[dataway]

Originally Posted by torqhead

What he said, looking at the one shot you have that includes the crossover on the drivers side you can see black soot like possibly exhaust leak.

Yep, I'd like to see both sides of the gasket at the cross over to look for carbon tracking. As everyone here knows, exhaust leaks can sound freakishly like a mechanical tick of some sort.

[glhs#116]

Well, gentlemen, the one thing I thought I HAD eliminated was the possibility of it being the exhaust crossover. The carbon you see is because my '71 crossover has a large hole on one side and a small hole on the other whereas the gasket only has the small holes both sides. But I hear you. And there are certainly times when I'm driving and listening to it and thinking "that sure could be exhaust leak". I didn't check the backside of those gaskets.

What I did do was guarantee a rerun of this whole deal when my gaskets and stuff arrive. See, I had hoped the valley pan gasket would stay on the valley pan (I had initially cemented it on there) but I guess all the splashed oil was too much for that. When I removed the valley pan the gasket pretty much stayed behind. But on the passenger side it wasn't quite "sticking" to the head and I was afraid of it slipping down when I put the pan back on. Now I COULD have and doubtless SHOULD have carefully peeled the whole thing off, then carefully cleaned and degreased the valley pan, then carefully cemented it on again. But it was SO close to being in the right place that I just put an upside down small piece of electrical tape under it that side to stick it to the intake manifold gasket until it was bolted in. I guess you can see this coming, I now have a coolant leak at the crossover that side even with the bolts tightened down (I've since backed them off a little). Yup, just a little piece of electrical tape was enough to upset the seal. I guess I figured the intake gaskets were more flexible than they are.

So, the car's going to sit there until I have a timing cover gasket set and new intake gaskets. A cam and set of lifters will come in the same order. I'll be taking it all the way down and probably just replacing the cam and lifters. I hate to throw parts at a problem but it just takes so much to strip the engine down and then I can't even leave it that way because of the dust. If I have to be in and out I'm going to hit all the main things I can think of.

I don't think I'm buying the loose cam retainer. It isn't loctited but it is torqued to spec (and a new retainer with new bolts) so since this made noise from day 1 I don't see it loosening that quickly and then not loosening any further. Plus, visually the cam seems in position.

That fuel line is a real gotcha. I found that out when I bumped the engine over. Splurt! Darn it, that's one time when an electric fuel pump would be convenient.

Intake hanging up on the valley pan gasket? Not so sure. The valley gasket is thin and cork. I'm sure the gaskets themselves didn't overlap.

Tom, the shields are on the exhaust valves because my guides are only machined for positive seals on the intakes. I figured it would help the o rings as per the stock design.

Sam

[steve25]

Sam , any signs that you have a bum spark plug that's leaking Around the shank seal until it gets hot enough to seal?

[torqhead]

Agree Sam, probably not a retainer based on what you said. It sure looks like that crossover is potentially the culprit. If I recall correctly there are at least a two versions of the intake gasket where that center crossover port is small in one case and the other version is where their closer to intake runner size. You could consider using a sealer if you’ve got pitting or anything on the head or intake in that area to ensure you get a good seal.

[gtofreek]

Originally Posted by glhs#116

Well, gentlemen, the one thing I thought I HAD eliminated was the possibility of it being the exhaust crossover. The carbon you see is because my '71 crossover has a large hole on one side and a small hole on the other whereas the gasket only has the small holes both sides. But I hear you. And there are certainly times when I'm driving and listening to it and thinking "that sure could be exhaust leak". I didn't check the backside of those gaskets.

What I did do was guarantee a rerun of this whole deal when my gaskets and stuff arrive. See, I had hoped the valley pan gasket would stay on the valley pan (I had initially cemented it on there) but I guess all the splashed oil was too much for that. When I removed the valley pan the gasket pretty much stayed behind. But on the passenger side it wasn't quite "sticking" to the head and I was afraid of it slipping down when I put the pan back on. Now I COULD have and doubtless SHOULD have carefully peeled the whole thing off, then carefully cleaned and degreased the valley pan, then carefully cemented it on again. But it was SO close to being in the right place that I just put an upside down small piece of electrical tape under it that side to stick it to the intake manifold gasket until it was bolted in. I guess you can see this coming, I now have a coolant leak at the crossover that side even with the bolts tightened down (I've since backed them off a little). Yup, just a little piece of electrical tape was enough to upset the seal. I guess I figured the intake gaskets were more flexible than they are.

So, the car's going to sit there until I have a timing cover gasket set and new intake gaskets. A cam and set of lifters will come in the same order. I'll be taking it all the way down and probably just replacing the cam and lifters. I hate to throw parts at a problem but it just takes so much to strip the engine down and then I can't even leave it that way because of the dust. If I have to be in and out I'm going to hit all the main things I can think of.

I don't think I'm buying the loose cam retainer. It isn't loctited but it is torqued to spec (and a new retainer with new bolts) so since this made noise from day 1 I don't see it loosening that quickly and then not loosening any further. Plus, visually the cam seems in position.

That fuel line is a real gotcha. I found that out when I bumped the engine over. Splurt! Darn it, that's one time when an electric fuel pump would be convenient.

Intake hanging up on the valley pan gasket? Not so sure. The valley gasket is thin and cork. I'm sure the gaskets themselves didn't overlap.

Tom, the shields are on the exhaust valves because my guides are only machined for positive seals on the intakes. I figured it would help the o rings as per the stock design.

Sam

If that's a new cam retainer plate, pull it off and check it for wear. The new ones I've seen were warped and didn't give any cam end play. If your's is like that, it could have worn that plate. Not saying this is your noise, just a warning while you're in there. Also, any runout on the closing side of the base circle will prevent the lifter from refilling like it's supposed to, so the lifter will be noisy.

[LeGoaT/As]

Good morning, Sam,

I was looking through your thread and went back to your post #221. The one that shows the heads on the block with the intake gaskets installed. The next picture shows the cross over set in place. It looks to me like the I can still see the head surface above the cross over. Going by that, if you were to replace the intake gaskets with a set that has the small square hole for the cross over this would seal that area up.

Lynn

[glhs#116]

Originally Posted by gtofreek

If that's a new cam retainer plate, pull it off and check it for wear. The new ones I've seen were warped and didn't give any cam end play. If your's is like that, it could have worn that plate. Not saying this is your noise, just a warning while you're in there. Also, any runout on the closing side of the base circle will prevent the lifter from refilling like it's supposed to, so the lifter will be noisy.

Paul,

Thanks for the suggestion. I will certainly look at the cam plate when I take this apart. One thing, what do you mean about "runout on the closing side of the base circle?" I understand all the words but I still don't know what you are saying. Can you let me know what I should look for?

Thanks!

Sam

[glhs#116]

Originally Posted by LeGoaT/As

Good morning, Sam,

I was looking through your thread and went back to your post #221. The one that shows the heads on the block with the intake gaskets installed. The next picture shows the cross over set in place. It looks to me like the I can still see the head surface above the cross over. Going by that, if you were to replace the intake gaskets with a set that has the small square hole for the cross over this would seal that area up.

Lynn

Pretty sure that's just the silver heat-proof gasket you are seeing there.

Sam

[steve25]

Sam what Paul is talking about is if just the closing side of the base circle of any given lobe is warn, in effect not a perfect circle any more , then that can make for lifter noise.

[glhs#116]

Originally Posted by gtofreek

Also, any runout on the closing side of the base circle will prevent the lifter from refilling like it's supposed to, so the lifter will be noisy.

Paul,

Just thinking about this some more. If you are asking about whether the cam is non-straight or the grind non-centred. In other words, if the lift varies whilst the cam is on the base circle. In that case I can safely say that I didn't see any evidence of that when I was degreeing the cam.

Sam

[LeGoaT/As]

Originally Posted by glhs#116

Pretty sure that's just the silver heat-proof gasket you are seeing there.

Sam

I see it now, my mistake.

Lynn

[gtofreek]

Originally Posted by glhs#116

Paul,

Thanks for the suggestion. I will certainly look at the cam plate when I take this apart. One thing, what do you mean about "runout on the closing side of the base circle?" I understand all the words but I still don't know what you are saying. Can you let me know what I should look for?

Thanks!

Sam

When you degree it you will see the dial indicator move about .001", or even more in extreme cases, as the lifter goes around the base circle. It's real important that the cam and lifter are clean and dry so there is nothing influencing it.

[glhs#116]

OK. Well, I've been busy for a while and then the site had issues. So I've got pictures but way too many at this point. Let me try to cover (and remember) everything so far.

As promised, I actually went and threw ANOTHER new 702 Voodoo cam in there with a new set of Lunati lifters. On the teardown I did notice one thing. A couple of the pushrods seem to have some contact even though these are 1.5 rockers



I had a pretty good look at the eccentric, timing chain, cam plate, position of cam, rockers, springs, couldn't see anything that looked bad.

I broke in the cam and dumped the oil after the twenty minute breakin. Filter was clean, oil looked good. The tick was even louder. But car still ran great.

I got to thinking, what if I messed up on the calculation for the length of my new pushrods. Well, now that I actually had my old Melling and my just-replaced Voodoo out I was able to re-measure the base circles and re-calculate and I came up with basically the same number. But I still wanted to be sure so I did the marker thing


Darned if that doesn't look right on the money too. Did another lash adjustment, drove it some more. It is definitely getting louder. It's kind of moved from where it bugs me but people don't notice to the sort of thing that any random person would hear and say, "Do you hear that? Is that supposed to sound like that?"

Since I had the intake off and on I was able to assess the gasket seal. Crossover is definitely sealed up tight as a drum. I took another look at the downpipes where they mate to the RA manifolds. There is a bit of a leak on passenger side but I made it better and it didn't change the very mechanical sound.

I replaced the spark plugs. Twice, actually. I saw #6 look a little dirty like maybe it wasn't firing and replaced that spark plug lead. I also started the car eight times removing a different spark lead each time (got tired of doing with the engine running and getting zapped). No change in the sound nor much in the way it idles. I thought about torque converter bolts although I have had that before and it's usually loud near idle and not at speed. My sound is as loud at speed as at idle. Anyway, torque converter bolts are tight.

I know it isn't anywhere in the front accessories because I get the sound with no belts on. It seems to be really internal because it is loudest from the oil pan or valley pan. I've replaced the fuel pump, yes twice.

I had some refusal to rev over 4000 or so at full throttle. Getting a bit farty. But when I kept in it it came back to itself and pulled strongly to 5000 plus in third. Obviously it's hard to do that kind of testing much in town. I was a little excited it might be valve spring or something at first but that wouldn't clear itself up. Probably just the secondary air flap sticking or something. Plus, these valve springs are less than ten years old.

I've double-checked with the slo-mo and it is definitely at every second revolution. So really there's ignition events like a rod (which should get quiet with the spark plug lead pulling) and there's the cam-speed stuff like cam, lifters, rockers, timing chain, fuel pump, oil pump...

I'm really stumped and really really frustrated. Since I've established that the cam isn't going away, it seems unlikely to be rods, and the torque converter is firmly attached I'm mostly minded to keep driving it until it gets loud enough to be obvious or break whatever it is. Oil pressure good, temps staying good, it does idle a bit unevenly but not much.

To really make this nice I have to pass inspection with it the next week or so. I've got rust holes and everything to take care of. It's really driving me round the bend!

Sam

[MXTex]

Fascinating thread. You've confirmed that the sound occurs on every second revolution of the crankshaft. So in my simply mind, this narrows down the search to the cam or anything driven from it. You've replaced the cam, lifters and oil pump so perhaps those can be ruled out as well. If it were mine, next step would be to remove the mechanical fuel pump and get it to run with a temporary/auxiliary electric fuel pump. This way you can eliminate the fuel pump lever/eccentric interface as the issue.

[dataway]

I think he's ruled out the fuel pump and eccentric in previous examinations.

Every other revolution could still be based on combustion, which happens in each cylinder every other revolution.

I'm still following this thread, very interesting .... I'm still betting on ... exhaust leak. He has pulled plugs which would rule out individual cylinder combustion and possibly rod knock or slap ... but what about the possibility of exhaust in the center ports crossing over to adjacent cylinder exhaust port. If that is even possible.

[steve25]

Any chance it's the sound of the pvc valve rattling?
You can check in 2 seconds by crimping the hose off!

[glhs#116]

OK. Well something is up. I sealed up my exhaust much better. I had installed the new downpipes with clamps and I took it all apart and puttyed up the joints. Now my only remaining exhaust leak is a small one at the front of the passenger side downpipe to manifold joint.

Anyway, went out for a test drive and there was less traffic. So I tried it in second and it is again farting out around 4000 in second. Shift to third and it pulls strong (obviously can't really top out third). I pull onto a side road also empty. Tried a roll from first. Same farting out and losing power around 4000 in first and second so not fuel. Afterwards, the tick is a lot louder and the engine more feels like it is running unevenly. I could imagine a valve spring breaking but wouldn't I need a problem with all the valve springs to suddenly have a sort of rev limiter on the car. A few hundred miles ago and it was up over 5000rpm easily.

Anyway, the saga continues. Would be great if it wasn't just stupid amounts of heat and humidity right now.

Sam

[steve25]

I guess you could have a one or more broken inner springs which might be hard to see such!

I have also seen valve springs busted way up at the very last coil which means that you can not see the failure when the retainer is in place!

Can you now pin down better where the noise is coming from since its unfortunately louder?

Sam are you 200% sure on the firing order as it quite possible to have it be off in such a way that the motor will start normal, not back fire thru the Carb, but yet not rpm and get ruffed in the way it runs as the rpm's do go up .

[glhs#116]

So here's a clip of the noise as it is now:
https://youtu.be/WnjFGBBkOlA

[glhs#116]

What I did yesterday (which was one of the most humid days of the summer so far - it was brutal) was a sort of ignition system r and r. I put in a new GM HEI module and a new GM coil. I made up a new set of MSD wires and put them all in. Along the way I did find one loose spark plug but I tightened them all down. The video above is after all of this work.

The car was much more even (probably the loose spark plug was a factor). It was also more alert. Maybe the old coil wasn't 100% or something. Or the wires. However, the noise is still there and loud. Test drive was difficult since the roads weren't very clear but I did get it up in second enough to still hit my new 4000rpm "rev limiter". Still, I'm not 100% sure it's related. I still think it might be more something to do with the secondary air door flap.

Anyway, by the time I fix this there sure will be a whole bunch new stuff on the car...



Yeah, the job took a while. Did I mention all the humidity?




Sam