a friend of mine is building a .030 454 with 10-1 compression. also has 049 heads pocket ported with 2.19-1.88 exhaust installed. running performer RPM with a 750 dp and small tube headers. car has 10" 3500 converter and 3.73 gears. he was already to order the comp cams Xtreme energy solid 274 grind. with all the discussion of how well liked the ultradyne grinds are I asked him to hold off. the comp specs out at .552in-.562ex. net lift. dur@050 is 236in-242ex. it is part#11-677-4. it seems as if this would make gobs of torque. the timing events are 31-63 74-26. 110 lobe centerline installed 4 deg@106. I am wondering how the UD 276/284 gring will perform in the same engine. I believe it specs out at .561in .575ex. dur@.050 is 243-251. also ground on 110 deg lobe center installed at 104 deg. timing is 34-62 77-27. the car will be street driven but raced 6-7 times a year and performance is very important. the car has power brakes and the cam must operate them. he wants to order the cc grind but if the UD will be better he is willing to wait. also car is 3700#'s. any input as to how each of these cams will perform in this engine is appreciated. he really wants to optimize what he has and if one of harolds trick cams can beat out the competition. thanx harold and anyone else. mike

Its tough to compare ( ok impossible) against a cam no one here has yet run, and then even then, to make any reasonable comparison to another cam.

Your buddy has enough converter for the bigger cam, and then some I should think. The closest cam in the Comp line is their 280S and the XS282S. Then again, with all the assymetrical rates and such, where two grinds that measure the same seat, .050, .200, durations might not perform the same.

For the time being, supply of the Lunati/Brookshire cams is the only holdback IMHO, but I bet the 280S would perform rather similarly.

BTW, the gross lift of the 276/284 is .603/.585.

Gene
more lift on the intake? thats something you dont see often, well at least I havent.

this is the cam you are using correct? i swear i remember you posting something about the 276/284 solid being an oval track cam????

Back in the summer when I was talking with Harold about a cam reccomendation he stated that the 276/284 as being similar to the LS6 cam but with more power...

UD 276/284 cam specs. Mine is on a 110 LSA.

dur @ .050: .243/.251
lift: .3450/.3533
seat duration at .050: 276/284
gross lift: .587/.601
lash: .026/.026
degree intake lobe to: 104 ATDC
seat timing intake: 34 BTDC 62 ABDC 104
seat timing exhaust: 77 BBDC 27 ATDC 116
(all taken directly from my cam card hand written by Harold himself.)

Gene posted the intake and exhaust lift figures reversed.

Actually, on Ultradyne's (former) website they advertised the 272/272F (solid), which is what I have, as their LS-6 replacement cam. It's the closest in specs: 238/238 @.050 vs 242/242 for the stock LS-6/L-78. Gross lift is .550/.550 for the 272 vs .520/.520 for the stocker. Stock LSA is 114. I got 112 but you can order any LSA. Anyone planning to use a moderate to big aftermarket cam with Speed-Pro forged pistons be warned. Valve to piston clearance can be a problem, mostly on the intake valve. Mine were flycut .040 on the intake side so intake clearance isn't a problem with this cam, but when you advance them 4 to 6 degrees as recommended, the exhaust valve clearance is reduced. I have a minimum of .112 exh valve to piston clearance with this cam advanced 5 degrees. .100 is generally thought as bare minimum and .120 is usually recommended on the exhaust valve.

Oh goody. Harold strongly recommended I put in my 276/284 4-6 degrees advanced so I'll have to be very aware of that issue as well. I have SRP/JE pistons which have huge valve reliefs but the domes are sizeable so I'll be checking my clearances carefully!

Rich, you'll be OK, but I got down to around .120 on the EX's when I dialed the cam up +6 like UDH recommended.

Yes, I did get that bassackwards. And yes, Harold did mention that the 276/284 was first designed for short tracks.

Originally posted by Rich-L79:
Harold strongly recommended I put in my 276/284 4-6 degrees advanced so I'll have to be very aware of that issue as well. I have SRP/JE pistons which have huge valve reliefs but the domes are sizeable so I'll be checking my clearances carefully! Rich, I wouldn't worry too much.
I checked piston to valve clearances when assembling the 540 for future reference in case I decide on a cam change. With Harold's 287/295R10 installed at 105, I had over .240"!! This is with a SRP 10cc dome piston, .660 lift, heads were flatcut .030 to 114cc and a .048 quench.
SRP's provide plenty of clearance.

That's very good to know. At the very least, those SRPs are pretty to look at! I did have the block decked 1 or 2 thousandths just to clean it up and I may still have the heads surfaced but I suppose I can make up for any of that with the proper head gasket choice.

I'll be measuring the stuff up anyway. Hopefully I'll get that cam degreeing wheel/dial indicator package I want for Christmas! LOL!

Thanks for the correction Von! Sometimes my brain goes on a lunch break without me... :rolleyes: