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Technical Engine angle fuzzy math

Discussion in 'Traditional Hot Rods' started by AGELE55, Oct 11, 2021.

  1. AGELE55
    Joined: Jan 4, 2018
    Posts: 398


    I'm stalling getting the welder out and nailing down my engine mounts in the 39 Poncho. In my mind there is ZERO way to accurately achieve a specific angle prior to hanging the engine.
    Yes...I've read virtually everything I can find on the HAMB and everywhere else. So, I am gonna stand back, eyeball it and apply my best SWAG (Scientific Wild Ass Guess).
    I can level the frame back along the rocker area, but thats not realistic. When the motor mounts take on the weight of an SBC, the front is gonna come down, who knows how much, so leveling the engine to the frame is a false target. Any angle I build in would also decrease with weight. If I choose to lower the car, again, more change. No way to load up the weight for a test, so... I'm back to swagging it.
    Lets have a show of hands from everyone that thinks I'm nuts. 20211011_152241.jpg
    loudbang likes this.
  2. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 8,142

    Bandit Billy

    Ditch the level and use a magnetic angle finder thingy. I bought a digital one for $40 that is pretty handy and "nuts on" (pardon the pun).
  3. deuceman32
    Joined: Oct 23, 2007
    Posts: 363


    I don't think that you're nuts. For me, the engine mounting angle is pretty simple. I mock up the frame at my intended ride height and rake, which requires that the body, firewall, fenders, and tires of the exact diameters that I want to run are in place. Having determined that, I can get the front sheet metal out of the way and position the engine and trans with a level on the carb mounting flange while having a look at driveshaft angle as well. Carb level or tipped slightly forward is ok by me. The time consuming part for me is dialing in the buggy spring suspension parts to achieve that ride height and stance. I haven't done it enough times yet to "just know".
    samurai mike likes this.
  4. Johnny Gee
    Joined: Dec 3, 2009
    Posts: 9,561

    Johnny Gee
    from Downey, Ca

    Level the rockers and place a level on carb base of intake. So what if front end settles! Hell every car that's be lowed in the front would need they're engine reangled then!?

  5. squirrel
    Joined: Sep 23, 2004
    Posts: 50,216


    I level the engine so the carb flange is parallel to the main center frame section. Rocker panels will work too, I suppose.

    Then, just don't think about it any more, and it'll be fine
  6. KevKo
    Joined: Jun 25, 2009
    Posts: 654

    from Motown

    As others said, level the carb base, not the valve covers. If your rear axle is already installed, THAT's what you need to match. If no rear yet, you can match it to the engine/trans when you get that far.
    -Brent- and AGELE55 like this.
  7. RJP
    Joined: Oct 5, 2005
    Posts: 2,043

    from PNW

    Just position it to make sure everything is going to clear, and your carbs sit relatively level. It's not really rocket surgery. Everything else can be adjusted....
  8. AGELE55
    Joined: Jan 4, 2018
    Posts: 398


    All set. Thanks for the input. I put an inclinometer on the frame below doors and then matched that angle to the carb base. Now I’ll take Squirrel’s advice and “don’t think about it anymore “.
  9. I've got a couple pieces of flat bar that bolt to the front of a Chevy engine; set these on the frame and hold the trans up with a bar and chain. With the weight on the chassis you can move the engine around, shim it up, etc and get it in just the right place, then weld up the mounts. Been using similar bars for 50 some years for swaps. Easy.
    X-cpe, 427 sleeper and RMR&C like this.
  10. Under normal circumstances with the carburetor level the output shaft of transmission will be 3* down. The rear end should be parallel or 3* up.
    Hot Rod Nut likes this.
  11. BamaMav
    Joined: Jun 19, 2011
    Posts: 5,188

    from Berry, AL

    Guess I did mine bass ackwards. I positioned my transmission where it had to be without taking out the floor, then set the engine height with the angle finder sitting on the carb pad. Turned out to be about 3* down at the rear of the transmission. Since I was using the factory welded in crossmember, I couldn’t drop the transmission tail to set the angle, I could only raise the engine. Worked for me, your results may vary....
    AGELE55 likes this.
  12. blue 49
    Joined: Dec 24, 2006
    Posts: 1,466

    blue 49
    from Iowa

    I thought I had a picture, but I can't find it. I built some legs off of the water pump bolt holes down to the frame. At the frame, I had treaded rod adjusters. With the weight of the mock up engine and tranny on the frame, I could level the carb pad front to back and side to side and make a tranny crossmember.

    X-cpe and loudbang like this.
  13. vtx1800
    Joined: Oct 4, 2009
    Posts: 1,377


    If you have a smart phone this Tremech app might take some of the mystery out or at least you'd know you were in the ball park.
    You will have to down load the app. Here is a little more info.
    AGELE55 likes this.
  14. PotvinV8
    Joined: Mar 30, 2009
    Posts: 190


    Firsts things first, I set the chassis up with the intended rake.

    Then, I like to mount the engine/trans as low and as far back as possible and work from there. Positioning things so that the tailshaft clears the floor, the oil pan doesn't hang lower than the front crossmember (in a perfect world; at least an inch or two above scrub line), and the mechanical fan, etc clears the front crossmember and things will pretty much tell you where they want to be. From there, you can make minor adjustments so it looks right and fits as it should. Get it close to the firewall and go for it. The actual angle doesn't really matter, as long as the rearend matches at the end of the day. That said, I prefer to keep it around 4-degrees or less. I'm building a roadster now and it's at 0.5-degrees. Hope that helps!
    vtx1800 and loudbang like this.
  15. Joe H
    Joined: Feb 10, 2008
    Posts: 1,112

    Joe H

    Fan to radiator clearance first, then angle up or down, then firewall clearance. Remember the u-joint working angles are measured from the driveshaft, not the frame, ( transmission to driveshaft, driveshaft to rear axle ) so there is a lot of room for adjusting later in the build.
  16. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 2,189

    from Brooks Ky

    The very first thing you need to do is make sure your vehicle is sitting in the correct stance you want it to sit when the car is done. Don't level the frame if your car isn't going to sit level when done. Yes, adding the engine will cause the front to drop some more, maybe an inch depending on engine choice. So allow for that.

    After you have the frame correctly positioned, here is how I do it. Works great every time. Make a temporary (junk) trans crossmember that centers the transmission in the frame and hold the trans at approximately the correct height. Make the center mount in it lower to the ground than you want. That will allow you room to raise the trans with spacers later. The trans mount will act as a pivot point for the engine from side to side. Let the engine sit on the front crossmember or something temporary.

    You will need a cheap engine tilter from Harbor Freight. Here is the one I use, and I modified it so that it supports an engine with a spreader for each engine corner. Its not necessary, but it works well for me.
    Engine Tilter 4x.JPG

    Remove the engine tilter from the normal location and turn it 90 degrees so it is mounted sideways to the engine. The crank handle will point toward the side of the car.

    If using a cherry picker, pull it out and move it to the side of the vehicle so the beam is going from side to side. You may find that the front tire is in the way. If so, put a jack stand under the frame at about the front door hinge position. Maintain ride stance.

    Reattach the engine tilter to the engine and cherry picker. With the engine hung this way, you will have COMPLETE CONTROL of ALL 3 engine axis.
    So now you have the engine pivoting side to side from the centered transmission mount.
    You can change the engine/transmission angle by raising the hoist.
    You can level the valve covers by cranking the engine tilter.

    Now you check to see if the trans mount is as high or low as you want/need and it relationship to the rear end. This is why you just cobbled a temporary/scrap trans mount. Adjust as needed.

    Now you have the engine and trans hanging in the EXACT location you want. No wedging boards and fighting to get all 3 axis where you want.

    At this point, you make a bar that goes across the front of the engine and bolts into a couple accessory bracket holes. Then you make two legs and tack weld them to the bar and the frame.

    Now your engine is hanging EXACTLY where you want it and there are no boards or brackets in the way of side mounted engine mounts. You should be able to disconnect the cherry picker and roll it out of the way and you have open access to fabricate your engine mounts. temp mount.jpg
    The engine is aligned exactly where you want it and you can make cardboard patterns for your engine mounts without worrying that the engine moved or you need to jack it up or move it again.
    AGELE55 likes this.
  17. If the engine is out in the open; aesthetics is sometimes a better choice than ideal angles.
    deuceman32 and AGELE55 like this.
  18. -Brent-
    Joined: Nov 20, 2006
    Posts: 6,501


    There are A LOT of spot-on comments in this post. We went round and round with my chassis because we were at this point of "what comes first?" when planning and laying it out.

    Model A Hot Rod Chassis.jpg

    The frame was perimeter and everything got built to accommodate the drivetrain.

    The rear needs to be angled correctly, the rake wasn't exactly known because it the rear wasn't finalized. So, we mocked the rear and mocked the front mount.. We had a couple non-negotiables, for example - keeping a flat floor, which actually helped.

    In the end, we had to shim the front of the engine mounts to get it right where it was best.
    Last edited: Oct 12, 2021
  19. I always found it simple to measure the original crankshaft centerline (height) and trans output shaft position and duplicate them. This is assuming you are using the original rear end. It also assumes the factory knew what they were doing.

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