Bbc cam timing
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Bbc cam timing

  1. #1
    senior member turbo wog's Avatar
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    Default Bbc cam timing

    well i checked my cam timing from last time i set it ( the first time ever doing it). when the lifter rises .020 the degree wheel is at 28 not the .031 listed on the paper work . at .050 it is supposed to be 15* & i am at 12*, same thing with all the specs . that would make the cam 3* retarded correct? . the timing is set at 8* advanced on the crank gear. if i am correct the cam sprockets are @ 11* each tooth? that would mean i have 1 tooth off on the cam gear? i did notice it is a little slower right out of the hole but once it gets going the upper end is incredible. will i loose the incredible top end if i advance or set to
    0* cam timing. will it gain lower end initial pull & loose top end pull or will i keep the top end power?
    Last edited by turbo wog; 09-01-2012 at 09:58 AM.

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    Quote Originally Posted by turbo wog View Post
    well i checked my cam timing from last time i set it ( the first time ever doing it). when the lifter rises .020 the degree wheel is at 28 not the .031 listed on the paper work . at .050 it is supposed to be 15* & i am at 12*, same thing with all the specs . that would make the cam 3* retarded correct? . the timing is set at 8* advanced on the crank gear. if i am correct the cam sprockets are @ 11* each tooth? that would mean i have 1 tooth off on the cam gear? i did notice it is a little slower right out of the hole but once it gets going the upper end is incredible. will i loose the incredible top end if i advance or set to
    0* cam timing. will it gain lower end initial pull & loose top end pull or will i keep the top end power?



    Why not just try it straight up and find out? Jocko

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    Senior Member EVILFORCE's Avatar
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    Advancing the cam will shift the basic RPM range downward. Four degrees of advance (from the original position) will cause the power range to start approximately 200 RPM sooner. Retarding it this same amount will move the power upward approximately 200 RPM. This can be helpful for tuning the power range to match your situation. If the correct cam has been selected for a particular application, installing it in the normal “straight up” position (per the opening and closing events at .050” lifter rise on the spec card) is the best starting point.

    This from Summit tech.
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    senior member turbo wog's Avatar
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    Quote Originally Posted by EVILFORCE View Post
    Advancing the cam will shift the basic RPM range downward. Four degrees of advance (from the original position) will cause the power range to start approximately 200 RPM sooner. Retarding it this same amount will move the power upward approximately 200 RPM. This can be helpful for tuning the power range to match your situation. If the correct cam has been selected for a particular application, installing it in the normal “straight up” position (per the opening and closing events at .050” lifter rise on the spec card) is the best starting point.

    This from Summit tech.
    good info thanks! does this info refer to a hot rod motor with a usuable rpm range of 5000 in a car that usually would be in the much lower rpm range & would it apply to a wot boat at 7000 rpm+? 200 rpm i probably wouldn't notice at all in the boat.?

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    Quote Originally Posted by jockorace View Post


    Why not just try it straight up and find out? Jocko
    i dont want to change anything yet . i ran so incredible that i will get it back running first & get what i can get out of it . i will then change the cam timing to see if it helps. just need to know more about it.

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    gn7
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    Never seen a cam, EVER, that didn't lose more power from being retarded than from being advanced from its optimum. Virtually any cam that makes max power straight up, will lose more power retarded, than advanced the same number of degrees.

    Never seen a turbo motor that liked a retarded cam.
    Using .020, and .050 lifter rise DOES NOT tell you if the cam is advanced or retarded. It only tells you the relationship between how you installed it, AND HOW IT WAS GROUND!
    If the lifter rise is 3 degrees retarded, but the cam was ground 4 degrees advanced, then your really only 1 degree from straight up.

    If you're cam is 3* retarded, and you put the crank gear at 8* advanced, then you lined up on the wrong tooth on the gear. GUESS YORU DAMN LUCKY YOU DID PUT THE GEAR ON STRAIGHT UP! YOU WOULD BE 11* RETARDED!!!!!

    I DETEST CAMS GROUND ANYTHING OTHER THAN STRAIGHT UP. THEY'RE FOR FREEK'N AMATUERS!!!!!!!

    This statement NEVER ceases to amaze me. Like timing your ignition blind and deaf.
    Quote Originally Posted by turbo wog View Post
    well i checked my cam timing from last time i set it ( the first time ever doing it). ?


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    Last edited by gn7; 09-01-2012 at 11:01 AM.

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    Senior Member EVILFORCE's Avatar
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    Like Bob says. Get a good cam that is made to spec. Run it straight up. You can spend 2 days on the dyno messing with that stuff. Pick the right cam, by a quality maker for your needs and be done with it.
    No Fool Like A Old Fool is there?

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    senior member turbo wog's Avatar
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    can you tell from the cam card if it has the advance built into it? i noticed that the deg. was left blanck. does that mean that it was left up to the engine builder to set?
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    Last edited by turbo wog; 09-01-2012 at 12:04 PM.

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    not sure what you meant about never ceases to amaze me, deaf blind comment but i used a degree wheel & messed with it a whole bunch the first time i set it. i now have a little more knowedge & caught the fact that it might be a tooth off. i remember not being able to get it right last time & it seemed that was as good as i could get it. i apriciate all the help you guys are giving here, thanks again.
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    Last edited by turbo wog; 09-01-2012 at 12:16 PM.

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    Not sure what the 10L is on the cam. Maybe Cstraub knows. I normally think that it meant it was ground on a 110 intake center line, but the timing events say no. Also, Isky isn't known for grinding cams for dummies. I have never seen a Isky cam ground advanced except for some late model EFI stuff and some smaller torque/milage cams.

    Thats a handful of cam for a 505 turbo deal . How did you come about that camshaft?

    From the looks of the pic, if your seeing 3* retarded with that, that timing set or the camshaft, or the crankshaft or all 3, is OFF! One degree here and 1 degree there and BAM! your off 3*
    Just another lesson why you should time in EVERY canshaft!



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    Quote Originally Posted by turbo wog View Post
    not sure what you meant about never ceases to amaze me, deaf blind comment .
    Quote Originally Posted by turbo wog View Post
    well i checked my cam timing from last time i set it ( the first time ever doing it)

    I made that comment based on this in your first post. Just curious, how long before you starting timing your ignition with a light? I guess there is a first time for everything. But without timing in the cam, how do you know which direction you should go if you were to try something else. If its 3 degrees retarded now, imagine if your went further retarded. Same if it was advanced right now. Like 6 degress advanced, and you added another 4!

    Like shooting ducks in a fog!



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    Quote Originally Posted by gn7 View Post
    I made that comment based on this in your first post. Just curious, how long before you starting timing your ignition with a light? I guess there is a first time for everything. But without timing in the cam, how do you know which direction you should go if you were to try something else. If its 3 degrees retarded now, imagine if your went further retarded. Same if it was advanced right now. Like 6 degress advanced, and you added another 4!

    Like shooting ducks in a fog!
    i remember the power brake till it stops pinging.. lol! never just threw a motor together. had it done . now i got the tools to save a little$$$.

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    Quote Originally Posted by gn7 View Post
    Not sure what the 10L is on the cam. Maybe Cstraub knows. I normally think that it meant it was ground on a 110 intake center line, but the timing events say no. Also, Isky isn't known for grinding cams for dummies. I have never seen a Isky cam ground advanced except for some late model EFI stuff and some smaller torque/milage cams.

    Thats a handful of cam for a 505 turbo deal . How did you come about that camshaft?

    From the looks of the pic, if your seeing 3* retarded with that, that timing set or the camshaft, or the crankshaft or all 3, is OFF! One degree here and 1 degree there and BAM! your off 3*
    Just another lesson why you should time in EVERY canshaft!
    that is what i thought when i did it for the first time. it was difficult with everythg off in the same direction. but the 8* advance on the crank ! + the 3* actual retard. + 11* ! that might be 1 cam tooth off?

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    gn7
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    Your not off a tooth on the cam sprocket. After blowing the pic up as big as I could, it looks like your smack dab between two marks on the crank gear. I would say your off by a tooth. But a tooth on crank sprocket is more than 11*, and tooth on the cam sprocket only half as many CRANK degrees and your measuring CRANK degrees when you time in a cam.

    Unless I am mistaken, a BBC has 25 teeth on the crank and twice as many on the cam.
    That would make a crank tooth 14.4 degrees, or a cam tooth 7.2 crank degrees.
    Your not off on the cam sprocket!



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    Last edited by gn7; 09-01-2012 at 03:53 PM.

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