Mi16 Rolling Road Issue

[welshpug 1,626]

lots of data for standard engines here, and on the other pages there are some for the upgrades Pete does.

 

http://www.taylor-eng.com/xu9j4/16v_overview.html

 

standard Mi cams are 0.362" or 9.19mm lift, so you'd need a DTI with more than 10mm travel to measure them as you need to take up some travel as preload.

 

 

#4 pulley gives 1.37mm lift @ TDC, lobe centre at 106 degrees, so you have some base figures to work from to see if you do have standard cams or not.

Edited June 15, 2010 by welshpug

[craig_007 1]

Thanks for that bud much appreciated.

 

We were just curious if we moved inlet to 1.8mm and exhaust to similar if the power/torque on the graph would maybe rise a little more at 5600rpm istead of starting to flatten out/drop ?

[petert 554]

1.8mm lift at TDC is too much advance for the standard inlet cam if chasing top end hp. Provided you have sufficient duration (like an Mi16 cam) you can advance it to improve the low-mid range without sacrificing too much top end, but there is always a trade off.

[craig_007 1]

Is there anyway I can measure the cams to find out duration at all,I'm going to measure lift later today.

 

I'm 99% sure there after market cams it's just trying to work what they actually are so I can try and get the best set up for them.

[petert 554]

It's easy to measure the duration if you're handy with the dial indicator. Put a protractor and pointer on the harmonic balancer. Measure the angle when the inlet valve is at 0.050" opening lift. Measure again at 0.050" inlet closing, after BDC. Add 180 to your two figures and that's the duration @ 0.050" lift.

 

eg.

 

inlet opens 2 deg. BTDC

inlet closes 38 deg. ABDC

 

2 + 38 + 180 = 220 deg.

 

OR

 

inlet opens 2 deg. ATDC

inlet closes 36 deg. ABDC

 

180 - 2 + 36 = 214 deg.

[craig_007 1]

Excellent thanks for that.

 

I'll take some measurements and put them on here and see if you can point me in the right direction.

[locosaki 0]

Hi mate,

 

What rolling road did you use,I didn't realise there was anywhere close by that were of much use ?!

 

Are your figures not quite low considering it has high lift cams and carbs,I would have thought 140 plus at the wheels would have been a decent enough figure around 175/180 at the fly wheel.

 

The power looks to climb well but seems to stop climbing so steep at 5.5rpm,I thought that was where these engine are meant to hold there own !!

[craig_007 1]

I have tooken some measurements today of cam lift and duration.

 

Cam lift appear to be standard 9.19 lift

 

Duration at 0.050 for both cams is 218.

 

At present I have the exhaust cam dialled into 1mm lift at TDC

 

Inlet cam is dialled into 1.3mm lidt at TDC

 

I believe these figure to be as accurate as I can get.

 

Before I refit the rocker cover,Is there anything here that can be adjusted either way or is the gain not worth the bother of readjustment ?

Edited July 2, 2010 by craig_007

[craig_007 1]

The readings I took were as follows

 

Inlet valve open 1 deg BTDC

Inlet valve closes 38 deg ABDC

 

So after re calculating I have

 

1+38+180= 219 degrees

 

So aboves 218 was wrong due to making an ar£e of the calculation !!!

 

All readings were done at 0.050 for duration

Edited July 2, 2010 by craig_007

[craig_007 1]

Well I thought I would just update this rather than start a new thread.

 

I stripped my old cams out tonight to fit my petert stage 2 inlet.

 

I was always curious as to what cams were originally fitted as I was told that it had "High Lift Cams".

 

I removed both inlet and exhaust and I found stamps on both camshafts at the back of the pulleys ( bp 270) So I assume now that the car did infact have some kind of after market cams on both inlet and exhaust. I'm assuming these are Piper regrinds as the the rest of the markings on the cams are identical to my stage 2 camshaft.

 

Anyway here's hoping for a slight improvement with my new cam combo and I now should have settings for both inlet and exhaust.