Hi guys I need someone to teach me what means all specification a cam can have. Draw something or explain me as well as you can. here's a exemple: Elgin cam #2853 specs 2000 to 5500 RPM 6500 redline @.050 duration int 224 ex 234 lift int 498 ex 520 centerline 107 Does it good, Does it for short race or long race I wanna know everyting:confused: :confused: :confused:
Well, we'll try. RPM=2000 - 5500: The usable range recommended by the cam manufacturer. Power must drop off signicantly by 6500 rpm or it has hydraulic lifters which won't rev any higher. .050 duration: The time, as measured in crankshaft degrees, from when the valve is raised .050" off the seat untill it is .050" from closing back on the seat. The intake valve is open 224 degrees and the exhaust valve spends 234 degrees of crankshaft rotation between these points. Lift: How far, measured in thousandths of an inch, each valve lifts off the seat as measured at the valve. Most manufacturers calculate this number assuming you are using stock 1.6:1 ratio rocker arms. If you run 1.7:1 rockers you will get more lift at the valve and a tiny bit more duration, too. Notice for duration and lift the numbers are larger for the exhaust valve. Since Ford heads historically have poor breathing exhaust ports, the duration and lift of the exhaust valve is extended. Lobe center: For each cylinder pair of cam lobes (intake and exhaust) the distance measured in crankshaft degrees between the peak of one lobe to the peak of the other. Lobe center along with duration gives you an idea of how much overlap exists (the time when intake and exhaust valves for a particular cylinder are open at the same time).
thanks for all this good explanation I will sleep less stupid now but just one more question please. what it means in real life you know on the road what it makes to have more intake or exhaust?? Finaly what all this number change when I press the gas pedal to the floor sorry for boring some but I need to know Thanks David
Your intake flow and exhaust flow need to be somewhat balanced or all of the burned gasses won't be expelled from the cylinder on the exhaust stroke. Then you don't have as much space for fresh fuel mixture to enter the cylinder and make power. The specs stay the same no matter how far you push the pedal. Big lift and duration numbers are for racing cams to operate at high RPM's. The lower, more conservative numbers are what you want in a street driven application where you need more low RPM torque. If you want to go street/strip you have to compromise with something in the middle range. The best thing to do is call a cam company, tell them what your combination is and what you want to do with it, and let them make suggestions.
Hi David, What do you want to do with the car , street/strip or just a daily driver to cruize around. My cam that you talked about will be hot on the street but you would have to check piston to valve clearance with the .520 ex lift ! Richard
An "extreme" is a relative term. Some guys think a cam so "big" that it won't idle at less than 1400 RPM is just right for a street car, others think one that idles anything more than smooth is too big. I saw a cam listing the other day for a Ford 429-460 based engine that had specs of 292-298 @ .050" duration, and a .914-.888 lift. That's a big cam! The cam you have is considered "mild" by today's standards. It will have a slight rough idle, but should idle well in an automatic at 700-800 rpm. I have about the same thing in my mustang, but made by Erson. Great street car camshaft with both automatics and standard tranmissions.
comet 75, you ask for real life info in the car; I can tell you it won't idle too smoothly with 107 degree lobe center and low end suffers. If you have an auto trans--not to good. I would not use this cam in a near stock engine for road use unless your determined to do so and accept the results. None of the 5L roller letter series cams from Ford are this long in timing at the .050 points. IMO you need to stay in the 214/220 range at around 112 lobe center for the street unless you want to use the car for specific performance goals with supporting modifications. I'm trying to convey some specific info for you to get a handle on because you don't give enouth info on you intent.
Forgot to mention that Elgin is owned by Crane Cams. If your refering to 3/4 race, full race designations; those were used in the 40s and 50s to define the first cams that cam out for the Ford Flathead engines. These designations mean very little in relation to cam timing except possibly one would not use a full race cam on the street. Full race durations would have been from about 280 degrees upward to over 300 degrees for those old engines and used with solid lifters. I have built Briggs modified single cylinder engines with cam timings in the 296/310 range. These little engines with that kind of cam run in the 4000 to 9800 rpm range. Hardly what one would use in a lawn mower as well as needing an electric battery powered starter to get started on Alky fuel.
I'm bulding a 302 1975 with edel. rpm performer 600 cfm intake, 600 cfm carb, for now that's it but if i have enough money at summer time i'll may put bigger pistons but I don't wanna race with this it's just for fun on the street. I don't like speed as well as a good start, but I wanna go on high way too So what do you suggest me ?? I realy don't know any thing about rebuilding engine but want to do it my self cause I thing this is the best way to learn
Cams for manual and autos A cam that makes a car idle at over 1500 rpms will typically run better in a manual tranny car. If you have an A/T, look at your tachometer when idling at a stoplight. You are probably revving between 700-1400. A stall converter will allow your A/T car to idle higher at it's comfort zone with a 'big cam' without putting all those rpms through to the rear wheels. They were designed for racing so that you can launch quicker. They will heat up the tranny however due to the unused rpms. You don't have this problem with manual cars. If you have ever driven a car with a 'big cam' that is a manual you may have noticed that the motor has to be revved to get going from a dead stop. It all has to do with the comfort range of the engine. A small block Ford with over 300 degrees of duration and over .500 in valve lift is typically a performance setup and will idle at much higher than normal rpms. I hope all of these posts help. Seth
Ok, you definded what you want. For a lot of pulling power, I would go with a cam known as an RV cam, with a 600 cfm vac secondary carb. This combo will be very inexpenive overall. Will give you just a little lope at idle and be very smoothe and hard pulling but will not rev beyond what the cam makes says and much of the time is done pulling by about 5200 rpm or there abouts. I have run this combo and can tell you it is explosive within the rpm range.in a light car. These cams are usually single pattern and have this shorter rpm range because of it. Also there would be no need to change converters with this kind of setup. It's a lot of fun to have that kind of throttle response even with stock 3.08 gears.
Seth, great breakdown! It made me pull out my timing card to view what I put in 15 years ago when I REALLY did not know what I was doing.. Here is what I am running........ CRane F-280 Lift @ valve INT 553 EXH 572 Duration: 280 INT 288 EXH @.020 @.050 INT 224 EXH 252 Did not know much at all when I bought it (and likely nothing worked together then) but I have been lucky puting parts together. I run Weiand Acceleratr intake with a Predator Card, 3000 stall and 4.11 in the rear. 1965 289 heads with 1.94/1.50 stainless valves Scotty
comet 75 Why didn't you just buy the cam that Edelbrock makes to go with the manifold? Which, by the way, is speced at .496/.520 lift and 224/234 deg. I don't see a lobe center spec but it looks like your cam is pretty close to what Edelbrock intended.
