1275 head on 1098 engine

[Motojohn]

Hi all
Quick question. Does the 1275 head fit on the 1100 with no mods? And what increases would I expect to see?

Cheers
John

[panky]

It will bolt straight on - I've done it But.......
There is a danger of the exhaust valves hitting the block as the 1275 head valves are bigger and set wider apart. There needs to be 0.320" between the valve face (when closed) and the face of the block without the head gasket. This can be achieved in a number of ways.
Pocketing the block. Where the top edge of the bore is cut away slightly where the exhaust valve could make contact.
Sinking the exhaust valves into their seats by cutting/grinding the seats.
Or, which is what I did, skimming the face of the valves. The head I used was an A+ one and the exhaust valves have plenty of meat on them to allow skimming.
First thing to do is to check the clearance and decide how much you need to 'loose' and decide which approach is best. I had to find .020" off each valve so the skimming approach worked for me. As for increase in performance the head, along with an 1 1/2" carb and decent exhaust system, will give a very noticeable increase in power - which is most enjoyable

[Motojohn]

Nice one thanks!
I've just bought an mg metro 1300 engine for 85 quid that runs so will transplant the head then.
Cheers

[Declan_Burns]

There are a few other issues which will require attention.
The water pump may need to be dressed for cylinder head clearance.
The heater valve will be at a different angle.
The thermostat housing will be at a different angle.
The rockers may need re-aligning.
You will require the 1275 cc head gasket.
Check the search function before proceeding to avoid pitfalls as this has been discussed in much detail over the years.

Regards
Declan

[panky]

Yes there a a few more bits to fettle but I found the A+ head went on without modification, just needed to blank the water pump stub that originally went to the head and made an adapter for the heater valve. Here's how I approached it.

http://www.mmoc.org.uk/viewtopic.php?f= ... d&start=20

I've finally finished the conversion with a water heated inlet manifold (the Metro one will be Ideal) and a Midget exhaust manifold. The MG cam is a particularly good one, but not in the 1098 I believe, as the profile make the valve clearance problem even worse.

[don58van]

The MG cam is a particularly good one, but not in the 1098 I believe, as the profile make the valve clearance problem even worse.

Panky
I have a MG Metro cam that I am intending to put in a 1098. Can you explain why the profile of this cam makes the valve clearance problem worse, please? I would have thought that as long as it has no more lift than the standard 1098 cam, it would be fine.

Don

[panky]

I think the MG cam does have a higher lift, not talking from experience but from what I've read on here. I might be completely wrong so hopefully someone with more knowledge can confirm if the cam is suitable or not. If it is then I'll be looking for one myself

[liammonty]

I think the MG cam does have a higher lift, not talking from experience but from what I've read on here. I might be completely wrong so hopefully someone with more knowledge can confirm if the cam is suitable or not. If it is then I'll be looking for one myself

Pretty certain that it's longer duration only and not higher lift (252 inlet and 268 exhaust duration from memory, vs. the standard cam's 252 for both) - the newer designs of cams (such as the Swiftune SW5-07) tend to be much higher lift. Don't take my word for it though - check it out. The info is all available (AC Dodd has very usefully measured various cams and posted the results online) and you'll find the details of the MG Metro cam in Vizard's book, as it's been around for a while. If you don't have any other confirmation, I'll dig my copy out when I get home and confirm.

I've only used an MG Metro cam on a small block with a 295 head, so clearance wasn't an issue

[panky]

That's interesting

[philthehill]

These are the figures relating to the lift on 1100cc and MG 1275cc Metro camshafts.

Cam lift inlet/exhaust..............1100..0.250/0.250 MG Metro..0.250/0.250.

The main difference is in the inlet/exhaust opening and closing degrees (duration as quoted above by liammonty 252 inlet & 268 exhaust).

The full specification of the two cams can be found in David Vizards book 'Tuning The 'A' Series'.

For a comparisons and comments by Vizard relating to the MG Metro cam in use in small block engines see Section II Camshafts, Cam Timing and Valve Trains of Vizard's book

[panky]

Excellent, apologies for my mis-informed advise.

[Motojohn]

Loads of info chaps cheers. If the heater outlet is blocked but the bolt holes are there do you drill the head externally to fit the heater tap?
Do you use the 1275 rocker assembly as well?

Cheers folks

[panky]

Not sure about the heater take off but it makes sense, are the bolt holes threaded?
Yes use the 1275 rockers, but they should be re-aligned with the valve stems as they sit off centre as you can see in the link I posted. Most of then can be done with packing washers but there are a couple that need the sides of the rocker arm machining or filing down. They will work as they are but nice to have things looking right.
Another little mod that will be needed is to cut a notch in the engine steady bar bracket - the end that fits under the head stud. This is to get round the angled heater take-off. I guess you could always pipe the heater up as it was on the Metro, from the connection on the sandwich plate under the thermostat housing - it would save drilling the block.

[Motojohn]

Not sure about the heater take off but it makes sense, are the bolt holes threaded?
Yes use the 1275 rockers, but they should be re-aligned with the valve stems as they sit off centre as you can see in the link I posted. Most of then can be done with packing washers but there are a couple that need the sides of the rocker arm machining or filing down. They will work as they are but nice to have things looking right.
Another little mod that will be needed is to cut a notch in the engine steady bar bracket - the end that fits under the head stud. This is to get round the angled heater take-off. I guess you could always pipe the heater up as it was on the Metro, from the connection on the sandwich plate under the thermostat housing - it would save drilling the block.

The head is threaded but no centre hole, only prob with using metro set up would be having no heater tap control I think as the water would go straight to matrix without a mechanical shut off valve?