Technical angle of a motor in a chassis

whats the rule of thumb for the degree a engine sits in a chassis.
im at that point its just waiting for a answer.
thank you

 

Bout like this, Lol.

 

@c/h I'll try to answer your question...Commonly, engines are installed at an angle that results in the carb mounting pad being level. That is typically about 3 degrees down in back.

However, when these angles are being set, the chassis should/needs to be at the angle it will be when the car is at normal load and ride angle In other words, if it is going have a 'rake', the chassis should be supported at that 'rake' when installing the engine.

You may already know the following, but if not........the center line through the engine crankshaft and transmission should be parallel with the center line of the pinion in the rear axle. Those lines can be above, below or beside one another as long as they are parallel. That is known as 'pinion angle' when being set to match the engine.

Ray

 

For drag racing, ideally you would want the driveshaft/driveline to be straight with maximum weight transfer onto the rear suspension.
So you could guess this by using a "string line" and allowing about 2"-3" of suspension compression.

But don't overthink it.
On road racing cars it is common to have the engine/trans centreline below the pinion centreline . The gains from low centre of gravity outweigh potential driveline losses.

 

Yeah so in simple terms, set frame to ride height, put level on carb mounting pad and set engine until the bubbles are level, then tag you have it.

 

Can't tell from the photo what what style you are going for, but here is some shots for comparison. As Ray stated, I usually set the ride angle and height of the chassis before mounting the engine and trans.

 

thanks for the help I think I have now

 

Yes C/H just go ahead and set it the way you were going to do it originally. You were right. Lippy

 

I made my own mounts for the SBC conversion in my Ford. I made up a mock-up gauge to finalize the mounts, which were made in 2 parts and finally welded together after I was happy with them. I also blanked out some .090 thick shims in case I needed them at the trans mount, turns out I didn't need them. I agree with keeping the carb flange level as possible. On the mock-up we set the angle with a cheap HF protractor.

 

That's the way I have always installed the engine. HRP

 

Textbook chassis plan.

 

This. I knew I would have a rake so deducted the driveline angle from the rake and welded up the mounts it was 3* down at the rear relative to level ground. Relative to the chassis it was 7.5*, but that's pretty much irrelevant as long as you have the same angle on the pinion.

 

Hi Ray.... got a question about pinion angle. With my 32 frame, buggy spring and ladder bar rear, I set up my mock rake based off of wheel/tire size. Not sure of the final height due to not having doors and other components installed. Is using the rake only acceptable for setting pinion angle or must ride height be known? As my chassis sits now, my pinion points up 2.1 degrees. I installed my SBF engine pointing down 2.2 degrees. So I have both centerlines parallel but my intake carb pads are not level. They slope back with the engine. Should I reposition my engine to level the intake or leave it as is since the lines are parallel? Thank you sir.

 

As long as the pad angle is not too extreme you should be fine, carbs go up and down hills all the time.

 

The lower at tail shaft thing and matching angled intake to make carb level of stock engine,was designed to make more room inside the stock auto{lower hump}. The set up works fine. How ever in the case of a hot rod engine with a aftermarket intake that may have a level with crankshaft ***crab pad,is OK to mount motor level with ground{ I think they look better in a hot rod that way} but depends on your intake/what you like. Home made log intake and header so motor/intake/header are level to ground on my own..
.

 

Generally, I agree with the above two posts...........I will add, though, that while carbs do go up and down hills and function okay, that is usually only part of the time. They are designed to function best when level. Compensations can be made , if needed, either by adjusting float levels or wedge shaped spacers under the carbs. Probably in most case the angular difference isn't enough to matter.

Ray

 

Carbs need to be level- ??? Well,,,,,,,,,,,
Ever drive in Ohio? Around the Ohio valley?
1/3 of the time you’re driving up a grade, 1/3 of the time you’re driving down a grade, 1/3 of the time you’re likely to be driving sideways on a crowned road that may be up or down grade.

Ever set up drive line angles when using a blower on the engine? The blower sets dead parallel with the crank and the carbs set on the blower. The crank of course, and conservative the blower and then the carbs must follow the driveline angles.

Carbs do not need to be level, it’s proven over and over daily. Now big wide ass factory air air cleaners do need to fit under low profile hoods though. At the factory If the engine settled in at 3* and the carb were to follow that then The front of the air cleaner would be hitting the hood. What’s the solution?

 

Out of the 7 mins of footage, time the amount that the cars probably have the carb level.

 

This video shows just HOW IMPORTANT a level carb is to get the max performance from an engine. See 4:00 or so for a good view.
6sally6

 

I'll just comment on u-joints. The need to work so give them a few degrees. Watch a you-tube on rear end movement on an IMCA Modified if you want to see what they can take. A total arc of 20+ degrees is not uncommon.

 

Hey sally,
How about you go find a google pic of a “4 port hilborn injector.”

 

I'm probably the lone wolf here but for engine location in my own hot rods I'm all about the visual. I hate electric fans so I install the radiator and set the engine up for an acceptable mechanical fan-to-radiator relationship and work from there. This tends to put the engine a little higher in the chassis than current street rod trends but that's fine with me. I'm not afraid to contour a firewall or put a little hump in the floor. As for angle; it's level left to right, but I will compromise a little on driveshaft angle if the engine appears awkward compared to the frame and body when viewed from the side with the chassis at ride height/angle. Pinion angle will be set to work with the engine angle. Carburetor pad angle is the last thing I consider. So far I've never had any vibration issues or worn out any driveline parts prematurely.
Drag race chassis are a whole other deal, like someone said your baseline set up should put the drive line all in line under acceleration. You'll figure what the car wants for pinion angle, instant center and pre-loads once you've made a few passes at the track.

 

WTF is your problem? Your rant is all out of proportion to my comments.

Ray

 

Ride height and rake
Then set angles
Make it all fit
Carbs don’t have to be level but they do look a little goofy leaning forward if the engine is set level and the carb mounts are not.
driveline angles is what determines engine angles for me.

 

Building a car’s driveline around such an irrelevancy as the carb being level is nonsense.

 

I never said that it was.....from time to time you make lot of sense.....a lot of other times you pull this crap.
Are you aware of your instability?

 

I've put together a lot of street cars & trucks in my days, getting a carb level was never that big of a deal. As far as the pinion angle, its a lot easier to adjust the rear axle for the correct angle then it is to modify the motor and trans mounts, as far as I'm concerned. Gene

 

Lmao
Occasionally I’m aware of this phenomenon you refer to as instability. It appears to manifest itself most when I don’t take time to unpack a detailed explanation and just figuratively kick open someones box of assumptions, scattering the mess across the floor and then leave it for them to sort out the crap from truth.
Sometimes again figuratively I’ll lovingly take the time to go through their box of bullshit and help them sort The good gold nuggets out and help them let go of the bullshit they thought was a good assumption to use as a foundation to build a knowledge base on or from.

There’s not one Empirical fact at all to support any claim at all that a carburetor needs to be or must be level in the context and realm of driveline angles.

If the carburetor needed to be leveled then every single situation where a car operates perfectly fine without the carburetor being level must be a fallacy. Either that OR The notion the carb must be level is False and of little concern at all when setting up driveline angles. The more important things are ground clearance, fitment issues, encroachment into the cabin and visuals. If it looks wrong or goofy it is wrong or goofy. Once those MAJOR issues that you’ve got to live with are worked through then you can easily twirl the pinion around so that the U joint working angles are equal and finish it up.

 

Thanks Vic!
Was going to add, the driveshaft u-joints like a 3° offset (total) in order to circulate grease.
Any less, you're inviting a visit from Mr. Brinnel!

 

Good info. I just laid out my engine level assuming this was the norm. Looking at the stk flathead intakes I have the flange looked level to me. Is this the case? I was actually more worried about getting my driveline angles right, but if I can I angle the engine down slightly just to get a bit more room.