I'm getting ready to set up my flathead block in my model a frame. If I have the frame at ride height and ride angle what angel would I want the intake manifold surface sitting at. I was told 10 degrees but for some reason 3 degrees rings A bell for me.
I'm no expert but it seems to me that you would set the engine so that the carb mount on the intake manifold is level front to back.
I've never understood this discussion. My cars don't konk out going up or down hills. Why is this an issue. I'm not trying to be a jerk. Looking for a serious concern.
I'm thinking that the 3 degrees down you mention may be pinion angle. Thats pretty normal in later cars. o experience with model A's
Carb base level which usually puts the driveline (think crankshaft) angle 3 degrees down to the rear from level.
Dont nit pick it, just set the intake manifold flange close to level and let it fly. The engine should be 5 deg or so then.
Because by being level on level surfaces, the carb can tolerate being 'tilted' a few degrees either direction on inclines.........if it started out at an angle, it would get worse on some surfaces and better on others. The reason is the float chamber and how the float will affect fuel level when the carb is tilted. The fuel level in the float chamber affects how much fuel is drawn into the venturi and consequently, leans or enrichens the mixture. Ray
Post #12 kinda has the right idea, but has the cart before the horse. Three degree driveline angle is not some sort of 'magic number'. It is a consequence of body engineers setting the engine/trans at an angle to keep the front of the engine high enough for chassis/suspension/oil pan/ground clearance and tilting the trans down at the rear to reduce the transmission encroaching too much on passenger floor space. Once that angle was established, then the carb pad on the manifold was angled a corresponding amount to keep the carb level for obvious reasons. Finally, the rear axle pinion angle had to be set to permit correct u-joint geometry for smooth and reliable driveshaft performance. So, it all starts at the front and works it's way rearward.........not vice versa.. as so often seems to be misunderstood.......judging by posts in myriad threads on this subject. Ray
and of couse the frame should be set level front to back and side to side before setting up the engine.
That's a damned good answer to an often asked question. If you start out with the carb adjusted when it is sitting level it gives you a little bit of leeway uphill, downhill or on a slope.
I was going and post the same thread. Than I see a lot of cars where they are lowering the front of the car now the carburetor is at a different angle. Frenchy
I often wonder about some of these redneck pickups down here with the front or rear a foot higher runnin up and down the city steets. Seems like everything would be a little off---including the drivers.
The intake manifold is built on a slight angle to allow the carb to be level while the engine is tilted the 3 degrees or whatever. The reason for a tilt to the engine (and the rear end pinion angle on open driveshaft cars, for that matter, is to make sure the U joints are not trying to constanty "seek" a balanced position. So keep that in mind, the driveshaft angle is more important than the carburetor base being dead level.
Sleep deprivation makes some people really testy!...... I did not contradict you on the the 3 degree (give or take a degree) engine angle being common to many vehicles, where I disageed most was the order in which you said things were determined. When setting up the driveline the pinion angle is determined by what came before it.........not the other way around. Ray
Not really. All these elements serve different purposes and are coordinated to work together. One is not more important than the other IF you want a well engineered vehicle. Ray
Actually, the frame should be at what ever angle (front to rear) it will be at final ride height. That may be level or it may be sloped. That needs to be determined first, then set the engine in place with carb pad level, then determine the pinion angle.......... Ray
I would think that you want at least three degrees on the pinion because the car would never overcome that angle, and the U-Joints would never be flip flopping from an upward angle to a downward angle, and binding up somewhere in between. Also make sure that your drive shaft isn't pushed snugly into the transmission. You want at least a third of that end to be able to slide in and out as the rear end travels.
If you set most intakes on a level surface and throw a level on the carb mounting pads they are 3°, which kind of ties in with the prefered drive shaft angle of 3°. With the trans tipped down 3° the carb pads are level. I have run into some old hotrod intakes that were meant for boats that had 8° carb pads. Sent from my Droid powered Samsung Galaxy S
If you look at your motor the carbs are usually set at an angle if it's level. 3 degrees is what I've always used... not sure where I initially heard it, but 10 degrees sounds severe.
And side to side as well. If you have an intake you just set a level on the carb pad and that will get you as close as possible. I don't recall what the crank shaft angle is on a flatty.
I think sometimes if the engine is exposed and close to the firewall and has too much up or down angle in it, then it makes it appear that the frame is bent.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o> Not to contradict anything that was said but maybe something to think about.<o></o>
And what do we do with a blower on top ? There's no angle built into that or the carb adapter. Level carb flange gives you 0* on the crank and trans out put shaft.
Sometimes the frame is bent, or swept. I am just saying that because there was evidently an argument and I got left out. The Op has his car set at approximate ride angle already or so i believe I under stood, so it is just a matter of setting the engine up at the proper angle according to the radius of the earth's surface. Here is something to give some thought to. The crank angle was determined by the design engineer for a reason, it normally has to do with keeping the pick-up for the oil pump submerged. If one is running a stock pick-up and pan it is advantageous to maintain the design crank angle, or close to it. All things being equal the crank angle will be correct in most if not all instances when the carb pad is level. To be off a degree one way or another is not the end of the world, but for optimum performance obviously right on the button is your best choice. By some it is not considered to be as critical on a street vehicle as it would be in a raceing environment. My way of thinking is that it is more critical for a street vehicle because they see extremes of all types over a longer duration. I have been told that my thinking is backward.
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