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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Jonspeed cyliner heads

Hi all - I hope everyone had a good Xmas. Fortunately Santa left me some cash that now means I can maybe afford a decent stage 2 head for the midget. Does anyone have experience of Jonspeed's offerings? They seem to be quite competitive on price.

Any input would be greatfully received, or suggestions of reasonably priced alternatives.

Thanks, Matt
Matt

Matt

Check out theminiforum.co.uk for more info on Jonspeed.

Shaun
Shaun

Matt,

I might be able to save you some money.

I have a 2nd hand 33mm Inlet Stage II 12G940. I'm planning to de-coke, fit new guides, clean up the valve seats and valves, and paint. I can offer for this for £210 (or just about 1/2 what Johnspeed or Minispares will charge). I will also burette it so that you can work out how much to skim it by to get your correct CR. The head has double valve springs, it is not unleaded.

You could also buy a set of larger valves and have the seats cut to take these and blend the new seat into the throat. The port will not require enlarging for a bigger inlet.

Talk thru the forum or I'll be back at Ford Powertrain, on jeastwoo@ford.com, from Monday 5th Jan.

Regards James Eastwood,
J E G Eastwood 1

I once had a Sprite head reworked by Jonspeed. Would never use them again.
f pollock

Matt-
I would suggest that you contact Peter Burgess in Derbyshire. He can custom modify your head to your needs or, if you don't want to bother with shipping yours, sell you one outright. I've been recommending him to owners for years and never heard anything but praise about the results. Click on this: http://www.mgcars.org.uk/peterburgess/
J Strange

Peter Burgess or Peter May for an A-series head.
Daniel Thirteen-Twelve

Jonspeed didn't have a very good reputation in the late '80s/early '90s. I don't know if they've improved since then.
Dave O'Neill 2

Here is my dream head...dont know where to get one, but 8 ports are better then 5 IMHO

http://business.fortunecity.com/lerner/445/head.htm

prop
Prop

Keith Calver does all the heads for Minispares and has an excellent reputation for them, he is constantly developing them and has his own flowbench specifically for the job.

Another excellent worker of heads is Nick Swift of Swiftune, but he is so loaded with work, time may be an issue there.

And as Daniel mentions both Peter Burgess and Peter May supply superb heads.

As I know all the above people personally, I cannot, nor will not recommend any one of them over and above any other....

The choice is yours, but all I will finish with is that an older modified head will NOT be a good as one done more recently.

Mark.
Mark T. Boldry

Many thanks for all your responses so far - much appreciated.

Cost is a major factor although I'd much rather go for a freshly reworked head because, if I'm spending this much, I want it to be unleaded as well. I'll maybe just have to save a bit longer.

Lastly, does anyone have any experience of head/engine work done by 'British Classic Car Spares' in Perthshire? They seem to one of the few A-series specialists north of the border.

I do have a good spare standard head to exchange.

Cheers, Matt
Matt

Matt,

IMO if you need a good value alternative, that isn't a second hand or new head, follow the 'Simple Porting Modifications' in Vizard's 'How to Modify the A Series' book (page 162 in my '89 copy).

I've done several of these heads and they do work very well. In the book the mods take an engine from 60 to 65 hp, i.e. 10% which I would vouch is about right. Make sure you start with a 1.4" valve head. You will need a dremel set, a very steady hand (when working around the valve seats), and plenty of patience. Don't rush it, do the head one night and the valve reshaping and lapping the next. It's a lot of fun, and very satisfying to drive the results. My last (1.4" inlet) head with the MG Metro cam (252/268) would rev well to ~6500, on a pair of HS2's and a 9.5CR.

(Note, just to avoid confusion, my head for sale is a propriatorty head, not one of my home mod'd heads).

Regards, James
J E G Eastwood 1

Hi Prop,

Have you seen the tasty exhaust manifold?

Grtz,

Alex
Alexander M

This thread was discussed between 26/12/2008 and 02/01/2009

MG Midget and Sprite Technical index

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