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Thread: Is there any thing for engine angle?

  1. #1

    Is there any thing for engine angle?

    I got a car and the engine is crooked and sitting too high in the front. After looking at the car more, (full 2x3" chassis) they welded motor mounts in but they have the motor moved over left in the engine bay to clear the rack, and the oil pan is sitting on the rack. I'm thinking and been looking and maybe they placed the cross member too high? Maybe before the car had a SBC at first and now with a BBC, or better yet they were lost and did not want set-up the car right. What would be the best way to get started?? Buy a new crossmember or ??

  2. #2
    Senior Member DYNO OPERATOR
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    cut the stuff that's in the way and reset the motor where you want it.
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  3. #3
    yep, that is what I'm thinking, cut the crossmember and get it where it needs to be.

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    I used a torpedo level on the intake ,put in and welded it up.
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  5. #5
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    PROPER ENGINE ANGLE

    Hello,

    First and foremost, the engine/transmission centerline must align exactly with the chassis centerline. Chassis Centerline: is determined by measuring exact center between the main framerails from the front of the chassis to the rear. The crankshaft and transmission output shaft centers must be mounted in the chassis at exact center.

    If you are really committed to checking and refitting/fabricating new mounts and motorplates to fix the problem it will require some basic tools and patience and the end result will be a better launching race car. A properly aligned and mounted driveline (engine, trans, driveshaft), this assures safety, performance, and reliabilty of any race car.

    One important race car fabrication rules is: higher crankshaft centerlines raise the CG, center of gravity. This increases weight transfer to the rear wheels on acceleration. To some this may sound great but instant weight transfer equals wheel stands which multiplies into lost E.T. Think of an NHRA pro stock car they just squat and go, this is because of ideal CG and weight transfer. There is no real set formula for ideal crankshaft centerline height because there are too many factors in many types of race cars but between 9"-12" from the race track surface is found to be most suitable, depending on the chassis design this can have some limiting factors when considering suspension mounts and steering mechanisms.

    In most tube chassis race cars, level mounting of the engine/trans assembly will almost always leave the transmission output shaft too low.
    This causes the installed driveshaft to operate the universal joints at angles. Most would say, isn't that what u-joints are for? Yes, the design inherantly takes up miss alignment and angle but this is applicable in passenger vehicles and trucks. Angular operation of u-joints in a drag race car application causes a non-constant turning velocity of the driveshaft. The result can be driveline vibration, stress and power loss.

    Most professionally built race cars actually have an engine angle of 1-2 degrees, meaning the tailshaft or the transmission output is actually angled upward which aims the transmission outputshaft directly at the rear end drive pinion.

    The correct angle is determined after the engine crankshaft centerline height is determined (crankshaft centerline height from race track surface). Once the crankshaft centerline height is set you will determine the correct angle by pulling a string or light guage wire from the front of the crankshaft snout centerline to the rear end drive pinion. Measure the angle with a protractor (angle finder). This process is usually performed with a "dummy" engine block installed in the frame rails without a transmission bolted on and a wood or aluminum puck installed in the #1 main saddle of the engine block. A small hole is drilled in the center of the #1 main puck to feed a string through. After the angle is determined, bolt on your transmission and raise the engine/transmission angle until you reach your determined angle. BE SURE TO MAINTAIN THE ORIGINAL CRANKSHAFT CENTERLINE HEIGHT DISTANCE AT THE FRONT OF THE ENGINE. You will only be physically raising the rear of the transmission output shaft to meet the desired angle. After the engine/trans is mocked-up at the correct angle then you will proceed with making new mounts and motorplates.

  6. #6
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  7. #7
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    hey Dude,what if transmission placement can't be change or don't want to change trans placement do to floor boards?
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  8. #8
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    montecarlo84 Posted: 13 Sep 2009 22:07 Post subject:

    --------------------------------------------------------------------------------

    hey Dude,what if transmission placement can't be change or don't want to change trans placement do to floor boards?

    Does this refer to a full tube chassis race car? The reason I am asking is to address backhalf type race cars and to clear some unanswered questions on this topic. Backhalf race cars usually retain the original OE frame from the B pillar (back of the door frame) forward to the front of the car and will usually retain factory transmission mounting (crossmember), in conjunction with a front motorplate. These designs put the engine/ trans assembly either back to factory mounting position/angle or most will be set at 0 degrees or level. Also these types of applications usually have a higher vehicle ride heights unlike their lower slung tube chassis style race car counterparts. The higher vehicle ride height in and of itself will be the deciding factor as to whether or not the CG and engine angle will have any room for adjustment. Measuring your engine crankshaft centerline height (crankshaft centerline from race track surface), will be the first dimension you will need to determine. Remember that between 9" - 12" from the race track surface is ideal, next measure your rear end drive pinion center height, then the distance between the transmission output and the rear end drive pinion. These three recorded measurements will immediately indicate how much angular driveshaft misalignment is in question. To be perfectly clear, you would never want to try to fix an angular driveshaft misalignment problem that was overly extreme. You would never exceed more than 3 degrees of engine/transmission angle, (transmission output angled upward).

    Also to clear up some other questions in stock type or backhalf race cars where the rear end drive pinion center is lower than the transmission output center, there really is no remedy to fix operating the driveshaft in an angular position. Again, the vehicle ride height plays a major role in the rear end drive pinion height. The last post mainly refers to lower ride height tube chassis race cars where there is between 3" - 5" of ground clearance and the rear end drive pinion center is higher than the transmission output center.

  9. #9
    Senior Member RACING JUNKIE lively's Avatar
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    GEEEEEEEEEEEEEE
    THEN THAT MEANS MY GASSER WON'T WORK BECAUSE IT SITS HIGH IN THE AIR/MY CRANKSHAFT IS 4 INCHES HIGHER IN THE NEW FRAME THEN THE OLD ENGINE
    MY ENGINE SETS BACK 4 INCHES FARTHER TO THE REAR/ THE FRONT AXLE IS 6 INCHES FOWARD OF THE STOCK WHEELBASE AND [ FINALLY] THE REAR WHEELS ARE 9 INCHES FOWARD OF THE ORIGINAL ONES
    ops: :cry: ops: :cry:
    WIEGHT TRANSFER WORKS :lol: :lol:
    YOU JUST LEARN TO DRIVE DIFFERENT :lol: :lol: :lol:
    NOT BEING MEAN JUST DO NOT LIKE TO COMPLICATE EVERYTHING :wink:
    NOT EVERY BUILDER OF HOME GROWN CARS CAN AFFORD OR BUILD PERFECTION 8)


    MY 2 CENTS , LIVELY

  10. #10
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    lively Posted: 14 Sep 2009 01:42 Post subject:

    --------------------------------------------------------------------------------

    GEEEEEEEEEEEEEE
    THEN THAT MEANS MY GASSER WON'T WORK BECAUSE IT SITS HIGH IN THE AIR/MY CRANKSHAFT IS 4 INCHES HIGHER IN THE NEW FRAME THEN THE OLD ENGINE
    MY ENGINE SETS BACK 4 INCHES FARTHER TO THE REAR/ THE FRONT AXLE IS 6 INCHES FOWARD OF THE STOCK WHEELBASE AND [ FINALLY] THE REAR WHEELS ARE 9 INCHES FOWARD OF THE ORIGINAL ONES

    WIEGHT TRANSFER WORKS
    YOU JUST LEARN TO DRIVE DIFFERENT
    NOT BEING MEAN JUST DO NOT LIKE TO COMPLICATE EVERYTHING
    NOT EVERY BUILDER OF HOME GROWN CARS CAN AFFORD OR BUILD PERFECTION
    lively : I was in no way trying to portray that all other chassis set-ups (in reference to the engine/transmission angle or ride height example) are wrong. In fact the whole evolution of the drag race chassis it derived from experimentation and testing. The gassers, stock & super stock eliminator cars were the forefront testing beds for the current advancements in chassis design that we see today. My roots of chassis and engine building started from necessity and it is actually a very common story shared by most backyard racers like yourself. Not having the resorces to afford astronomically priced professional chassis work or engines and a the undieing driving passion to race is where most of us have begun our journey. I built my first race car at age 15 from a shell of what was supposed to be a '66 Chevy II. From there progressing to building backhalf race cars and today I have built many tube chassis race cars for myself and other satisfied customers. For me, race car chassis building is a progression of learning and experimentation to achieve the safest, best handling and launching race car and because there is limited literature and educational learning avenues when you consider this guarded trade, I find it rewarding to give some advise or opinions where I can lend it to save somebody time. I know that I learn everyday, and I enjoy hearing worthwhile advise when it is given, especially if it can save me time. By the way, nostalgia racing is very cool!


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