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Collecting parts for testing



The last two weeks have been spent collecting parts for dyno testing in the coming months. So far I have two additional headers to test back to back against the MM pulse chamber header - an Ireland 1 5/8 to 1 3/4 step race header and a Stahl 1 3/4 race header.

Here is the Ireland header (black) vs the Stahl (silver)


And here is the Metric Mechanic header


I dug out a set of my old TWM intake manifolds to test against the MM intake manifold too


I spent the entire weekend machining a prototype venturi for my Weber 50 DCO carb borrowing an idea I have seen used in Formula Atlantic. This design in theory should improve CFM flow thru the carb while at the same time boosting signal strength and fuel atomization. It was worth 6-8hp on a full tilt FA engine using my same carbs so I felt it was worthwhile to try to build some. The prototype came out well but still tweeking a few dimensions before sending it to a CNC shop to machine up several copies. Besides these custom chokes, I will be testing my big 46MM Weber chokes and need to pick up sets of 42 and 44MM Weber chokes to round out the testing on the intake side.


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So its now early August and I am still waiting on parts LOL. I didn't anticipate holdups on the actual parts (plus I bought a 1972 Tii street car that needed a few things eating up further garage time) so I have had to make adjustments.


I am leaving the bottom end completely as is, but just ordered up a new cam and fresh valve springs from Metric Mechanic. The cam we used when we built my motor 15 years ago produced good results, but Jim at MM believes I can get a better powerband with his current race cam which has a bigger intake lobe and less aggressive exhaust. The specs look to be closer to a 328 Schrick but nothing super aggressive like the 336. Cam and springs should take about 4 weeks to get. I am also buying a set of VAC billet rockers because my old engine was running the MM massaged factory rockers (they didn't break at 9000rpm but the VAC rockers are extra insurance). Those are also out of stock so looking at 4 weeks or longer there...The challenge will be shimming these and checking clearances because everything is going to be pretty tight!


In the meanwhile I have finished a prototype venturi for my DCO Weber 50s but need to make so changes to the fuel grove (its way too big). Sending some final CAD pics over to a machining place to punch out several finished pieces.  I will be testing this against the regular Weber chokes hoping to pick up some velocity and better fuel atomization. I had a pair years ago inside a pair of 48MM Solex sidedrafts - felt faster but never verified on a dyno...Ton of work to make these in hopes of picking up a few HP.





Edited by 2002GT3CAR

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