McDonald Imperial Super-Diesel

Hi mamoth, I did try that and made very little difference. All it did was to put simply move the position of the gears around a small amount, possibly half a tooth.
At the moment I am not worried about the injector timing just the basic timing of a 4 stroke engine. IT all goes through the steps as it shouls starting from TDC on compression then exhaust then inlet and then compression again. It is just not with the timing marks aligned. To say it is confusing is an understatement. At the moment I am not confident enough to assemble the rest and try a start up until I get my head around this. It almost makes me want to fight with the spare engine and remove the flywheel on that side and look at that set up and compare the cam gear as well. Remember I did have to build up the lobes on the cam and to do that I followed the profile of what was left behind the badly worn part.

Paul: just to confuse things, remember this is a Brons "injected" engine. The injector allows a little fuel in during the intake stroke and then auto-injects under compression.

Cobba: I see your white Nikko marks, but are there any factory marks? You may just have to time it by seat of the pants. I'm sure my exhaust opens before BDC as is usual, closing immediately after TDC. I can check tomorrow. The clearance on the rocker arm can make a huge difference to the perceived cam timing. In the absence of factory marks, I set the rocker arm clearance to get overlap (exhaust open for full stroke) and then adjust timing to get desired BBDC and ATDC setting.

Jarrod.

No idea what that is Jarrod
Tried Googling but got lost, sorry

Paul

Hi Paul. If you have a lazy hour to waste and you want to learn about the Brons / Hvid system, go here www.eldensengines.com
Scroll down to Homebrew Hvid engine. By the time you get to the end of it, you will have a full understanding of how it works. Sadly, the guy is no longer with us, but his work lives on.

Jarrod

Hi Cobba
I wouldn’t be too concerned about the timing marks not lining up on compression TDC if everything is working in the correct order and your valves are rocking at TDC it must be right
Is there a mark on one or the other flywheels that lines up with a mark on the block which gives you TDC because you normally wouldn’t be able to see the marks on the gears when the motor is assembled so you would line that mark up on compression to adjust valves ect

Cheers Bluey

The fuel is pulled into the fuel cup by suction in the cylinder,no more can go in after compression starts,so the injector valve must shut at approx BDC compression stroke....the small holes in the cap delay initial firing (hopefully) to the correct point of the compression stroke (near TDC)......The system saved Mc Donald from the precision work needed in a proper injector pump.

Once again remembering I dont know stuff all about bugger all

Is this how the timing marks are meant to line up ?

Does anyone know for sure ?

Even if it was lined up this way when disassembled that doesn't mean that it was lined up correctly

And also I have noticed with small volume manufacturers that not everything is as it should always be


Paul

Well lets line these up and see if it helps



Now Im not the brightest spark here by any stretch of the imagination but is everything still lined up right ??

I dont know, the crank key way doesnt match how it came out to my untrained eyes

Paul

The exhaust should begin to open at a bit before BDC,and be closed at TDC,as a low speed engine doesnt need any advance in valve timing.

Mrsmackpaul wrote: the crank key way doesnt match how it came out to my untrained eyes

Paul

Yep, & the Grub Screw in the gear Below appears to be in a Different Spot Too.......& maybe the dowel Pin(if that's what It is)in the little gear up Top ..