Harmonic dampener to crank snout fit

[tenxal]

How much 'fit' are you guys typically using between the harmonic dampener and crank snout? I've seen anywhere from almost gauge fits to .007 interference fits. Applications are typical n/a drag race, internally balanced SB/BB Chevy engines, driving a conventional 'v' belt to an alternator, RPM's to 7,500-7,800 using high quality aftermarket SFI dampeners (ATI, etc.).

Looking forward to your replies.

[statsystems]

.0008-.0012 and that's all they need. I don't know how you even get .007 on without splitting the damper.

[SupStk]

The dampers usually come with instructions covering the recommended fit. I tend to shoot for .
-.001 thru -.0013".

[Alaskaracer]

I go by the .001" rule....works.....

.007"?? Not even sure you could get that on the crank that tight...

[Walter R. Malik]

How much 'fit' are you guys typically using between the harmonic dampener and crank snout? I've seen anywhere from almost gauge fits to .007 interference fits. Applications are typical n/a drag race, internally balanced SB/BB Chevy engines, driving a conventional 'v' belt to an alternator, RPM's to 7,500-7,800 using high quality aftermarket SFI dampeners (ATI, etc.).

Looking forward to your replies.

WoW -- You have actually witnessed .007" interference ...?
.0035" is the most interference I have ever seen in over 45 years; unless it was some kind of mistake.

I like to see .0009" +/- .0002"

[tenxal]

To clarify, the '.007s' have been honed to better fit the snout before installation.

[peejay]

.0008-.0012 and that's all they need. I don't know how you even get .007 on without splitting the damper.

I had a new damper for an LS engine that had a .004. That was a complete mofo to install. Broke the installation tool, so I went at it with a block of wood and a hammer. Wore out my elbow trying to hammer it on. (It still gives me fits now and then)

Of course I didn't adjust the fit, I was a lot younger and trusted that they meant it to be that tight!

Nowadays, I'd hit it with a hone and be done with it.

[zums]

When dealing directly with a decent company i have them hone for .0012-.0015 interference fit, from 7500-9800 rpm engines i haven't had any issues
Tom

[resurrectionjoe]

ATI instructions

I usually shoot for the tighter side of the spec

IMG_20180114_222836.jpg

[jsgarage]

2X on a 0.0006"-0010" fit. When I bought a Romac elastomeric balencer for a 351-C, the man asked if it was to go onto an Eagle or Scat stroker. He said the crank snouts on those are so severely undersized that Romac makes a special undersized balencer for them. So, snap gauges and a good 1-2.000" mic' is your friend with custom cranks- especially if you shop engine parts on E(vil)-Bay... Most shops caution against hammering a balencer onto a crank. You can destroy a thrust bearing that way.

[modok]

No more than .001" per 1.000" press fit

To ease installing a tight one, rough up the inside a little with some abrasive paper and apply ARP lube to it. A fresh honed finish is fine just as it is, but if it's super-smooth burnished finish in there the lube won't stick.

[Geoff2]

A 0.007" difference means it is not going to go on....

[modok]

It will if you push hard enough

But it's not going to have .007 press after you pull it back off
Might even crack, depending on what it's made of.

[induction apprentice]

I for years have been begging the question why the aftermarket is not producing cranks and dampners splined. I was tickled to see back when they finally started doing it for top fuel and alcohol. But why has it not become an option for popular pro street, bracket engines etc. No puller needed. Why is it Germany Japan, and China have to be the only leaders in common sense?

[swampbuggy]

If that spline was NOT tapered (like an OEM steering wheel)i can not see how it would hold up and not become a problem. Then you would need a puller. Am i missing something? Mark H.