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711 Cross flow thread sizes
steve m - 5/9/13 at 08:46 AM

Hi

Can any one help with what thread sizes for the head bolts con rod bolts and crank bolts on a 711 crossflow engine

Thanks

Steve

redturner - 5/9/13 at 11:47 AM

Do you mean the thread size or spanner size. ?

steve m - 5/9/13 at 11:49 AM

It was thread size, so I can order some taps, to clean out the crud

redturner - 5/9/13 at 12:59 PM

I would be very careful. The threads are rolled and if you push an ordinary tap in I feel sure it will knacker the thread. For the head and main bearing threads I would cut some flutes, say three like a tap with a hacksaw, into an old bolt and gently screw in in to remove the crud...I believe they are 1/2" UNC.

adithorp - 5/9/13 at 01:13 PM

In truth I don't know, but I'd doubt they're UNC (which is very course). More likely to be UNF.

The only UNC threads on older engines tended to be where they were screwed into tapped holes in ally'.

Dick Axtell - 5/9/13 at 01:41 PM

quote:
Originally posted by adithorp
The only UNC threads on older engines tended to be where they were screwed intotapped holes in ally'.

And cast iron - e.g. engine block, gearbox casing. Bolts clamping bell-housing to engine are UNC (as fas as I recall).

Paul Turner - 5/9/13 at 06:21 PM

Just about every thread in a x-flow is UNC with a few UNF thrown in for confusion.

To clean out threads if I don't have the correct tap I simply take an old bolt (needs to be in good condition) and cut a slot with a hacksaw about 1/2" down its length slightly off centre. The crud collects in the slot, take out bolt occasionally and clean out the slot. Works a treat.

redturner - 5/9/13 at 07:32 PM

What I said.....