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With nothing better to do I have been playing with the thought of up grading my cam
Any thoughts on going roller instead of flat tappet
My interest is in COMP Cams Xtreme Energy Retrofit Cam and Lifter Kits SK12-408-8
vrs
COMP Cams Magnum Hydraulic Cam and Lifter Kits CL12-212-2
Motor is 350 board .030 over
Flat top pistons
Edelbrock performer heads and intake
Distributor recurved by Lars
2 1/2" rams horn manifolds with 2 1/2" Magnaflow exhaust
Last edited by redwingvette; 05-10-2020 at 10:24 AM.
Also check out Howards retro-roller cam kits at Summit. Good priced quality kits and they have been in business a while. Just another idea. I’ve had mine for 10 yrs. runs great.
Going retro roller will cost an extra grand or so, but IMO very worth it. No special high zinc oils to worry about, you’ll get better vacuum for same duration and you can get more lift without worrying about wiping a lobe.
i went roller and never looked back.
it is more complicated and expensive though so up to you and your comfort level with making the switch. The head set up you have may actually dictate whether it good for roller or not. It takes more spring for roller and the heads typically allow more lift, so those things would have to be checked as well.
That roller is MUCH smaller than the 280H Magnum you posted and you will go backwards as far as performance a ton.
I use Howards when doing street rollers.......better pricing and better lifters.
You will need to change the valvespring, lock, retainer as well as well as new pushrods.
The conversion is about $1000 after all is said and done.
A set of long tube headers will be worth power everywhere.....in fact, I would put headers on your existing combo before you changed the cam out......you have decent heads and the Magnum loves headers.....
I don't know if I would even bother with a roller cam unless it had headers......
.Thanks for the input
I guess I should have posted the cam I have now is a Crane Cam H266 with a 440/454 lift
May I ask why I would have to change the springs and retainers on the Edelbrock heads, they are listed as max lift .510"
Last edited by redwingvette; 05-10-2020 at 01:47 PM.
.Thanks for the input
I guess I should have posted the cam I have now is a Crane Cam H266 with a 440/454 lift
May I ask why I would have to change the springs and retainers on the Edelbrock heads, they are listed as max lift .510"
Because rollers have a very quick opening and closing rate......this is what makes them make power. This will wear out a flat tappet spring in short order.......even with a mild cam such as the one you posted, I still would not run a flat tappet spring.
If you want to go through the break in process....the 280H Magnum and a set of Elgin Z/28 springs are an old staple....runs great and sounds very chunky. Malke sure you upgrade to one piece pushrods and replace the valve seals on your Edelbrock heads to viton......this is a problem with older versions of these heads bleeding oil past crap valve seals.
Because rollers have a very quick opening and closing rate......this is what makes them make power. This will wear out a flat tappet spring in short order.......even with a mild cam such as the one you posted, I still would not run a flat tappet spring.
If you want to go through the break in process....the 280H Magnum and a set of Elgin Z/28 springs are an old staple....runs great and sounds very chunky. Malke sure you upgrade to one piece pushrods and replace the valve seals on your Edelbrock heads to viton......this is a problem with older versions of these heads bleeding oil past crap valve seals.
Jebby
Isky 280 Mega cam is another old school grind with 232-232 @ 050, .485-.485 lift on a 108 lsa that would have a nasty idle to it !
.Thanks for the input
I guess I should have posted the cam I have now is a Crane Cam H266 with a 440/454 lift
May I ask why I would have to change the springs and retainers on the Edelbrock heads, they are listed as max lift .510"
a roller cam like Jebby said open faster and closes faster. So more spring pressure is needed to insure the roller follows the cam. Also roller cam likes a good 130 lb on the seat. A flat tappet cam is in the range of 90 lbs. with insufficient spring the roller lifter will leave the cam profile, valves will float, and the valve will bounce on the seat leading to valve seat wear and loss of power
Since your head is limited to .510 then that’s your limit for lift.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
When you buy your kit, get a full kit that has the lifters, springs and pushrods. Also invest in a good timing cover that is either a 2 piece cover that you can take just the front off to get at the cam or complete chain to set the forward thrust, or either put in a threaded thrust button in the timing cover so you can set the thrust then locktite the button or buy one that already has it.
Also I had to get button head bolts and do a little massaging to get mine to fit under the short water pump.
The lifters are the most expensive part and you want to buy the best. I here Cranes are some of the best for hydraulic, I went with Comp solids myself.
Don’t forget spacers to get enough room under your covers or get tall ones if you haven’t already.
If you are going with .500 or more lift you may want to upgrade to 7/16 studs or get stud girdles
Last edited by Rescue Rogers; 05-11-2020 at 08:12 AM.
Roller cams can give you an improvement but a retrofit is an involved and costly upgrade. The roller lifters are heavy and the aftermarket roller cams move those heavy lifters up and down at a faster rate so the valve springs need to be stiffer to control the faster, heavier valve train. Heavy springs combined with higher lifts means higher over the nose spring pressures. Those required higher over the nose spring pressures can exceed the 350# limits of the pivot ball rocker arms so you have to upgrade the rockers to a needle bearing setup and poly locks at a minimum. Many times you will need taller rocker covers to fit all this hardware under them. You then hope the taller covers do not interfear with your other accessories and brackets. Less expensive roller lifters are not as reliable as more expensive ones so you pay up for those too.
Jackson mentioned the ZZ factory roller cams and they are very good choices particularly if you build a factory roller block. Saves some money and runs hard without breaking the bank. OEM reliability. Not as much rumble/shake to go along with the power but it is a cheaper, reliable middle ground.
Flat tappets still go down the street fast and can make noise. Direct oiling EDM drilled solid lifters have tiny oiling holes on the face to improve reliability over conventional solid flat tappets. Not as nearly as complex as a roller conversion. High RPM limits typically. They are much simpler and economical to build. You can use more of what you already have now. Use tighter lobe centers to increase overlap if you want a mean idle.
05-10-2020, 10:21 AM
New Cam thoughts
