Doing a new build on a future 53-56 Ford truck. (no body yet) Working on a bare frame and mocking up the angle and location of a 289 small block Ford. Got a block mocked up with the distance from the front I want and need for fan, radiator etc. Without getting into a driveshaft angle debate which I understand and will address that later. My question is ……Should the motor be level front to back or should it be angled to the rear a bit? Any suggestions on how much.
Depends on the rest of it I set all 3 angles at once. Rear, DS and engine. At ride height And depends on if you think the carb needs to be level at ride height. (I don’t)
I’m actually just checking my layout now. Always had my flathead on about a 0.5 degree angle, but most folks say it should be at zero degrees. Not really a concern over that half of a degree as it pertains to the carb float, but over the length from the engine mounts to the centre of the trans yoke (a distance of about 60”), that half of a degree translates to a 0.5” drop. In my case, that half of an inch in difference changes my driveshaft angle from 13 degrees to 5 degrees since my driveshaft is only 13” lg yoke to yoke. I know you said you didn’t want to get into driveshaft angles, but since I literally just posted about this in my build thread, I thought I would share my findings.
I’ve seen it done both ways. Personally I would go with whatever you think looks best. I angled the one in my T Bucket 3 degrees, mostly just to gain a tiny bit of foot room in the car.
When ever Ford installed the 289 motor, it was probably installed so the carb was level on level ground. Most intake manifolds (all brands from the 60s - 80s with the motor facing forward & rearward, not cross mounted) have the carb mounting flange set with a 3 degrees forward lower cut, so when the carb is level, the motor has the back end 3 degrees lower then the front of the motor, and is level side to side. Then the new car buyer put air shocks on the rear and jacked it way up. Then he dropped the front of the car lower then it was originally produced, and the entire plan went array. The world didn't disintegrate, so the plan became a suggestion. I speculate the original rear downward 3 degree angle was to aid in fluid draining, but there are probably 1,000 different explanations. Pick one, or ignore them all.
In the best of worlds, have your rolling frame completely done (and the engine location already determined from the firewall position, etc.), at the desired rake and ride height (or a tad higher?), and with the exact size wheels and tires you plan to run. Then mount the engine with the carb mounting plane level. Adjustments will probably have to be made for the weight of the body... but as long as you have reasonable suspension travel you should be in the ball park.
It may depend on fuel system used. If carburetor, many intake manifolds have a tilt on the carburetor mount flange. You typically want that level and this will set your engine downward tilt. EFI doesn't care.
I have always thought the carb level thing was silly. What’s the first things hot rodder does? The rake. Bigs and littles… What if we decide to change tire sizes? Then there are driving conditions. Do you always ensure that the intake is level when parking? What about when driving? Does this apply when crossing the Continental Divide? The manufacturer has the best world scenario. They create the car from scratch and the tire sizes. Once we leave that envelope, all R&D is null and void. If you are building a generator that sits, bolted to a concrete pad, then I say yes. Not being combative, just asking….
I was taught that the downward tilt was partly to aid in trans tunnel fitment, but also in the event of a wreck, the powertrain would be more likely to submarine instead of jump in the seat with you. I imagine the former, with the added benefit of the latter. Detroit was always trying to get that foot room increased, even to the point of the rope drive shaft, which I just think is bonkers, but it works fine. Once you get the engine tilt locked in, the carb sitting level for most of the drive time makes sense. -rick
Yah. Don't overthink it. I believe that the Earth is round, and that means it's downhill in every direction.
The level carb thing was probably a hang over from when the carbs were gravity fed. It was probably pretty important for the early carbs to be as level as possible, especially when the fuel tank had to stay above the float bowl since there was no fuel pump pushing the gas into the carb. It probably intensified when a 2nd venture was added to the carbs and the fuel had to flow to both sides or 1/2 the motor ran out of gas. Some of us old guys remember the old stories of the gravity fed fuel tanks, where the cars had to be backed up some steep hills so the gas would still flow into the carb. Fuel pumps and forced fuel to the carbs, and much later, fuel injection, and pressurized oil systems probably solved most of the level motor concerns, but once a precedence has been established at most auto companies, they are slow to change things.
Engine angle doesn't matter, transmission angle does. Set up your trans 3° down and wherever that leaves the carb angle, that's where it is.
Actually, no it does not! When you cross the Continental Divide it changes from 3* Fahrenheit to 3* Celsius
I was at tending the Portland Transmission show last year and while we were waiting to be parked (at 5 AM) a gent got out of his car and told me he loved that I got my flathead as level as I did. I never gave it any thought before but it is pretty level. 2 degree down bubble. His was pretty nose high, closer to 5-7 degrees.
Engine and trans angles match. The centerline of the crankshaft matches the centerline of the trans output shaft, so one can't be different than the other. I usually set a level on my intake manifold both ways to check that the intake is level front to back and side to side.
I build low. So setting things up at ride height is important. Sometimes that stock engine angle and location is worthless. Floors get modified if needed to get the angles correct. All those angles are dialed in during the build. You get a lot less uh ohs when completed that way.
Don't over think it level the carb mounting surface on the intake with your ch***is set at it's static stance angle. As for the 3 or so degrees thing. Look at flat head Fords or 49/54 Cad, Olds or Mopar V 8 engines and most of them have no angle on the intake and the engine sits level. Then look at 55 and later and what do you start seeing, engine and trans at an angle because the manufacture figured out that they couild lower the transmisison hump if they did that. That is why engines set in at an angle on most later non FI V style engines.
When I installed my engine/trans, I put the carb level at ride height. Which came out to 2.50 degree crankshaft angle at ride height, but that was not etched in stone. Along with a 4 link suspension rear end with coilover shocks. Now you have to consider drive line angle, with the crank angle down 2.50 degrees the pinon shaft of the rearend needs to be 2.50 degrees up. ****er recommends the driveshaft angle in relation to the angle of crankshaft and pinion shaft to be anywear from .50 to 3.00 degrees. If it is heigher than 3 or lower than .5 you will expreance driveshaft vibration. With both my crankshaft and pinion angle within specs. My driveshaft angle was 3.50 degrees, so to get the drive line angle back to spec. I had to raise my crank shaft angle by tack welding a 1/4" thick spacer to the trans crossmember. Decreasing the angle to about 2.125, this got my drive line angle down to 1.70 at the trans and 1.8 at the pinion shaft. So to some degree the final degree of the engine is giong to be determined if you want your drive line within spec for no vibration.
I think you missed the point. What I was saying is your engine doesn't care if the carb pad is at 1° or 0°. Your driveshaft cares what the angles are. Since the trans and engine are fixed together, driveshaft angles take priority. Set it up so your trans yoke and pinion are at equal and opposite angles, and don't worry about your carb pad angle. Focusing on carb pad angle makes no sense.
Based on my years of driving experience here in the Ozarks, I can guarantee that a car will run just fine with the carb being un-level for 99.999% of the time.
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