well roller cams break without being reground lol. Then air gets into the lifters and they squish at high RPM where the cam works best.
Neither happens every time though, some people have a good setup and don't have problems.
I am not a fan of regrinds, high lift mainly. The follower pushings side ways on the guides with a high lift regrind, causes the valves and guides to ware faster. Mopar sold extra long followers for high lift cams to keep them from slipping off, which I haven't heard of with a roller. But I'd still worry about pushing on the edge of the valve tips. Another issue is the really high rocker ratio, but beehives were designed for that and high RPM.
It all comes down to how much you are spending. Doing an econo garage build then O well. Spending $1000+ on your head and other porting, don't get cheap on the last $160 and risk nuking your top end. Or pay more for a cam and not know your actually openning the valves....
Machine shops tear down junk cores from bone yards. Then toss everything into a pile and clean it. Then large cans filled with hundreds of cams goes off on a truck to a cam grinder for regrinds. They are beat worse on the way to the grinder than how they are treated after a grind job. There is a reason why the cores are so cheap lol. Now lets say that you have a really nice cam that hasn't giving you any trouble and has really nice lobes on it still. Sticking that brittle roller cam into a nice box with bubble wrap and sending that exact cam to be reground is different. And I have done that with Delta. But a core off the shelf? They get tossed in a 6' x 6' x 6' steel box then sent off. No thanks.
This BTW has nothing to say again by who you buy it from, it has to do where the core came from. So it isn't like Cindy tosses them 20' accross a room trying to hit a shelf lol. Has nothing to do with how they are treated after grinding again. It is the treatment of bulk cores, which is horrid. 1 guy in a machine shops rips apart over 50 engines a day getting minimum wage and tosses the stuff for cleaning. OK fine with a cast iron old V8, much of that survives lol. 2.2? It is hard on a cam just unbolting the cam wrong leaving the middle for last and can fracture a cam. I've personally watched a 2.2 get ripped down for cleaning in under 10 minutes.....
A brand new blank is held gently like a new born baby and packaged nicely into a soft box made to keep the blank nice. Then shipped off to be ground, then treated nicely as it is shelved and sent off to the new owner. Next to the computer tune running your engine the cam is the #2 most important piece to having your engine run right...
Entertaining as usual Pope...:)
Am I right that shadow ran the F4 with only spring upgrades and no changes to the stock lifters? Why are better lifters needed for a higher lift cam, if the stock rev limiter will be kept?
I got a good deal from Ed on +2mm valves and seats, and since Im in no hurry, Im going to try to build a big valve g head with high lift cam as cheaply as possible..so far I've spent:
$67 on head
$40 on pressure test and surfacing
$80 on four +2mm exhaust valves and oversize seats
So $187 so far.
So I still need:
-four +2mm intake valves $116
-four +2mm intake valve seats $40
-F4 regrind cam $239
-crane valve springs $59
-installation of oversize valve seats $80
-standard valve job $99
-s/h for the above parts $15
So another $650..which will end up being $837..thats pretty good right? Id spend $1000 for just a ported head from the vendors with no cam, but Ill do the porting myself (basic G port).
And if I can get more deals on the remaining parts that would be good.
But Im not sure if I need the lifters or retainers or other stuff..do I need the lifters because at high lift the stock lifters fill with air?