4age Bigport question

[mlewis]

Currently got a blue top big port in my ae82 that was rebuilt before i brought it. Its started making a knocking noise at about 3-4k rpm which is annoying since thats the cruising rpm level when I'm at 100kph

Found a couple big ports at pick apart today, both the later red tops.

Is there anything stopping me from using a block from a redtop big port on my blue top if my engine was to die? i realize the internals are stronger and the block is a 7rib compared to a 3 rib.

Im thinking it will raise my compression but should strengthen my bottom end quite nicely

Any help or advice would make it a lot easier to work out what to do.

[Shrike]

Thought it was rebuilt?

[mlewis]

thats what I thought, but its begun to knock a little. only does it when on a slight throttle or coming off from a light throttle.

maybe his grandad didn't rebuild it. maybe was only helping and didn't watch the bearing bit. or someone got gas pedal happy while running in the new engine

[xsspeed]

Having the heavier bottom end on the later bigports suck a bit, fine in a smallport but yeah.

It will work but, I'd be aiming to rebuild the bottom end if thats feasible