Does anyone know if I can fit a 1500 head to a recessed 1300 block

[AlexPettitt]

Hello I’m wondering if anybody knows if you can fit a 1500 head to a mk4 spitfire recessed 1300 engine as I’m hoping to give the car a bit more pep and my plan is to port a cylinder head do unleaded conversion and fit larger valves and springs however I don’t have the money to do it in one go so I intended to build the head independently so once I’ve finished it I can bolt it on with a cam and matched valve spring and from a quick look iv realised that 1500 heads are easier to find and cheaper than 1300 heads and so if you wouldn’t mined is 1) can you run a 1500 head on a recessed mk4 spitfire 1300 and 2) if you can are there any benefits of the 1500 head over the 1300 

Any help would be greatly appreciated  

[Clive]

Yes, it will physically fit, but will significantly lower the compression ratio. Down to something approx 8:1? That would take a significant skim to correct, and if you intend building an "improved" head you may be looking for 9.75-10? depends which cam you intend to use and so on.

The best 1300 head is the late mkIV with the larger valves, realistically a  Toledo head is the same but lower CR so would need even more of a skim.

If thinking about costs, the £50 difference in cost of a head soon fades away, extra skimming etc eats into that fast. 

Do some research into valve springs too. Many seem to think harder springs help, they don't. But do eat cam lobes. Std spit springs will work well enough unless looking for 7000+rpm. 

[NonMember]

As Clive says, it will fit but isn't the best place to start. I did the opposite once - fitted a 13/60 head on a 1500 because the 1500's valves were all stuck open and the 13/60's crank was shot - and it worked fine.

As to valve springs, they only need to match the required acceleration of the closing valve. If you're raising the rev limit, the chances are you're also fitting a longer period cam, which balances that out and the standard springs are still fine.

[AlexPettitt]

Thank you both for the advice apon reading what you have said I will try to get another mk4 spitfire head and iv already put springs in the current head as I not to long ago replaced the head gasket and laped the valves and discovered one of my springs had cracked in 3 and the springs I replaced it with were a set matched for a mild fast road cam thank you once again for your advice 

 

[Anglefire]

This is an interesting site - also gives a table of head combinations.

Triumph Spitfire Performance Enhancements (auskellian.com)

[Colin Lindsay]

Pity he only starts at the 1300 engines; I'd like to see if I can fit a later Mk2 1200 head to a MK1 block.

(He also has a photo of rear vertical links that I was looking for earlier in the month, but gave up... so have downloaded it now)

[Anglefire]

Something good came out of it at least!