14 replies to this topic

[GreaseMonkey]

Hi,

Can a decompression plate as fitted when doing a supercharger conversion be put onto a non turbo 1275 when installing a turbo ?

thanks !

[Turbo Nick]

they can yeah, not the best way of doing it though to be honest. most would class it as a bodge.

[insamoufonyx]

stupid question but what is a decompresion plate?

cheers

[In-a-mini]

its like a thick headgasket made froma sheet of metal to space the head away from the block which lowers the compresion ratio

[biggav]

you'd be better off with the head built for the job i'd reckon.

[Turbo Phil]

The easiest way to lower the compression is to have the chambers opened up.

[mini13]

Yep best to open up the chambers,

then if you need to change the headgasket you'll only need one!

I think the only time a decompression plate is worthwile is if you are converting an mpi and may want to take everything back off in the future.

[matty...]

Agree with all of above. ^^^^

I would think by the time you've bought the decomperssion plate and 2 gaskets you could get your chambers enlarged!

[Gavin Wakely]

Hi,

Can a decompression plate as fitted when doing a supercharger conversion be put onto a non turbo 1275 when installing a turbo ?

thanks !

I'm sure Minispeed do 2 types of decompression gasket, so no need for 2 gaskets and a decompression plate (ie thick gaskets)
No sure if they are any good but they sound better than a decompression plate.

[Turbo Nick]

yeah i've seen those advertised, something £120 for a 120thou gasket, cheaper to have the chambers opened up in the head.

[1963MKI]

im rebuilding my austin 1300gt engine +20 thou and was thinking would just using the 8.8 cr ratio pistons instead of the 9.7 ones that the engine had standard negate the need for the compression plate ?

[mini13]

Pretty sure the 8.8:1 pistons are made of cheese, the 9.7's might not be too much better either, find out what the part nos are and do a search

[1963MKI]

the 9.7 ones are the 21253 + 20

[mini13]

They would be OK then

[Turbo Nick]

there's also enough meat in the 21253's to machine the dish bigger to drop your CR