New Yank on the block with questions...

The Oily Bits S1 Specific Topics
21

Maddog… sent

Mikelr 140 thou on the inlet 120 thou on the exhaust.

Dave

22

To do an effective check on the cam timing requires a bit more expertise than Uldis explains.

I have a comprehensive document explaining how the cam timing is tested and set which I can send to you, you will need at least two dial gauges, preferably one anlaogue and one digital and some carefully crafted bracketry to attach them.

all this information was given to the engine builder(s) while your engine was being put together, whether it was heeded is hard to say.

If you would like a copy of the document, let me know and will mail it.

Dave

This would all be very fancy, but the fact is that you don’t really need two diels, you can do it with one.
And the bracketry I needed was only an extension for the dial gauge and a metal base which is bolted to the aluminum head, so that the maget can clamp on.

This alternative easy way is also explained in DVA’s website.

It can be very accurate as well if done properly, as when I visited Dave Walker for my first mapping he measured with his dual digital gauges (infinitely quicker) and the timing was spot on

If you’re doing it only once in a while, one dial can get you out of trouble.

23

Thanks Dave

24

Uldis,

I am well aware of the alternate method, however with a single gauge it is both tiresome and error prone, especially if the gauge is an analogue one.

In view of the less than perfect situation viz-a-viz Mike’s engine it seemed sensible to proffer the best solution to the problem for someone who is not as familiar with the engine as we are over here and who has no backup available to assist if it goes pear-shaped. If it were me I’d stump up for at least two gauges, the cost of getting it wrong will make it a sensible choice. You can’t be too careful when it comes to cam timing.

Dave

25

Don’t worry Dave, I’ve got two guages and I am definely going to use the multi-guage method. Like you said, you can’t be too carefull.

26

Checked out the cam timing today!
First while removing the airbox (just to check things out) I found that three out of the four trumpets had a fine mesh screen in the throat of the intake, the fourth was missing!

Set up my dial indicators and established TDC, checking the exhaust first I found the lift at TDC to be .135" so I adjusted it back to .120"
Moving on the the intake cam, I found the lift at TDC to be set at .167" so I adjusted it back to .140".
Pretty far out if I may say. After reassembly the motor right at tick over seems smoother , we’ll see hopefully next week when I get it on the rollers what improvement I will see from the cam timing change.
Would this amount of cam timing cause my wimpy 148 rwhp?

27

I’d expect your torque curve to be very lumpy with that sort of timing, especially the inlet timing, I’m surprised that you didnt get near to valve/piston contact with so much inlet lift, it might be worth doing a leakdown test to make sure you don’t have any bent valves…

Wonder where the mesh went?

Dave

28

Dave,
The last torque curve was like a roller coaster.
Are the screens important? I was just going to leave them all out. It looks to me to be nothing but a power robber. I could tell right away from the odd missing washer/bolt (intake screen) what kind of caliber mechanics had done the work on this car. Absolutely no respect for a customers car and a total lack of attention to detail.
What would be the best air cleaner assembly for this engine? It looks like what was on there was the stock GRP box with a single oiled foam cone right at the mouth of the airbox enterence, followed by a large spiral wound tube that is routed to the side air scoop area.
Is this the ideal setup or is there somthing better out there?

Mike

29

A foam filter or a K&N type would be fine. I would definitely have a leakdown test performed on the engine. A friend with a Caterham had one of my big valve heads and hotter cams on his VHPD and it always made disappointing power, turns out he had bent every single valve when timing the cams, this gave each cylinder a a 25% leak, after replacing the valves and fitting marginally different cams he picked up over 40BHP.

Dave

30

Wow!
And he had no other indication of a problem?
I tried to do a least a compession test but the one way valve in the guage I had removed for another project I have somehow missplaced
I will get a proper leakdown tester and check things out, it would be nice to see the condition of the rings anyway.
There are 13k on the clock but the motor was rebuilt at H.R. Owen in London after a spun bearing on cylinder #3. A new crank, rod, and piston rings where installed at 10,400 miles.

31

There was no other indication, all cylinders were equally low.

Dave

32

I’m having a hard time finding a leak down test gauge locally so I just did a simple cranking compession test. I figured that would give me a good indication of the cylinder condition (leak down tester just helps you find where the leak is), at any rate here are my findings…

Warm engine,
Cylinder #1 - 209 psi.
#2 - 210 psi.
#3 - 210 psi.
#4 - 211 psi. so less than 1% deveation between cylinders, probably the best that I have ever personally checked.
Do these look like #'s that would be expected from a healthy engine?

Cheers,
Mike

33

They look very even so valve leakage is highly unlikely although not impossible, without knowing how well the gauge is calibrated I cant comment on the overall values. Suffice to say that a compression test on the engine in question gave no great cause for alarm with a less than 10% variance.

Dave

34

OK,
Got the car tested on a rolling road at a friends shop. With nothing more than retiming the cams and running the original fuel and spark maps that were in the ecu when I purchased the car I have gone from 144 rwhp and 114 ftlbs/tq to 165 rwhp and 124 ftlbs/tq.
I know that there should be more power in there, but I think the port work on the head is less than perfect and that’s the best that it can do.
For now I’m happy with the power output and will leave it alone…for now

35

Here’s a copy of the rolling road report, remember this is at the wheel, not estimated flywheel hp.

[image]http://photos.fotango.com/p/eba00553478f00000004.jpg[/image]

I am in the process of installing a motorcycle exhaust can in place of the Lotus sport exhaust and will retest on the rollers hopefully next week