Flat Tappet Camshaft Reliability...

J

~JM~

Wrinkled Member
Joined
Oct 31, 2007
How many fresh engine builds are deciding to stay with a flat tappet cam vs. a roller?

Are there specific issues with the flat tappet cams & the Buick V-6 design?

How many have actually lost a lobe on their flat tappet cam & what oil were you using at the time?

Thank you
~JM~
 
Edelbrock 204/214 with about 20k on it, lots of beating on it on the street and track, no issues. I broke it in with 15w40 rotella diesel oil back in the day, and have never added anything since. Should be using ZDDP or something similar but really not too concerned with this motor. Daily driver, cross country trips, ~22 psi on Alky for the past year or more. No issues.
 
206/206 flat tappet with 1400 miles on a fresh build. 10W40 conventional with ZDDP on every oil change. Flat tappets were used w/o problems for how many years before the govt changed our oil?

Carl
 
I went with a 206/206 f;at tappet after the orig. lost a lobe. Now I make sure to use a good oil (brad penn) otherwise I would put ZDDP in
 
I went flat tappet on my cheap build last year. I have 12k miles on my Erson 208/208. My original cam looked great after 75k miles and regular ZDDP use so I figured with continued ZDDP use my new flat tappet cam should be just fine too. To answer what I think your question is, I have not seen anyone wipe a lobe with either ZDDP or other heavy Zinc oil and moderate to mild performance valve springs. Heavy springs and the wrong or not enough additives in the oil kills a flat tappet cam. Dirt guys still have to run them in some classes.
 
I don't see a real problem with flat tappet cams. You can loose a lobe if they aren't broke in properly. I recommend the ZDDP paste applied to the cam lobes and lifter bases. If you read the info Richard Clark has written about his testing on the paste, I think you will agree that it is a superior product to most any other cam "break in lube"
 
turbodave231 said:
I don't see a real problem with flat tappet cams. You can loose a lobe if they aren't broke in properly. I recommend the ZDDP paste applied to the cam lobes and lifter bases. If you read the info Richard Clark has written about his testing on the paste, I think you will agree that it is a superior product to most any other cam "break in lube"
Click to expand...

Honestly, you are leaving some power on the table, budget alone should dictate a flat tappet, rollers can get more aggressive with the same idle quality as a smaller flat tappet.

Lost a new cam in my 489 stroker with good oil and break in lube, first one ever for me in 35 years.
Went with a larger Hyd roller and love it.
Use zinc laden oil (diesel) good paste and additive you should have no problems with the flat tappet. Take quite a few oil changes with additive to make up the difference in price.
That said, I would go roller everytime, but thats me, I like to do things once....
 
When I replaced my original motor at the 130,000 mile point, I installed a 200/200 flat tappet in the engine going in. This was back in the mid 90's when oil was still pretty fair with zinc, etc. and did a proper break in. Cam still seems to be good today, but I am assembling my numbers matching engine to go back in sometime in the not too distant future. This motot is getting a 202/202 flat tappet cam, and I'm going to great lengths to make sure to use genuine GM lifter with the hardened foot, and of course ZDDP paste will be applied to the parts, a proper break in, and ZDDP for all future oil usage.

There's nothing wrong with flat tappet usage, just takes some attention to detail, and a correct break in. ( a mistake on either will kill a flat tappet in short order).
 
Diesel oils were hit as well. Best to use zddp. Bottom line if you read the starburst on teh back of the oil bottle and it says SM or SN then your flirting with disaster IMO.
 
I have taken a part maybe 30 or so engines, mostly they had an aftermarket flat tappet cam and ported heads with heavier springs as well as some stock engines (109 block ). The bone stock engine with stock original valve springs and cam seems to be ok for the most part but I found few with #3 exhaust lobe wiped. I guess there is a design issue from GM. Now all the build 109 blocks I took a part with heavier valve springs higher lift lobes cams I found them wiped or on their way out. They were few exceptions. I would say 8 out of ten failed. The miles were anywhere from 150 miles to 3000 miles. Some of them where broken in properly and some I am not sure. I don't find this issue in any 84-85 bone stock setup. I took a part build 4.1 that ran high 10's with about 5000 street miles and notice the cam was on its way out however I took a another 4.1 motor that we ran 10.009 @132mph with over 100 pass on it and the cam looked great. So I guess it's a hit or miss.

I guess what it comes to is; It all depends who you talk to, from what I have seen I will go with the Ductile roller from Full throttle and call it a day, never look back. For the past 7 years all the motor I have been setting up are with the Ductile roller from Full Throttle with awesome results and Zero issues. If you end up running a Flat tappet cam and get deep into tuning, you will pull hair out of your a$$ trying to chase where the miss fire is coming from. We went through hell and back on a buddy's car. We changed all sensors known to man including the wiring harness. At the end we found out that it was the FLAT TAPPET cam that was going flat.

HTH
Prasad
 
I have heard from one source that there is a design flaw with the lifter bores not being properly aligned with the lobe which prevents the flat tappet from rotating in its bore properly.

Anyone else notice this or heard of this before?

~JM~
 
~JM~ said:
I have heard from one source that there is a design flaw with the lifter bores not being properly aligned with the lobe which prevents the flat tappet from rotating in its bore properly.

Anyone else notice this or heard of this before? ~JM~
Click to expand...


If that statement was true, why are many stock engines able to get 100K to 200K out of a factory cam?

Out of hundreds of flat tappet Buick turbo engine builds, only 3 have had cams go bad, one thing they all had in common, they were run with Mobil I oil.
 
Nick Micale said:
If that statement was true, why are many stock engines able to get 100K to 200K out of a factory cam?

Out of hundreds of flat tappet Buick turbo engine builds, only 3 have had cams go bad, one thing they all had in common, they were run with Mobil I oil.
Click to expand...

I don't use the stuff but Mobile 1 WITH ZDDP added should be fine though I would think. Please correct me though as this is great info.
 
we4Mateo said:
I don't use the stuff but Mobile 1 WITH ZDDP added should be fine though I would think. Please correct me though as this is great info.
Click to expand...

It may be "fine" to use Mobil I, or any over-priced synthetic oil in a GN, but it certainly is NOT cost effective.

In a boosted application, oil will get contaminated at least twice as fast as NA performance, so oil should be changed at more frequent intervals. You can change oil at least twice with conventional oil vs. synthetic, and neither reach the point of being "worn out", just both are dirty and full of unwanted stuff.

Other than advertising hype, I have yet to find or hear of an advantage of using synthetic oil in a GN, but there are numerous reasons why NOT to use it besides the cost difference.
 
~JM~ said:
I have heard from one source that there is a design flaw with the lifter bores not being properly aligned with the lobe which prevents the flat tappet from rotating in its bore properly.

Anyone else notice this or heard of this before?

~JM~
Click to expand...

Yes, there is a long history of this. Look at any setup and you will see that the FT cam blank places the #3 exh lobe very nearly in the center and offset in the wrong direction. You can verify the effect of this with any running engine. With the valve cover off, all pushrods on that side will spin in the same direction, except #3 exh (and it will spin slower - not good). On the opposte bank, all pushrods will spin in the same direction like they are supposed to.

The proper procedure, which was discovered late, is to put a reverse taper on #3 exh lobe. Most (if not all by now) cam grinders are aware of this. You can verify this yourself with some v-blocks and a dial gauge.

There's your concrete proof.
 
87GN_70GS said:
Yes, there is a long history of this. Look at any setup and you will see that the FT cam blank places the #3 exh lobe very nearly in the center and offset in the wrong direction. You can verify the effect of this with any running engine. With the valve cover off, all pushrods on that side will spin in the same direction, except #3 exh (and it will spin slower - not good). On the opposte bank, all pushrods will spin in the same direction like they are supposed to.

The proper procedure, which was discovered late, is to put a reverse taper on #3 exh lobe. Most (if not all by now) cam grinders are aware of this. You can verify this yourself with some v-blocks and a dial gauge.

There's your concrete proof.
Click to expand...


Yep, I have seen the result of this issue first hand with the little experience I have with several engines. It was also confirmed by some of the Buick legends here on this board whom I have a great deal of respect. I will take their word any day over some people with the mentality of “I have not seen it therefore, it doesn’t exist”

Prasad
 
FYI ,
I was told that COMP cams will not warranty a flat tappet cam if it wasnt nitrided.
 
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