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swap 1300 for 1500 engine


digiman

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I need to sort my engine out on my 1300 Spitfire mkIV (1972) it has seriously low compression.
Is it straight forwards to change to a 1500 engine instead? Are Engine mounts and gearbox etc. all the same between the two?
Many Thanks for your advice.

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Hi, yes they are..... However if your engine doesn't rattle then i would recommend testing your compression with oil to see if its the valves or rings that are worn. The pistons and rings are good for many miles on these motors so in theory if your rings are fine then having your head rebuilt will only cost £100-£150 and you can refit it at home for the price of new gaskets. This is only if there are no rattles. But yes both engines are the same.

Chris

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Sounds like best be is new short engine. I had the head reconditioned and hardened exhaust seats last year. Compression is down at 110psi, doesn't seem to make any significant difference adding a squirt of oil into each cylinder when testing. I'm a suspicious that they are all low, I'd have thought it would have been a couple of the cylinders rather than all of them.
Recon short engine from Newark Engines is £275...anyone had any experience of them?
And while I'm at it swap gearbox and get a recon D-type...mine slips like crazy now.
Thanks for your help all!!!

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I had a 1500 head and short engine fome Newark. Very good value for money.
The one problem I had was knocking from the engine when hot. :(  Took awhile but found out it was the pistons hitting the fire ring on the recessed head gasket. This is because the bores were +30 and the champher on the pistons was not enough.
I had to take all 4 pistons out and take 2 thou more of the champher. Runs like a dream now.  :)

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digiman,
Low compresion that does not improve with oil down the bores usually indicates problems with the valves. Have you used this compression gauge before? Some gauges read lower than others, though 110 psi is quite low.
                                                                     Best of luck,
                                                                     Paul

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Hi Digiman, Drofgum is correct. Oil down the bores will improve the seal between the rings. As you have no improvement i would suggest you remove the head and re-lap the valves and check for movement in the valve guides. Any movement you can feel is too much. Hope this helps.

Chris.

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digiman,
I think Chris has said it well. It isn't a case of grinding, but rather of lapping them to their seats.
                                                                     Cheers,
                                                                     Paul

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