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Oilyrascal 10-28-2012 02:06 AM

engine mounting
Hello everyone, I am looking for guidelines on setting up an engine within my chassis.

After searching on the net I cannot find much concerning how to go about getting it straight ( side to side ) between the framerails.

I understand that it makes little difference if the engine is off to one side, it has to be in my case because of the steering box but how do I make sure that it is straight in the hole.

I have read to measure off the centerline of the crank and the centerline of the output shaft should be the same distance when measuring against the pass framerail but thats easier said than done.

I guess in this case it makes little difference but I am dealing with a 68 351 W going into a stock big truck 52 Ford chassis.

Thanks for any insight

BTW I have made my own motormounts and it is simply steel bracing that attaches to the framerails on both sounds using the stock isolator bushings.

I originally placed a F.I. 302 within the truck and it would run down the road but it had one heck of a vibration and I dont know if it was related to the engine not sitting in their correctly and now that I am going with this 351 I want to make sure I get it right.

Initially all I did when setting up the 302 was eye it for straightness and made some crude measurements using some reference holes that were already within the frame ( same both sides ) as my guideline for measuring and engine mount placement.

Getting rid of the automatic and have found the the clutch pedal linkages are not going to work unless I slide the engine backwards about a 1/2 inch so that the steering box is not an issue.

timothale 10-28-2012 07:48 AM

chalk line
Snap a chalk line grid on the floor to plumb, square, and level everything. Spray cheap hair spray over the lines so they will last longer. I have some RV leveling jacks I use to get the frame level. And use a floor jack to move It sideways.

delawarebill 10-28-2012 08:11 AM

eng to frame
u didn't say, but is the cab off the frame.. makes this job alot easier if working with a bare frame.. when i built my bucket i used a stock 8" ford rear. they come with an offset, so the driveshaft is off center a little. but i did center the eng/trans in the frame making sure the intake was level so i could measure the downward angle of the tranny to allow me to raise the nose of the rear... my d-shaft is about 18" long and no vib at all..

MARTINSR 10-28-2012 08:43 AM

The cab needs to be on at initial set up though to be sure you are clearing the firewall and all. And while the motor is setting there in the mock up stages you need to check for radiator clearance too, the Ford V8 is long and can be an issue with the radiator so don't take anything for granted.

Honestly, the motor being exactly in the middle has little to do with vibrations or anything else like that for that matter. There are many cars over the years from the factory that the motor wasn't in the center, look at a front wheel drive car, it's sitting sideways! The big block 67-69 Camaro motor is off to one side about an inch! The vibration would come from something out of balance, like the flywheel, clutch or driveshaft would be my first places to check, and the most common to be out. The flywheel and clutch assy are sometimes "clocked" together so you need to reinstall them as marked.

If you are measuring side to side at the crank in the front and transmission tail shaft in the rear to "control points" (points that are exactly the same side to side) on the frame you are good to go. Making it "somewhat" even is what we are talking about here. If the whole motor is off to one side a little it isn't a big deal.

Having the proper pinion angle to promote the U joints bearings to spin properly is next thing to think about. But with the motor about where the old one was this should fall into play. If it is level and the tail shaft on the trans is about the same height all should be good.


Oilyrascal 10-28-2012 08:51 AM

Thanks, I guess I was not clear enough, I am not concerned with getting it centered or off to one side more than the other, I understand that this does not make any difference with what I am doing.

I am concerned with getting the engine parallel with the right frame rail, straight in other words, even in another word, I dont want to get it cockeyed in there.

Looking down lets say from above I dont want the front dampner close to the R rail and the end of the output shaft close to the left rail if that makes better sense.

How do you guys make sure this does not happen?

MARTINSR 10-28-2012 09:20 AM

Measure the distance from side to side width of the frame at the front of the motor using the crank as center. Do the same at the rear using the output shaft on the trans. Once you have that width, you go to the center of that width and that is the center of the frame.

Put the motor into place and if the front is an inch off center to the right you put the rear an inch off center to the right. The center of the motor will then be even an inch off the center of the frame.


Oilyrascal 10-28-2012 09:27 AM

Yes thanks but I am assuming that will only work if you are dealing with a straight frame, one that has no waves in it if you were to look down. I am assuming that my factory frame is not straight like that. I guess I better take a better look.

Thanks for the reply

MARTINSR 10-28-2012 09:31 AM

The frame is symmetrical if that is what you are saying, it is the same from side to side.

If you have any doubt, cross measure it like this.

If you are using the same points side to side and you cross measure and the distance comes up the same, you are good to go.

Then using those control points that you have confirmed to be the same on both sides by your cross measuring.


MARTINSR 10-28-2012 09:37 AM

If you aren't clear on the cross measuring, measure from 2 to 3 and 1 to 4 in the first one, if they are the same, those points are "square". If you are confused on where exactly the point is on the frame you can measure from 2 to 4 or from 1 to 3 or 5 to be sure you are using the same ones.

But honestly, you see very quickly if you are wrong because the numbers are off a mile. These cross measurements on a frame like your truck should be within about a quarter inch difference from one to another.

You measure one, then cross to the other, when you find it's good, simply go to another point near by to confirm you are using a good point, once you have a few you KNOW you are good to go.


Oilyrascal 10-28-2012 01:50 PM

Thanks for the help, I am a bodyman so I pretty familiar with the tram. I guess I am or was overthinking it. I just wanted to be sure when I do this again that I have done it with a little more know-how.

techinspector1 10-28-2012 02:15 PM

Measure the center line of the car off the differential, not the frame. Use a plumb bob dropped off the center of the axle on each side right up next to the backing plate at EXACTLY the same place on each side of the differential.
Tie a piece of line (a piece of chalk line will work fine) around the diff tube on each side at exactly the same distance from the brake backing plate on each side, as close toward the backing plate as you can get. This line will be larger in diameter than the diff tube. For instance, if the diff tube is 3" in diameter, make your line maybe 5 or 6 inches in diameter. The idea here is to have a piece of line tied around the diff tube that is larger than the diff tube and will hang down around the tube. Now, when you run a piece of line through that hoop, with a plumb bob on the line, the plumb bob will hang down toward the floor at exactly the center of the diff tube. The circle of line around the diff tube will look like the lobe of a cam once the weight of the plumb bob is on it. Make a mark with a Sharpie where the plumb bob touches the floor. You will have two marks on the floor, each indicating the center of the diff tube and exactly the same distance from the backing plates on each side.

Have a buddy hold one end of another line down on the Sharpie mark. It will be helpful if you tie a knot in the line and keep the knot on the Sharpie mark. You will be on the other end of the line, with the Sharpie tied on the line. Holding the Sharpie exactly straight up and down and keeping the line taught, scribe an arc on the floor, approximately at the front wheel, fore to aft. Now, have your buddy move to the other Sharpie mark at the diff and hold the knot on that mark while you swing another arc. Where these two arcs cross is the exact center of the car, as referrenced off the differential. Now have your buddy shorten the line by tying another knot in the line, maybe two feet shorter than it was the first time. Same exercise over again. Your buddy holds the knot on one of the Sharpie marks at the diff while you swing an arc with the other end of the line. Now, your buddy moves to the other side, holds the knot on the other Sharpie mark and you swing another arc at the front. The centers of these arcs will be the centerline of the car and you can snap a line, front to rear, off the centerpoints of the two sets of arcs. Then use a 90 degree square to determine another line, either to the driver's or passenger's side of the car. Lay the square on the centerline at one of the arc centerlines and measure how far you want to move the engine/trans. Make a mark. Now move to the other crosspoint at the center of the car and measure the same distance. Now snap a chalk line fore and aft on those two marks and you have the center of where you want the engine/trans. This method will place the engine/trans exactly perpendicular to the differential.

You can swing as many arcs as you want to. Just keep shortening the line each time and tying a new knot in it for your buddy to hold on the rear Sharpie marks.

MARTINSR 10-28-2012 02:24 PM

Tech, what would be the difference if it was measured from the center of the differential or the frame?


MARTINSR 10-28-2012 02:29 PM


Originally Posted by Oilyrascal (Post 1604207)
Thanks for the help, I am a bodyman so I pretty familiar with the tram. I guess I am or was overthinking it. I just wanted to be sure when I do this again that I have done it with a little more know-how.

You got it, a bodyman huh, you know how to measure a frame, go for it just like it's a hit. :D Measure off that motor like you are doing an inspection on a wrecked car and make it straight again. :thumbup:


techinspector1 10-28-2012 02:31 PM


Originally Posted by MARTINSR (Post 1604219)
Tech, what would be the difference if it was measured from the center of the differential or the frame?


What assurance do you have that the diff is hung squarely? The idea is to get square to the diff, not the frame.

MARTINSR 10-28-2012 02:34 PM

Wouldn't you want it square with the frame and if the your rear end is off that far, fix it?


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