I was thinking of putting a 73 headed 455 in my 67 Gs 400 and I wanted to keep the stock intake and carb. I dont know if anybody has done this but I have heard that the 67 intake and carb/choke set up will not work on the 73 heads. Would it be better to just use the 455 and keep the 67 430 heads so the factory intake and carb/choke setup work. I want to keep the set up stock appearing. What would I need to do to use the new block with older heads. Thanks Ed
There are EGR passages in the 73 heads that need to be plugged in order to use the 67-71 intake. Four of them are in each head. Other than that, the intake will fit. Early heads on the later block are not a problem as long as you use the composition head gaskets such as Fel-Pro. Steel head gaskets will not work as they won't cover the oval water passages in the block and coolant will leak into the oil. You will have to use the 70 on up lifters/pushrods/rockers to get the proper oiling as the later blocks don't have oil holes to go through the heads. Mark
Pretty sure that the 73 head has a big square opening for the exhaust crossover. The older intake won't cover it completely. 71 and ealier only had two small holes and any intake would work. Friend of mine just pluged the round holes in towards the port with freeze plugs (not sure of the size, I used 18mm on my 70 heads) and then used epoxy to fill in the rest. He filed it smooth and everything was fine. He sold the motor after putting a couple thousand miles on it. He never had a problem with it as far as I know. If you don't like that idea you could always melt down some aluminum and fill it in.
I was confused with your first post. I thought you wanted to use the 73 heads with a early intake, but at the end you mentioned using the 67 heads on the 455 (which isn't a problem). Anyway, to clarify what I wrote earlier, the hole your showing isn't the one I was refering to. The two round holes under that rectangular hole is the exhaust crossover. The rectangular hole on those heads serve no pupose as far as I know. The intake gasket or valley pan gasket will cover that up. On the 73 heads there is a large almost square hole that's about 1 1/2 inches deep. Then there are two round holes that enter into the exhaust port. Your 67 intake will not work with the 72 and up heads without modifying them like I mentioned above. You'll also have to fill in the air injection or egr holes, four on each head. To do that I'd just get some aluminum rod, put a taper on the end and drive them in with a hammer. Then cut it flush. However, since there seems to be nothing wrong with your 67 heads, just use them. They'll prolly flow better than the 73's anyway, if they are big ports they'll definitely flow better. Regarding your choke assembly, unless your running it in the winter, it doesn't really need to work. After blocking up my exhaust crossover, I put my choke rod hicky on to hold the choke flap open on the carb. I either feather the gas or just let the car warm up a bit before I drive. No problems. Hope I didn't confuse you in my babbling. If I had a digital camera, I wouldn't have to write so much.
