Took some measurements - any clues?

[max71]

I spoke to Dave Anton and he wanted me to find TDC and then measure I thought the lift. I got one of those TDC tools and turns out my degree mark on the crank pulley is spot on. Exactly.

I then put the dial gauge on #2 rocker of #1 cylinder. I had to reverse the engine and the rocker came up (front of rocker which pushes the valve) 70º exactly on my dial gauge.

I checked all the valves and they were spot on. Spot on.

Does that tell us anything as to where the cam is timed?

Oh and a note to Jimmy. Please say something constructive or just pass on this topic. I'd appreciate it.

[Jimmy]

Does that tell us anything as to where the cam is timed?

In my opinion (if allowed), no.

[max71]

Dave Anton said he has some math that should determine it. I'll keep my fingers crossed. Remember it has a 2º key in there.

[malcolmr18zoy]

Hi Gary,
So are you saying that the exhaust valve reaches it's center of lift at 70 degrees before TDC? Did you measure the center of lift with a dial indicator? Without knowing the cam profile , that doesn't say much, except it doesn't seem right.
Malcolm

[max71]

I measured with a dial indicator. Again on the front of the rocker not the back. I think I mislead something as the front of the rocker went UP not down so that wouldn't be lift. Maybe I need to do it again but it was impossible to get the dial gauge on the back of the rocker/push rod.

APT is not the best at supplying specs with their cams. This is from their website.

[Martin Keller]

max71,
Have you look at a restricted exhaust system. Just a though as I know that will also cause the same issue especially at higher RPM's.
Just a thought.

[max71]

Thanks for the post Martin!

Yes, both resonators were replaced for different reasons since the engine has been put in.

[max71]

Followup: Just got off the phone. Dave doesn't want to deal with the rocker ratio. He want the rocker train removed and have me measure the push rod at Center oppose the lobe (hope I just wrote that right I forgot the term) and then rotate until I measure maximum lift.

I was just curious where the cam was timed. If I do all this I might as well have the engine ready to be timed correctly. Something I don't trust myself to do. I guess it will be a mystery until I get the budget to do that.

Thanks everyone for all your help.

[malcolmr18zoy]

Hi Gary,
If you want to measure the position of full lift on your exhaust cam, you will have to rotate the engine until maximum lift is shown on your dial indicator, and keep rotating until the reading starts to reduce. Then rotate the engine back the other way until the reading reduces to the same amount at the other side. Then take a mean of the degree disc readings, and that should give you the position of full lift of the exhaust cam. I still don't quite get the 70 degrees BTDC that you mentioned before.
Malcolm

[max71]

Thanks Malcolm.

I made an error when I said 70º. Since I haven't used the dial gauge in years I forgot the measurements. It was 70 on the dial which Dave said means 70 thou. But it moved quite a bit so I don't know how that could be 70 thou.

[malcolmr18zoy]

No Gary, that doesn't sound right. I would have thought that you need to measure lift and timing.
Malcolm

[max71]

What are the graduations on a dial gauge then? Sorry to be so basic.

Right now the method as you described it is to find lift and look and see how that corresponds to where the timing mark is since I have verified that mark is TDC. The I get can a 'rough' estimate of how far off it is. Just for education not for actually timing.

[malcolmr18zoy]

Hi Gary,
From the responses that you are giving me, I think it would be if you let me, or somebody else who is familiar wth the proceedure, carry out the checking for you. no disrespect intended.
Malcolm

[max71]

its fine. i keep saying i'm not qualified. I'm going to give it one more go.

[max71]

Just got the proper cam specs from APT. Their card was wrong and I was waiting on the corrections.

In/Ex duration 224 deg @ 0.050"
Lobe lift 0.280"
Lobe center angle 106 deg.

Timing specs:
Time to full lift on #1 intake @ 103 deg. ATDC (3 degrees advanced)

Lift @ TDC #1 intake 0.073" (This gives exactly the same timing set up as the method above, but is probably more accruate as long as your TDC point is very precise.

Lash with stock rockers In/Ex. 0.016"/0.018" and if using higher ratio rockers increase this a couple of thou. These are minimum figures.

The rockers should be removed from the engine to get the dial indicator onto #1 intake push rod. Set indicator to zero when lifter is on base circle of cam.

[Jimmy]

Just got the proper cam specs from APT. Their card was wrong and I was waiting on the corrections.
The rockers should be removed from the engine to get the dial indicator onto #1 intake push rod. Set indicator to zero when lifter is on base circle of cam.

I see no reason to bother with removing the rocker arm, unless you want to be awfully precise. Which isn't easy with a push rod flopping around in a hole, anyway.

[max71]

Its hard for me to get the Dial gauge onto the push rod with the rocker. Good point though.

[Jimmy]

I suppose that means that you don't have one of those $20-at-the-most adjustable magnetic stands for your dial indicator?

[max71]

I have a magnetic base its just too large to easily place without it being precarious and moving.

[malcolmr18zoy]

Hi Gary,
Just a stupid question here. When you installed the offset woodruff key, did you install it to advance the camshaft, or advance the timing sprocket?
Malcolm

[max71]

I don't remember but I do recall we had a discussion about that and I posted before we buttoned up to confirm with mechanics on the MGBE we were doing it right. Since we did the measurements afterwards with two different sized keys and finally got the proper reading of 103º with the 2º key I was confident that it was correct.

Still kicking myself for not opening the timing chain cover when it was on Steve's floor and having this discussion then. People have gone over this with me enough that it seems so easy. Without someone trained looking over my shoulder I really think its possible to just do it wrong again.

I still haven't had the time/incentive to measure #1 inlet. I will probably try it this weekend.

Its not a stupid question. It was just stupid people who set it up wrong if its off.