[Stan Weiss]

Originally Posted by Shockwave78

Out of all those, it is closest to late valve and late ignition timing. I am not sure which because I do not know what the vacuum should be with that cam. At idle the Vacuum I saw was 10" +/- .5". I disassembled the carb and the float was bent in the wrong way, so as the fuel level dropped, the needle never opened. With constant fuel pressure, I'm sure the needle was never seating. Everything else looked good so I reset the float and will be putting the carb back on today, if that doesn't fix the issue I will probably end up pulling the cam and reinstalling the stock one.

I am sure that a number of people here have different opinions able what may or may not be going on here. I don't know what the problem is. But JMO I think changing back the cam will not fix what is wrong.

Do you have a positive piston stop and a degree wheel? Is it possible that the timing mark on you dampener is not located correctly?

Stan

[Shockwave78]

Originally Posted by Stan Weiss

I am sure that a number of people here have different opinions able what may or may not be going on here. I don't know what the problem is. But JMO I think changing back the cam will fix what is wrong.

Do you have a positive piston stop and a degree wheel? Is it possible that the timing mark on you dampener is not located correctly?

Stan

Stan

I do not have a degree wheel, but I did rotate the #1 piston to tdc with a dowel down the plug hole and checked the mark on the balancer and it was dead on

[Stan Weiss]

Originally Posted by Shockwave78

I do not have a degree wheel, but I did rotate the #1 piston to tdc with a dowel down the plug hole and checked the mark on the balancer and it was dead on

The amount of piston movement around TDC is very small. You could be off 10 or so degrees and not see it checking that way.

Do you know the diameter of you dampener? If not can you measure the dampener's circumference? I could than make you a pdf of a timing tape.

Stan

[PunchT37]

Originally Posted by Shockwave78

Out of all those, it is closest to late valve and late ignition timing. I am not sure which because I do not know what the vacuum should be with that cam. At idle the Vacuum I saw was 10" +/- .5". I disassembled the carb and the float was bent in the wrong way, so as the fuel level dropped, the needle never opened. With constant fuel pressure, I'm sure the needle was never seating. Everything else looked good so I reset the float and will be putting the carb back on today, if that doesn't fix the issue I will probably end up pulling the cam and reinstalling the stock one.

Or, if no degree wheel, if I were to pull the cover again, I would use the 4 degree advance symbols and go from there. If you have a multiple key crank gear.

[Shockwave78]

Originally Posted by PunchT37

Or, if no degree wheel, if I were to pull the cover again, I would use the 4 degree advance symbols and go from there. If you have a multiple key crank gear.

Have you had the same issue? Just want to make sure, I am coming around to that idea as well.

[PunchT37]

Originally Posted by Shockwave78

Have you had the same issue? Just want to make sure, I am coming around to that idea as well.

I have run that same cam in a stock W72 400. It ran well, so the cam is not "too big".

It has been more than a few years since I installed that cam. It was not my car. But, it did have adjustable rockers and a 3 keyway chain. I did not use a degree wheel so, if I were to guess my own work, I most likely used the 4 degree advance setting.

This was a `79 Trans AM, SE, WS6 car.

[Stan Weiss]

Originally Posted by Shockwave78

Idle speed is set to 750 and I am seeing about 15" of mercury. With the stock cam, the vacuum was 18-19", I was expecting a drop with the new cam, but I wasn't sure how much it should be.

Originally Posted by Shockwave78

Out of all those, it is closest to late valve and late ignition timing. I am not sure which because I do not know what the vacuum should be with that cam. At idle the Vacuum I saw was 10" +/- .5". I disassembled the carb and the float was bent in the wrong way, so as the fuel level dropped, the needle never opened. With constant fuel pressure, I'm sure the needle was never seating. Everything else looked good so I reset the float and will be putting the carb back on today, if that doesn't fix the issue I will probably end up pulling the cam and reinstalling the stock one.

I am working on a couple of different things and so I don't catch this until now. Which one is correct? After your first post I did a rough calculation and came up with your engine, cam and 8.0:1 CR should show about 14.7" at idle.

Stan

[slowbird]

Originally Posted by Shockwave78

Out of all those, it is closest to late valve and late ignition timing. I am not sure which because I do not know what the vacuum should be with that cam. At idle the Vacuum I saw was 10" +/- .5". I disassembled the carb and the float was bent in the wrong way, so as the fuel level dropped, the needle never opened. With constant fuel pressure, I'm sure the needle was never seating. Everything else looked good so I reset the float and will be putting the carb back on today, if that doesn't fix the issue I will probably end up pulling the cam and reinstalling the stock one.

I thought you had said in a previous post (post 18 on 1st page) vacuum was 15 at idle with current cam (18 with stock)? Now it's 10?
Any chance you can post pics of spark plugs? I would be looking into carb and ign timing.

[Shockwave78]

Originally Posted by slowbird

I thought you had said in a previous post (post 18 on 1st page) vacuum was 15 at idle with current cam (18 with stock)? Now it's 10?
Any chance you can post pics of spark plugs? I would be looking into carb and ign timing.

The float on the carb was adjusted backwards, so it was running extremely rich, I got that dialed in and it seems to be running lean, but the mixture screws are only 2 turns out, in a bit I'm going to reajust the mixture screws and recheck the timing and take it out for a spin, I am going to swap the plugs today so Ill post some pictures when they come out. And yes, the vacuum was 15" and it is 10" now

[Stan Weiss]

Originally Posted by Shockwave78

The float on the carb was adjusted backwards, so it was running extremely rich, I got that dialed in and it seems to be running lean, but the mixture screws are only 2 turns out, in a bit I'm going to reajust the mixture screws and recheck the timing and take it out for a spin, I am going to swap the plugs today so Ill post some pictures when they come out. And yes, the vacuum was 15" and it is 10" now

Good luck. For that cam and your engine specs 10" sounds to low.

Stan

[Stan Weiss]

Is calculating cranking compression and exact science. No but it can be done fairly close. Could the ICL for the cam be way out showing 148 psi. Yes. BUT for that to happen the CR has to be far different than 8.0:1

Stan

[400 Lemans]

https://forums.maxperformanceinc.com...d.php?t=834899 Here is a good thread on the 60240 installed dot to dot.

[Shockwave78]

What would the maximum bore oversize that would work with file fit piston rings and stock pistons?

[Gach]

It depends on what the piston company recommends. As and example say they say .005 piston to wall, maybe you could get away with say .002 over if that would clean up the cylinder walls. Is that what your thinking on doing, use same pistons, clean up cylinder walls and some file fitted rings ?

[Shockwave78]

Originally Posted by Gach

It depends on what the piston company recommends. As and example say they say .005 piston to wall, maybe you could get away with say .002 over if that would clean up the cylinder walls. Is that what your thinking on doing, use same pistons, clean up cylinder walls and some file fitted rings ?

Yep, the engine still has the stock pistons installed.

[Gach]

I mean I’ve seen guys just hone cylinders out and re-ring and not have issues. But main thing is to check cylinder and make sure there’s no taper. Most important part is make sure it has right cylinder wall finish so rings will seat.

[Gach]

If it where me though, if your going to go through all that, I would just go .030 over and just put new pistons in it. Going with a hone and re-ringing it, is like flipping a coin. May be good for a while.

[b-man]

Thread where the 60240 gets some good marks in a low-compression late 400:

https://forums.maxperformanceinc.com...d.php?t=800911

[Stan Weiss]

Originally Posted by footjoy

Around 8.75-8.80:1 All cylinders were 156-162 with no leak down.

Thanks

Just another example of why some of us say the OP's problem is not the cam phasing.

Stan

[Gach]

Well then now that he got the carburetor adjusted, and dose the adjustable valve’s with poly locks and studs. Let’s see what he comes up with…how it turns out. Instead of focusing solely on Cam phasing.