Greetings!
Doug's Drugs is a blog about my adventures with old cars & motorcycles. I call it Doug's Drugs because it's such an addictive hobby. And because I've always wanted a drug store with my name on it.
This week I've been preparing for a visit from the owner of the '51 Chevy business coupe that's been under re-construction since last fall. There have been fitment problems as the engine goes into the chassis. It comes too close to the steering linkage when I try to set it down where I'd like it to be. I'm using one of my homeless shop engines to mock up the engine and transmission mounts and I have a used set of Hooker Hedders on the engine to test the clearance with the linkage.
The plan had been to use an intermediate joint to allow me to angle the steering rod up to the steering column, but it hits the exhaust headers in a big way. Usually, a 2X4 block of wood placed between the engine and the crossmember gives enough clearance and something to rest the engine on while I weld up the motor mounts. You can see the wood in the photo above.
As a general rule of thumb, the lower the engine is in the car, the lower the center of gravity, and the car handles better. Another clearance consideration is the rocking motion the engine makes under torque; there needs to be enough clearance to the side of the engine to avoid noisy contact with the suspension as the driver guns the engine. There's nothing worse than having six or seven really cute, screaming cheerleaders in your car, asking you if the engine's going to fall out because of the noise it makes whenever you burn rubber.
To affect a remedy I cut a slice of the frame out so I could eliminate the intermediate joint and try to run the steering rod directly from the steering rack to the end of the steering column. When I looked int the open frame rail, I was pleased to notice that the GM factory welded the frame together with a length of support tubing inside to support the frame sides when a bolt was put through the frame to secure the original front suspension crossmember.
The results were successful and the steering rod is now a straight shot. The intermediate joint wasn't a bad idea, it just prevented me from using an aftermarket exhaust header. I've used intermediate joints before and they are sometimes the only answer. Before I repaint this section of the frame I'm going to weld a section of 2" tubing into the slice I just made to restore the strength to this section of the frame.
As a general rule of thumb, the lower the engine is in the car, the lower the center of gravity, and the car handles better. Another clearance consideration is the rocking motion the engine makes under torque; there needs to be enough clearance to the side of the engine to avoid noisy contact with the suspension as the driver guns the engine. There's nothing worse than having six or seven really cute, screaming cheerleaders in your car, asking you if the engine's going to fall out because of the noise it makes whenever you burn rubber.
To affect a remedy I cut a slice of the frame out so I could eliminate the intermediate joint and try to run the steering rod directly from the steering rack to the end of the steering column. When I looked int the open frame rail, I was pleased to notice that the GM factory welded the frame together with a length of support tubing inside to support the frame sides when a bolt was put through the frame to secure the original front suspension crossmember. The results were successful and the steering rod is now a straight shot. The intermediate joint wasn't a bad idea, it just prevented me from using an aftermarket exhaust header. I've used intermediate joints before and they are sometimes the only answer. Before I repaint this section of the frame I'm going to weld a section of 2" tubing into the slice I just made to restore the strength to this section of the frame.
With this correction out of the way I put a piece of steel pipe in the lathe to bore the inside diameter to just over 2". Then, I cut a section out of the pipe and welded a pair of mounting tabs to it with the intention of mounting it just inside the firewall and putting the steering column through it so I could secure it to the floor. I put a hose clamp around the pipe and it grips the steering column through the cut-out section.
Since it was about time to have an engine in this car, I decided it was important to get the car to ride height so I could determine the pinion angle (the relationship between the end of the transmission tail shaft and the rear axle pinion. But, if the car is higher in the front, like Gary's car is now, I wouldn't be able to measure the actual angle of the transmission tail shaft until I leveled it. You see, as the engine is being fit into place with the transmission attached, it needs to be leveled from side to side as well as from front to back. Level from front to back is measured by putting a level on the carburetor mounting base of a carburetor intake manifold. The thought being that the carb needs to sit level so the float bowls will fill properly. Aside from being level, its important to get the angle of the pinion within 2 or 3 degrees of the angle of the transmission. Unwanted vibration or worse could be the result of a poor alignment at this point.
Instead of cutting and recutting the coil springs in an attempt to find the right length to get the ride height correct, I replaced the coil springs and shocks with a length of threaded rod. I made a pair of aluminum spacers that fit into the hole at the top of the spring caps and a threaded "T" that fit at the bottom and would be secured by the lower shock mounts. Then with a few appropriate sized nuts and washers I adjusted the threaded rod until the car sat with the lower control arms parallel to the ground. This also made the car level, according to my bubble level.
As you can see from the photo of the front of the car, there seems to be nothing in the way of the new engine. I did some measuring and noticed that there are only 22 inches between the insides of the frame rails. This isn't much, cars a few years newer have 8 inches or more of available space. The truth is; I can put the engine in the frame now, but not down on the 2X4 that I place on the crossmember, it's going to be a bit higher and forward. It reminds me of seeing some cars at the shows and in magazines recently that had the engine mounted purposefully high in the chassis just for effect. It made the engines look much bigger and they filled out the engine compartments, although I think its mostly a novelty design. 
I did happen to stumble onto an opportunity for the '51 recently; a newly acquainted friend sold me an engine from a 2004 Chevy Tahoe. It's a 5.3L Vortec engine with a cast iron block and aluminum heads. I understand that these babies make about 295HP in stock form and that you can bolt them to the 1st generation small block Chevy bell housing so an early transmission (like Gary's 4-speed) will bolt right on.
Speedway Motors sells a motor mount adapter made by Hooker that adapts the LS motor right to the 1st Gen motor mounts in the chassis. In other words, I could go ahead with the engine setup in the '51 as I have planned, but if Gary is interested in the newer generation engine then I just need to add the Hooker motor mounts and he's running a cool LS3 in the old coupe. It would likely need a rebuild and some dress-up stuff, but he would be the only guy on the block with this engine in his hot rod. If he doesn't want this engine then we'll go ahead with the fresh 305 and I'll use the new LS3 in one of my upcoming projects. Gary, we'll be talking about this option on your next visit to the lab.
Doug
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