cam break in

[moparker]

Got a new Lunati cam in the Duster. Lunati said to break in with the single valve springs then put the centers in after. I have talked to a lot of guys who never have done it that way. They installed the doubles and broke it in that way. Let me know what you guys think. Thanks

 

[Dustert73]

Usually can't go wrong with the instructions

 

[duster360]

Better safe than sorry.

 

[70aarcuda]

Never have removed the inners....broke in many cams that way...
Broke in a Hughes 6064 last week like that...

 

[tekslk]

Broke mine in using the doubles, not a problem.

 

[nm9stheham]

Is that a .40 lift cam, Tony? OP, what total lift and rocker ratio? Do you know your open spring pressure? All that can be a factor.

I have never removed inners or dampers either, on a few .48 to .50 lift cams. But all these recent year cam break-in problems have me a bit spooked. Not sure what has changed (besides the zinc thing) unless guys are just running a lot more lift and spring pressure in general than in decades past. Cam failures happened in days gone by, but not anywhere like it seems happens in this day and age.

I'll probably go with the lighter break-in springs this time... 'just because'.

 

[70aarcuda]

Is that a .40 lift cam, Tony? OP, what total lift and rocker ratio? Do you know your open spring pressure? All that can be a factor.

I have never removed inners or dampers either, on a few .48 to .50 lift cams. But all these recent year cam break-in problems have me a bit spooked. Not sure what has changed (besides the zinc thing) unless guys are just running a lot more lift and spring pressure in general than in decades past. Cam failures happened in days gone by, but not anywhere like it seems happens in this day and age.

I'll probably go with the lighter break-in springs this time... 'just because'.

Cam is a Hughes 260/264....with 1.6 rockers.....about .656/.662 lift...minus the lash and the 59 vs 48 degree of the valve train....spring are PAC 1903 140 lbs on the seat at installed height of 1.80 and were set at 1.80...open pressure is 394.....

Spring are the ones Hughes recommends for that cam.....

https://www.racingsprings.com/Hot-Rod-Series-Springs/PAC-1903/Item/1670

 

[fishmens67]

if the springs have high open pressure, inner spring should be removed.
the cam may live longer.

 

[diymirage]

you only spend a few hundred dollars on that cam and lifters
whats another few hundred to do it all again if you wipe a lobe during break in?


I'm sure many people have gotten by with it, but why would you stack the deck against yourself?

its kinda the same question as saying "the instructions say to use break-in oil but I don't want to"

 

[skrews]

^^^ This.

 

[70aarcuda]

Never have removed the inners....broke in many cams that way...
Broke in a Hughes 6064 last week like that...

Did a Mopar 590 in the same engine about a year and half ago...same thing...dual springs..

 

[cdlbrown]

Remove the inner springs. It's not worth the risk.

 

[moparker]

I will go with the singles. I do not want to do this again.

 

[nm9stheham]

Cam is a Hughes 260/264....with 1.6 rockers.....about .656/.662 lift...minus the lash and the 59 vs 48 degree of the valve train....spring are PAC 1903 140 lbs on the seat at installed height of 1.80 and were set at 1.80...open pressure is 394.....

Spring are the ones Hughes recommends for that cam.....

Hmmmm... that is a bunch of everything!

 

[jerry6]

You could get lucky and no problem with the dual springs , it's safer to use the single spring , more work yes , but might be cheaper in the long run not having to replace a cam .