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Cam grind numbers
i have a REED CAMS serial number TM264. grind number is 330 TM264H-TM272H-110A3 it has a duration of IN.214 EX218 @ .050 . lift IN.450 EX.461. running duration IN 262 EX 272. spring pressure open 260-280 and 80-100 closed. lobe centers at 110 degrees at cam. exhaust centerline 116 intake centerline 104. what would this cam be good for and how do you understand what these numbers do for performance? the only thing i understand is that a cam is 720 degrees and the duration degrees are the amount of time subtracted from 720 degrees that the valves are open. I would assume spring pressures are stock spring configuration and the grind number at the end sais A3 meaning 3 degrees advance ground into the cam. what does all this mean for horsepower, how would i understand what this cam could do in different engine configurations? also would this be a good cam for a 305? im guessing that judging by all the things that have been said about lsa and .050 duration specs, this cam is not much for a 383...but much too much for a 305. im trying to get clue how to "understand" application. i have blueprinting skills and have limited machine shop background (not automotive but still mill and lathe and blueprint knowledge) so SOME of these numbers i understand but some i dont. If i understand this correctly, correct me if im wrong, the duration of the exhaust at 218 @.050 with the lift of .461 is max for stock springs because if the lift were more than this the springs wouldnt fully close even at respectable rpm within the camshaft rpm spec. and the same would hold true if you kept the lift number the same and shortened the duration? so whats better, lift or duration? If i were to get some great valve springs would a small duration number matched with high lift be good for a low rpm 305? also the lobe centers i have no clue how that affects any of this. advise, correct and teach me please?
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by the way, this is a camshaft that i installed in a marine 350. it only made 300 hp on a desktop dyno at 4700 rpms with the parts list i used and the guy at the marina who did the desktop dyno for me said i am an idiot. and i am. he proceeded to show me how some double springs and a different cam would have made 400 hp with my flattop shortblock (that i build with silvolites) with some different grind numbers. and it would do it at 4000 RPMS!!!!!
i am an idiot and i want to get this 305 right on the money. shop that sold me the cam asked me about a parts list, i told him i had stock heads and thats the cam he gave me. he added no advise to this like the genius marine tech guy. the marine genius guy told me that the shop tech shoulda told me i was building a turd but i think he wanted to dust off this old cam and sell it. by the way the boat does haul some *** because it was origionally a 260 hp 350. i was able to prop up one size and ontop of that, i gained 1000 rpms above the old rpm and this thing sounds incredible at an idle, youd think i had a big block in that thing. did 46 mph, now it does 55 mph. id have the marine guy help me build up this 305 but he goes to florida in the winter and i am buying parts now. that is why i am asking so much on the forum lately. also whene i try to ask the marine guy to explain things he tells me to buy a book. hes probably right. he has been so far.
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duration is the length of time that the valves are open
you need to have the valves open long enough to fill the cylinder. think of filling a jar under a tap when its full some flows back towards the top or splashes back now put the lid on this jar,shake it and walk into another room,open the jar and pour out the water in another sink how fast you fill the jar depends on the neck size or opening size(valve size in an engine)the water pressure from the tap and tap size (intake runner size) lid on as soon as the jar is as full as possible without spilling empty jar by turning upside down with lid off(think of a long neck pop bottle Vs a short neck pop bottle for exhaust)put lid back on as fast as possible so you can go back and refill at tap. any wasted time and spillage is cam/head/carb/header inefficiency |
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A stock un modified 305 head will really limit the power. If you want the 305 to work and the cam to work the heads need to flow Either fully port or replace. 1.94x 1.50 best. You got to be willing to work the heads. You are right and I'm not going to type out 30 years of experience. The cr matters. But 10:1 is too high for a boat motor. but just right for the street and critical. Not a bad fun lil 305 motor for a Camaro or Malibu or light street rod. 330 ish HP. maybe more. remember, likes gear and a converter. built 305's need to rev up. the gears and converter make it fun and spunky on the street. Here is a .040" over 305 10:1 plan I'd be tempted to add a 1.6 rocker to the intake side with that cam and ported heads. Cleaned up vortecs shaved to 58cc and a RPM intake would rock on this 305. Last edited by F-BIRD'88; 02-12-2013 at 10:40 AM. |
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whene you say modified...if i were to grind the ports myself...could that help? as i understand it now, it is bad if i smooth out the intake runners and ports, i will loose precious atomization at low rpm? is it even necessary to port the heads if theyll never see any high rpms? how much "flow" do i really need at a low rpm? how do i know what flow number ill need to get intake velocity? there is so much experience needed to hop up a stock motor. i would just pick a old standby build and go to town if if i wanted raw power. speaking more of the heads, i dont even know what the intake runner cc's are, nor the exhaust. they are 1.84 434 castings. i guess at this point the heads are the real factor. parts matching is something for veteran builders i guess. i kinda understand it but once you figure out one aspect there is another limiting factor that kills any medium i thought there might have been.
thank you very very much for your patience and insight.
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the 434 heads stink. You cannot get high horsepower from a small motor at low rpm.
If you want tlow rpm get a diesel or a 454. live a little rev it up. you want to agressively port the head. but not polish . and don;t bother starting with a #434 head. Find a 4416 or a 601 or a vortec head. Or a 081 or 083 head. The 450 and 434 low perf 305 heads suck. start with the HO heads and port the crap out of them. You need flow to make HP. and RPM. When you port a stock head for power you need to make serious dent in it. YOU NEED FLOW. You will not get flow by *****ing around with a dremmel and sanding rolls. This is not a low rpm motor,,, cam, especially in a 305. when you cam up a motor you need to rev it up. when you hot rod a 305 you need to rev it up. In a 305, this cam does not get real busy till 3000 rpm. it wants to rev. Hot Rodded small motors want to rev ... You cannot increase the low rpm torque output by adding cam to it. especially on a 305. Find some 4.10's Last edited by F-BIRD'88; 02-12-2013 at 11:44 AM. |
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If you want fuel mileage get a Honda.. If you want fun Supercharge a 305.
You can buy a whole rusted out car with a 305 in it for $100. or less. If you want gas mileage from a L-30 305 vortec motor install it stock. Get all the stock stuff from the donor truck. Trans, computer, fuel system, exhaust cats everything. Install the WHOLE system in your S-10 in stock form and don;t touch it. Shut the hood and drive it. But of you want fun, Supercharge a 305. Last edited by F-BIRD'88; 02-12-2013 at 11:57 AM. |
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With the cost of aftermarket heads available you are wasting your time and money fooling with a stock head.The budget you have to work with will take some smart shopping for parts,the cam you have would produce some good low end and mid-range power but you should go for a 350 build as those parts are more budget friendly.
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In other words you don't know how to hot rod a 305. |
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not a damn clue....ooo look somethin shiney!!! im under the impression there the same parts and can be swapped to a larger 350 later on. need more rpm for 350 parts in a 305 to work right.
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305 Vs 350,which is better
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either engine will work. look around for a deal.If you want dirt cheap,dont care how long it lasts,moderate power, buy a complete running car from a wreck. take out engine,(pick a car that has a roller motor)regasket/clean/replace timing chain,buy a cheap cam,use FBs back yard porting method,drive a car that performs as it is built. enjoy,,, |
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