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Thread: timing

  1. #1
    Senior Member RACING JUNKIE
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    timing

    Ok the thread about headers getting red reminded me of something...Quite awhile back on this board or another,it was mentioned that having too much initial timing or having a locked out distributor could cause one to smell rich at idle and burn your eyes like it's really fat. Can someone explain to me WHY this is? I ask because my dad( 72 years old and stubborn as a mule) has a stock short block 400 with a mild hydraulic cam with around [email protected] .050. Lift is .472 I think...it is just one I had lying around....It has a brand new 600 Holley vacuum secondary carb and it runs really rich at an idle.( brand new because he blamed this rich condition on a junk carb) As much as I disagree with him,he still insists on timing it by ear because he has always done it that way.It has no reliable pointer on it anyway,just a cheapo chrome one....It runs great but smells really rich at idle.I've never had problems tuning a Holley but I cannot get this thing to not smell rich. The old carb responded to the idle screws so I know it was on the idle circuit...I even plugged the power valve as an experiment to see if maybe that was it...no luck.Still burns your eyes....I also drilled holes in the throttle blades.so the new carb was bought and while it helped,it still seems rich at idle...this new carb has non adjustable floats too.

    I am wondering if it is something way out of whack with the timing or the fact that it has low compression and a cam not suited to it or what? I need to get a reliable timing mark on it and set the total timing correctly....Any thoughts?


    P.S. Also tried running a little hotter plug too. It is a stock HEI

  2. #2
    Senior Member RACING JUNKIE TheYellaBrick's Avatar
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    Is this rig running with a cat ? Could it be old and plugged ?
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  3. #3
    Senior Member RACING JUNKIE
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    No it is his 67 el camino.I built the engine for him out of spare parts I had.It is a .030 over 400 sb with dish pisons, double hump heads and a performer RPM and the above mentioned 600 holley and erson Hi Flo 1 cam. It has headers and 2.25" dual exhaust with turn downs.

  4. #4
    Senior Member EXPERT BUILDER
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    Have you tried smaller jets just to see?
    Is there no way to adjust the floats at all?
    If no on the above, it may just be what you suggest... too low of compression with too big a cam. What is you lowest compression reading?

    I had one do that same exact thing, and tried everything. Then found the compression was terribly low, so I tore it down and found worn out dished pistons. After boring and rebuilding with flat top pistons, and using the very same exact cam and top end without changing anything else, the rich condition went away... and wow how it came alive!
    I'm not hatin... I'm just sayin...

  5. #5
    Senior Member RACING JUNKIE
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    I haven't messed with a compression check. The engine had new pistons and a fresh bore and valve job when I put it together. The heads are 64 cc chambers with stock replacement 400 pistons.They are just stock cast .040 over pistons. I said .030 over before but I forgot it was .040, but obviously that doesn't matter. I stuck that cam in it cause I had it and it sounds good but I'm thinking I may swap it for an "RV" cam sooner or later. The cam is small but has a choppy idle. But to answer the question about the jets,I haven't done anything to this carb but the other one I did. I had the smallest jets they make(I think) in it.63 or 64 can't recall. They were the smallest ones in the jet assortment kit I have...you know the kit they sell that has 2 of every jet up to 99.

    Oh well.


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