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MG MGA - New Cylinder Head

Unfortunately I've discovered that the head on my 1959 MGA has cracked! It is a 1500 head on a 1622 block and am now looking for advice on what and where to buy another (new) one.

As it's cracked exchange is probably not an option so will be looking to buy one outright.

I understand that bigger valves will help breathing and therefore performance so I am tempted to go down this path.

I will be in England at the end of August and will be going to the Autojumble at Beaulieu as part of my holiday. Do any of the UK contributors know if there are reputable sellers at this event or should I look elsewhere in England, Peter Burgess for example?

I will appreciate any advice you have.

Regards

Paul









P Dodds

I bought a new unleaded head from Cameron Gilmour in Errol, Scotland who is an experienced engine builder. The price, with no exchange head, eight years ago and which included valves,guides,springs and freight was £245. I also got a new rocker shaft for an additional £10. No problems with it so far................Mike
m.j. moore

Sorry to hear about your cracked head, Vicky does not know her own strength.
We will be at the autojumble with some fantastic friends so perhaps we can catch up.
Go Well
Frank
F Watson

One advantage of purchasing from a reputable supplier such as Peter Burgess or Cameron Gilmour is that the head will have been crack tested.

The Auto-jumble option is a little less certain.
John Bray

Surely a 1500 head on a 1622 block will give a very high compression ratio unless you have very dished pistons. Barney has lots of info on heads (of course) http://mgaguru.com/mgtech/engine/ch100c.htm

Wouldn't you be better off looking for an early MGB head?

Malcolm
Malcolm Asquith

Certainly you don't want a 1500 or 1600 head on a a 1622 as most of the significant additional power came from the improved head. The MGB engine also has the improved design but you have got to be careful as valves can hit pistons on an MGA. This may not be an issue with a 1622 block but certainly can be on a 1500. Going MGB would be the easiest as lots around but you need advice on the point I raise.

Pau
Paul Dean

Are you carrying it home in hand luggage!
Graeme Williams

My brother in law recently bought a complete head for his
5-bearing mgb from Octarine Services here in the UK.

It was a beautifully finished cylinder head which looked absolutely brand new although I think it was a recon unit and cost approx £400. It did seem to give a performance increase to his car too.

I know it will fit onto the MGA block but you would have to take advice on whether the compression ratio and the valve to piston clearances would be ok.

Colyn
c firth

All depends on whether you have the high compression flat top pistons in your 1622 engine.

Bill Spohn

Thanks for the comments so far guys. Malcolm I have a suspicion that the pistons are dished so the compression ratio should be OK. The car runs very well on 98 octane unleaded with a lead additive.

I'm not averse to using a MGB head but which one and who to purchase it from? I'll look at Barneys site to get some more info.

I take your point John regarding buying an unknown item from the Autojumble but never having been before I thought there may be someone reputable to deal with there.

I will pull the head before I travel to England to be absolutely sure of the piston configuration.

Again thank you for your advice and recommendations.

Regards

Paul
P Dodds

> I know it will fit onto the MGA block but you would
> have to take advice on whether the compression ratio
> and the valve to piston clearances would be ok.

IIRC, the valve clearance issue comes about only when you are putting an 1800 (and maybe 1622) head on a 1500 or 1600 block, AND you have had the head shaved to reduce the combustion chamber volume (if you do not do this, the combo of the earlier block and the later head results in very low compression, and poor performance). And the problem is not of the valve hitting the piston, but of the valve hitting the cylinder block, because the bore diameter is smaller than what the head was designed for, and the larger valves will protrude beyond the bore, and over the deck surface.

Barney has a section on his site covering this, and describing the "eyebrow cuts" that must be machined into the cylinders to provide for adequate valve clearance.

http://mgaguru.com/mgtech/power/cm203.htm

-Del
D Rawlins

Thanks for that Del,
if you are going to have to skim the head AND modify the block to prevent the valves from hitting it, then it probably is just too much work to fit the MGB head to your 1622 block Paul.

It may be worth asking Octarine if they have any MGA heads though.

There must be plenty of 1500/1600 heads out there, the 1622 head would be ideal but I would think that they are pretty rare these days.

Colyn
c firth

I have a MGB head on a 1622 (Austin A60) block.
Works fine. Haven't checked the CR or the compression figures though. Lots of grunt.
Art Pearse

You don't have to skim the head to put an early MGB head on the 1622; the B (18) head is essentially the same as the 1622 (16) head, and more available. The clearance problems people were alluding to, occur when putting the later head on the earlier engines, AND when the head is skimmed to maintain compression ratio. And are dealt with by making the eyebrow cuts, not dished pistons (which would be counterproductive).

Paul's engine should be best served with the 1622 head or early MGB head as a replacement. The only problem that could arise, is if dished pistons were previously fitted to maintain proper CR with the "15" head. In that case, going to the "16" or "18" head would have the same negative result as putting one of those heads on a 1500 or 1600 engine. But in the case of the 1622, it's probably better to change to flat pistons than have the head shaved like you would do with a 1500 or 1600 motor.

Mind you, I haven't personally made any of those modifications; the reason I have a fairly good handle on what is needed, is that my dad fitted an MGB head to my 1500 about 45 years ago, and I had to figure out what was the best thing to do (mostly from reading mgaguru.com). I ended up salvaging a "15" head from a blown engine, and am using that instead.

-Del
D Rawlins

Paul, have you considered an aluminium alloy replacement head. I have one fitted to my 3 brg 1800 engine with no problems except having to rectify poorly cut valve seats and valve guide clearances initially - from my experience I wouldn't buy an assembled head but rather have an engine builder you trust do the job. There are some advantages with the alloy head such as cooler running and less weight - as they say about 50 year old cast iron MGA heads "if yours isn't cracked you haven't looked hard enough!"
Mike
Mike Ellsmore

Mike

Haven't thought about an alloy head. Where did you acquire yours? What would the difference in cost of an assembled head as opposed to a bare head and having to get valves etc. fitted?

I must admit I'd rather get a head that bolts straight on over having to get additional work done.

Cheers

Paul
P Dodds

Paul

If you want an assembled alloy head I would speak to Cameron Gilmour as he has lots of experience with them, both new ones and the original Derrington ones. Best to find him through Facebook.

I think though that one would cost a lot more than a cast iron one.

Paul
Paul Dean

Octarine/ Chris Betson gets his heads from Peter Burgess
dominic clancy

Better figure out what pistons you have - unless you want less than 8:1 compression when you stick an early MGB head on it.
Bill Spohn

Dominic,
that would explain why the heads from Octarine are so good then. :-)

Paul Dean, on the subject of alloy heads, if I recall correctly, dont you have to significantly increase the compression ratio to allow for the increased thermal efficiency of the alloy material as compared to cast iron?
Are the combustion chambers in alloy heads modified as a matter of course with this in mind?

Something else that you may need to factor into the equation along with your dished piston before you buy a head Paul.

Colyn
c firth

What Bill said.

-Del
D Rawlins

1622 heads can't be that rare, surely?

1961–62 MGA Mark II
1961–69 Austin Cambridge A60
1961-67 Morris J2 1/2-ton vans
1961–71 Morris Oxford VI
1961–71 Wolseley 16/60
1961–69 Riley 4/72
1961–68 MG Magnette Mark IV
1961–67 Austin 152 & Morris J2 1/2-ton van
1974–78 Sherpa van

Or Peter Burgess would know for sure what other head options there are.
Nick and Cherry Scoop

Actually, it's not a 1622 head, it's a 16 head and I suspect it was only fitted to the MGA for about 14 months of production with the 1622 engine. Maybe the 16 head was never used on any other car. As far as I know other cars with the 1622 engine used the 15 head and dished pistons (and also no mechanical tach drive).

barneymg

Just an update on my head search. I've never removed a cylinder head before but it wasn't as daunting as I imagined!
It turns out that I do have dished pistons with "020" stamped in them.
Chris Betson at Octarine Services has found me an early MGB head and is sending it to Peter Burgess to be machined to his Econotune standard.
I was seriously thinking of bringing the head home with me as hand luggage,(I never travel with much) but didn't realise it weighs 18kg!! So in the post it will go.
Thanks again for all your advice and comments and I'm looking forward to putting it all back together again.
Paul
P Dodds

Hi Paul
Alloy head is 22 lb (10 kgs) lighter than CI. WIth the A$ at current level buying from the US isnt as attractive as it was a couple of years ago
http://www.bpnorthwest.com/mg/mga/engine-cylinder-head-components/cylinder-head-alloy-mgb-complete.html
Experts (people 20 mile from home with a brief case) reckon that you need a 0.1 increase in compression ratio to compensate for heat loss due to better thermal conductivity.
Mike
Mike Ellsmore

You can't do better than buying from Chris at Octarine, he is the genuine article.
Plus, if he sources the head from Peter Burgess, it will be state of the art.
Colyn
c firth

Just to finish off this thread. I met Chris Betson from Octarine Services while in England. Very nice to deal with and has some great stories from when he worked at British Aerospace!
He supplied an early MGB head to Peter Burgess who machined it to his Econotune standard.
The head was here when I returned form holidays and got it fitted last weekend. Great bit of engineering and the A goes better than it has ever done.Chris even supplied the Payen gasket and other sundry items. Great service.
Highly recommend Chris and Peter.

Paul
P Dodds

The only thing is that Chris is now retiring as his health isn't that good. He has already closed his web page apart from the forum part. If you need something and aren't in a hurry, he may still be able to help. He will be visiting me in the next week or so to deliver a reworked engine plus a couple of five speed kits for me to fit over the winter. I have always had great experiences with Chris, and his level of service is second to no-one
dominic clancy

This thread was discussed between 17/07/2015 and 26/10/2015

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