if a only change my cams for some kelford 272 , will i have to change my springs and do the whole haed rebuild? or can i stay with my standard springs and the new cams?

thanks!

 

I've been on my kelfords with stock valvetrain for a couple years now... Heavy roadracing, no issues... i just dont rev past 7800

 

the idea is to go 8500 rpm or 8200!

 

anyone else?

 

The question was answered. With the lobes on the Kelford 272's it is safe to run them below ~7500 rpm, anything over that and head work is needed. Not necessarily a port and polish but, springs and retainers would be necessary.

 

Yes you will need valve springs and retainers. You will also need adjustable cam gears. You need those to have the cams degreed. You will NOT get the max benfit if they are not degreed. You could even drop some power and torque if degreeing is not done.

 

Could some explain why please. I'm also considering these cams for an E7 and would like as much info as possible.

 

i got the cams gears but not the springs and retainers , i also have ferrea valves 1mm bore , new guides , ported head (intake and exaust) so just want to know how maximun RPM can i get with standar spring and retainer!

Also if i buy some springs should i use the double springed?

thanks

 

If you rebuilt most of the head why cheap out on the parts (springs and retainers) that are actually necessary to run aggressive cams? The max you should rev is 7500 as stated! Holy hell! The lobe on that cam is agressive, hence it is going to compress the spring more than a standard cam would. That is alright up to a point, in this case ~7500 rpm, after that the spring can crack or fail causing a failure in the valve itself leading to serious engine issues.

It is not necessary to go double springs, some decent aftermarket springs like supertech, kiggly, etc would work well.

I don't know what you are looking for, a magic rpm value for when your valvetrain will fail, but there is no definite answer. Anything over 7500 rpm and you are pushing the limits of the stock springs and retainers with the Kelford 272's.

 

If you're putting on a ported head with bigger valves, may I ask why you're not changing your springs?

On a stock turbo you should be fine because the power range isn't going to be past what you should be rev'ing it but even then - since you're putting some parts in the head you should be putting in springs too.

 

I reved my VIII kelford 272's to 8000 on stock valve springs for a couple thousand miles making over 500hp and never had any issues... Parting my car out and the cams are for sale also if anyone wants them $400 shipped.

 

Bump!!

 

The only thing u need to change is the springs and retainers. mostly to be safe so u dont get valve float at high rpms. i bought my manley spring and retainer kit for pretty cheap. a 200 dollar insurance on springs and retainers is better then a bent valve or blown motor imo.

 

All you need is springs and retainers if you plan to rev high, i reccomend the duals for the 272's. You dont need adjustable cam gears for these cams. A good tuner will make sure your car is good.

 

Guys, it is not a necessity to have upgraded springs/retainers with the Kelford 272's...it's always a good idea when upgrading camshafts, but it will NOT hurt your head to run the stock ones, when revving under 7800. I will be upgrading from the HKS 272's to the GSC S2's (a little more aggressive than kelford 272's), and will not be touching the valvetrain.