Brief update.
My source never replied to repeated queries concerning the Prout Javelin headers. He has said in past blog posts that he was responsible for building the engines in '70.
But we are concerned with '69 as the engine pics are from Daytona in July of '69.
To recap, Ronnie Kaplan had dogleg port heads on the '69 TA Javelins. He apparently worked with David Potter, AMC's engine man. This would be several months before these heads showed up on production AMC's.
There are interesting photos afloat, including the headers on the Penske Javelins. Their headers don't look convential either. But, we are discussing why Prout used cast "spigots" coming out of the port and small header tubes that are are apparently welded/threaded into these castings. The question at the end of the day, is are these dogleg heads and exhaust?
Now is where the legwork comes in. Absent a telling qoute from a principal involved with designing and building these headers (Warren Prout) or someone associated, studying pictures and making comparisons to known items, as well as making dimensional comparisons will tell the story.
First, why the hybrid design? Simple, to continue exhaust port shaping outward past where the manifold joins the exhaust port. It is my understanding that even today it is next to impossble to stamp a steel tube in such a manner as to smoothly continue the exhaust port arc (a mirror) dimensionally . In simple words, you can't make a stamping hug the head like a casting can. Unless you sectioned and welded little pie slices together akin to two-stroke motorcycle GP practice from 35 years ago or as is evident by going on Ebay and looking at current Japanese aftermarket chamber makers for RZ350 Yamaha two-stroke twins, a steel header on a four-stroke is going to arc out 2 inches or so further from the exhaust port than a purpose made casting or billet formed exhaust "stub". That is because either steel tube or the stamping die can't conform to the tight arc that the optimally dimensioned casting/billet can. I am not a machinist or toolmaker so I take what they say as ground truth that the die or the tube would break in the process.
Why is this important? Because apparently the intake through to the exhaust "system should be reverse mirrors of each other, and smooth, optimally shaped flow at velocity is key. Velocity being the operative term. All those years ago Prout figured out that velocity was the name of the game (notwithstanding that the crossram intake wasn't optimal in that regard, at least not below "mid-range". Nevertheless, in '69 the crossram must have been thought to be optimal and Prout concntrated on the exhaust. Hence the small tubes. Why not just a small tube conventional header? Because conventional design small tube headers give up power up top.However, an unconventional exhaust can combine velocity and flow shape together to deliver timed volume to maintain power while delivering responsiveness. Perfect for coming off slower corners or after braking.
So, does using a cast flange mean that the head or the exhaust are dogleg port? No, it's either rectangular or dogleg. The famous "trapezoid" exhaust didn't show up until later on Penske/Traco/Nascar engines. That is entirely another discussion. For this discussion, casting clues(heads), and bolt dimensions (exhaust) will have to tell the story.
Stay tuned for results from comparing casting features of the heads and after doing some math.
Steve
