ienotsr

ok...i'm gunna be putting in a new cam along with all new timing gears and chain ,springs, and proform rockers.as soon as my injection system gets here in a couple of days.my question is this.how difficult is the timing part of installing a new cam?

jaykar

If your talking about degreeing your cam and I don't think
you are, A degree wheel and reading up on how to accomplish it as to advance or retard.

Or just installing it correctly, Just line up the dots.

Later

Irocing

ienotsr

all i know is that the instructions that came with the cam talk about hand cranking the engine till one valve is open.then it starts talkin real complicated.

85_305

Uh.. if you don't know what you are doing, don't even bother. You aren't going to do it

jaykar

Are you talking about installing your timing chain?

Adjustings your lifters?

Or timing your Motor after all above has been done
(Correctly).

I think it would be a good idea to get some help from
a knowledgeable friend or mechanic and save yourself
some grief.
If not, myself or someone will walk you thru it

Later

ienotsr

thats just the problem.the instructions are vegue at best on the last steps.i've done cams on overhead engines.just not pushrod.odds are i'll take it too a shop if worse comes to worse.timing chain i can do.lifters isn't a problem.and geting the cam rotated properly isn't either.but the instructions are very confusing.

angel71rs

When the #1 piston is at TDC, #1 or #6 can be at firing position on a sbc. It all depends on the cam timing. What I like to do to make sure timing doesn't end up 180 degrees out:

I loosely install timing tab, balancer, then put the balancer mark at 0 degrees on the timing tab. Lots easier to rotate engine with spark plugs out. Pop off balancer and tab. Then I install the timing gears with the dots aligned. I also like to put a white paint mark on the balancer every 90 degrees. Use the factory original stuff... there are different tab positions depending on year/engine. Use aftermarket stuff and timing tab might not correspond to balancer mark.

I forget what the torque spec is for the 3 cam bolts, but I always give it extra, cause they have a habit of coming loose. Not as common as fords with just the one bolt, but it happens. And I use blue loctite. Install the front cover, balancer, timing tab.

At this point your engine could be at #1 or #6 firing. I'll have the intake manifold off cause I want to eyeball the lifters in the valley. I install them all, but play close attention to the ones for #1 and #6. If both of #1's lifters are all the way down, it's #1 firing. If both of #6's lifters are all the way down, it's at #6 firing. You have to observe carefully cause sometimes it's not that obvious.

If it's at #6, I'll install the pushrods & rockers for #6, then I'll adjust them: twirl the pushrods with your fingers as you tighten the rocker nut. When all the lash is all taken up (I'll presume you're using hyd lifters) you'll feel a slight drag on the pushrod. It's harder when the lifters are new cause they won't be full of oil. Because the manifold is still off, all you have to do is eyeball the pushrod seat on the lifter. As soon as it starts to move down, lash is at zero. You then have to give it the preload. I think the factory lifters are supposed to be 1 turn down from zero lash. I use 1/4 turn, helps delay lifter pump up.

Then I spin the engine by hand to the next 90 degree mark on the balancer (this is why you put the paint marks on the balancer). This is #5 on the firing order. 1-8-3-6-5-7-2. Do #5 pushrod, rockers, adjustments. Do the same for the next 6 cylinders.

When you are done, you will end up on cylinder # 1, ready to drop the distributor in. If when you started you were on #1 vs #6, I'd recommend spinning engine by hand once till the timing mark comes back again so you'll be on 6 and start there. Again this is so when you are done with the lifter adjustments you'll be back on #1, ready for the distributor drop in.

Installing the distributor: your cap has a #1 terminal. Eyeball the distributor before you pull it. Observe it's general orientation, note which wire goes to #1 spark plug. Install the distributor so the rotor ends up pointing at #1 terminal on the cap when it's all the way down. You'll see that the rotor will rotate a little as the distributor gear meshes fully with the cam gear. Just make sure it ends up pointing at #1.

Most times the distributor won't go all the way down, it will sit about 1/4" above it's seat on the intake. This is because the drive tang on the bottom of the distributor isn't engaging the oil pump drive rod under it. You can do 2 things here:

Pull up distributor, look down in the hole, use a long screwdriver to put the slot in the drive rod so it points at #1 terminal on cap. But remember the rotation as the distributor gear engages, so you have to be a little CCW on the slot position. You might have to pull distributor up again to try another adjust on drive rod if it doesn't drop fully.

Or... when the distributor is sitting on there with the rotor aligned with #1 terminal, but the drive rod not engaged, bump the starter a bit. When the distributor drive tang and drive rod slot align, the distributor will drop down on it's own. Pop on the distributor hold down and tighten so you can still turn the distributor with some effort for final timing. And you're there.

Note: I know the manuals say to just put #1 piston at TDC, align the dots on the gears, and you should be at #1 TDC firing. Wrong! Sometimes you are, sometimes you're not, don't know why, but it's true. I can't remember how many times I've seen guys not able to start an engine cause the timing was off 180 degrees due to this.

Note, part deux: don't ever use chrome distributor hold downs, they will slip. Use the factory piece, and make sure bolt doesn't bottom out if using an aftermarket manifold.

Note, part 3, flogging a dead horse: I presume you're working on your 85 305. If so, you're probably installing a flat tappet cam. The 1st few minutes of a flat tappet cam's life are the most dangerous, especially aftermarket cams with higher lift rates. Break it in wrong and you'll probably be doing it again soon with a new cam. First, you need to add a bottle of GM engine oil supplement (EOS). It has extra ZDDP (zinc) and other extreme pressure point lubes to protect the tappet/lobe contact point. The contact point pressure here is so high that no oil can provide proper protection, not even synthetic. After engine starts, don't let it idle, keep the rpms varying from 1,500 to 2,000 to splash the cam for 20 minutes or so. After that, change the oil & filter and it's ready to rock.

One last thing: engine oils used to have plenty of zinc. To protect emissions equipment, govt regs have pretty much mandated the removal of zinc from the latest rating engine oils. They are even pulling it out of diesel oils, which used to be loaded with ZDDP. There has been an increase in flat tappet cam failures due to this. I like to run a good synth with a bottle of CD2 Street Legal Oil Boost. It has a decent load of ZDDP and other EP lubes, and makes for good insurance. I get it for 2 bucks a bottle at Big Lots. STP has ZDDP too, but it's too thick for my preference.

Good luck with your 1st swap, and remember... we were all virgins at one time.

ienotsr

thank you so much.that was so much clearer than the crap instruction that the cam came with.should make my install much easier.thank you again.

jaykar

Good explanation

Later

Irocing