fat bob 09 rev limiter???

dolt

Beg to differ. My stock but ported heads with stock valves and springs in my 95"Deuce, rev limiter set at 6200 rpms (I bump it regularly) and engine is holding up fine. I suppose that if I missed a shift and over revved the engine to >7500, the springs might not be able to keep the lifters on the cam lobes but with springs that would keep the lifters on the cam lobes valve train noise would be louder that I want and the valves would beat up the seats during normal operation.

The stock springs will work just fine in most streetable builds that produce 100TQ/100HP or thereabouts.

Hobbit

there is a vid on youtube which is cannot get (at work ) that shows how much the valve springs move on the stock heads its scary, mine have stronger springs as a precaution and i am running much higher comp than most street builds, i am at 10.6 corrected and as you know i ride a tlot harder than most, so yes a normal riding and hitting limiter everyso often will not be an issue but when your running 6500+ daily it dont do em much good and yes i really do ride this hard i barely use 6th on the mways and do not use 5th/6th when on the back roads i rarely get out of 3rd

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glider

This one?

 


 

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dolt

Seen plenty of videos but none that show erratic valve spring behavior in a Twin Cam at 6200rpms. I just had a problem with such a general statement that indicates that the stock valve train is weak; it's not that bad.

JMHO but I wouldn't build any engine for myself for the street or touring with a corrected CR above 9.5. Most, not all, 95" builds rarely exceed 9.0 corrected CR and the stock springs are up to that task. Once the corrected CR is > than 9.0, more spring pressure should be considered depending on the cam choice.

I am not challenging what works for your riding style but just wanted to make the case for the stock beehive valve springs; they are actually pretty good hardware. They will hold up in a stock application as well as most 95" or 103" big bore upgrades.

Hobbit

i fully understand what your saying and agree but people need to be aware that hard riding can induce float which in turn can reduce the piston and valves to well you know
it may not happen that quickly but it may happen the first run of the limiter - dont ask how i know - not a HD pushrod motor but other first run of the limter i ended up on the back of the recovery vehicle with a scrap head and piston and bore

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dolt

I cannot disagree with such a general statement. However, the original discussion centered around the potential for valve float with stock springs. The point that I was trying to make is that if the rev limiter is set at 5800-6200rpm on a stock or a typical big bore upraded engine with "bolt in" cams, valve float will not occur. The stock beehive springs will hold the valve train together to the rev limit. Any discussion outside this context is a subject for another thread. I have articulated the point I wanted to make and really don't have anything to add so I will leave this one here.