70MCx2

thanks, that was what I was thinking, just wanted to make sure. It's a '79 block, and I'm planning on using ARP studs on top and bottom to try to prevent pulling any threads out. I know early '70s blocks were stronger, but couldn't turn this one down - did some yard work for a guy one day in exchange for a complete engine to rebuild.

I'm in the process of building a big block engine to drop into my '70, and have a question. I got a 1/2 NC bottom hole tap and cleaned out the threads for the main cap bolts; got to the bottom of the hole with no problem. Switched to a 7/16 NC bottom tap and started cleaning out the threads for the head bolts, and the holes are different. I never did bottom out with these, just kept going. Are these "pass through" holes, or are they much deeper and I just didn't get to the bottom?

thanks for the pic; it tells me that I've got the correct pulleys and how to route my belts when I get the a/c back in. As for the color, I go to get the paint, and I find two choices. Dupli-Color has Chevy Orange and Chevy Orange-Red, which is darker. VHT's Chevy Orange is dark and matches Dupli-Color's Orange-Red. I was told that '70 was during a transition period; before '70 it was Orange, and after it was Orange-Red. Basically it comes down which is correct, the darker or lighter shade of orange?

okay, thanks. the car is in the shop right now getting the rear windows adjusted, or I would go look. I do know that the pulleys that I have off the the engine going in match the ones in the car now; i.e., 3 groove crank and 2 groove water pump. I will look and see what the p/s pump has when I get it back. Does anyone have a pic of the belt setup on a big block with a/c they can post or send me?

I'm pretty sure the color of the engine in '70 for big blocks was orange, right? That being block, oil pan, heads, timing chain cover, and harmonic balancer? Were the crank pulley and fan pulley black or orange? Also, I will be reinstalling the factory a/c, so I want to make sure I go with the correct pulleys. For those of you with a big block and factory a/c, does it run off of the crank pulley or the fan pulley? And how many grooves does that pulley have? The crank pulley I now have has 3, and the fan pulley has 2.

currently building a Largus Ratonis (latin for big rat, 454) to replace the one in my '70, and I'm assuming that they were orange like the rest of GM's engines?

Thanks for the info. I came across that website when I was looking, guess I didn't dig deep enough. The numbers on the pad where the VIN goes makes me think that the engine was put back into service as a short block; I'm guessing that the VIN was machined off and then it was restamped with the "080 010 010". The heads are slightly different, one is a '72 and the other a '75, so that also makes me think it's been rebuilt. Looks like I will be rebuilding the block and replacing the heads with rectangular ports. Thanks again for the help.

okay, so now I'm REALLY confused. The block casting tells me it's a 1975 (or 1978, depending on site) to 1990 454. When I found a list of engine assembly code suffixes, all of the ones that were Xsomething were 396's, and there was no XJ even shown. Also, the number that is on the pad on the right front, in front of the cylinder head, doesn't appear to be a partial VIN, as it does not begin with 1 for Chevrolet and doesn't have a letter for final assembly plant plus the last six of the VIN. Instead, it has 9 numbers, in 3 groups of three (080 010 010). This number looks as if it might have been put there as a replacement number, but the engine assembly code looks original. Any suggestions?

I found the engine code - T07119XJ - where you described, and am about to go try to decode it. What I described as the engine code must be the VIN, as I found it where you described. It was a very poor job of stamping, as two of the numbers are incomplete, as I don't think they would use a backwards 'C'. Still trying to 'figger out what the "H Per Pass F4" and "GMT12" casting numbers are all about.

I am rebuilding a 454 to swap out with the one in my '70, and have some questions about the info I found on the block. It has "H Per Pass F4" on the rear end, along with F28-79 and 14015445, all cast into the block. If I'm correct, I think the 14015445 is the casting number, and that reveals a "1978-1990 454 2 or 4 bolt main", and F28-79 shows it to have been cast on June 28, 1979. But, I don't know what "H Per Pass F4" is. High performance, maybe, but what does that mean, and the F4? The engine number is even more confusing, and it looks different than any of the others (few) I'e seen. It's stamped on, but look like smaller letters than the others I've seen. The best I can tell, it is "080 010 ?1?", with the ? marks representing either a partial 0 or what looks like a backwards C. Maybe a replacement or crate motor of some type?

Well folks, to answer my own question: it ain't easy. I finally got them out this evening, but it was harder'n hades to do it. It took me a couple days with a drill and chisel, and I finally got the top half and the internal parts out, leaving just the base. The problem wasn't oil underneath causing a vacuum, or the base being stuck on the bottom by carbon buildup. The problem turned out to be the inside diameter of the rotator was VERY tight against the valve guide. What I ended up having to do was to take a dremel and cut across the outer edge of the base on two opposite sides. Once I got that done, I took two small screwdrivers and placed them underneath opposite ends of the flat spots, and pried up as I turned the base in a circular motion. This allowed it to spin upward as opposed to trying to pry it straight up, which was impossible. Once I got it up off the bottom and about halfway up the valve guide, I got some large Channelocks and grabbed the two flat spots and rotated it back and forth as I pulled it up and finally out.

Okay, thanks. I tried putting some heat to them yesterday, thinking they might expand a little and loosen from the valve guide, but didn't have any luck. I will try the air hose and if that fails, will have it vatted and see if that helps. Barring that, may have to go to a machine shop. A friend, who used to wrench on Eddie Hill's Top Fuel ride, is helping me with the rebuild, and he told me the same thing about throwing them in the trash and using spacers.

I'm in the process of rebuilding a 454 for my '70, and the rotators under the exhaust valves on the passenger side came right off, not so lucky on the driver side. All four are stuck, and I've managed to break them and get the top half off, but the base is still stuck. I can get them to spin, but can't get under them to lift them up and out. Anybody ever had this problem, and hopefully got a suggestion?