bandsdean

Just got my engine back from the engine shop and have a question about the engine block. I can't seem to find the casting #. It is date coded 1968 and on the back of the block it has the "C" weld mark. Also, the VIN stamp is present behind the #8 cyl and it matches the car vin number. This is supposed to be a 390 S code. I was told the welded "C" on the back of the block denotes a 428CJ engine. Could this be a 428 CJ block? Thanks

FFR428

It could be. What bore size is the block at? Also look on the edge of the crank counterweights. A 1U or 1UB stamping is for a 428. 2U or 3U would be a 390 crank. If your not certain on the bore size ask the shop what pistons they used and the brand and part number. Also what is the build date and plant of your car? And the date code on the block? The "C" sandscratch normally means it's a 428 CJ/SCJ block. But anything is possible. Do you have any clearer pictures? Also one of the bottom with the crank and maincaps? Also what's the casting number on the heads?

bandsdean

Plant is Kansas City. Serial # is 8K42S241177. Build date is 7-12-68. Date code on intake is 8F28. Partial VIN # on rear of block is 8K241177. Timing chain cover date is 6-68. Casting on heads are C8AE-H. I have to double check the dates for the heads. I ordered the pistons for the shop and they were .030 over a 390 bore which should be 4.05+.030=4.08 (is that correct?) Where is the date code for the engine? The oil pan and intake are already installed so I am unable to check the crank. :( Thanks again.

FFR428

The blocks date code is right below the oil filter adpater mounting pad. Same format as the heads year/month/day. Yep .030 is 4.08 on your 390 pistons. Could very well be you have a underbored 428 block. You can drill bit test the cyl wall cores through the freeze plugs and or look for the "428" cast on the floor if you want to be persistant. The fact the VIN is stamped on it kinda seals the deal. That's pretty cool!

bandsdean

Block date is 8G3. July 3, 1968. I was going to ask if the "C" on the back of the block is in the correct location? What is the drill bit test and how is it done? Where on the block will I find the "428"? Top of engine or bottom? Thanks for all your help.

FFR428

The C sandscratch comes in all shapes and sizes. Can be on either side and also backwards depending who made the sandscratch. It's just scratched into the core sand thus the name sandscratch. Drill bit test is a test made up by Dave Shoe in which you use drill bits to gap the space between the cyl walls inside the block. You access this area with the freeze plugs removed. The "428" on the water jacket floors are also inside the block. So it your engine is built and all nicey nice it's up to you if you want to remove them or not. Dave test involves drill bits in 64" increments. So you can adjust with the bits you have to measure with. When you remove the freeze plugs (6 total 3 on each side) you'll see the cyl wall cores and gaps. The gap is simply where you stick the blunt end of the drill bit to see what size is a snug fit. It's good to scrape away any rust or built up crap to get a acurate reading. Commonly 390 block cores will accept a 17/64" bit and 428 block cores 12/64"-13/64" bit. Keep a good grip on the bit so you don't drop it inside the block. To remove a freeze plug simply put a socket and extension on one side of the plug and tap inward. You want the plug to spin sideways so you can get a pair of plyers/visegrips on it to pull it out. To reinstall the plug use the biggest socket you have closest to the inner dia of the plug itself. Simply tap it straight in till the lip is flush with the block. It WILL go into the block if you tap it too far so note the position it's in beofre you remove it. I smear some sealer on the inside of the plug and run a bead around the outer lip after it's installed.