Cylinder head porting

[KKson]

Hi all, I'm toying with the idea of buying a used pair of standard 3.5 EFi heads so I can have a play with them and do some porting and fettling. Many years ago I ported and polished the cross flow head on my Capri 1600GT which seemed to make a difference and prior to that I'd similarly ported the cylinder head on my Morris 1000, which was actually running a Cooper head, cam and twin 1 1/4" SU's.

The plan is to have a tidy set of clean heads ready and waiting for the time when I decide to take the existing heads off and fit a new camshaft. Anyone got any top tips for improving the breathing on a standard set of heads? I know a set of later 400/450 larger valve heads would fit but I'm looking at keeping the costs down and tidy standard EFi heads can be had for less than £50. Thanks.

[KKson]

mike various said:

Please forgive my ignorance but what does the plenum insulator do ?
is it some sort of heat shield if so has it been proved to give an increase over stock and if so how much ?

Mike

Likewise - I'm assuming it keeps the plenum a little cooler but does it actually improve performance? If so then I'm also up for one if available! Cheers.

[KKson]

3 bhp is well worth it. It's a personal challenge to beat my rolling road bhp each year. So how much for the insulator then?

[KKson]

Right, two very tidy late 3.5 EFi cylinder heads bought for the grand total of £39 off flea. Just need to get a good flexi drive and suitable grinding burrs. The room above the garage is starting to fill up with spares now, but you can never have too many!