Ok guys I probably already know the answer to this but my father in law gave me conflicting advice to what I was thinking and now Im second guessing myself. And this is my first go around with a nailhead engine. As mentioned in my introduction post I am installing a 364 nailhead in a 48 chev sedan. I have the ch***is engineering mustang 2 bolted onto my frame. When mounting up the engine and transmission to the frame I want my valve covers to be as level as possible right? I have the commonly seen Offy 2x4 intake sitting on it that is angled pretty heavily to the front of the engine. My father in law is telling me to lower my trans to get the carbs level. My engine would then be tilted up in the front to do this. (not drastically but noticeably) That can't be right.....can it? I was just ***uming that the angle is how that intake is designed and the engine itself should be level like normal. Thanks for any replies.
Listen to your father in law, you want the carbs/ carb mounting surface of the intake level and the valve covers don't count in this equation. Look at most any carbureted engine's and you will see that the valve covers slant slightly to the rear while the carb sets level if it is set up right.
Thanks for the advice guys. So if I were to get a traditional flat intake in the future I would need to modify my trans mount to get that carb back to level too?
No. You need the engine trans at 3-4 degrees down regardless of what your running for carb or intake.
Not likely you will find a "flat intake". Most automobiles since at least the late '40s/early '50s have had the engine/trans centerline about 3 degrees sloped to the rear. Typically the front is up enough to clear front suspension/frame crossmember, rear is down to minimize transmission hump and driveshaft tunnel. If it is really important to you to have the engine level, you could possibly have your manifold carb surfaces machined or maybe make angled carb adapters. Either way you will have mounting stud angle differences to deal with.
If you level the carburetor mounting flange level front to back and side to side . Then put an angle finder on the output shaft of the transmission you will find it to be 3-4* down angle. that is why your pinion angle should be 3-4* up angle. remember allow for engine and trans weight.
So how could you possibly get the carb floats to work correctly? Do the laws of gravity not apply to the fuel levels in your carbs??? Driveline angle is NOT the deciding factor for engine placement. Without the carb base of the intake perfectly level, the engine will not perform correctly no matter how much adjusting you do to the floats.
Your father in law is absolutely correct carb pads level. Not the intake manifold level, if it is a multi carb intake and not a log intake the rear carb probably sets higher then the front carb, but the carb pads want to be lever back to front and side to side. I would use the stock intake if I had it to set my engine angle then bolt my hot rod chit on and let the chips fall where they may. If the carbs end up not level after that then you can shim them to make them level.
Cool thanks guys. I understand about the carb levels and the floats but just thought it looked retarded sitting like that. Didnt wanna be "that guy" at the car show that screwed up and didnt know what he was doing. Im a mechanic and am just used to seeing all the engine's sitting near level. I will adjust and bolt her down.
Put a GMC blower on...then the carbs will be parallel to the engine. Surprisingly, they still work at that angle.
That made me laugh out loud rich, good one. I just wasnt sure if the intake was designed to be that way or what. I didnt grow up in the hot rod era so my experiences are limited. Plus im not sure if im even going to run that intake. Ive read they dont work well unless you send it to centerville to get worked over. Ive got a pinion angle meter at work. Im gonna throw it on the tailshaft set it up and let 'er buck. Thanks again for the experience guys, thats why i joined up.
Sometimes the obvious alludes me... that is a very good point. . So if the carb plane on the intake does not need to be level, why is it on a different plane than the heads? I honestly thought making sure the carbs being level to the ground, when fabbing engine mounts, was THE most important aspect of setting up the engine.
The carb wants to be level, but it'll work if it's not level. If you look at an automatic transmission, you'll see that the pan is also at the same 3 to 4 degree angle as the carb.
But why do intake manifolds have the carb plane on an angle? For instance, my Offy 3 carb on my 322 nailhead has a rather pronounced angle towards the front (when its on a level surface). From all the research I did before making the engine mounts, I found that it was most important to have the weight of the engine and trans resting on the frame with the suspension set and the wheels and tires I planned on using, to get the engine set at the correct angle for the carb plane to be level. To get that, I moved the trans up or down until the carb plane was level with the floor. I then put the angle finder on the tailshaft housing and found it to be about 3.75 degrees angled down. From there, I rotated the rearend to face up at 3 degrees and welded the rear crossmember in place. Is that wrong? I figured the starting point for all that was getting the carb plane level and working from there. Is there a better order in which to set everything up? I have had my roadster on the road for 16 years and don't have any bad vibrations nor does it run poorly... but I am getting ready to build another T so I would like to know if there is a better way to set up the driveline.
You have it correct! Virtually all automobiles since the late '40s/early '50s have the engine trans installed at an angle, down in back. Clearance issues for the oil pan/crossmember/suspension requires the front a bit high. To reduce floor ****** hump and driveshaft tunnel height intrusion in p***enger compartment......down in back. Carbs should be level at ride height on level ground so that they CAN function best when the vehicle is operating on non level surfaces...I.e. hills. Otherwise, they would be non-optimum on the majority of near level roads and get worse, or better, on hills depending on whether you were going up or down.
That seems to be the answer of "why". For practical reasons, I think it looks/works best on a hot rod when the engine is installed in the ch***is the the original angle, so the carb flange is parallel to the frame rails. Quick check on cars with an auto trans, if the trans pan is parallel to the frame, it looks right. But that's just me. Really, you can install the engine however you want to.
There are intakes that don't have the angle built into them, and many of them are newer aftermarket designs. If it's possible to mount the engine with carbs level, then I try to, but as Squirrel mentioned, carbs will work if they are angled slightly, as long as float levels are set to that angle. Don't worry if your present intake has a certain angle, and the next one is slightly different. A small adjustment might be needed, but only if the difference in carb base angle is huge. Not sure if it's real obvious, but my Weiand tunnel ram can have the top mounted in either direction. The top is angled, so it will either angle the carbs uphill slightly, or close to level in 180 degree installation. I've played with it both ways, and never changed my float levels. It works just fine, so it's sitting slightly uphill now, as I like the look better.
When cars used torque tubes, the engines sat level between the frame rails and the driveshaft basically ran parallel to the frame. The conversion to U-Joints requires that there be angles in the joints (a U-joint will prematurely wear with 0 Degrees). The other thing that occurred is that the pinion placement was lowered in reference to the ring gear which made it possible to lower the driveshaft hump in the floorboards. The result was that engines tilted down in back, and carburetor mounts tilted in an equal but opposite direction. The bottom line is that if you are running an open driveshaft with U-Joints, you should tilt your engine and not level it with the frame rails.
see that was my issue too. My 2x4 intake has the same rake as your 3x2 and that what was confusing me. Im used to the typical chevy 350 flat intake. Figured it was a design thing for performance or something. But as i mentioned im not experienced with these engines. I flipped my adjustable trans mount plate upside down and the trans dropped enough to make the carb plane damn near level. For mock up purposes i have larger tires in the rear for now. Once i get all tires the same size like i want the rear of the car will drop and the carb surface will be level. Just a little welding and all will be good.
LOL there aint no hills where you race. There is more to the angle of the engine than just the carb flaots or carb pads. The otiginal designers made the crank angle to ensure that the oil pump pickup was always emersed in oil and that the U joints had some angle to them to keep them properly loaded. There is a whole science to the angle and load on your U joints that I don't fully understand and certainly cannot explain in a fashion that would make anyone else understand it but basically you don't want your U joints to be perfectly flat and straight.
...and fuel slosh on acceleration (and cornering, braking, etc) causes a lot more problems than a carb being a few degrees off of level.
take a look at a boat and you will notice they have some pretty steep carb. spacers on them to keep things level and working correct.
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