Over the past month i have read true most of the P2V post, degreeing cams, v2v post ,etc
and in doing so i seem to realise a few trends, and i guess that me posting would help comfirm them and also help those out there that are ignorant and desire the little knowledge to help them get by. SO i would like to compile most of the FAQs and myths in one post so it is easier.

In my research i have seen that stock lobe centers are 98-103* IN 103-106* EX,
I have also noticed that most guys that run bid aftermarket cams with lobe centers 103+ IN and 106+ exhaust, ONCE dialed in correct run something like 0 - +3IN and +2- +4 EX. Very rear have i seen cam gears in the "-ve" numbers. Is this common?

i have only ever dialed or help dialed in 2-3 sets of cams, Pro2 in my friends GSR and we got +1+3, Buddy Club Spec 4 in my old GSR and i got +2, 0 , and recently i did my B20Vtec with M24xx cams and got +1-3 ( wanna recheck that, i dont trust the dial gauge i was using), so by no means am i an expert with dialing cams. Any thoughts on the settings for my M24xx? Lobe centers for those are 102 IN 110 EX, stock deck and head heights.?

I have seen someone once say subtracting the lobe centers would give you an idea of where to start (not that it is exact but a rough idea). Is this true?

I am not gonna go tru where P2V and V2V occurs cuz "1 2 NV" has a great post on how to check these home with relative ease and patience. How ever most big Cams , Pro2 , Pro3 , Rocket M22, Rocket M24, Blox, Buddy Club, all of these seem to like no more than 3-4* lobe seperation, meaning ( for the ignorant) dont have you cams set at 0,+5 or -3, +2. once again after tons of reading i am pretty sure this one is correct.

anything else?

 

Stock VTEC cam lobe centres are 98* ATDC for the intake cam and 103* BTDC for the exhaust cam.

If aftermarket cams are intalled with the cam gears set to 0-0, the cams will be installed at the same factory centerlines as stock. The cam cards supplied with the cams will tell you where the cams need to be set for their centerlines when degreeing etc. For example: Skunk2 Pro2's 99* ATDC for the intake cam and 106* BTDC for the exhaust cam, are where they should be set at, before tuning begins. You can either degree them in (ideal situation) or you can use some simple math to figure out roughly where that is on the cam gears.

Remember how cam timing events operate on a 4-stroke engine, and we can determine that you will be -1* on the intake cam (98* retarded -1 degree = 99* ATDC) and +3* on the exhaust cam (103* + 3 degrees advance = 106* BTDC). Your actual cam timing may be off by +/- 1-2* (sometimes even more) depending on your deck height, any milling of the cylinder head, and headgasket thickness. But it gives you a good starting point."

As for your M24xx cams, using this math, it would work out to be -4 Intake (crank degrees) and +7 degrees on the exhaust cam as your starting point (assuming there's no milling or decking and a stock 3 layer head gasket is being used). I would be concerned about V2V clearance with those cams and those settings so you'd want to check before you install them.

All cams are going to generally work within a similar range of lobe centers and seperations, the key is to finding what cam gear settings work for your exact motor and setup which is why testing/tuning and clearance checking must be done. For reference I could run my cams M22x at either of the settings you say to never use and I wouldn't have any problems. I might not make as much power but cam settings depend on so much more than a "basic range of adjustment".

A general note on the above degree settings: All degrees discussed are in crank degrees. The cams rotate at 1/2 the RPM as the crank so if you have cam gears that are marked and adjusted in cam degrees, you'd have to adjust accordingly. For example, the M24xx cam settings I listed above -4 intake and +7 exhaust would actually be -2 intake and +3.5 exhaust in cam degrees. This is very important to keep in mind. The pro 2 settings would have been -1/2 a degree on the intake and +2 on the exhaust in cam degrees.

 

I used the method that "1 2 NV" used to check my v2v , and they came out that anywhere over 3* seperation i get < 0.030.

for the M24xx the lobe centers are 102 IN and 110EX (think you read it wrong) , so with what you are saying then it would be :

98*ATDC - 4 = 102
106*BTDC + 4 = 110

so using my Skunk 2 Pro-Series Cam gears that puts me at -4 crank degree on the Intake side and +4 on the Exhaust side = -2 on the Intake cam gear and +2 on the Exhaust cam gear. Did i do that correct?
but then i dialed in my cam i got +1 -3 which is the other side . did i do something wrong?

 

I have altered my post above to correct a couple things that I found to be incorrect. I still dont like the settings I come up with for the M24xx cams but for all I know, the V2V may be ok on them with those settings where they wouldn't be on a set of Pro 2's or 3's. I always thought the stock centerline on a b-series exhaust cam was 110* but from additional research, It' looks like it's 103*. Obviously if I'm wrong about that number it will throw off my calculations so if anyone wants to correct me, feel free.

I still believe in the math part of figuring this out but measuring your clearances is the best way to be sure about everything.

 

ok cool . i know for sure that i can run more that 3-4* or i will have the valve touching when vtec is engaged.

now weird enough i got those same readings however only in the reverse, i.e using math you got -2IN +3.5EX and dialing them in i get ~+1(closer to +2) on my IN and -3 on my exhaust.

right now i am still questioning my dial gauge readings, reason being from my reading(posted before) i see most "big" cams run advanced on the exhaust . I dunno if i am paranoid and just freaking my self out. But i just wanna be sure. and you are not the first person i heard of using the math, but those who i know use it have actually come out very very close to the actual degree.

Anyone else have any input ?

 

thank you very much for explaining that. now milling and decking will alter these #'s. now ive read different opinions,but im gonna ask what is the magic # of milling and decking can be tolerated b4 you need to start advancing the cam gears to compensate?

 

there wouldnt really be a magic number. sad to say . most ppl dont mill or deck pass 0.030 and depends on the cams you use where your degree settings are . you may "never" get to advance.

that is from my understanding. i hope i am learning

lol

anyone please feel free to correct me

 

great info!

 

anymore suggestions?

 

Just dialed in my cams again and got 0 on my intake and -3 on my exhaust cam. So I guess that is where my cams work.
I would like to hear what some of you guys say on that and that that 'big' a cam cant work with such a 'big' degree of retard on the exhaust side. Cuz I read in another post that someone said Skunk2 Pro2 can't work 0, -3 , and if the kid ran his car with those settings and VTEC and if he did it wouldn't last for long. Why?

 

That's why you need to measure the V2V clearances as well to see what's safe and what isn't. If your cams were pro 2's it my put those clearances into an unsafe range but they may be fine on the M24xx cams.



The magic number is .040" removed in total. So if you mill the head .020", deck the block .010", and run a 2 layer headgasket = .040" total removed. To compensate for this you must advance your cam gears 1 cam degree which is the same as 2 crank degrees if that's how your cam gears are marked.

 

yeh as i mentioned in previous post i have done those. It seems that v2v is more critical and more of a problem than p2v.

I cant find my sheet that i wrote the p2v values but i am sure that i was safe +-5 so i think i cam cool , and good to go

 

so you're saying at any cam gear settings between +/-5, intake or exhaust was safe clearance wise? That's a rather large range and is possible but you want to make sure you're not guessing or expensive things will happen.