clearance issue with big cams

[RBKIDD]

i have a set of 272 kelford cams,i got them from top hat.the guy mike said that the tomei 272 cam has clearance issues i guess meaning piston to valve contact,but the kelford 272 dont have clearance issues.my compression was 120 on all except for #3.

[cdorhout]

I assume when they say cam clearence, they mean that the lobes are so much bigger that the head needs to be clearenced for the cam to rotate without hitting the head.Also, I believe that Tomei Pon cams bolt right in without clearence issues, but the Tomei Pro cams have the clearence issue.Not 100% sure on that, can someone confirm?

[BoostFab]

that's right, it's referring to the side clearance in the head, where the lobe spins and it may rub the side of the head. if it won't clear, you will have to shave off the metal where the lobe hit the head.

unless you are running oversized valves, you may also need to do a clearance check on the valve-to-piston cleance w/ a plastigauge.

[Darius]

Anything over 9.0mm lift is going to have cam lobe clearance issues and Tomei Pro Cams have lift of 8.5-9.15mm on the lash-style cams. Solid lifter style has even more aggressive lifts of 9.25-10.25mm.

Confirmed.

[gawdzilla]

What motor? What is the lift? the 272 you are stating is a duration. the duration is not what causes the clearancing issue where the lob hits the casting in the head itself. You need to look at the lift, then there is a maximum lift for stock heads. 9.0mm seems to be max for rb25. 9.15mm i think is max for rb26.

then obviously with extreme lifts and durations you can have piston to valve contact, but i doubt that is what the guy who you're buying from is referring to.

[rbsileighty]

Tomei Cams for Pro "lash type" are limited to the following:RB20's are limited to 8.8mm lash typehttp://www.tomei-p.co.jp/_2003....html

RB25's are limited to 9.15mm lash typehttp://www.tomei-p.co.jp/_2003....html

Can't help with the head clearance info though... not yet at least

I have 270 lash type pros 8.8mm lift for the RB20... uninstalled to date due to rebuild

[BHFR-GTR]

wow man you have a massive set of cams, i also have a set of kelford cams but mine are the 264,s. also from my buddy over at tophat. the first set they have ever put in were mine ( rb26 as well ). it depends on what cams that you have, they have three 272 cams one is the 272 mild lift street cam at 10.00 and 9.95mm lift intake and exh, one is 272 high lift 10.55 and 10.50 both of these cams need head clearancing, my 264's did to 10.00 9.50. or if you have the 272 pt# L182-b then they dont need clearancing. either way i want to congratulate you on a fine purchase on some bad *** cams

[Carl H]

if the lift is over 9mm then you need to convert the head to solid lifters.

[Coolwhip]

as well, make sure you are ready to shim for lash clearance as well if going to solid lifters.

[BHFR-GTR]

if hes running a 26 then its allready solid lifter

[Coolwhip]

tru... Well, in that case: to the OP, what motor are you running?

[RBKIDD]

yea i have a rb20 sry bout that.and yes i know 272 is the duration.the lift is .365 of an inch,and i have stock lifters in it, and the lob does not hit the head up in the valve train.thanx for all the info guys!!!!!!!!!!!!!