Went to buy a 3.9 cam yesterday to replace my 3.5 cam and the guy behind the counter talked me out of it. My truck has at least 180k miles on it and it seems tired. I dont think the cam has ever been changed. The sales guy told me that unless I was hearing knocking from the lifters then there is no reason to change the cam. I'm thinking that after 180k whats the harm? And changing from the original 3.5 cam to the 3.9 would give me at least a little performance gain. Should I only change it out if I hear lifters knocking?

How many miles on the timing chain?

At 180K, you're on borrowed time on several fronts!

If you want to be overly anal about it, pull a valve cover and measure the lift on a coupla lobes and go from there. My experience has been that you will find a coupla lobes near the back of the engine badly worn. Last year when I needed an engine for Shopgrrl's truck, I went through every engine I had and none of them had a good camshaft! The engine out of Discochef's truck had one lobe almost gone.

At 180K, while your engine may have many, many more miles in it, if you've noticed a diminution of performance and you wish to keep the vehicle, it may be worth it to you to re-ring it as well.

PT

How many miles on the timing chain?

Not sure but I was going to buy a new timing chain also.
The guy I bought the truck from had some work done to it in South Africa but I think he just had the LT85 put in it there, I dont think he did any engine work. I am going to try and track down the previous owner today and pick his brain. My thought is that it cant hurt and probably needs it anyway.

PT, thanks I will look into that. I have a few trips coming up in the next few months and I dont want to get in over my head before then otherwise I will be driving my wifes Disco. Priority #1 right now is making some sliders before next weeks run. Thanks all for the input. I think I will go ahead and get the cam, lifters, chain etc...

Kevin:
Before committing to a stock cam, give Crower a call. I'd be very surprised if they couldn't get you a cam with a profile close to that of the 3.9 for considerably less than what an OEM cam would cost. IIRC, their cams run around $135. The best and least expensive chain and gears is available from D&D, get the double roller!

PT

You don't just go the the local shop and get chain & gears for a Buick?

I haven't changed the 3.9's timing gear, but that's what I did on the 3.5???

Told the kid I needed timing set for a '64 Tempest, or whatever...w/ a 215.

Installed "straight up" too, no retard. Sssh, don't tell Jimmy :)

KAA

You don't just go the the local shop and get chain & gears for a Buick?

I haven't changed the 3.9's timing gear, but that's what I did on the 3.5???

Told the kid I needed timing set for a '64 Tempest, or whatever...w/ a 215.

Installed "straight up" too, no retard. Sssh, don't tell Jimmy :)

KAA
You can get a nice double roller from Summit for less than 50.00. :D

Cool!!! And I see three keyways too :)

Almost makes me want to take the 3.9 apart just for fun ... almost :)

That is not the correct picture for a Rover cam gear. It looks suspiciously like it belongs on a SBC...

Thanx, OS!

The Crower cam for a 215 buick works fine although it has a different base circle and to operate correctly you need to shim the rocker arms to get the correct pre-load on the lifters (if you use Rover lifters) I think if you use Crower lifters (I have no idea what the difference is, but they are much,much less $$'s) they claim you dont need to shim. DO use NEW lifters.
Pt is right about the timing gear/chain...I got a set from summit once and you wouldn't have been able to fit them with a BFH. I think the set from D&D has the multiple keyways to fiddle with.

Matt Browne
Overland Engineering