AZDoug

As you know, the intake manifold has a rake to it such that the carb base at the rear is higher than at the front of the intake manifold.

I would assume that the downward angle of the engine, when in the car, is such that the carb base is perfectly level, or parallel to the ground, ideally. Correct?

Now,was any extra angle allows for to accommodate additional rear end squat due to passengers in a rear seat, and stuff in the trunk?

In other words, when an unloaded car is parked, does the front of the carb sit just slightly lower than the rear of the carb to account for vehicle loading? if so, how much? What is the specified mounting angle?

Thanks,
Doug

ricks327

Doug,
I would think that the engine wouldn't change as it is attached to the frame and any additional weight would lower the frame not the engine.
But I have been wrong on so many things in the past, I'm inclined not to think.
Rick

MikeM

I believe intake manifolds picked up that forward rake to compensate for lowered driveshaft tunnels (lowered transmissions) starting sometime in the '50's. Older designs didn't have the angle on the carb pad until driveshaft tunnels started to get lowered when car chassis got lower to the ground. The chassis designs wouldn't allow the engine/transmission to drop straight down so they just dropped the rear of the transmission to get the driveshaft down and that allowed the tunnel to be lowered.

Engine swapping books recommended to place a level on the carb pad to level any new engine, front/rear based on the pad when installing a new engine in an old chassis.

I'd guess a level carb pad would be a good place to start but not absolutely necssary because as you point out, that angle changes when you start loading the car.

BADBIRDCAGE

Doug:

On a quick read I thought you said a stiff in the trunk. Growing up in central NJ I never paid attention to trunk loads. Of course when I was in the Border Patrol in Chula Vista, CA I paid a LOT of attention to trunk loads.

Back to your original observation on engine angle. In my experience a level carb pad has always been the starting point. Now with EFI and dry sumps it doesn't matter so much. For a non EFI engine I would go with the level pad and pay attention to the oil sump being in proper attitude as well.

Rich

65tripleblack

Hood clearance issues.

JohnZ

The design engine installation angle on midyears is 3*; on solid-axle cars, it's less than 1*, close to zero (horizontal) due to the close clearance between the bottom of the transmission tailhousing and the center "X"-member and reinforcing plate on the frame (which results in the terrible U-joint operating angles).

AZDoug

Ha! In NJ, stiff in the trunk was probably right, on the way to Meadow Lands to bury it.

I was thinking that I should allow for an inch of settling at the rear for normal fuel and payload lowering, over dry, unloaded stance, for carb base attitude.

It sounds like it isn't that critical to carb operation, if midyears got 3* down angle and C1's got only 1* down angle of the motor.

Yeah, Tennessee for moonshine runners, I-5 for illegals in the trunk with bumper dragging.

I had to go through a grease trap on I-10 just west of Las Cruces last month, the BP agent started looking in the rear windows of my pickup, and the bed shell, and then when I told him I was on my way back from BORTAC, he immediate waved me through with a get outta here comment.

Doug

AZDoug

Actually, this is for the 327 going in the '37 Ford P'up project. I could stick a 6-71 blower or tunnel rum under that hood and still have room. I just picked up the 200-4R yesterday.

I think I will buy some 100 pound bags of sand or ready mix, and place them strategically on the frame to simulate body, bed,and fuel/passenger loads when welding in the trans mount bracket.

Doug

vetsvette2002

ALL of the engines we test are set at level in two planes. The dyno is also level. The connecting drive shaft has a 2* angle at the engine and dyno. This is done so the u-joint bearings rotate and prevents them from cupping and spauling.
These are usually 550+ hp engines, but have gone to 1200+ HP for special clients.

nassau66427

For a mid-year, the carb base should be 1* down towards the front when installed.

Intake at 4* down towards the front.
Engine installed at 3* down towards the back.

65tripleblack

Quote:
Originally Posted by 65tripleblack
Hood clearance issues.


Doug,

I made the comment because there was speculation about the reason for the carb-nose-down-angle in the midyear Corvette................not your application. The reason was solely because of hood clearance limitations on the midyears with small block hoods. They finally had the right idea for smallblocks in 1966, when they began using a drop base air cleaner. They used the gained clearance to finally put on a decent, 3" tall open element air filter. They finally were able to go to a decent intake manifold (with an additional 5/8" of rise) by further increasing under hood clearance with the C3 and the LT1 hood/intake manifold.

vetrod62

I say level at standing. My carb still works fine when the wheels are two feet in the air.

mashinter

I'll guess that the carb base is designed to be level at design load, which is with two 150 pound passengers and luggage.