302 HO engine

need to know which ports cross over on a 302 HO engine as the firing order is differant to normal 302,
my firing order is 1 3 7 2 6 5 4 8 normal is 1 5 4 2 6 3 7 8 can any one help
 

Randy V

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Port Crossover?

It's basically only a camshaft change - the ports (on all the manifolds I'm aware of) are arranged the same between the HO and non-HO 302s..

Or are you speaking on header cross over in a 180 degree format?
 

Doug S.

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Agreed, Randy...I think Dave is talking about which "ports" cross over when building a "bundle of snakes". I can see firing order being important in that issue, particularly if one is trying to arrange the header tubes so that the exhaust pulses follow a "circular" path as they enter the collector...might be important for exhaust scavenging?

Cheers from Doug!!
 
Hi Dave

The picture is a bit rough on a bit of card as my car is , but shows the collectors with the number cylinder in the circles the link lines are the sequence.
The right hand set of four run clockwise however the left don't and run in a Z, if I swapped 5&8 they would run anticlockwise. Don't know if it makes any difference!


Steve
 

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Its the two center cyl that crossover on each bank regardless of firing order, but as doug points out you should endeavour to make them fit in each collector in a circular firing order, this require a bit of pre planning to get the most suitable layout. So for:
13726548 its ..1-7-6-4..RHS set and 3-2-5-8...LHS set.
15426378 its ..1-4-6-7..RHS set and 5-2-3-8...LHS set

Now when you look hard at those numbers you find that the circular sequence works for either firing order as the only thing that really changes is the direction of rotation at the collector and that is not an issue .
 
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