[novaboy009]

Just swapped my good heads, camshaft and 1.6 roller rockers onto my junk 350. Fires up and runs okay, but not below 1200 rpm or so - wants to die a lot. Engine goes down the road, but has no power. Feels like the timing is way off, but it's not.

When I installed the timing chain, I installed with dot on the cam gear on top (12 oclock), instead of on bottom and pointing right at the crank gear. I didn't think it would matter because you have to spin the motor 360 around to get back to TDC if I remember correctly - 12 oclock position. Crank spins twice as fast as cam, so they should line up at 12 oclock and 6 oclock if my thinking is right. Please correct me if I'm wrong and I'll pull the timing chain back off.

I found TDC by putting a napkin in the #1 hole and spinning the motor until it popped out. Lined up TDC a few degrees later and dropped the dizzy in. Timing is at about 20 BTDC at 1200 rpm. Any less than 1200 and it wants to die. This is a 218/218 cam, so it should idle at 600 rpm without any problems.

I've been through the valves at three times. Set them cold using the pull up and down method until slack is out, then another 1/4 turn for a little pre load. Thought the valves might be too tight. Set them again using the rotate until they stop spinning method (warmed up engine this time). Set again after reverifying TDC today. Didn't really change much from the last adjustment.

I'm hearing a little clacking out of the one valve cover, not sure what that's all about. I don't think the rockers are hitting and nothing seems loose. Might just be the exhaust leaking again - but that usually sounds like a tick more than a clack. Pushrods were all spinning when I lifted the valve covers during cam break in.

Where should I look next??? Carb hasn't been touched since coming off a perfectly fine mostly stock 350.

I'm running out of ideas! Help!!!

Kev

 

[levisnteeshirt]

what

timing chain did you use ?? I think if it was me , i'd take it back apart and make sure those timing marks line up this time....

since its a single pattern cam , you can check to see if the cam is close to being in time by comparing the rockers when #1 is on TDC but in overlap. They should be close to being depressed equally at this point. It depends if you used a new timing chain that has no strech , that kinda thing , but they should be close

 

[1969NovaSS]

What size cam are you running with what duration and what is your compression? I had a 350 out of a 74 Impala. Motor had between 8.5 / 9 to 1 and I put a low lift rule stock car cam in it. Duration was around 310. Motor wouldnt idle under 1000 as it wanted to die. Didnt have much low end power either. Reason of the compression was to low for the duration of the cam and was bleeding to much off.

 

[Baddbob]

Why not set the timing gears dot to dot??? In theory I guess it wouldn't matter being the cam spins half the revs as the crank but what it you were one tooth off by just eyeballing it at 12 oclock? Have you done a compression test-this would probably shed some light on if the cam timing is right. The engine will run (but like crap) if you're 180 degrees off on the distributor-seen that happen a few times. And that cam should run with way less timing like you say. Is this a three keyway crank sprocket timing set? maybe it was stamped/marked wrong. Given the info you posted I agree it's mostlikely cam timing or a spark timing problem. Time to start checking stuff.

 

[novaboy009]

This was a three keyway deal. Set the 0 mark on the crank sprocket over the crank keyway. Dot on the sprocket ended up at 12 oclock like normal. Instead of lining the cam gear down at 6 oclock and spinning the engine around again to get to TDC #1, I took a straight edge and lined up 12 oclock on the cam gear with 12 oclock on the crank gear.

I found TDC using the napkin popping trick. It does seem like it's running like 180 out, but I'm 98% sure it's right. It starts right up and runs okay, just won't idle and down on power. Timing is pretty close at 20 degrees (since mechanical advance is starting to come in).

Looks like I'm gonna have to tear the front of the engine back down and check my timing chain - just for my own sanity.

Kev

 

[veno]

valve lash. are you sure of it.... try adding some more timing too.....

 

[Paul Wright]

My first guess is the cam timing is off or you used the wrong dots if it's a 3 way.
While you are correct that you could line up the dots opposite, in practice that's very difficult to get right, especially with the engine in the car.

You could put a degree wheel on it before you tear it down. If the cam is in right that will save you some work. If it's not, hopefully you haven't bent any valves.

Do a compression test.

Another guess is your balancer outer ring may have slipped, so check true TDC against the line on the balancer.



If you hear noises under the rocker cover, pull the cover, have someone bar the engine slowly over while you look closely at all 16. You've had a lot of broken valve springs for some reason and I don't think we ever found out why. I think the pushrods slots were elongated for 1.6 rockers so the pushrods shouldn't be binding. Better check that anyway.

I wouldn't ignore carburation. A stock 350 and one with good heads and a cam require different fuel curves. It could be real lean. Have you checked the plugs?
If the carb sat, the gas may have turned to shellac. It could even have a spider nest or just plain crap in it.

Make a list and systematically go through all the variables.

 

[novaboy009]

I wouldn't think a carb would be lean enough to kill idle and complete down the road power. My A/F gauge looks normal, a touch rich if anything.

Engine was at true TDC when the balacner/timing marks lined up. Double checked it when the heads were off.

I don't have a degree wheel.

I can do a compression check, but I bet it's low because of valves or cam timing. Wouldn't really tell me much, but I could do it. I bet I lined it up a tooth off.....

Kev

 

[Ironman]

I always line up dot to dot.

I have a degree wheel if you want to borrow it. I'd come over but I am knee deep in work the next few days.

 

[D-Man]

I wouldn't think a carb would be lean enough to kill idle and complete down the road power. My A/F gauge looks normal, a touch rich if anything.

Engine was at true TDC when the balacner/timing marks lined up. Double checked it when the heads were off.

I don't have a degree wheel.

I can do a compression check, but I bet it's low because of valves or cam timing. Wouldn't really tell me much, but I could do it. I bet I lined it up a tooth off.....

Kev

That's a lot easier to do when you do the 12 and 12 o'clock dot position install. When you do the dot-to-dot (12 and 6) install the little differences and easier to see.:yes:

Either way, 5 minutes with a degree wheel and a piston stop would have caught it.:yes: Still could and might save you from tearing apart the engine if you don't need to.

In my experience, an engine that doesn't want to idle is usually facing a lean idle condition more times than not is a vacuum leak.:yes: Throw a rag over the carb and see it the idle picks up at all.

 

[71SS454]

A couple of things I'd do is relash your valves. A 1/4 turn on a hydraulic usually isn't enough preload. I usually go 1/2 to 3/4 turns. If you don't have enough preload and your lifters are pumping up early, this will cause your engoune to be down on power.

Also definately check for vacuum leaks. Make sure you didn't do something simple like forgetting a plug somewhere on the intake. I forget the one on the back of the plenum once (where the power brakes would of hooked up) and spent the better part of ther day trying to figure out why the engine wouldn't run right.

Then I'd tear into the engine and recheck the timing chain. Is it a good tight chain? Does it have alot of stretch to it? Are the right dots really lined up?

 

[novaboy009]

I've hosed the thing down with starter fluid. Nothing. Put my hands over the carb and it dies immediately. Double checked all my vac points - trans modulator, vac advance, intake, carb gaskets, pcv. Nothing doin'???

Kev

 

[D-Man]

Sounds like it's time to put a degree wheel on it and see if it is in fact a tooth off.:yes:

If it's not off then you KNOW you've got either a lash or tuning issue.

 

[The Big Al]

What about this clacking noise??

Are you sure you did not wipe a cam lobe?

Are all rocker arms moving the same?

Is plug wire 5-7 crossed?

Spray wd-40 around the intake while running check for leaks.

Put a vacuum gauge on it.

What "O" mark did you use?
One at the teeth or at the crank key when lining up the gear?

 

[The Big Al]

If you have a the cam specs and a dial indicator you can check cam timing without tear down.

Al

 

[Ironman]

Any updates there Kev?