# Interchangeability of cylinder heads
**URL:** https://forum.motoguzziclub.co.uk/t/interchangeability-of-cylinder-heads/1653
**Category:** Small Block V Twins (not new V7s)
**Created:** [30 November 2014 10:26 UTC](https://forum.motoguzziclub.co.uk/t/interchangeability-of-cylinder-heads/1653 "2014-11-30T10:26:03Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@WilliamHunt418](https://forum.motoguzziclub.co.uk/u/WilliamHunt418)
#### Post date: [30 November 2014 10:26 UTC](https://forum.motoguzziclub.co.uk/t/interchangeability-of-cylinder-heads/1653/1 "2014-11-30T10:26:03Z")
Just a couple of simple questions - can I physically fit Mk III heads to my Mk II engine ? And would the bigger valves have any real effect. or would I need to make other changes ?
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### Author:  [@cyclobutch](https://forum.motoguzziclub.co.uk/u/cyclobutch)
#### Post date: [1 December 2014 13:33 UTC](https://forum.motoguzziclub.co.uk/t/interchangeability-of-cylinder-heads/1653/2 "2014-12-01T13:33:40Z")
Hmmmm. I think the mk III came with bigger round slide carbs didn’t it? Might at least need a set of those too.
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### Author:  [@iandunmore](https://forum.motoguzziclub.co.uk/u/iandunmore)
#### Post date: [1 December 2014 16:34 UTC](https://forum.motoguzziclub.co.uk/t/interchangeability-of-cylinder-heads/1653/3 "2014-12-01T16:34:24Z")
Same 36mm round pumpers.
I didn’t know the MK111’s valves were bigger.
Might be cheaper to have the MK11 macined and bigger vaves put in.
The oil feed to the valves would need modifying.
And round barrels look prettier.
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### Author:  [@guzzibrat](https://forum.motoguzziclub.co.uk/u/guzzibrat)
#### Post date: [1 December 2014 17:41 UTC](https://forum.motoguzziclub.co.uk/t/interchangeability-of-cylinder-heads/1653/4 "2014-12-01T17:41:30Z")
> [@WilliamHunt418](#):
>
> Just a couple of simple questions - can I physically fit Mk III heads to my Mk II engine ? And would the bigger valves have any real effect. or would I need to make other changes ?
Hi William,
Good question. Just to clarify you’re talking V50 here are you?
Bigger valves won’t do much on their own so you’d need later/larger/upjetted carbs and, possibly, better airflow. Is there much difference in the performance figures? All the best Steve
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### Author:  [@WilliamHunt418](https://forum.motoguzziclub.co.uk/u/WilliamHunt418)
#### Post date: [2 December 2014 19:40 UTC](https://forum.motoguzziclub.co.uk/t/interchangeability-of-cylinder-heads/1653/5 "2014-12-02T19:40:55Z")
Yes, to clarify, my question relates to V50 Mk II and Mk III.