Thread: Question on Lobe Seperation.....

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....I'm confussed, I read some info on how lobe seperation effects Tq. & HP & I still don't understand. So if I go with a cam with 108 lobe seperation {instead of 110} will I lose any low end TQ???? Thanks everyone Bill

....ah ha, Thank You Denny ... So on a street machine w/ a low stall converter this would not be a good thing to do??? I'll stick with the 110 degree seperation then..... Thanks again, Bill

Your compression is more due to the point of intake valve closure. On a tighter LSA, you will have more dynamic compression unless you retard the cam. Most are advanced. Here's a decent link to some Cam Tech.

On a 110 vs. 108 with same cam duration, power band will change about 300 RPM meaning it will come in 300 later and leave 300 sooner but will make more torque in the usable power band especially with handicapped heads, but you need a free flowing exhaust with the tighter LSA because it doesn't have the additional cylinder blow down that a wide LSA will provide with an earlier opening exhaust valve.

Originally Posted by DennyW

He was talking only lobe center line. I assumed the cam lift specs to be the same.

He's talking lobe separation angle. Cam lift doesn't matter, although duration would. All specs identical, if you had a cam on a 110 lobe separation installed at 110 intake centerline, it would have less compression than a 108 lobe separation installed at 108 centerline. If you advanced the 110 LSA cam 4* to a 106 installed center line (ICL), the 110 LSA cam would have more compression.

I agree totally. That link I left above explained it real simple with the terminology and towards the bottom it explains what happens when certain specs are changed.

...Thank You .... Ok, so tightening the lobe seperation from 110 to 108; 1) increases TQ. 2) narrows the power band 3) brings the TQ. in at a higher RPM..... Good article, I think I've sort a got it..... Bill

Bill,both Denny & camaro fever68 know more than I do but I'll add one more note.LSA doesn't necessarily have such a 'hardfast' rule.But they are both correct.You in fact can have a tight LSA and yet the cam be ground as though it is a wide LSA. I only mention this because if this is someones reasoning in cam selection they better be sure and study all the characteristics of the cam or it won't be what they wanted,there are plenty of 'odd' ground cams on the market.

....hummm, Ok, Thanks for adding that ... Yeah, in looking at the different cam manufactures web sites I noticed that alot of the 108 lobe sepertion cams were for {as they called it} 'special applications'. 108's that are installed + 4 degrees that make them a 104, etc. etc. etc.... Seemed like a lot of the oval track cams were ground at 108 & it would say "these cams can be used for other purposes also".... But anyway, I've decided to go with a cam that is ground on 110 seperation & split duration.... Thanks again Bill

maybe a bit late but 105-108 is peaky 110 i think may work better for you hard to say what do you want to do ?

Originally Posted by pat mccarthy

maybe a bit late but 105-108 is peaky 110 i think may work better for you hard to say what do you want to do ?

....Pat, as s-l-o-w as I am to getting around to getting things done your NEVER to late to give advice .... Thank you for the imput & yes I am going with a 110 lobe seperation cam..... What I am doing is trying to pick up more HP in a motor that had to small a cam before.... 413 cubic inch small block, AFR 195 heads, 10 to 1 compression, 1 5/8" headers, 750 double pumper, Performer RPM air gap manafold. Used to have a cam that was {forgot exactly} but either 222 or 224 intake duration, 232 or 234 exhaust, lift around 510/515 with 1.6 rockers. It put out 499 Ft. Lb's @ 4000 & 438 HP @ 5200.... It is now going into a 2500 pound car {'32 Ford}, turbo 400 trans {trans brake}, 10" converter w/ 2200 to 2500 stall, 9" rear { 3.00's but I'll change to lower gears}, will use 10" to 12" wide tires..... Anyway, last guy who built the motor said that it could use a bigger cam, would put out more HP & probably not even lose any TQ.... So just want to pick up some more HP,...... Thanks, Bill
Oh, street/strip car..... mostly street.....

well the car this light you may want to run the 106-108 lsa the stall will work better and you have to watch out for the dur or you will need more stall if you go up to to much gear to you will need more stall to . if you want more power get them headers off and go to 1 7/8 and here is are some cam that you may like520/520 251/261 lsa106 howards #11752 stump puller soild or 500/510235/240 112 lsa hyd#112601 they very a bit but this would be what you do more on the street maybe the last one . on for the track the 106

Originally Posted by pat mccarthy

well the car this light you may want to run the 106-108 lsa the stall will work better and you have to watch out for the dur or you will need more stall if you go up to to much gear to you will need more stall to . if you want more power get them headers off and go to 1 7/8 and here is are some cam that you may like520/520 251/261 lsa106 howards #11752 stump puller soild or 500/510235/240 112 lsa hyd#112601 they very a bit but this would be what you do more on the street maybe the last one . on for the track the 106

....Thank You Pat, Ok, I'm going to check these cams out. I'm limited for now on the headers as I've already bought some Sanderson 1 5/8" headers for the car. They didn't have them in a larger size & I didn't know of anyone else that made then that large for a '32 Ford {may be custom ones later on, but I want to get the car going with what I have for now}. I absolutly don't want to have to get a different converter {at least not now}. The one I have was like $600 plus 10 years ago. A good one, just not that high of a stall. In fact, my car is mostly street, when I say strip it's not as if it'll actually ever even see a strip. I just want it to be fast for when I go out in the country to impress myself... Well, I live in the country & I like to impress myself OFTEN ..... Thanks again Pat..... Bill

Pat's recommendation is what I am setting here looking at that a guy by the name of David Vizard suggests,ever hear of him? Some consider him the be the 'guru' of cam.Mr. Vizard's book suggests a tighter LSA per 'more-cubic-inch.But that may be for max performance motors? I certainly can't speak for him,just trying to pass on info.

Originally Posted by DennyW

Do I smell Nitro, and alcohol in the air ? He did say streetable.

thats is the smell of victory

Na,,,,thats an old timers trick,,,a cool can by the drivers seat for your Bud(alcohol smell) gas doesn't run thru it unless it's a mobile shinestill .Just don't let Tech see it,,,where is he anyway,havn't seen a post by him for a while?