performance parts

hello all, im new to the forum. I have already started a build thread on another forum, feel free to view it.
http://c10forum.com/forum/showthread.php?t=18628
now that the fromalities are over, I have one question, have any of you guys with inline six's ever bought parts from Clifford performance? I talked with one of their techs and he seemed to know his stuff.

I have had a Clifford intake on my six for over 20 years now, They do know their stuff.  If you are after performance info you have come to the right place. 

Clifford Research was founded in the middle to late 60's by Jack Clifford. He started out by selling Hudson racing parts, then branched out into everything 6 cylinder, and later also 4 cylinder.
At one time they had everything, very good headers for all purposes, intakes, 2bbl, 4bbl, 3x2,2x4 or 2x2, cams and valvetrain components, and driveline components to build a high performance 6 or 4.

Jack died several years ago but the company is still around.

The last time I've had any dealings with them directly was in the late 80's, so I really can't make a accurate judgment on the current Clifford Research.

The maximum rpm can be considered the point they reach just before they come un-glued.  Picking a TSM at random from my files, 1974 a 258 developed 110HP at 3500 rpm and 195 ft lb of torque at 2000 rpm.
Once modified, that will change as the OEM cam shaft is decidedly on the weak side and the BBD Carburetor is rated at 193 cfm which goes rather flat around 3200 rpm.
Changing the cam shaft on my modified 258 gave about 110 Rear Wheel HP about the same RPM which depending on how you calculate crank shaft HP from comes out about 145 HP with a flat HP curve through the 3000 rpm range. 
Changing the BBD carburetor to Fuel injection which removed the restriction of 193 cfm from the equation moved the HP peak further up the rpm range and is now estimated to be in the area of 180 hp at the crank.
I have the automatic transmission shift point set for 4500 rpm for a WOT 2/3 shift which is when it shifts out of passing gear.
Which reverts back to maximum rpm is just before it comes unglued and it sees 5000 rpm on occasion and has not come unglued yet.
but keep in mind, others have built more hp and rpm into the engine and have had fairly successful drag racing careers with them.
My motors are street motors with at least one objective that they also pass smog for my state.  And they do.

tyrodtom wrote: Potter says the engine has a 3rd order torsional vibration peak at 5400-5500 rpm that won't allow the engine to stay in that rpm range for more than one minute without the danger of crankshaft breakage. It says you can rev thru that range to above it, but doesn't state a maximum rpm. I have buried the needle on a 7000 rpm tachometer ,with a 232, when a throttle return spring popped off on a downshift.

Kinda what I was looking for?