Truely **FLAT** lifters (tappets)

[aribert]

Greetings all:

This is a slightly off topic post in that I need to replace the cam in my other in-line 6 cyl non-Ford car (Triumph, push rod, solid lifter) - but I figured the physics is essentially the same. Thank you in advance considering this off-brand question.

I managed to wiped a cam lobe after a mere 10K miles. The badly worn lobe looks like this: http://i290.photobucket.com/albums/ll27 ... 751725.jpg.
The rest of the lobes look like this: http://i290.photobucket.com/albums/ll27 ... 20a1b8.jpg I did all the proper: cam break-in time & lube, high ZDDP oil, etc. I like the cam grind, so after poking around the net, asking a few questions, etc, I decided to buy another from the same vendor. This grind is on a new chilled cast core.

This time I will buy the replacement lifters from the same source as the cam. When I went to order the lifters I see that the vendor's lifter description states that the lifters tappets) are ground truly flat. I have always heard that all "flat tappets" are slightly crowned. I contacted the vendor and his response is that his cam is "... ground without a taper on the lobe and should be run with a perfectly flat tappet..." and that his lifters have been ground flat for the past year (and that his race car and road car both still have crowned lifters).

I am a bit spooked with so little "in the field" development time on his flat lifters. I don't want to be spending $500 every 10K miles to replace cams.

I have always heard that flat lifters are really slightly crowned. All lifters that I have ever handled were crowned on the face - two contact surfaces could not be wrung together. Your thoughts?

 

[xctasy]

No way I'd ever, EVER run a flat lifter...they all have a radius and are designed to look after the cam lobe. But if the cam is designed to fit a flat lifter like he says, then your locked into his development program. And camshafts are something US cam makers excel in.


The 803 cc Standard 10 engine the Triumph sixes are based on was always a concave lifter, standard Pommy child iron, and it worked a treat like every other Limey dancing knitting needle engine.

There are engine building savants around, and your stuck with what the cam sell recomends, so you have to trust him.

But why the heck would anyone change?

 

[CNC-Dude]

That's why his first cam wiped a lobe....The lifters can't rotate if the lobe doesn't have a taper and the lifter bottoms aren't radiused.....run from him quickly!

 

[oldgrezmonke]

his lifters have been ground flat for the past year (and that his race car and road car both still have
crowned lifters).

:nono: Which is why your cam wiped out and his race and road cars still have cams . If you haven't yet ordered : Don't . If you have : Cancel or Return .

 

[THE FRENCHTOWN FLYER]

The 803 cc Standard 10 engine the Triumph sixes are based on was always a concave lifter...

Did you mean to type convex?

 

[aribert]

Thank you all for the replys.

What you are saying is inline with my thinking. When I read about the "truly flat tappets" I got spooked. I don't want to replace cams every 10K miles.

Again thanks.

 

[CNC-Dude]

When you wipe a lobe, it trashes the whole engine, not just the cam. That metal embeds in the piston skirts, which then gouges the cylinder walls, and the degrading process accelerates from there. So its not just a "put a new cam and lifter set in and go again" kind of exercise.

 

[mike1157]

When you wipe a lobe, it trashes the whole engine, not just the cam. That metal embeds in the piston skirts, which then gouges the cylinder walls, and the degrading process accelerates from there. So its not just a "put a new cam and lifter set in and go again" kind of exercise.

What he said. The liquid metal is now running its course through all orifices in the engine. Oil pump: trashed, Bearings: trashed, if you have ran it long enough, rocker fulcrums: trashed.

A wiped lifter lobe is a death sentence for the engine,....not necessarily firing squad quick, more like cancer.
It just eats the engine away from the inside.
You should tear down the engine and inspect/replace what needs to be.

Sorry to be so crass,...but I'm so glad I decided to install a roller cam now.

 

[xctasy]

The 803 cc Standard 10 engine the Triumph sixes are based on was always a concave lifter...

Did you mean to type convex?

Argh! Yes, concave.

http://repairguide.autozone.com/znetrgs ... 0879a9.gif
Sorry to be a dingbat.

 

[80broncoman]

I'm not sure on this. I will say nearly every one of us here has run a truly flat tappet if you had a engine with over 100K on it.
as long as it keeps turning Not much wear is going to happen.

I never have heard of of some one grinding cams with out a taper. I will say That is NOT going to work on a old school SBC.
All tapers on those point one way to hold the cam in the block.

If this guy can make a cam and lifter work as well without the taper/convex lifter I'm open minded to it.

When I worked at Crane we told people that had a hard time on break in to cut a slot in a old valve cover so you could see if the pushrods were turning. Also told them to remove inner springs on dual spring setups.
I head years ago tat the NASCAR people had spin fixture engines or even running engines just for breaking in cam and lifter sets.

If you can't get the lifters turning quick you will see more wear down the road.

 

[THE FRENCHTOWN FLYER]

The 803 cc Standard 10 engine the Triumph sixes are based on was always a concave lifter...

Did you mean to type convex?

Argh! Yes, concave.

http://repairguide.autozone.com/znetrgs ... 0879a9.gif
Sorry to be a dingbat.

I beg to disagree. That drawing says to "check for concave wear", meaning the lifter has been worn to a concave shape from its intended convex shape as designed. That pic is misleading since they tried to show it in perspective, but the cam lobe would have been eaten off long before that much wear would have occurred at the base of the lifter. As was stated earlier, lifters should be slightly convex, and lobes should be slightly tapered, and the lobes placed off center from the lifter bore axis for everything to live a long time. Excluding roller cams of course.

 

[aribert]

A follow up to the "truly flat" lifter question I asked earlier. I did some digging and sure enough Triumph (at least for the 6 cyl) did spec a truly flat lifter. The lifter rotation was provided by the lifter position off center to the cam lobe position (fore/aft in the engine).

After talking to a different Triumph cam (profile) developer who corroborated the flat lifter info, I went up into the garage attic and pulled some of the original (used, factory) lifters out my used engine parts pile and after cleaning the oil film off of the cam surfaces, I was able to wring the surfaces together (like gauge blocks). I was even able to wring two of them together and have one suspended by the 2nd for a few seconds. BTW, I appreciate the image of using the diameter of one lifter to check the surface of the second lifter.

I figured you all might be interested to know - even if it does not apply to the Ford sixes.

 

[80broncoman]

I'll add the most Senior tech guy at crane told me when he lived in south Florida there was a guy in the business of rebuilding engines in Miami. He said the guy would check the Old used lifters as they came out of a engine to see if they still had a "crown" on the bottom.
If they did, He reused them with a new cam on his rebuilds.
The boss said swore he didn't run to problems in doing this.

 

[MustangSix]

There are some engines whose cam lobes are off center from the tappets. This also induces a spin as the lobe contacts the lifter. There are also engines whose cam lobes are not flat but angled to get the same effect. A cam grinder might use a combination of things to reduce wear.

There are many ways to skin this cat and if a cam maker decided to use something different than expected, you could end up with a cam to lifter mismatch. Unless you are doing a dead stock rebuild, use the lifters recommended by the cam grinder.

 

[motzingg]

Hey while we're on this subject (and somewhat off topic) I have a general question for you gurus out there.

If you're building a motor with stiffer brand new valve springs, would it be advantageous to re-use the stock springs (providing that they dont crash, clear, etc) with the new cam for less pressure during break-in?


Kind of the same idea as leaving out the inner spring of a dual spring setup.

Tell the truth, cam break-in is never something I've thought much about, put the special lube on the cam and just do the engine break-in as usual. Now i'm kinda scared.

 

[80broncoman]

Hey while we're on this subject (and somewhat off topic) I have a general question for you gurus out there.

If you're building a motor with stiffer brand new valve springs, would it be advantageous to re-use the stock springs (providing that they dont crash, clear, etc) with the new cam for less pressure during break-in?

Kind of the same idea as leaving out the inner spring of a dual spring setup.

Tell the truth, cam break-in is never something I've thought much about, put the special lube on the cam and just do the engine break-in as usual. Now i'm kinda scared.

AS long as they are not dead and have the clearance for the lift I'd think you would be fine for a break-in.
I have heard of people cutting slot in a old valve cover so you see the push rods. then taking a pen and Marking a line on the pushrods so that when the engine was running during break in you could see if the pushrods were turning.