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09 Feb 2012 19:14 #22150 by alsancle
alsancle replied the topic:
Would the later Ram's horn manifold make a difference?

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  • Bob Roller
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09 Feb 2012 19:37 #22151 by Bob Roller
Bob Roller replied the topic: Rams horn manifolds
I don't know and will defer to Randy on this one. Treating the engine as two 4 cylinder engines on a single crankshaft with tandem manifolds seemed to work with the "special" but it was being run at sustained high speeds for hours whereas putzing around town at varied speeds may not be a good idea with such a system. IF I owned a "J",I would drive it and drive it a lot so my choice would be either a stock downdraft carburetor or tandem manifolds each equipped with a carburetor but no supercharger.

Bob Roller

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14 Feb 2012 21:59 #22192 by landmark
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RandyEma wrote: Bob I probably have four different four carb manifolds here and I do not think any of them worked that well. The best for hp was a single carb SJ then a dual carb Winfield then a std J Randy



Hello Randy,

thank you for the informations about the four carbs. That is very interesting for me.

I have some thoughts about that (just a theory)

I had expected that a four carb SU configuration (maybe together with 8:1 compression Pistons) will supply a power-output of 300 hp +.

Regarding tuned "oldstyle" Harley V2 Shovelhead engines (equiped with 1.3/4` SU-Riviera or S&S Carbs), which were bored and stroked (near the Bore & Stroke relations of J engines) up to 50 cui per cylinder. These engines reach easily 80 hp and more (or 40 hp per 50 cui cylinder), but have nearly always a camshaft timing, with longer valve openings than the std J engines.

What I have learned is that the SU-Carbs (on Harleys) are a little tricky for to find the correct jets and jetneedles to adjust/find a correct gas-mixture -not to "lean" or to "fat" (through the complete "RPM-regions").

An other cause for that could be that the original (conservative, torque optimized) camshaft timing works best with factory fitted one-carb SC and std. manifold carb. The two carb SC and four (single) carb configuration would (maybe) oversized for the (relatively short) original camshaft timing.

I would expect that a four carb (or two carb Winfield SC) configuration would work more proper with (hotter) camshafts, camshaft with longer valve opening times.

But that is a theory and guessing (for my own pleasure)


Randy can you tell me if the factory always used a "one and only" timing for the two cams or have they sometimes mounted cams with other timing-parameters? (maybe for the Mormon Meteor engine)


Cheers

Matt

P.S.: Excuse my (not perfect) english, it is not my mothertongue

Was man besonders gerne tut,
ist selten ganz besonders gut

Wilhelm Busch

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14 Feb 2012 23:19 #22194 by RandyEma
RandyEma replied the topic:
To my knowledge there was five different cam timings over a period of time the last coming to Lycoming in 1933. The owners manual is incorrect timing Randy

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19 Feb 2012 21:56 #22263 by landmark
landmark replied the topic:

RandyEma wrote: To my knowledge there was five different cam timings over a period of time the last coming to Lycoming in 1933. The owners manual is incorrect timing Randy


Hello Randy,

once again, thank you for the information.

Do you know if there were "big" differences in timing, power-output and torque between the different cams or only some (very) few degrees?

Have these different cams own marks/punches on it or is a cam only identifiable by expert knowledge (like yours) or measurement/metering?

Matt

Was man besonders gerne tut,
ist selten ganz besonders gut

Wilhelm Busch

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20 Feb 2012 00:58 #22265 by RandyEma
RandyEma replied the topic:
Matt. To my knowledge the cams except for one change I think remain the same . It is the timing of the chains that does change and nothing was ever written what those net results were. Randy

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