[Stan Weiss]

Originally Posted by Sirrotica

One other thing that I thought of that can cause revision, a clogged exhaust, or catalytic convertor. I have no idea if your cat is still in place, or not, but there is a slight possibility that you have a clogged catalytic convertor. Likely not that it would happen all at once just after a cam change, but a remote possibility.

If you suspect this, loosening the crossover pipe at the exhaust manifolds will confirm your suspicion. You don't need to remove the pipes, just lower them until they leak, and test it.

I just wanted to cover that possibility, even though it's not high up on the things I would check. I have found a handful of times that somehow the exhaust gets restricted internally, causing this same symptom.

I have seen this also.

Originally Posted by Shockwave78

The car has side pipes on it without cats, about as simple as it gets

Still doesn't mean something cannot break inside and cause a blockage.

Stan

["QUICK-SILVER"]

Originally Posted by Shockwave78

why would it be different if the cylinder that was being adjusted was on tdc of the compression stroke? Wouldnt the lifters have to be on the base of the lobe? Im not trying to be stubborn, just genuinely confused as to what difference it would make.

Doing one cylinder at a time at TDC Compression is fine. Following firing order it takes two turns of the crank to get it done. 90° at a time.

Just like the directions posted says to do #1 intake and exhaust when #1 is at TDC Compression.

Clay

[Gach]

Are you more confused then when you started. What you need to do is, have a phone conversation with someone experience who can get whole story and walk you though the steps to get it straightened out. Its nice getting all this suggestions and guys are trying to be helpful lots of times it helps. But until you start with basics and Eliminate things it can be confusing. There’s been a tremendous amount of help here

[78w72]

Originally Posted by Gach

You don’t have to do in the firing order either. When exhaust starts to open adjust intake when intake starts to close adjust exhaust. That way your on heel of the cam in both events.

That is the best way to do it... but for smaller cams, adjusting certain valves at a certain engine position works very well like in the link I posted earlier. I have done that on cams with ~.480 lift as well as stock pontiac cams I made adjustable.

[Shockwave78]

Originally Posted by Gach

Are you more confused then when you started. What you need to do is, have a phone conversation with someone experience who can get whole story and walk you though the steps to get it straightened out. Its nice getting all this suggestions and guys are trying to be helpful lots of times it helps. But until you start with basics and Eliminate things it can be confusing. There’s been a tremendous amount of help here

I wouldn't say I'm more confused, but there is definitely more to think about. I would have never thought of half of this stuff on my own. I do have a buddy that I have been talking to and he has come to many of the same conclusions as here. I'm going to be checking the cam timing off of the timing cover/balancer today if I can get around to it.

[78w72]

Originally Posted by "QUICK-SILVER"

Doing one cylinder at a time at TDC Compression is fine. Following firing order it takes two turns of the crank to get it done. 90° at a time.

Just like the directions posted says to do #1 intake and exhaust when #1 is at TDC Compression.

Clay

Good to know it works on each cylinder.. IF it really is at TDC compression for each one. The link posted only requires 1 complete turn of the crank, then can do multiple valves at each position.

Pull the plugs to make turning it easier or bump the starter to get close, then creep up on TDC by hand.

[Stan Weiss]

This shows the lobe data for the Crane version of the 041 (I got the Cam DR data from Ken Crocie / HO Enterp.) The other is the Chevy 30 30 / Fuelie solid lifter cam. You can see how the TDC method will work for the 041 and not the Chevy.

Stan

[Stan Weiss]

Originally Posted by 78w72

Good to know it works on each cylinder.. IF it really is at TDC compression for each one. The link posted only requires 1 complete turn of the crank, then can do multiple valves at each position.

Pull the plugs to make turning it easier or bump the starter to get close, then creep up on TDC by hand.

If you look at the graph I posted you can see that you be a number of degrees on either side of TDC and both will still be on their base circle.

Stan

[Gach]

Let me explain cam timing hopefully this helps. Lets say cam card says installed at 109. So you think if you put it dot to dot. Piston on top dead center you should be ok. But thats no guarantee that its actually in at 109. This is why you degree a can in, and its the most accurate way of making sure it’s actually in at 109.

I once got a cam from H-O racing, when I installed it, dot to dot. Piston on top dead center. I went crazy, thing had no power and it was a bigger cam then what was in there, so god it should make a little more power and not be slower. Finally degree it in.

Long story short, I degree it in with heads still on, when we checked it, it was supposed to be in at 108. It turn out to be in at 113-1/2. Come to fine out, a whole batch of those H-O Crane cams ended up on a 114 instead of the 108.

So what I’m telling you is checking the timing Marks and piston being at top dead center while a good idea there’s no guarantee that cam is actually in at 109.
It could very well be in at 112-113 which would be really retarded.

But who knows you could be also experiencing valve adjustment issues. If you get the valve adjustment issues straightened out and still have same issue then I would definitely get that cam degree in.

[Gach]

One more thing, if the base circle on the new cam is bigger then old cam, now that push rod is going to be to long, so why I said try going just a 1/4 turn vs 1/2 turn. Kind of Reason we check for push rod length. Made me think of that when he said backing off the nut then did compression test and compression went up to 175. Obviously it was Holding valve open. We don’t always think to look or compare base circle of the cams. And make sure Valve train geometry is correct.

[Shockwave78]

Originally Posted by Gach

One more thing, if the base circle on the new cam is bigger then old cam, now that push rod is going to be to long, so why I said try going just a 1/4 turn vs 1/2 turn. Kind of Reason we check for push rod length. Made me think of that when he said backing off the nut then did compression test and compression went up to 175. Obviously it was Holding valve open. We don’t always think to look or compare base circle of the cams. And make sure Valve train geometry is correct.

I actually did check the base circle difference, the new cam is 1/8 inch smaller than the factory cam

[Stan Weiss]

Originally Posted by Shockwave78

I actually did check the base circle difference, the new cam is 1/8 inch smaller than the factory cam

Unless the factory cam don't use all of the cam bore space, which I am sure it did. Then the only way to increase lobe lift is to reduce base circle diameter.

Stan

[slowbird]

Anyone want to explain post 89? That seems like it could be pointing to an issue.

[Gach]

Originally Posted by Shockwave78

I actually did check the base circle difference, the new cam is 1/8 inch smaller than the factory cam

Smart move. Was you able to check valve train geometry. Other question are those same valve spring as the old cam ? Or you put new ones in.

[Shockwave78]

Originally Posted by Gach

Smart move. Was you able to check valve train geometry. Other question are those same valve spring as the old cam ? Or you put new ones in.

I have not checked the geometry yet, I replaced the valve springs with the recommended crower springs with the new cam.

[Gach]

Originally Posted by Shockwave78

I have not checked the geometry yet, I replaced the valve springs with the recommended crower springs with the new cam.

Great ! You did your home work thats for sure. If and when you can check valve train geometry. With the shorter base circle being 1/8” shorter. Its a good possibility, being push rods are same length as old cam. That its not opening the valves all the way. Making push rod seem shorter

[steve25]

Slowbird yes it can be pointing to a issue.

The air flap will only open when there is air demand even though the second secondary throttle blades may be fully open.

Lack of normal air demand as rpms go up may be due to wrong cam timing as we have been discussing at nauseum here, or the firing order being wrong.

These are the only two things that I can see taking place which is assuming that since he has no valvetrain noise his cam and lifters are ok and opening and closing the valves with the lift that it’s designed with.

[Shockwave78]

Originally Posted by slowbird

Can you clarify this statement?? You saying the secondary air valve is only opening about a quarter? If so have you verified that the secondary butterflies are opening fully? Have you pulled all the plugs to see what they look like?

Sorry, I just saw this post when you mentioned it, I did confirm that the secondaries do have the full range of motion and that the air valve only opens a quarter or so under wot. I pulled the plugs a few days ago and they were carboned up, so I cleaned and reinstalled them. I have not checked since, but I will be pulling the plugs today for compression testing so I will add what they look like.

[Gach]

The very first thing I’d check is the cam, make sure it’s in at 109. Its best to Eliminate that as a possibility of being the issue.

[Shockwave78]

Originally Posted by Gach

Great ! You did your home work thats for sure. If and when you can check valve train geometry. With the shorter base circle being 1/8” shorter. Its a good possibility, being push rods are same length as old cam. That its not opening the valves all the way. Making push rod seem shorter

I will add that to the list of tests, taking that into account, the valve lift would be .297/.321.