cam measurements and compression test results

[chrisdurham]

hi guys, done some testing today and will do some more tomorrow as i ran out of time. as per my other thread looking to get some baseline data for the engine.

this was all done on the drivers side bank: will do other tomoz.

i measured valve lift using a dial gauge i have. i measured it at the point on the rocker where the pushrod is. heres what i got.

1) 8.60
2) 8.15
3) 8.45
4) 8.37
5) 8.35
6) 8.20
7) 8.75
8) 8.95

they are all within 10%. how do they compare to others? one thing i noticed was a few times i got odd low readings, i think the tappets were emptying? so i cranked the engine over a few time till the oil pressure built up and then the readings were back up to 8 ish.. does that sound normal?

Also done compression test on all 8 cyls. engine was cold which i know is not ideal but gives an idea:

drivers side bank
1) 185
2) 165
3) 175
4) 195

pass side bank
1) 175
2) 180
3) 170
4) 175

[Barkychoc]

No idea if it's coincidence but I have seen one or two cams now where the 5th lobe from the front was the most worn - and I think that could equal your 8.15 position?

Compression looks ok to me.

Looking at it again I don't think it is 5th lobe anyway!

Edited by Barkychoc on Saturday 9th June 19:47

[Alexdaredevilz]

Can't measure cam lift in that way with hydrulic lifters very well,

Compression looks ok.... But you need to do a leak down test IMO

Your compression was out about the same as mine, but after a leak down I found my valves were leaking

[chrisdurham]

ah, ok, I am assuming then the only way to check for cam wear is to remove it then and do it on the bench?

[Alexdaredevilz]

You could pop the inlet/valley off and measure the lift of the cam, but your almost there to change it then

[debaron]

Alexdaredevilz said:

You could pop the inlet/valley off and measure the lift of the cam, but your almost there to change it then

+1

It's not that hard to do - why not pop a new cam and new lifters in for peace of mind?

[Bassfiend]

debaron said:

Alexdaredevilz said:

You could pop the inlet/valley off and measure the lift of the cam, but your almost there to change it then

+1

It's not that hard to do - why not pop a new cam and new lifters in for peace of mind?

If only it really was that simple...

...not brave enough to attempt to do mine!

Phil

[chrisdurham]

Hi guys how much wud a stock cam plus followers cost for the 430?

[skiver]

Going against advice, I inspected my cam from below after removing the sump, and it was possible to look at the condition of the lobes. If you can get it on a ramp this is an easy option and if you can get hold of a borescope, even better

HTH

Edited by skiver on Sunday 10th June 10:14

[ChimpofDarkness]

chrisdurham said:

hi guys, done some testing today and will do some more tomorrow as i ran out of time. as per my other thread looking to get some baseline data for the engine.

this was all done on the drivers side bank: will do other tomoz.

i measured valve lift using a dial gauge i have. i measured it at the point on the rocker where the pushrod is. heres what i got.

1) 8.60
2) 8.15
3) 8.45
4) 8.37
5) 8.35
6) 8.20
7) 8.75
8) 8.95

they are all within 10%. how do they compare to others? one thing i noticed was a few times i got odd low readings, i think the tappets were emptying? so i cranked the engine over a few time till the oil pressure built up and then the readings were back up to 8 ish.. does that sound normal?

Also done compression test on all 8 cyls. engine was cold which i know is not ideal but gives an idea:

drivers side bank
1) 185
2) 165
3) 175
4) 195

pass side bank
1) 175
2) 180
3) 170
4) 175

Don't be discouraged, I checked my cam in this way and while I freely admit it's not ideal, it did help me identify the worn lobes.

How do I know this?

Because the cam came out in the end and it matched what my "at the rockers" lift test told me.

So given the additional work of going in deeper I would say the method has it's place.