Except for the Thermactor provisions, the 302 heads are the same as the 289 heads stated before. A truck head (C9TE-C) with a 58.2-cc chamber is also available with slightly greater compression. Finally, all 302 heads were carryovers from the previous 289 heads, making them interchangeable. Aftermarket parts will fit most any version of the 302 head.
The main difference between the 301 and the 302 heads is the shape of the combustion chamber. The 302 has a flat top while the 301 has a domed one. This changes the flow patterns in the engine a little bit which allows for better fuel efficiency. Also, the 302 uses three valves instead of two. These are the intake valve, exhaust valve, and spark plug cover valve. They work almost exactly like their 289 counterparts except they are made of steel instead of aluminum.
New heads were available for $750-$1000 at this time. It is estimated that we can expect to see about a 25 percent increase in power with these heads compared to the 289 heads.
Heads may be removed by removing the four torx screws holding the unit in place, then lift off the head. Installation is basically the reverse of removal. Be sure to use a fresh gasket when replacing heads!
Overall length of the 302 head is larger than the 289 head by about 3/8 inch. Width is about the same. Height increases by about 1/4 inch.
The only difference between the 289 and the 302 is a 1/8-inch longer stroke on the 302. The 289 will not roll off the line while the 302 will. The 289 will run about 100 rpm faster than the 302.
The 351c heads will not fit on the 302, which is a whole different block. People used to mill 351w heads for fitment to 302s before there was such a large assortment of aftermarket heads available. Those mills were done at really low speeds with a lot of torque, so they'd strip the head if you tried to use it on its original block.
If you want a performance version of the 351c engine, then the only way to do it is with an aftermarket head replacement set-up. The camshaft in the stock head is too aggressive for regular production vehicles, but it would work fine for a track vehicle or some other application where weight and strength are not important factors.
It's very much the same block. The bore of the 289 is 4" with a stroke of 2.87", whereas the bore of the 302 is 4" with a stroke of 3". Both trucks use a H-beam as a frame, with independent front suspension and a live axle at the rear. The differences are in the engine compartment--the 289 has a 1.6L four while the 302 has a 1.9L version of the same design. Otherwise, the engines are exactly the same.
The chassis number ranges from SC1 to SC4 for the 289 and SD1 to SD4 for the 302. These numbers are located on the lower left corner of the body shell next to the tire hole. The chassis number can be used to find information about that truck model. For example, the chassis number of my 289 truck is SC3. That means it was built in March of 1964. You can also use this number to order reproduction parts or buy original equipment (OE) replacements from aftermarket manufacturers.
These numbers are found by removing the outer skin of the vehicle, called the unibody, which consists of two main sections: the floor pan and the body shell. The floor pan contains the engine bay and driveshaft tunnel, while the body shell includes the remaining body cavity.
That implies that practically all components are interchangeable between a 302 and a 351. This contains the following items: heads, cams, lifters, timing chain, timing chain cover, water pump, engine mounts, and several other components. Because the bellhousing bolt pattern is identical to that of a 302, any trannies that bolt to a 302 will also bolt to a 351. The only component that might not fit is a hydraulic roller camshaft adjuster, but there are mechanical versions available.
In addition, because all these parts are interchangeable, it does not matter if your 351 has 4 valves per cylinder or 2 valves plus two intake valves (as in a 302). The parts are exactly the same for both variants.
Finally, a 351 has an OHV V-8 while a 302 has an OHC V-6. However, this difference is very limited since both use pushrod engines. The only real difference is that a 351 has a stronger block and heavier crankshaft than a 302. Otherwise, they are very similar.
There are many aftermarket parts available for the 351. Just like with most other GM products, don't be afraid to experiment with different combinations of parts on one vehicle. You can always swap out parts that you don't like anymore or that caused problems for maintenance purposes. In fact, this is a good way to save money too!