Inliners International Forums General Discussion Engines Questions on Stock GMC 302

I found a 302 GMC engine in a 1950’s (?) flatbed dual wheel truck. I confirmed that it is a 302 by the number stamped on the raised casting by the distributor. It appears bone stock and complete except for the missing air cleaner. The engine is for my 1937 Chevy sedan project. A couple of questions:

The 302 has a dual outlet exhaust manifold. One outlet is directly under the carb and the other exits farther forward. So some GMC engines had dual exhaust?

The engine has a 2-barrel carb. Is this stock?

I did not see an oil filter. Maybe it was removed? Where should the filter be, on the intake manifold?

I’m familiar with the chevy 235 engines but not the GMCs. Thanks for any help.

It's anyone's guess what could have happened in the past 50+ years etc.

That's a good choice for your 37 project.

W/O seeing it, or pictures (my guess) "somewhere along the way it was altered" etc.

It's not important anyway, as you probably won't be using those things in the final version.

Good luck & welcome to Inliners Int.

The two-barrel intake and carburetor would be stock items on the GMC 302. The dual exhaust is more likely to be a modification. Does the "forward" outlet appear to be cast as part of the manifold, or is it welded onto the manifold? If it is welded, then you have a "split manifold."

The oil filter would be optional equipment in the 1950s. You can modify the block to use a modern, "full-flow" filter.

God's Peace to you.

d
Inliner #1450

I have never looked at 302 that did not have an oil filter. They were located on the distributer side of the motor attached to the side plate cover bolts. The filter was fed from the front of the oil gallery. There was a 3 way fitting from the block to the head for the rockers and to the oil filter. The filter returned to a fitting at the distributer gear. (that's the one every one plugs and wonders why they loose a distributer gear)If there pugs at these places some one took off the filter. Good Luck

Thats good info. Since I am converting to a full flow filter, should I put a restriction in the line teed off the rocker arm line to feed the distributor, say .062", so the rockers have first priority on oil volume?

The 90 degree fitting I screw into the block is restricted. I fill it with solder (brass fitting) and drill a .060 hole in it at a slight angle which feeds to the gear. I always use a valve in the line to the to rockers. I set it when I'm priming the pump prior to the first starting the engine. I run a lot more rod side clearance for the flow than stock. A stock oil pump has always run at 50# for me at any RPM.

I looked at some of my stock engines, they have the filter return going to a hole by the engine mount near the front of the engine, not to the base of the distributor, although the istributor hole is there and plugged. Looks original to me?

If you guys take a look in the "Tech tips" section to the left of the screen, you will find an article on converting the GMC to full flow filtration. There is also one on doing the 235/261 Chevy.