I was cleaning up the intake on my 38 and noticed the carbs are pitched forward about 6° (guess). I have had the truck my whole life and just discovered this. No biggie; just curious. I am just wondering what the logic behind this was. It wasnt done by accident or modded after the fact. Any idea why this was done? (pics) https://scontent.fhio3-1.fna.fbcdn....=e5626d6ed9084aaed7a5034ddd2180da&oe=5EF0911E https://scontent.fhio3-1.fna.fbcdn....=88e620f800bd715eac1f370943de3a4e&oe=5EEE534C ~JH
^ Many vehicles have engines / trans that run down hill to the diff - who knows all the reason's why - but you have to compensate for that angle by making the carb mounting bases on the intake manifolds slope the same number of degrees in the opposite direction.
I'd have to say that they are both correct. If the engine is a 250 or 292 that explains it better as the rigs with those engines in them did have the engine positioned at an angle rather than having the crank perfectly level. Looking at this photo of the Aussie Speed intake for my 292 it does look like it has the carb set at a similar angle to the centerline of the crank.
Engines typically angle downward in the back to lower the trans and driveshaft hump and bring the driveshaft into line with the diff. Intake manifolds are angled to bring the carburetor level so the float will work right.
I was getting too critical getting my engine perfectly level side to side with the perfect pitch downward in the rear when making my motor mounts. My dad looked at me knocking myself out with my attempt at perfection and said, You realize once your car leaves this garage the engine will never be level again.
Good point. The carb must have a built in tolerance operating range.We set the float in the middle of that range,and it works well enough to keep the car operating in hill country like San Francisco.Get to far to one end of the float range,and a hill could be trouble. In World War 2 there were airplanes with carbs that had limits on the moves they could pull off due to being carbed.A plane that was injected could do things like barrel rolls,and get the jump on the carbed plane.The pilot of a carbed plane had to understand its weak point,and not get in the postion.
I think the tilted engine thing started in the 30s, when designers decided cars had to sit low, and tilting the engine nose up about 4 degrees helped with that. The carb should be level when the car is sitting still, because otherwise folks will think it won't work right. When driving, they're pretty forgiving. Notice in my avatar, the carb sitting at a bit of an angle...blowers don't have the compensating angle build into them, like normal intake manifolds do. But the car runs fine.
"blowers don't have the compensating angle build into them, like normal intake manifolds do" Some in fact do have the angle integrated into the top plate... - EM
Going up or down hill is not a normal situation, as are bumps. The carbs should compensate, less so at altitude. Not being an engine builder (I'm sure those guys must have THE answer), I'm going to hazard some guesses on why engines are tilted down a few degrees: it would aid water flow / percolation and therefore cooling or cooling down when the engine is shut off; aids in purging the cooling system of air; better bell housing / tranny clearance at the firewall / floor / xmsn tunnel which might allow you to put the seats lower; aids in engine fan air circulation back, down and out of firewall / toe boards. The front suspension / frame has a lot to do with engine height, as does the difference in the tranny yoke height and the pinion yoke height. Same for general rear end types and designs. Driveshafts don't always go up or down hill, eh? And you also have to have that 2-3 degree difference in them anyway, to keep the universals lubed and vibrations down.
Dont know enough about planes to be sarcastic,but the Spitfire,and Hurricanes were carbed,and Germanys planes were all injected giving them a edge.Bothered the Brits enough that they invented a pressurized carb to off set the German advantage..Day to day....I do put the Sar in castic................
Even jets didn't fly too long inverted when they first came out. Till they fingered out multiple pickups and pressurization stuff. Same with the oiling systems, too.
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