Engine swap

[bengaku]

Ok hoping someone can help out here .so I have a 1976 spitfire 1500 engine had loss of compression so rather than spend tons getting new pistons rings etc I got another engine 

So turns out the old engine wasn't a 1500 but a mk 4 1300 .now I did get the old engine cylinder head stripped and rebuilt before we had discovered the bores had problems now the 1500 engine now may have problems with the cylinder head. So the question is can I put a 1300 rebuilt head onto the 1500 block .any help would be greatlyappreciated many thanks for looking regards Paul 

[dave.vitesse]

If you fitted a 1300 head on a 1500 engine this would give a high compression ratio. For me too high - Pinking problems, fussy on fuel and maybe overheating.

Dave 

[bengaku]

But it is possible I only asked as seems to loss of compression and my mate the mechanic was thinking if we swrapped over the head that has already been rebuilt be easier and cheaper. Regards Paul 

[Clive]

You could see if the low compression pistons from Canleys (or elsewhere) are still available. Fit those to the 1500 and your 1300 head would be OK. But then you may as well fix the old engine....

used 1500 heads used to be cheap, so that may be an idea? And not much to go wrong with a head unless it is cracked or valve guides badly worn. Just thoughts....

 

[Nick Jones]

I'm confused.......

Do you have some of your 1300s and 1500s switched around.

If you started with a 1500 and had that head rebuilt, it seems more likely you are wanting to put that on the 1300?

It will physically fit but the compression ratio will be very low. It will run but will be down on power. You could get it skimmed to match the 1300 head thickness but it will then be useless for a 1500.

IMO you'd do better to bite the bullet and either rebuild you 1500 bottom end or get an exchange short engine.

Nick

[bengaku]

2 hours ago, Nick Jones said:

I'm confused.......

Do you have some of your 1300s and 1500s switched around.

If you started with a 1500 and had that head rebuilt, it seems more likely you are wanting to put that on the 1300?

It will physically fit but the compression ratio will be very low. It will run but will be down on power. You could get it skimmed to match the 1300 head thickness but it will then be useless for a 1500.

IMO you'd do better to bite the bullet and either rebuild you 1500 bottom end or get an exchange short engine.

Nick

I have two engines the original engine was not a 1500 but a 1300 I had the head rebuilt but it then seem to have problems with the bores now rather than spend money on a set of pistons and rings I got a 1500 engine which the guy said he had stripped rebuilt with new gaskets at 150 it seemed the better choice. But after getting the engines swapped out it still seems to have problems. 

[Nick Jones]

Ah, ok. All is clear.

Just a thought..... in case the heads have also been mixed up over the years........ what are the cylinder head numbers (the stamped number) on each one. Alternatively, what are the thicknesses of each head (to nearest mm).

Nick