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Original Message
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| Here's what i've copied from various forum's |
| By Bob - 07/12/2002 11:31:22 PM; IP 65.80.203.165 |
over the last year. Note that the MT cross ram has the two plenums connected while the Edelbrock does not. The Edelbrock is not recommended due to this as the old PI maniold makes more power.
Crossram Setup
I have a '56 T-Bird with a .040 over 428. It has Edelbrock heads, .520 lift 232@.050 solid Engle cam, 2 inch custom headers, and the before mentioned X-Ram. The manifold has two 1850 600 CFM Holley carbs. Had to put 50cc accelerator pumps to get rid of a huge bog, I assume from the plenums being so large and the signal to the carbs being weak. Shortening and quickening the advance in the distributor helped a lot. Havn't noticed a lean condition.
The car isn't really a racer. It's a pro-streeter with 13X31's tucked under the back. Its for go'n to church on Sunday. My Mustang with the 427(454) is the serious car in the family.
Power Ram on my 428 powered '56 T-Bird for a while now. It's really cool looking, and works well from about 3000 to 5500 rpm. Then it falls off pretty hard. Also I experience spark "scatter" about 5000+ rpm I'm assuming because of the long distributor gizmo and the high pressure oil pump I'm running. Took a little time to get the carbs to like street situations. I wouldn't consider taking it off, as the reactions of folks seeing those carbs and the distributor above the fenders are priceless!
I'm running Holley 1850 600 cfm vacuum secondary carbs. The first problem I had was with a HUGE flat spot off idle. After much monkey'n with squirters, pump cams, power valves 'n stuff, I ended up with 50cc pumps, yellow cams, and 3.5 valves. I'm assuming the flat spot was a combination of two very large plenums and a very weak signal to the carbs off idle. I also shortened the mechanical advance in the distributor to 16 degrees, and set the initial to 20 for a total of 36. This also helped the throttle response a lot. Sometimes its hard to crank, but I now have that ironed out. Hope this helps anyone who runs this combo. Also, this manifold set-up doesn't appear big cam friendly.
MC Steiny: The M/T has the plenums connected. This is very important for the street to help balance the pulses. The guys that used it before me had it on a puller truck with double pumpers that made a lot of horsepower. I would use them with vacuum secondary carbs. Holley makes a vacuum balance kit between carbs for them, and I highly recommend that to anyone using this manifold.
As I understand, it does make a lot of horsepower in the 3-4000 rpm power range. Because of the long runners, it starts producing reverse pulses in the higher rpm range, and actually starts over-filling, and pulsing back up the runners, and sometimes produces a little cloud above the carb. Don't laugh!...and don't light a match to check it out either! I suppose SOMEONE, along the way, who is pretty smart, has done some testing with them, and couldn't get them to set the world on fire. It seems to me though, that with more vacuum balance tubes added to the manifold to smooth the pulses out even more, and two not too big vacuum secondary carbs that are balanced, you could get it to work with some cam and timing work. You might even help it by playing with the runners themselves. Nothing looks more menacing than that big cross-ram under the hood though.
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This thread, so far...
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