Landracing Forum
Tech Information => Technical Discussion => Topic started by: BALS aSALT on January 21, 2011, 09:03:04 PM
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i am wondering if anyone knows...................................on a stock big block second generation camaro, where is number 1 spark plug in relation to the spindle? is it ahead, even, or behind? and if it is ahead or behind, by how much? i have an after market front subframe with no motor mounts. (ordered that way) and since i am allowed a 2% set back. i need to know how far back to place my bullet. i am going with a 2 inch setback so i need some dimensions. just where a stock motor mounts. i can figure the rest.
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Why don't you go 2% of the wheelbase back from the front spindle centerline?
DW
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so maybe i am misunderstanding the rules...........................again. so if i understand by what you say dw, i am allowed to set back engine from spindle centerline rather than the engines original location? in that case it would be more than 2% set back? no????? understanding now................i now know where to place Das Bullet :-D :-D :-D :-D :-D :-D thanks DW.
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Read 4.aa again and again, no reference to original locations, just spindle, sparkplug and Wheelbase.... You must read but try not to read in... or just ask for help understanding.
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If you are 2% of the wheelbase front the front spindle centerline how in the F can it be more than 2%?
DW
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If you are 2% of the wheelbase front the front spindle centerline how in the F can it be more than 2%?
DW
:-D
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If you are 2% of the wheelbase front the front spindle centerline how in the F can it be more than 2%?
DW
it's a complicated thing the way my mind works sometimes :? :? :? :? :?. like i said earlier, i misunderstood. i was thinking that if the original location is forward of the spindle, then a setback of 2% from spindle would equal more than 2%. but now that i understand, thanks for the fn help. :-P :-P :-P :-P :-P :-D :-D :-D :-D :-D
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The wb must remain the same--- :-o what ever the stock wheelbase is you are allowed to move it back 2% on our truck the stock wb is 143"--- so we are allowed to set the eng back slightly less that 3" we are going for 2.75 but the eng will be back almost 5" from a stock 454 because the stock spark plug is in front of the front axle cl. :-D
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now thats what i was talking about :-o :-o :-o :-o :-o :-o :-o. and since a 73 camaro never came with a bigblock i was asking about a 72 stock bigblock engine location. but don't know if the measurement is taken from sparkplug hole or what. and in relation to what. :-D :-D :-D :-D :-D :? :? :? :? :? :?
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Front spindle center line to first spark plug. If the engine has off set heads, the forward head will be measured.
DW
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Dan, if it doesn't, I would like to see the crank and rods............ no rotary engines please......... :-D
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Fork and blade rod :evil: :wink:
Ed
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yep they are out there
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Bob,
Had to make that clear.
DW
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You could always put a spark plug in the water pump -- but I'd bet Dan would figure that out.
Stan
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You could always put a spark plug in the water pump -- but I'd bet Dan would figure that out.
Stan
You think?
'cuz that would sure make things easy for me! :evil:
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We had a problem understanding this rule 35 years ago and it was not until somebody..... if I recall correctly, it was JD Tone.... pointed out that IT IS NOT IN RELATION TO THE ORIGINAL POSITION OF THE ENGINE.... THE ORIGINAL POSITION OF THE ENGINE IS NOT RELEVANT.... it is only from the criteria included in the book.... if you have a 100" wheelbase car, the setback is a maximum of 2" BEHIND the front axle centerline.... being that we were allowed a 2" body stretch (similar to NHRA pro stock rules and which put us into Altered-where 25% setback was allowed)... it all went out the window for us anyway... but boy do I remember the snail mail exchange!!!!! and you would think that, after all these years, (and NHRA having similar rules too) that the definition of setback would have been made clearer....
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For Altered class my rule book says 2% body stretch (not 2") in front of the fire wall.
It also says engine set back is maximum of 25% of the wheel base per Section 4.AA
Page 42, 4.AA of the 2010 rule book states........
The feature of a car is represented by the formula D/WB where D is the distance measured from the front spindle transverse centerline to the front-most spark plug hole or centerline of the front most cylinder on compression ignition engines and WB is wheelbase.
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For Altered class my rule book says 2% body stretch (not 2") in front of the fire wall.
It also says engine set back is maximum of 25% of the wheel base per Section 4.AA
Page 42, 4.AA of the 2010 rule book states........
The feature of a car is represented by the formula D/WB where D is the distance measured from the front spindle transverse centerline to the front-most spark plug hole or centerline of the front most cylinder on compression ignition engines and WB is wheelbase.
Yes that is exactly what it says.... the 2" was because the car was 100" wheelbase.... you gotta give me some slack here .... these discussions were over 30 years ago!
As you correctly point out in the word for word rendition of the setback rule, the criteria for its determination is there.... only thing is ....many of us assumed that you arrived at a number from that formula and then you SET YOUR ENGINE BACK THAT MANY INCHES FROM THE ORIGINAL STOCK LOCATION.....
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been there done that :-D
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IIRC, JD that told me that if you change from a bbc to a sbc using the same mounts, the set back to the spark plug will be different. Legal with a bb will give too much with a sb.
Ron
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"many of us assumed that you arrived at a number from that formula and then you SET YOUR ENGINE BACK THAT MANY INCHES FROM THE ORIGINAL STOCK LOCATION....."
In that case many of you made the wrong assumtion.
DW
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Yes, Dan, you are absolutely correct....