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Thread: 1975 455 timing

  1. #1
    BigPimpN
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    HCP 1975 455 timing

    I have a 1975 pontiac 455 that i am rebuilding, i read in a haynes book that my timing marks on my greas should both be at noon, crank and cam gear both straight up, i did it like that, but have not tried to fire yet, just wanting to know if that is correct before i install it in the car. also when i put the harmonic balancer on it, the timing mark in the balancer is sitting about 12 deg atdc, that is how it is just put together, i dont think that sounds right, shouldnt it be closer to the zero mark on the timing cover scale...I would like some good info on this by in the morning as i will be starting to do more work on it then....thanks

  2. #2
    Dead Head Roller GratefulDiver's Avatar
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    If the marks are straight up you're fine. The balancer will only go one one way. You should be at 0 on the compression stroke of the #1 cylinder (front driver side) and your rotor should point to #1 when you drop the distributor in, you may have to use a long flat tip screw driver to turn the oil pump shaft to get it to line up, should be around 2 o'clock position.

    1972 LeMans W/Endura Front End & 461 CID

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    THE BESTEST poncho1961's Avatar
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    Quote Originally Posted by USMC-0311 View Post
    I have a 1975 pontiac 455 that i am rebuilding, i read in a haynes book that my timing marks on my greas should both be at noon, crank and cam gear both straight up, i did it like that, but have not tried to fire yet, just wanting to know if that is correct before i install it in the car. also when i put the harmonic balancer on it, the timing mark in the balancer is sitting about 12 deg atdc, that is how it is just put together, i dont think that sounds right, shouldnt it be closer to the zero mark on the timing cover scale...I would like some good info on this by in the morning as i will be starting to do more work on it then....thanks
    Not sure on your combo, but here are some ideas on why.

    1. your engine is not set at TDC, possibly bumped that 12 deg your seeing.
    2. The damper/timing cover combo are not correct. Various years used different timing covers with the timing marks in slightly different locations. If the cover is from a different year than the balancer, your marks may not be correctly matched


    Verify that you are at TDC, do not rotate the crank while installing the balancer, scribe a new line on the balancer that lines up with 0 on the timing marks.
    I'm the Rick in prick.

  4. #4
    BigPimpN
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    well the timing cover is from this motor and it has a built in marker on the housing, as far as the damper it should be original, i have it in my garage building it complete and, the crank gear is set straight up, and when i put the cam gear in with the chain it was also straight up, and it hasnt moved since, it was at TDC when i put it together....is there play in the crank before and after TDC, meaning if i was to set it at TDC, i would actually be able to move the crank some clockwise and it will still stay on TDC but will throw that mark off....thanks for you info so far....

  5. #5
    Dead Head Roller GratefulDiver's Avatar
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    There should be a little play in the timing chain. The balancer is a two piece unit with a rubber ring between the two pieces. It's possible that the outer part moved, but not likely, they usually just wobble when bad. That's what mine did anyway

    1972 LeMans W/Endura Front End & 461 CID

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    THE BESTEST poncho1961's Avatar
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    I have seen balancer that the outer ring was of. As mentioned above, the two piece design means the outer ring can slip on the rubber ring between the two pieces. And yes, depending on the condition of that chain, the amount the crank will move before the cam moves can vary.
    I'm the Rick in prick.

  7. #7
    BigPimpN
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    ok I was thinking about replacing the balancer, but they are outrageously expensive, ill look into it, ok one more thing on that, i have a Haynes book for trans am it tells me that the timing marks should go with, crank gear at noon and cam gear at noon, now i also have a Motor book for the 80's that goes from early 70's to the 80's and it says the timing marks should read crank at noon and cam at 6....so this is a 1975 455 that cam out of whatever i have been buying parts for grand prix and lemans......sooooo.....where are the dots actually suppose to be on this 1975 455...

  8. #8
    Dead Head Roller GratefulDiver's Avatar
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    It's the same either way, just make sure the rotor is pointed at #1 on the compression stroke

    1972 LeMans W/Endura Front End & 461 CID

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    THE BESTEST poncho1961's Avatar
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    Exactly as GratefulDiver said. Its all in the installation of the distributor.

    As a young man on my first ever cam install, I did the timing marks on the cam and crank per the Chiltons manual, installed the distributor at TDC, but it was the wrong TDC. Flames shooting, and I mean really shooooting up out of the carb when I tried to crank it over. The book was lousy at explaining the difference between the two cam timings and actually showed both, depending on the year of the engine. Like an inexperienced fool, instead of knowing to just pull the distributor and install it at TDC on the comp stroke, I pulled that whole damn cam out and turned its timing mark 180, then put it all back together. Oh, and never let your friend add the water to the radiator before you do your break in. I had been washing some stuff and had a bucket of soapy water sitting there. He filled my radiator with that. The bubbles in the radiator/engine were unbelievable.
    I'm the Rick in prick.

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    BigPimpN
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    ok thanks for all your info, i ended up taking the timing cover back off just to double check, and it is tdc with dots straight up, so i guess my balancer must be off....my dist. should be here this weekend, so ill find out for sure if it lines up to number one..i hope so iim ready to fire this bad boy up...Another question now. i am going to run a barry grant race demon 750 on a stock intake, ? should run vacuum advance to the dist or just run with no vac advance...

  11. #11
    Dead Head Roller GratefulDiver's Avatar
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    What dist are you running? If its an OEM then you must run a vac advanced, if its aftermarket like my Mallory there is no vac advance off the dist.

    A word on BG, you may want to pull it apart to check for burs at the jets or any other drilled areas. I've even heard of people say they found shavings from machine work in the bowls. I'm not knocking BG, I run a mighty demon and a street demon before that and I LOVE THEM. I'm speaking from experience. I found burs on all of the jet holes, easy to clean up but......I don't know what to think about it really. The gaskets are special so they can come apart and reassemble a few times with out worries of leaks. Just a word of caution.

    Now rock on with that 455

    1972 LeMans W/Endura Front End & 461 CID

  12. #12
    Dead Head Roller GratefulDiver's Avatar
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    Quote Originally Posted by poncho1961 View Post
    Like an inexperienced fool, instead of knowing to just pull the distributor and install it at TDC on the comp stroke, I pulled that whole damn cam out and turned its timing mark 180, then put it all back together. Oh, and never let your friend add the water to the radiator before you do your break in. I had been washing some stuff and had a bucket of soapy water sitting there. He filled my radiator with that. The bubbles in the radiator/engine were unbelievable.

    Thats some funny shit there

    1972 LeMans W/Endura Front End & 461 CID

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    BigPimpN
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    its a new oem style dist. higher volts in the coil and an upgraded module from stock...other than that its just like a stock one..

  14. #14
    THE BESTEST poncho1961's Avatar
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    Quote Originally Posted by GratefulDiver View Post
    Thats some funny shit there
    Funny now, but I wasn't laughing back then.
    I'm the Rick in prick.

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    Verified User Gtomonster's Avatar
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    Quote Originally Posted by USMC-0311 View Post
    ok thanks for all your info, i ended up taking the timing cover back off just to double check, and it is tdc with dots straight up, so i guess my balancer must be off....my dist. should be here this weekend, so ill find out for sure if it lines up to number one..i hope so iim ready to fire this bad boy up...Another question now. i am going to run a barry grant race demon 750 on a stock intake, ? should run vacuum advance to the dist or just run with no vac advance...
    You have to line up the distributor and theres three things happening at once:
    1. The distributor shaft has to align with the oil pump shaft, if it (Oil pump shaft)doesn't, turn it with a long flat head screw driver until it does.
    2. The distributor gear will slip into place with the cam gear but as this happens it will spin about 10 degrees or so.
    3. Finally you have to line up the rotor to your number one firing location.
    If it doesn't line up try again. Sometimes it goes the first time, sometimes it takes 10 times. You'll figure it out, but DON'T do anything with the crank or cam gears... They are done the way they are. You will only have 2 adjustments to work with...
    1. Turning the oil pump shaft
    2. Turning the rotor by hand before it's installed.
    That should get everything lined up.
    70 GTO, 461, 200-4r, 3.90 posi, in the making.
    62 Catalina, original, 389, auto, 4dr, cruiser!

  16. #16
    BigPimpN
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    Thanks GTO I have most of the motor assembled now im waiting for my dist and carb, oh yah and some headers too....then ill be ready to try and fire it up....

  17. #17
    BigPimpN
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    Hey greatfuldiver when you put your 400 together what did you put in the hole in the valley pan, did you block it off or what, i need to know what to do with mine...i was gonna put a pvc in it if i need it...

  18. #18
    Dead Head Roller GratefulDiver's Avatar
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    You need your PVC hooked up or you will have blow-by (i didn't spell that right) I run my PVC to the intake and use the large vac outlet on the BG for the brake booster. If your running w/o a booster you can use that for PVC, I attached a few pics to show how I run my PVC, it's little over the top, but I LOVE braided line

    1972 LeMans W/Endura Front End & 461 CID

  19. #19
    BigPimpN
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    ok great that is what i will do with the pvc..looks good and i planned on the braided line also.... ok i am also running a BG 750 race demon and i dont have any vac on it so where would be a good place to run the brake booster...

  20. #20
    Dead Head Roller GratefulDiver's Avatar
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    This is straight from the manual:

    Vacuum Lines
    All GC model Demon carburetors have three
    vacuum sources on the baseplate that can be used
    for PCV, distributor vacuum, diagnostics, or any
    other vacuum operated accessories. The large
    fitting on the back of the baseplate, and the
    smaller angled fitting on the front of the baseplate,
    are direct ( below the butterfly) manifold vacuum
    sources. The smaller fitting on the side of the
    baseplate, opposite the throttle linkage plate,
    provides a ported (above the butterfly) vacuum
    source. DR(Drag Race), OT(Oval Track),
    TR(Tunnel Ram), RR(Road Race) and BC(Blower
    Carb) competition models do not have vacuum
    ports. Be sure all vacuum lines are connected or
    plugged before you attempt to start the engine.

    I guess if you have one of the above mentioned carbs w/o vac ports you will have to run another vac off the intake. I'm not really sure because I have one on my Mighty Demon. What kind of combo are you running that you need a race Demon?

    1972 LeMans W/Endura Front End & 461 CID

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