8v head on a 16v block?

[Akinesis]

Ok, would a 16v block work well with an 8v head? I know the compression will be up, and I know of one that started fine, but is this a good idea?

Cheers all!

[Brunty]

You'd need to check clearances. The 16v block's pistons are pocketed for the inlet valves.

[Akinesis]

You'd need to check clearances. The 16v block's pistons are pocketed for the inlet valves.

The guy's had it running, so the clearances are fine. Apparently the compression is so high a (only) slightly flat battery won't turn the engine. What would that do to the valves and/or bottom end?? Anyone done this before? Apparently it'll be a really great engine, or a really bad one (according to a renowned mechanic).

[Brunty]

Well, you could run good ignition advance, but the piston rings would need to be nice and tight!

Just wondering what the point is. If you wanted mega compression why not just deck the block and skim the head, or fit longer con rods etc...

[Akinesis]

He originally had a 1.6, but that got tired so he looked for a replacement engine. He just happened to have an 8v head and 16v block

[monzajake]

or do it round the other way a slap a nice turbo on it
But im with brunty seems a bit pointless as the 16v engine is now cheap enough to buy ie complete running set up 250 cheaper if you get lucky on fleecebay

[Akinesis]

Ok, to solve the clearance problem with the pistons and valves the guy had a thicker head-gasket manufactured. But apparently there is still so much compression you'll only start it on a fully-charged battery. He says it runs fine, but hasn't tested it other than running up and down the road (no tax/MOT since the engine has been changed). The reason he used the 16v bottom end is because it was a very low-miler, and the top end was proven from his old engine. Apart from relocating the dizzy, changing the bottom pully for the smaller 8v one and running it a bit richer that was all that was different between the two blocks.

What are people's opinions of this?

[big nick]

if it starts and runs without blowing up, then he's done it right. just check it's not smokey at load or idle and you shuold be good to go!