Hydraulic roller or flat tappet?

[Blown&Injected]

Some say that there is not much gain by going to roller cam in a thread I opened just asking about the difference.

My heads flow a lot more above about .350 to .500 lift and it seems like the valve on a roller would spend much more time at those lift numbers.

However, what seems like it should make a big difference does not mean it will translate to good power in the engine. I would believe that I would feel a difference going to a much bigger cam but I noticed nothing - a bit more rumble that lasted a bit in to the revs.

Really want to hear of a go to roller with no other mods report.

 

[Slow91z]

Originally posted by GN-231
I am switching to the comp roller and the only negative I see is that the small metal shaft that retains the lifter roller wheel just adds another possible failure mode to the engine over life. It is in a constant cyclical load, and who knows where on the S-N failure diagrahm the loading is for that small shaft?
I am going to switch out the roller lifters about every 20k?? just to make sure I don't ever fail any roller wheel shafts.
Everything else is pure benefit! No more lobe wipping or friction.

You're kiddin right?? Chevy's been using roller cams in stuff since 85, my camaro had 175,000 miles on it with no valvetrain issues AT ALL...And this car was not taken care of, I mean the previous owner didn't even change the plugs the entire time he had it (2 years) and when I changed em it had 3 different brands of plugs in it...Oil wasn't changed as regular as it should have been, just driven and ignored.

 

[Garycar]

I'm not convinced that a roller cam is necessary for most Buick turbo motors. Rollers are without a doubt more efficient but they are also much more expensive. Buick turbo motors make use of torque, not high rpm to get the job done. Jim Bell said it correctly years ago when he said that the turbo Buick motor is a "cam makers nightmare". That is to say that the power range for most Buick turbo's is approximately 2500 to 5500 rpms. It is very difficult to develop a cam profile that will make appreciable hp and torque gains in that narrow window. Its nice to say that "I have a roller" but does it really do that much more for you in actual performance for the dollar spent? My recommendation is to go with a flat tappet cam from a reputable cam maker such as Comp cams and use the saved money for upgrades that really wake up the Buick motor such as heads, turbo's and intercoolers.

 

[Slow91z]

You guys confuse me...With a Roller cam the lope ramp can be SO much more aggressive, meaning that with the same lift and duration a roller cam will make more mid-range torque, and this doesn't even address the less friction issue which WILL make more power no matter what yall think...will it make a LOT more power???I doubt it, but if you figure the friction differences, plus the lobe profile differences, plus the reliablity differences, a roller makes as much sense as anything you can put on teh car.

 

[wants a tr]

Originally posted by Garycar
Its nice to say that "I have a roller" but does it really do that much more for you in actual performance for the dollar spent? My recommendation is to go with a flat tappet cam from a reputable cam maker such as Comp cams and use the saved money for upgrades that really wake up the Buick motor such as heads, turbo's and intercoolers.

i said this very same thing when i put a new cam in my car...went with a flat tappet comp...GM lifters and everything. it went flat...the next one....went flat..

whats going in my car next weekend?

a roller...

should have done it right the first time...

Go with the roller...

 

[Garycar]

The flat tappet cam concept has been around for decades with excellent results. Turbo Regals are running around with the original stock cams and lifters with very high mileage. Clearly, there have been problems with some aftermarket cams ranging from incorrect cam lobe taper to incorrect installation and break-in. Losing back to back flat tappet cams leads me to believe that there are other issues here beyond the basic flat tappet concept.

 

[Snorman]

An update to this...
I went with a full roller setup.
Comp 206 with a 1.65 roller rocker.
The motor is done and will be in the car next week.
I'll be running the 63 for now, and might go bigger in the spring.
Thanks for all the input.

S.

 

[TurboTR]

Unfortunately rollers can go bad in a Buick too, lol. You also have to watch the available physical lift space, seeing as how we have 1.25" springs installed at only 1.75" height. With guides and seals and all it just doesn't leave much room for high lift + margin. Now that you have much more aggressive roller lobes you really need better springs and pushrods as well. It adds up fast. Plus how do you keep the thrust in check, how do you retain the cam gear, etc are other things to worry about. On a stage block you can use the positive method of Danny Bee plate to retain a roller cam, but the stock block doesn't really lend itself to that setup.

The lobe taper and lobe offset on a flat tappet MUST be checked. On the Buick, the odd bank and the even bank are offset and tapered in opposite directions, except the #3 exh lobe is offset and tapered the same as the even bank. Lately I've seen more that were tapered wrong than were right, lol. Even after the cam mfgr was informed. Sometimes they're all tapered the same direction, sometimes the wrong lobe is tapered opposite, etc. Since the lobe taper is on the oprder of 1 to 1.5 thousandths, you may need a micrometer to check it unless you are really good and patient with a high quality set of calipers

TurboTR

 

[Snorman]

I guess I'll have to trust that Dan sets it up right.

FYI...this is a 109 block, girdled, forged pistons, Eagle crank, SFI balancer and plate, 212 Comp roller cam with 1.65 roller rockers with a set of nicely ported heads (227/184cfm) and intake.
Thanks!
S.

 

[GNX423]

really wish that i knew about the #3e being cut wrong on so many cams before i put mine in last year. I think i may have wiped a lobe, im getting alot of noise after letting the car sit for 2 months with out staring it. have to pull the intake this weekend.

 

[GNVAIR]

Originally posted by GNX423
really wish that i knew about the #3e being cut wrong on so many cams before i put mine in last year. I think i may have wiped a lobe, im getting alot of noise after letting the car sit for 2 months with out staring it. have to pull the intake this weekend.

If you are getting noise after it sits then it most likely is an oil pressure related problem from the oil draining out of the filter. A bad check valve in the filter can cause that.
If you had a wiped lobe you would know it. It would be popping/missing or just generally down on power.

 

[denn454]

i didn't have a chance/don't have the time to read through all the replies. i'm doing a rebuild very soon, and i don't think i should keep the stock cam, why would i want a 160k mile part in a brandnew motor? a roller is out of the question for me. is there a tappet cam that DOES last for everyone? i'm sure every cam out there has worked for a few people, but i'm looking for something i can can put in and not have to worry about. i'm sure it exists, if gm could do it why can't the aftermarket?

if this question was already answered i'm sorry, tell me and i'll read more.

THANKS!