 admiral

Your current springs will handle .608 with no adjustment. What about seat pressure needed between the 2 cams. What is your compression. Auto stall? Or manual. Gear ratio?
Your current peak is 5700. What are you doing. That if you changed your peak to 6500. Do you benefit. I don't think the cam will raise your current peak. Single or dual plane The herbert cam has a 285/285 adv duration. What is your current?

I almost ordered from them. They look like quality parts.

black_89_vette

MY CR is 10:1
6 speed
3.33 gear
RPM Air Gap is a dual plane.
My current cam is listed above. 230/230 , 0.598" with 1.6 rr.

Mustang dyno gave 385 rwhp / 387 rwtq (431rwhp/433rwtq Dynojet equivalent)

cardo0

Always match your cam to your compression ratio. On large cams (>280 full duration) this becomes more important. This is mostly D. Vizard doctrine as i never have run that large a cam so u can take it for what its worth. But u need run a dynamic calc for both your cams. And u need accurate numbers for compression and from the cam card to make it work right. There are plenty of DCR calcs on line so find one that u are comfortable with. I like this very simple one: http://www.wallaceracing.com/dynamic-cr.php.
U can decide for your self which cam gets u a DCR <8.8 (8.5 really) to use 91 octane fuel.
Too low and u leave power on the table. Too hi DCR and u can have detonation issues.

U can be surprised a smaller cam will produce more pwr under the full curve if the DCR is low on a larger cam. Even cams with higher max hp can be slower as the low end sags behind the smaller cam.

As for single pattern cams they work best with and unrestricted exh sys - entire sys. Only u can know what your running for headers, cats, mufflers, H or X pipe. Restricted exh sys needs like 10 extra duration but i assume your dual exh w/dual cats maybe very low restriction so a single pattern cam may work well.

Hope this helps and good luck, post your feedback.

cv67

I think youd be real dissapointed with the bigger cam and the 3.33 gear


Edit: 10:1 is a little light on compression also.

black_89_vette

I am using AFR 195 Eliminators where the exhaust is 75 % of the intake flow.
Hooker Super Comp headers 1 3/4" to 3" collectors, 3" X Pipe, full 3" mandrel bent exhaust and some Magnaflow hi flow cats 3" in and 3" out.
My exhaust is very un-restrictive.
I was also thinking about going to 4.11 gears after I try out some 1/2 mile radar runs. I was also wanting to try some 1 mile runs , if I can find any fairly close to me.

I heard something on a video where a guy was dynoing some engines with different cam swaps and he said that for every 6 degrees increase in duration, he expected to see 12 hp gain. Rule of thumb?

I just checked that calculator and got 7.77 DR. Did I do it right?

cardo0

Actually 7.7 is a very good DCR for 91 octane fuel. U can read more at: http://cochise.uia.net/pkelley2/DynamicCR.html.
But 8.5 is the max according to that link - and my previous 8.8 DCR would require race gas so let me correct that.

Yea only u would know how accurate your static compression numbers and cam numbers are. So i really cant say from over the internet whats correct. And u really need to sort this out for yourself as too many experts on the internet that goof out some numbers no matter what.

How was your current cam installed? U can advance your current cam to increase DCR but if already 4 degrees advance not a good choice. Other than that u need tighter chambers in your heads to support a larger cam. Not a big issue with AFR's as they have plenty of metal for flat mill if u choose to.

This 6* thumb rule needs to be supported with enough compression otherwise u end up with a 3 legged buffalo for the low speeds on the street.

Hope this helps.

Wheel Stander

..... I'd run 4.10s with that cam. With that much duration, you want to get the motor into the prime rpm range more quickly. Driving 3.33s on the street is going to give you a lot of cam surge and prevent the car from reaching its full potential at the track.

bjankuski

A rough rule of thumb is an extra 10 degrees of duration at .050 will add 500 more RPM to the peak RPM of the engine if the rest of the combination can support it. My opinion is your combination will be fine with the that cam. I ran a 240/240 112 LCA cam with .594 lift on my 406 and it peaked at 6250 RPM and pulled well to 6750 RPM. I also ran 3.45 gears and a 3500 RPM stall and the car ran great.

96 lt-4

You could also install it 2 degrees advanced for a little more low end if you didn't want to change gears.