flat tappet vs roller

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inkjunkie

inkjunkie

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Did not want to hijack http://www.forabodiesonly.com/mopar/showthread.php?t=107141. But I have been on the phone with several Hemi builders. Pretty much everyone agrees that with todays oil flat tappet cams are not an ideal choice. Builder #1 has told me that he stays away from flat tappet cams unless it is for a resoration. Has told me that he will do his best to push me towards a roller, a mechanical one. Said that if a hydraulic one is used in a Hemi that the tappet length will cause vavle train geometry issues. And with the failure rate of flat tappet cams, and the carnage that can occur when one does go flat, it is just too risky to use a flat tappet cam.
Builder #2 said that they will steer me towards a flat tappet cam. Explaination was that spring pressure for a roller will cause problems in a street car. Also told me that it takes very little valve float to start problems with the roller tappets. Example given was motor gets revved to float (accidently) while doing a burn out. He said that when float occurs it is possible to create flat spots on the tappets wheel, setting up harmonic issues which will lead to failure. Opinons? I will be using a roller.....
 
What level of performance are you looking for??I just sent my comp 848's solid rollers to be rebuilt with 10k miles and 50 1/4 laps.Mid .600 lift with 525 lbs of spring pressure over the nose.Unless you really "WING IT" hard in the burn out box,I doubt you will float,but pulling out of the hang out and wackin the GO PEDAL blowing the tires off will have those lifters bouncin off the cam.DON"T ask me how I know:angry7:

2009-04-25-1536-03.jpg
 
I am hoping for 800 hp or so....I will be going 572 or perhaps 604....
 
The flat tappet failures are caused by the oil additives (namely zinc), being removed through the years due to ever increasing emmissions regulations. Very seldom will you see a failure of a flat tappet camshaft as long as it is from a reputable camshaft company. Since the influx of some of the cheaper Chinese made stuff, there have been some failures there blamed on the actual shafts and lifters, but those are the exception. A good chosen solid flat tappet can actually make MORE lower end power and torque than a comparable roller, too. Here's why: Due to the roller lifter's extra weight, there is a good bit more parasitic drag to get the lifter moving. A standard solid lifter is MUCH lighter. I've spoken with Dave at Hughes Engines in depth about this and he has the dyno results to back it up. As long as you use a good zinc additive with your oil, you won't have a problem.
 
I do not think low end performance will be much of an issue with a EFI 572-604 Hemi. And just the thought of a cam going bad depositing itself into the oil system of a $20000 motor is kind of frightening....
 
inkjunkie said:
I do not think low end performance will be much of an issue with a EFI 572-604 Hemi. And just the thought of a cam going bad depositing itself into the oil system of a $20000 motor is kind of frightening....
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Even that junk going into a $5000 engine would ruin my day.
 
inkjunkie said:
I do not think low end performance will be much of an issue with a EFI 572-604 Hemi. And just the thought of a cam going bad depositing itself into the oil system of a $20000 motor is kind of frightening....
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Looks like you just answered your own question. 8)
 
inkjunkie said:
I do not think low end performance will be much of an issue with a EFI 572-604 Hemi. And just the thought of a cam going bad depositing itself into the oil system of a $20000 motor is kind of frightening....
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You did ask for opinions, remember?
 
inkjunkie said:
That I did, sorry about that....
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I'm startin to get used to that around here. Glad I got thick skin cause I wouldda been gone by now if I didn't. Yall just need to remember there's more than one way to skin a cat. Not everybody does it all the same way.
 
I think a solid roller is fine for high revving race motors...mine is a lower revving street motor hydraulic roller motor..as far as valve train geometry issues it has more to do with the rocker setup that you use...M2C

HemiRockerStands_small.jpg
 
inkjunkie said:
Did not want to hijack http://www.forabodiesonly.com/mopar/showthread.php?t=107141. But I have been on the phone with several Hemi builders. Pretty much everyone agrees that with todays oil flat tappet cams are not an ideal choice. Builder #1 has told me that he stays away from flat tappet cams unless it is for a resoration. Has told me that he will do his best to push me towards a roller, a mechanical one. Said that if a hydraulic one is used in a Hemi that the tappet length will cause vavle train geometry issues. And with the failure rate of flat tappet cams, and the carnage that can occur when one does go flat, it is just too risky to use a flat tappet cam.
Builder #2 said that they will steer me towards a flat tappet cam. Explaination was that spring pressure for a roller will cause problems in a street car. Also told me that it takes very little valve float to start problems with the roller tappets. Example given was motor gets revved to float (accidently) while doing a burn out. He said that when float occurs it is possible to create flat spots on the tappets wheel, setting up harmonic issues which will lead to failure. Opinons? I will be using a roller.....
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what I like here.. is that both builders have valid points/reasoning, though some is based in 'fear of' or 'what if'

now lets see if some turdcutter comes on here and says he's offended over these builders 'opinions'.lol
 
bremereric said:
I think a solid roller is fine for high revving race motors...mine is a lower revving street motor hydraulic roller motor..as far as valve train geometry issues it has more to do with the rocker setup that you use...M2C

HemiRockerStands_small.jpg
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I know with the Hemi's that is very true. Both of the guys I spoke with said that with modern day Hemi parts geometry issues are more less a thing of the past, unless you cheap out on the stands or use the wrong rockers. Unsure of which way I wil be going, and I have a long while to think about it. Funds permitting I would like to use Bartons setup...but I have read some not so favorable things about dealing with them so I do not know.....Stage V might get my money....
 
I'm definately not a Hemi guy... But.. I would be concerned with a solid roller spring pressure so I'd be thinking about a custom solid roller that can use a milder spring. The pushrods, rockers and valves in hemis are heaaavvvy, and there's more friction than a wedge. So I think I'd be looking that way. I like flat tappets, but to get big power the flat tappet will need to be larger, and then the springs, etc etc etc. A milder solid roller will last a while without the lifters needing repair. Also, look into GOOD lifters. Bullet has some coming out with pressurized oil feeding the wheel. That is the best way. Not cheap, but long lived.
 
You say you were talking to Hemi Builders. Did you ask specifically about Hemi's, or just FT vs. Roller in general? Since the post your trying to avoid hyjacking is the one about my wiped out cam, I'm very interested. I was against spending the $700+ for a roller set-up, but am starting to reconsider.
 
inkjunkie said:
I know with the Hemi's that is very true. Both of the guys I spoke with said that with modern day Hemi parts geometry issues are more less a thing of the past, unless you cheap out on the stands or use the wrong rockers. Unsure of which way I wil be going, and I have a long while to think about it. Funds permitting I would like to use Bartons setup...but I have read some not so favorable things about dealing with them so I do not know.....Stage V might get my money....
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The ones in the picture I posted are not cheap...one other guy with a 572 crate hemi had a problem with geometry and I googled it, these are what I found..good luck with your hemi build....Eric
 
inkjunkie said:
Do not now if they are titanium, but he has a set that is close to $6000 I believe.....
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probably the ones I'm thinking of.

my friend mopar mac has a set that cost upwards of $9000!!!!!!!

I think they are purple looking things if I remember right.

he has 471 hemi pushing close to 800hp and is set up for nitrous to make even more kapow
 
64physhy said:
You say you were talking to Hemi Builders. Did you ask specifically about Hemi's, or just FT vs. Roller in general? Since the post your trying to avoid hyjacking is the one about my wiped out cam, I'm very interested. I was against spending the $700+ for a roller set-up, but am starting to reconsider.
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I was asking specifically for my plans, which are a Hemi. I kind of think that the theory/logic is the same. The shop that was for a roller told me that he uses nothing but Comp Cams CC829 tappets and has never had an issue with them. I have talked to a few guys that use the same lifters and other than sending them back every 10000 miles for an inspection have never had an issue with either the tappets or the higher spring pressure. I fully understnd that there is more than one way to skin a cat. But if given the choice of, in my case with a mechanical roller, a few lash adjustments and some occasional maintenance or being faced with what happened to you, I will take the maintenance. I will not be putting 50k miles on my car a year, so it is not like the maintenance will be an issue. If you were to put a flat tappet cam in there and have it go flat again, you will be out an additional $300 or whatever for the new cam and lifters, plus the nightmare of the filings everywhere. Is the roller set-up really going to be that much more?
 
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