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MG Midget and Sprite Technical - Camshaft

I am currently having my 1275 rebuilt and talking to the guy who is doing the work, since my camshaft is slightly worn, we discussed putting in a scatter cam. Has anyone used one and if so, what's your opinion of them?
Martin

Personal opinion
If you are staying under about 290deg duration you don't need one and even over 290 depends on the combination of head manifold etc as to if one is an advantage
If you have really big ports, bigbore inlet and large carbs there is an advantage to reduce port robbing but having said that the best cam I had in my hillclimber was a non scatter patern monster 320+deg
I'd be looking for something with the inlets offset forward approx 5deg for eg.
Instead of 70-30-30-70 timing look for something like 70-30-35-65
example specs only-not saying buy this just something for you and your engine man to think about
Timing like this gives an early cutoff of inlet flow and does (semi) what a scatter cam does
I'll be interested to see what others with more A series knowledge than me say
willy
William Revit

Martian (intentional nod to Prop),

The direct answer to your question is that I have no experience with a scatter pattern cam. But....

When I was building my autocross Sprite, I knew that I did not really know enough to spec the cam.

So, I wrote up the details of how the engine was built, and how I wanted it to perform. Then I sent that to David Anton at APT (Advanced Performance Technologies) and asked them what cam they recommended.

I was happy with the choice. It did exactly what I told them I wanted it to do.

Charley

C R Huff

I am with you Willy, we have always found, when used in race engines the scatter pattern comes on earlier but also fades off earlier.
I cannot see the point of using a scatter pattern less than a race cam if one even used one. I would question a builders knowledge if they were to put in a scatter pattern cam which would just cost more money for no gain in my opinion.
I am lead to believe the scatter patterns were 'invented' by Harry Ratcliffe.
http://mk1-performance-conversions.co.uk/brt_history.html
I never met Harry but two of my customers knew him and spoke very highly of his skills and knowledge.

For mild road I am starting to favour the milder cams such as Kent 266 and Piper 255. Performance can always be pepped up with hi lift rockers.

Peter
Peter Burgess Tuning

It sounds like you have a standard engine in which case you probably want a near standard cam. Give David Anton a ring at APT, who grind their own cams and ask him would he would suggest for your engine. Probably he can grind you what amounts to the MG Metro cam or the cams Peter has suggested.

My car's engine does have a scatter cam and my experience is that it out performs the previous Kent MD286 cam, while being of similar duration etc. I'm advised the scatter pattern cam is very critical in respect of cam timing. My experience is not so much that the scatter pattern comes in earlier but that it comes in extremely strongly and quickly when it does (I felt a very strong surge in power). Maybe it does also fall off a bit sharper - it's clear when you need to snatch the next gear. Nonetheless it still has about as wide a power range as the Kent MD286 did in a similar spec of engine (this engine has a quite different cylinder head).

One day I'll get over to Peter's and after a run on the rollers look at some graphs!.
Daniel

You would be most welcome Daniel
Peter
Peter Burgess Tuning

Just a thinking out loud thing---
With a scatter patern cam
No's 1+4 inlet timing are retarded compared to 2+3---so if the cam was to be set up normally on No.1 then 2+3 would be advanced in comparison causing 2+3 cylinders to come in earlier and drop off earlier--but if it was set up on say No2 instaead then 1+4 would be retarded in comp. and power would come in late and be peaky
There is probably a magic spot in the middle there somewhere, but crikey, there would be a lot of runs to find it--
For me, simpler the better---
I think there is more to be gained by playing with inlet manifolds, rockers and things
I was struggling getting good performance out of a big Webber on my jigger a few years back until Peter B. suggested a particular length of manifold-I thought I'd previously tried everything semi normal but spent a whole weekend adjusting runner lengths and testing and as usual for Peter and his suggestions, the manifold had been the issue-- ended up with the carby mounted remotely out under the guard with a monster long manifold and it made more difference than most of the other mods done trying to get it hooked up--
Don't know why I blurted that out but there you go Peter
Cheers
willy
William Revit

What would be recommended for a very mild 1275 road car? I’m thinking of something that will go well with a PB Econotune head and an otherwise standard engine (maybe a bit higher compression). I’m thinking something even milder than a 266 for smooth idle and economy. Sorry for the thread invasion!
John Payne

You could try a 567 profile John, this is 16/56/51/21 and is same as MGB,Healey BJ8. It is a lovely cam for road use. It was fitted in the 998 Cooper as OE. I notice Kent cams list it on a billet. I think I would put it in at 106 degrees to get best oooomph.

Willy, I was only making it up to sound like I knew what I was doing :)

Peter
Peter Burgess Tuning

Found an old piccy
I blame you for this---lol
willy

William Revit

Cheers Peter, sounds interesting. I’ll give you a call sometime soon if you’re ok to take on my engine rebuild over the next few months.

The 286 non scatter cam in my Sprite is great, it just keeps pulling with no discernible fall off in power right up to and past 7k.
John Payne

I like it Willy :)

Happy for you to contact me John, emails are best.

Peter
Peter Burgess Tuning

Thanks for the replies. Since the engine is going to have slightly higher compression (about 9.5:1) and just some cleanup work on the head and I'm not going racing, just a solid street driver, I think that I'll stick with a Kent 266 or so cam. Cheaper than a scatter cam, too.
Martin

I can't fault you Martin. I am sure the package will work well for you.
Peter
Peter Burgess Tuning

Thank you, Peter. Your advice is always appreciated.
Martin

This thread was discussed between 08/08/2018 and 10/08/2018

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