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MG Midget and Sprite Technical - Rolling road

Feedback on Novatech, Slough - all good. Ran the new engine in for 45 minutes at 3000-4000 rpm then did a few power runs. Given it was hottest day of the year so far and 30+ ambient in the workshop I'm happy with this. Upped the main jets to get the a/f below 13, ignition max advance 28 degrees.


David Smith

Nice! Bet that goes well, I'd love to have mine set up on a dump properly.

What engine and mods do you have?
Karl Bielby

Of interest what was the afr before you dropped it below 13 and what difference did it make to bhp? Have you got the two runs with the afr overlaid by any chance? Did you experiment with timing?
Peter
Peter Burgess Tuning

Peter, afr was about 13.25, changed jets from 160s to 165s and it went to 12.25 with an extra 1.5 bhp. That was at 26 advance. Went to 28 advance and found another 1.5bhp.
Karl it's a Peter May built 1380 with light flywheel and 286 cam and using my old MED race head. Valves 35.7 & 30mm CR 10.75:1 and 1.5 roller rockers. It's an 'endurance' spec really, the head dates from 2005.
The block it was built into I bought from Dave O'Neill - thanks Dave!
David Smith

David, that's a very similar spec to mine. A really good compromise between power and drivability. Mine was probably similar power when on Peter's old road about 7 years ago.
john payne

No idea who auto correct decided to ride dump instead of rolling road!?

Anyway, that sounds great, you have done a fair bit of work really!
Karl Bielby

Thanks David, what fuel brew are you using? When you had to change jets had this been done on the same rollers and same operator in the past?

Peter
Peter Burgess Tuning

Karl

I assumed that dump = dyno
Dave O'Neill 2

Fuel was 20 litres left over from free supply at the Race of Remembrance at Anglesey last November, mixed with 15 l of Jet super unleaded. (I normally use Tesco Momentum.)
According to my book the 160 main jets were put in by Southern Carburettors back in June 2006,m so different r/r and op. Their figures were always silly optimistic which is why I stopped using them.
David Smith

Interesting, I was wondering as we are finding we are having to alter afr as they have changed with the ethanol content so not same afr as the last time we ran them!!
Peter
Peter Burgess Tuning

Karl, it is not some auto correct that converted "rolling road" to dump. Look at the Qwerty keyboard layout for the letters d - y - n - o and you will see that they are adjacent to d - u - m - p.

So your fingers have typed "dump" when you actually thought you typed "dyno".

You did not do a visual verification of what you typed before you clicked on the "submit" button.

It happens all the time - people always blame "the computer" :)

How do I know? Well I have been working with computers since the mid-1970's and before that the qwerty keyboard on an IBM typewriter.

p.s. I am an MG midget enthusiast and not a computer pedant or amateur Sherlock Holmes - just having a bit of fun with you and that dump!
S R Phillips

David, would you be willing and able to share the full jetting recipe for your (I assume) DCOE?

Cheers,
Malcolm
Malcolm Le Chevalier

sure, gimme yr email addy...
David Smith

malcolmlechevalier at gmail.com

Cheers,
Malc.
Malcolm Le Chevalier

This thread was discussed between 19/07/2016 and 26/07/2016

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.