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X-flow

PostPost by: billwill » Thu Jul 24, 2014 10:11 am

Can someone in the know, please explain what the Cross-flow and Pre-Cross-flow designations on the Ford engines actually mean?
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PostPost by: rgh0 » Thu Jul 24, 2014 10:28 am

Which designations do your mean - the block casting numbers?

i.e.
120E 6015
681F 6015
etc


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PostPost by: billwill » Thu Jul 24, 2014 10:41 am

Just what does the word Cross-Flow mean in this context.

Is it because the coolant crosses the head or because the inlet & outlet valves are on opposite sides of the head etc etc. or what?


The name "pre-Cross-Flow" is particularly confusing. :D
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PostPost by: rgh0 » Thu Jul 24, 2014 10:49 am

The first ford version of the engine the twin-cam was based on was a non cross flow head and 1500 block ( same block as used by the twink) with the inlet and exhaust ports on the same side. The later cross flow had the inlet and exhaust ports on the opposite sides of the head and used the taller 1600cc block. So pre cross flow is talking about the non cross flow head.

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PostPost by: billwill » Thu Jul 24, 2014 10:55 am

Ah, thanks.

I'm so used to the shape of our twin-cams that it seems like an engineering nightmare to have both inlet and exhaust on the same side of an engine.
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PostPost by: rgh0 » Thu Jul 24, 2014 10:58 am

The reason the dizzy, oil pump and fuel pump are on the RH of the engine is that the single down draft carb and exhaust were on the other side in the non cross flow engine. So originally it was a great design for easy access to components :D

The non cross flow design however limits the valve sizes and porting more than a hemi head cross flow does which is why the change in the twin cam

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