[DeTomaso] 400 Exhaust

gow2 at rc-tech.net gow2 at rc-tech.net
Tue Sep 4 18:02:12 EDT 2012


As Will said we were taking about my failed headers. I originally had not
considered firing order when I built them. It seemed pretty stupid when I
got done.

With a firing order of 1-5-4-2-6-3-7-8  The cylinders laid out :

5     1
6     2
7     3
8     4

My grave error was to collect 6&7, 5&8, 1&4, 2&3

If you look at each paring it was the perfect storm. For instance, 5
chambers fired, then #6, one other chambered fired then 7. #6 is separated
by 5 cylinders firing and #7 is only separated by one other cyl firing.
Each pair I did has the same problem. Half were leaned out, not even
running and the half were rich.

This is what intrigued me about putting in a butterfly to control back
pressure and trying to collect all 4 at once as late as possible. I know I
am compromising scavenge but.....




>
> In a message dated 9/4/12 9 39 38, gow2 at rc-tech.net writes:
>
>
>> I originally built these to go over the suspension but the firing
>> order/back pressure left every other cyl lean:
>>
>
>>>>Wouldn't that be attributable to not having the collector close enough
> to the exhaust ports--or not having one at all?   I admit I know squat
> about
> exhaust theory, but I seem to recall that there is a somewhat optimal
> distance from the exhaust ports to the collector, and that individual pipe
> systems
> with no collector don't work particularly well.
>
> Edjumacate me some more?
>
> Mike




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