Reply With QuoteHee hee, I had to laugh at some of you guys giving all that advice for a cam with 3 sets of duration specs.
Better recheck the listing Slotracer.
Intake Duration 050 inch Lift: 308
Exhaust Duration 050 inch Lift: 316
Duration at 050 inch Lift: 228 int./235 exh.
Advertised Intake Duration: 244
Advertised Exhaust Duration: 252
I don't get it...these numbers make no sense at all. You have three duration numbers, two at .050 lift, and advertised numbers less than .050 numbers.
I'm guessing the advertised duration is 308/316, but which .050 number is it? The 228/235, or the 244/252, 'cause it can't be both, and you don't usually have advertised numbers that are less than .050 numbers. This is all screwed up.
Hee hee, I had to laugh at some of you guys giving all that advice for a cam with 3 sets of duration specs.
Better recheck the listing Slotracer.
Who is the manufacturer and what is the part number?
It's a Erson. Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 3800-6800 RPM
Intake Duration 050 inch Lift: 308
Exhaust Duration 050 inch Lift: 316
Duration at 050 inch Lift: 228 int./235 exh.
Advertised Intake Duration: 244
Advertised Exhaust Duration: 252
Intake Valve Lift with Factory Rocker Arm Ratio: 0.576
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.576
Valve Lash: 0.000 int./0.000 exh.
Lobe Separation (degrees): 112
Advance: 4
Computer Controlled: No
Grind Number: JB300
Quantity: Sold individually.
396-502 CID Chevrolet Big Block V8 Engines
Part number/Grind number: E125521 / JB300
heres all the info from their add
PROFERAL BILLET Cam from Erson Cams.New in the box. Made in USA!
High performance jet boat cams.
These JB hydraulic flat tappet camshafts from Erson were developed to compliment the unique characteristics of jet boats. Designed to work with the unusual shaped power absorption curve of the impeller, these cams produce power over a broad range and provide excellent acceleration if matched to the impeller curve.
The JB Cam
Erson JB Cams were developed to complement the unique characteristics of jet boats. The jet unit has a power absorption curve similar in shape to the power output curve of an engine, except at the top-end where the impeller power absortion curve becomes very steep. The RPM, where the power developed curve crosses the power absorbed curve, is the absolute maximum RPM the unit can turn. The spread between the curves is excess power and translates into acceleration.
The JB Cams are developed to complement the unusual shaped power absorption curve of the impeller. These designs produce power over a broad range and provide excellent acceleration if properly matched to the impeller curve.
MARINE Application:
Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 3800-6800 RPM
Intake Duration 050 inch Lift: 308
Exhaust Duration 050 inch Lift: 316
Duration at 050 inch Lift: 228 int./235 exh.
Advertised Intake Duration: 244
Advertised Exhaust Duration: 252
Intake Valve Lift with Factory Rocker Arm Ratio: 0.576
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.576
Valve Lash: 0.000 int./0.000 exh.
Lobe Separation (degrees): 112
Advance: 4
Computer Controlled: No
Grind Number: JB300
Quantity: Sold individually.
396-502 CID Chevrolet Big Block V8 Engines
Part number/Grind number: E125521 / JB300
Application/Characteristics:
For the more serious jet boater. New lobe technology builds higher cylinder pressure. Must have good exhaust (no wet manifolds), tunnel ram style intake, blueprinted pump and loose impeller.
pat(slotracer)
Can you scan the cam card? Those specs are all screwed up..........MP
My guess is that, using those numbers, it's:
228 int/235 ex @ .050
244 int/252 ex @ .020
308 int/316 ex advertised (probably .006)
.576 in/.576 ex lift
LSA=112*
228/235 dosen't seem like much .050 duration for a cam with .575 lift. Compare to a Comp XM298H Extreme Marine hyd flat with .575/.578, 254/264@ .05. :idea:
BTW...to answer your question, it sounds like a decent cam, (going by advertised and lift numbers) but you'll need headers and a B impeller to get the best of of it. (The 244/252 numbers are probably the .05 duration.)
the cam i have in it right now is a comp cam extreme marine cb xm 278h-12.
it turns a b imp. 5200 rpm's. just looking for something to pump it up alittle more. this is just going to be a lake jetboat to play with when i have the kids with me. the boats a 19ft. mariah with a dominator pump. thanks
pat(slotracer) :rollside:
heres just exactly what the comp xm278h is. right out of the book. rpm operating range=2000 to 6200. advertised=278/292 .050 =234/244 lift=.564/.566 112 degree lobe sep. hydraulic-jet with A impeller, needs improved intake, likes headers.
I'm just going to throw this out there for conversation. How many of you have engines that can talk to you and tell you what they do. . .I mean this BBC knows its a jet boat engine so it does this and this BBC is an I/O engine and it does this. Cams are not application specific, marketing is. Cams allow an engine to make a powerband at some specific rpm, marketing doesn't.
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