LT5 Assembly Project

[A26B]

Lee,
No one else has chimed in on the cam damage, so I will offer my 2 cents.

I am concerned about the integrity of the cam and re-using it. The cam nose design was modified for the later 405 Hp engine to add a second flat to address problems with the sprocket/vernier assy security to the camshaft. The bolt does hold the assy axially secure to the camshaft but does little if anything to secure it radially. That job is the function of the flat. With the amount of slack shown in your video, it is evident that the flat is damaged and does not have the fit & surface contact area as intended. You can time the cam with the slack taken out, but under operational load, it will have a higher propensity for failure. There may also be cracks that are not visible, further affecting structural integrity.

It may not immediately break the cam nose off when it fails, but at a minimum, when the flat shears and the sprocket/vernier rotates on the camshaft, metallic particulate will be released into the crankcase.

I would not use that camshaft in a new engine.

[LGAFF]

Thanks Jerry,

I was concernd also, thats alot of play in the cams. I was also wondering if this was part of the issue with cam timing variance, or is that related to chain stretch?

Anyone have pics of the 405 hp cam snouts?

LGAFF
92 ZR1
#234

[lbszr]

Originally Posted by LGAFF

Thanks Jerry,

I was concernd also, thats alot of play in the cams. I was also wondering if this was part of the issue with cam timing variance, or is that related to chain stretch?

Anyone have pics of the 405 hp cam snouts?

LGAFF
92 ZR1
#234

From Marc's website there's a 3 degree play with the pin in. The fine adjustment is done by holding fixed and torquing cam bolt, which is very tight. His website also talks about other variances that can affect timing.

So in theory, it doesn't need the pin. Just helps in adjustment.

I went through 4 bolts on one cam to get it right on the money at $25 a bolt since there not suppose to be retorqued. The other three didn't put up a fight like that one.

[8upZR1]

I dont think the damage is of concern cause its the bolt that holds the gear to the cam. Ive seen quite a few DOHC 4.6L & 5.4L Ford motors that are used for endurance racing. No keyways what so ever. If the bolt were to loosen, the sprocket would spin. The engine builder has quite a class wins in 12 & 24 HR deals so when I saw it I was dumb struck. I had spent the majority of the previous week in the machine shop fabbing custom offset keyways for my 4.6L, which was apparently a waste of time.

Haibek has reuseable ARP bolts for cam sproket.

[Pete]

Originally Posted by 8upZR1

Haibek has reuseable ARP bolts for cam sproket.

I would not reuse the ARP's.
The cam bolts at 19 flbs and 85 degrees is 120-125 flbs our huge head bolts go to 118flbs.

I would not reuse the ARP's or you'll have front cam snouts like Lee's pictures.

Pete

[phrogs]

Originally Posted by Pete

I would not reuse the ARP's.
The cam bolts at 19 flbs and 85 degrees is 120-125 flbs our huge head bolts go to 118flbs.

I would not reuse the ARP's or you'll have front cam snouts like Lee's pictures.

Pete

I tried to use the ARPs and ended up breaking one of them off in the camshaft while torquing it

[LGAFF]

Pete,

Why do you think the cam snout broke? The prior owner stated that the piece came off with little torquing if the bolt.


LGAFF
92 ZR1
#234

[Pete]

I think either he over tighten the cam bolt and the bolt stratched to far at this point the holding power is not there or he under tightened it and was too loose and once he wacked the throttle the cams flat spot hit against the vernier flat and broke the cam.

I have tested over tightening bolts the bolts broke but never broke a cam snout.

Next time your at my garage i will show you cams and vernier plates that moved and beat up the cam flat spot.

I used to have cam slipping issue,until i figured it out.
There is a trick to putting these on so as not to move.
Never had the issue again i have rechecked them after a few thousand miles with no issues.

Phrogs when you broke the bolt did your cam snout break?

Just my opinion.
Pete

[8upZR1]

What trick are you using Pete?

[Pete]

Originally Posted by 8upZR1

What trick are you using Pete?

Lots of Loctite.

Pete