360 to 390
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From: Thief River Falls, MN
360 to 390
To make this short and sweet, I have 2 blocks, 1 360 block out of my truck, and 1 390 block out of a car - car one sat a long time and I buggered up the cam bearings getting the cam out, but i still have the rotating assembly.
Because I'm trying to get a 390 back in the truck as cheap as possible, I want to put the rotating assembly out of the 390 into the 360 block, instead of getting new cam bearings put into the 390 block. (don't have a cam bearing tool)
What's keeping me up at night is the ridge. I measured the inside bore diameter about an inch down the bore and got 4.058, so I ordered a new set of std rings and was just going to throw it back together. I used a ridge reamer to knock some of the ridge down at the top, but there is still a bit there.
Am I going to end up with broken rings because of this ridge and the longer stroke of the 390?
Is there any way I can get away with not having to bore this 360 block and run the 390 rotating assembly?
Because I'm trying to get a 390 back in the truck as cheap as possible, I want to put the rotating assembly out of the 390 into the 360 block, instead of getting new cam bearings put into the 390 block. (don't have a cam bearing tool)
What's keeping me up at night is the ridge. I measured the inside bore diameter about an inch down the bore and got 4.058, so I ordered a new set of std rings and was just going to throw it back together. I used a ridge reamer to knock some of the ridge down at the top, but there is still a bit there.
Am I going to end up with broken rings because of this ridge and the longer stroke of the 390?
Is there any way I can get away with not having to bore this 360 block and run the 390 rotating assembly?
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From: Thief River Falls, MN
I'd like to work with the 360 block as I have future plans for the 390 block, since there was some rust in a couple of the cylinders. Is my only option to have it bored?
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From: Thief River Falls, MN
well, after honing and inspecting the 390 block, it'll have to be bored to use it,the rust pitted one cylindar and i found a couple other odd things in one of the cylanders that i can only explain as a factory defect. almost looks like it was nicked by a grinding stone or something, it's very weird, and it's a std bore.
So back to my question - is it possible to cut the ridge out of the 360 block and get by with it as a 390?
So back to my question - is it possible to cut the ridge out of the 360 block and get by with it as a 390?
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The problem isn't so much the ridge at the top, but the taper at the bottom of the cylinder. (Yes, the piston might come up a bit more than the 360, and that IS an issue, but read on)
The 390 with it's longer stroke will have the piston go down to BDC a little further than the 360. If there isn't a ridge down there, the taper will be pretty radical.
It's a toss-up what to do at this point - if it were me, I'd start doing whatever I'd need to do to get the money for a set of pistons and a bore. And getting cam bearings installed
The 390 with it's longer stroke will have the piston go down to BDC a little further than the 360. If there isn't a ridge down there, the taper will be pretty radical.
It's a toss-up what to do at this point - if it were me, I'd start doing whatever I'd need to do to get the money for a set of pistons and a bore. And getting cam bearings installed
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From: Thief River Falls, MN
I didn't even consider bore taper. I'll have to check it out. Problem with the bore job is where I'm at, I've got to drive an hour + just to get any machining done...
I have the money to do it, I just didn't want to spend it if I could get away with not doing in for a year or so. Right now I only have about $90 into this motor project. All but 2 compression rings were broke on the 360, which was a "rebuild".
I have the money to do it, I just didn't want to spend it if I could get away with not doing in for a year or so. Right now I only have about $90 into this motor project. All but 2 compression rings were broke on the 360, which was a "rebuild".
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