checking cam lobe taper/nitriding lobes

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Rapid Robert

Rapid Robert

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cant go roller (rules) plus its pricey. I want to have a successful breakin with failures being epidemic. been watching some utube vids & they talked about miking the lobe taper & one mentioned that comp cams can nitride a cam. what are your thoughts? thank you for your time. RR
 
I just broke my flat tappet 340 in.....So far no problems after an hour of run time. Comp cam and comp hydraulic lifters.

When would a bad break in present itself?
 
Rapid Robert said:
^^^ that's good to hear. just all of the horror stories have me worried. RR
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I heard all of the same stuff and was getting spun.......Finally I just said "F" it. I used the best assembly lube (and lots of it) checked all of the lifter bases and cam lobes.....Installed them all and test spun them with a speed wrench and observed rotation. Top quality high zinc break in oil and primed the hell out of the oiling system just before fire up.

I tested my carb and ignition system on a mule engine to avoid any problems there.

Set my timing to fire at about 10* BTDC and primed the carb with fuel. She fired right away and I took it up to 2500 RPM and advanced the timing to 34* BTDC. It ran like a champ for 1/2 hour as I varied the RPM from 2000 to 3000. Shut her down and drained the hot oil and changed the filter. Re-filled with Lucas Hotrod 10w30 and a new filter and ran it for another 1/2 hour varying the RPM.

We'll see what the future holds.

The way I looked at it, they sell a **** load of flat tappet cam and lifter packages.......We hear of a few failures here on FABO. To me, I went for it...But That's me. :)
 
It is not the cam you need to worry about, it is the lifters.....
Find some 25+ yr old lifters [ factory or aftermarket ] & have them re-faced. Lobe taper is used to counteract the thrust created by the oil pump load.
 
I cannot disagree that it's the lifters. I still think Comp can use every cam it makes for a suppository.
 
Good luck
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from what I read on the utube chats I'm gonna need it and it is a howards cam, its just that one of the vids said that comp cams offers nitriding & hopefully that is for any cam that you send in not just for one of theirs. I'll give em a call.
 
As for how how long it might take to show signs of failure.
I built a 340 for my 340 4sp Dart Sport using a Hughes .513
hi energy cam . Breakin seemed to go well . Drove it around for a few weeks before driving from Boise to BIR in Minnesota to race it . On the way home in the middle of Montana it started losing the cam….
 
When I freshened up my 340 I stayed with the Original 340/4spd. cam. I used Comp. Cam lifters .Knowing what I've learned now I would of resurfaced my originals. Luckily all went well. It's been 3 years now.
 
I like a lifter with an EDM hole. Just make sure the lifter rotates when turning it over by hand with the lash set.
 
All you need to do, after verifying lifter rotation, is prime the oiling system if it’s a hydraulic lifter, and get it to fire off instantly. Get it to 2500-3000 rpm as quickly as possible and don’t let it idle.
 
You’re best bet is to send the cam and lifters to 300 Below and get them both cryogenically treated.

Its relatively inexpensive and it’s the single best thing you can do to increase your chances of not having a failure.

Yes, I’ve done it and yes I do it and yes, I’ve pulled stuff apart after it’s run and the cam and lifters look much different when they have been cryo’d.

It’s a couple of weeks turn around including shipping both ways. 300 Below is usually 3-4 days to get them done.

Absolutely worth the money and the extra time.
 
Post #14. You cannot put an EDM hole in hyd lifters....& the OP is using hyd lifters.
 
Newbomb Turk said:
You’re best bet is to send the cam and lifters to 300 Below and get them both cryogenically treated.

Its relatively inexpensive and it’s the single best thing you can do to increase your chances of not having a failure.

Yes, I’ve done it and yes I do it and yes, I’ve pulled stuff apart after it’s run and the cam and lifters look much different when they have been cryo’d.

It’s a couple of weeks turn around including shipping both ways. 300 Below is usually 3-4 days to get them done.

Absolutely worth the money and the extra time.
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Can you give us a ball park $$$$?
 
Bewy said:
Post #14. You cannot put an EDM hole in hyd lifters....& the OP is using hyd lifters.
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No, but you can get some with a flat ground down the side. My experience with them wasn't good.
 
Using a Dremel, I have been grinding the flat on FT lifters for well over 20 yrs.
In my opinion, none of these 'fixes' are really necessary, they just make you feel good....
Another marketing gimmick...
 
Bewy said:
Using a Dremel, I have been grinding the flat on FT lifters for well over 20 yrs.
In my opinion, none of these 'fixes' are really necessary, they just make you feel good....
Another marketing gimmick...
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IMO on hydraulics, it reduces the plunger efficiency.
 
RustyRatRod said:
Can you give us a ball park $$$$?
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Pricing is based on pieces. So it’s cheaper if you do the cam and lifters together. I did the cam and lifters together and it was 150 bucks. Then, I didn’t use that cam and had to send the other cam in and that was $125.00 all by itself.
 
Newbomb Turk said:
Pricing is based on pieces. So it’s cheaper if you do the cam and lifters together. I did the cam and lifters together and it was 150 bucks. Then, I didn’t use that cam and had to send the other cam in and that was $125.00 all by itself.
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That's pretty reasonable. Besides increased durability are there any other benefits? Less friction and heat, possibly?
 
I will say that I saw the difference between a cryo treated cam and untreated while Tim was switching intakes on the dyno. Both were near identical 408 builds (cams/valve springs) and the treated cam looked brand new after break in and 30 or so pulls where as the untreated showed normal wear.
 
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