Question : CAM timing - front vs rear

[Kihlmenow]

My apologies if this is a stupid question, but after reading the Sticky, I was left wondering the exact order in which to tighten down the CAM gears.

I'm working on a 95 3.4...I get the flats up hold downs front and rear to start, but then there is mention of rear exhaust timing after turning the crank 360 degrees, all after reinstalling the idlers and tension pulleys.

So the question, is when do I tighten the front intake and exhaust? The rear exhaust is apparently after 360 degree crank turn for timing, but what about the rear intake?

This car would be fine with stock timing, I don't plan on keeping it, so when would I tighten down the CAM gears for stock timing?

It was a long day, maybe tomorrow I'll think I'm a dumb a$$, but better to ask twice and fix it once then the other way around. I'm old school small block chevy, 18436572, I don't have a lot of wrench time on OHCs.

Thanks for your patience.
Kihl

Alright, a little more research....so If I understand correctly, TDC with front flats up, lock down front CAM gears. 360 degrees with rear CAM gears loose, rear flats down, tighten rear CAM gears. Is that correct? Thanks again

[pocket-rocket]

It doesn't really matter if you tighten fronts or rears down first as long as the cams are 180 degrees from each other (360 crank degrees). When you are done when one bank has the flats up the other should have the flats down. Which ever you chose to set first, both intake and exhaust get tightened down at the same time.

So basically:

1) All 4 cam flats up and hold downs in place
2) #1 TDC
3) Install belt, idlers and tensioner pulley
4) Pull the pin on the actuator, set tension on tensioner pulley like the sticky mentions and rotate the engine BY HAND a couple revolutions on the crank to work out any slack in the belt. Using the starter is a no-no. The gears can catch and rip the threads for the hold downs right out of the cam carriers. Ask me how I know...
5) Lock down one bank (your choice, front or rear) and remove hold down.
6) Rotate crank 360 degrees
7) Lock down other bank and remove hold down

Which bank you lock down first really doesn't matter. The thing that matters is that the front and rear bank are 180 degrees from each other, otherwise you get two cylinders firing at once. I know I'm repeating myself, but that's the biggest thing that confuses people on this engine. Hope this helps

Also, welcome to the site, and 123456

[Kihlmenow]

Awesome! Thank you for that clarification! I guess I just didn't expect it to be quite that simple. I always try to apply the rule of KISS, even working on computers all day, but there is a fine line between Keeping It Simple....and Simple Minded. lol

Even your firing order is simple...see what I mean?

Thanks for the welcome, and thanks again, much appreciated.

Kihl

[Kihlmenow]

Well, this belt replacement is a story in itself. 1/2 of the belt was gone (width), and a bunch of nubs were gone right on the crank gear, which is why it died, AND why I'm redoing the CAM timing. Everything else is in amazingly good condition, I got a coffee can full of fuzz and belt chunks.

Question, any alternatives to the official CAM gear tool? Any work arounds that are feasable without damaging the gears? At $250-300, I do not want to own these tools, but neither does anyone else to rent them out. Which leaves me in a bind. I have created my own flats tool, no problem, it the gears that are an issue.

If anyone has any ideas/workarounds I'd love to hear them. In the meantime I'll be testing some ideas of my own. Just thought I'd ask.

Thanks for any input/thoughts on this!

[pocket-rocket]

If you dig around you can find some posts on making some of the tools required to do this. The easiest is the hold down tools.

http://60degreev6.com/content.php/25-Make-your-own-cam-hold-down-tools

As far as the other parts, the only one you need is the cam GEAR holder (different than the hold down). It holds the cam gear in place so when you are honking down on the cam gear bolt you don't rip the hold down threads out from the torque. It has 3 fingers and fits into the holes on the inside of the pulley. You won't need pullers because 94+ engines don't have lockrings like the 91-93. They have tapered collettes that hold the gear in place on the end of the cam by way of friction from the bolt. Simply loosen the bolt, take a 2x4 and put it on the back side of the pulley (drivers side) and smack the end of the 2by with a hammer to knock the gear loose.

In this pic you can see the guys right hand holding ratchet attached to the cam gear holder and the socket for the cam gear going through the hole on the holder.



I know what you are going through, but when the belt shredded at the bottom pulley, the rest of the belt looked fine so I was freaked out thinking the timing chain broke (yes, this engine has a timing chain too, part of the carry over from the pushrod design but left in place to drive the OHC and oil pump). We got a crash course in belt changes that weekend, lol.