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Well everything just kinda went downhill all at once. My 351w blew a head gasket due to an dowel pin alignment issue. Was taking off the old gasket and there is now scratches in the cylinder head and in the block. This is the kicker the block and heads have already been resurfaced both to .010", the block was just freshly rebuilt and I don't want to tear it apart again, or worse get a new block. I am planning on talking to the machine shop that did all the work for me last time and see what they think.
All of the scratches are on the edge of the cylinder wall where the gasket and head meet. I can get my fingernail into them which isn't good at all. I am going to call the machine shop in the morning but wanted to get some insight into the issue. Do you guys think I should start looking for a new block and a new set of heads.
Also in my defense, the head gaskets didn't come off at all I have been working on it for several hours trying to get the material off of the mating surfaces and a metal razorblade is the only thing that has been somewhat useful. I have also been using scotchbrite and carburetor cleaner, but the gasket material is just so much I can't get it off with just the scotchbrite.
The dowel pins don't really do anything other than help during assembly.
Certainly an important question - why did you blow a head gasket?
I would "fix that" in all kinds of ways no mechanic or machinist would ever recommend, because the "right thing" would be to have the head resurfaced and block decked again. No way I'd do that without doing a full rebuild, so I'd do "other things".
The dowel pins don't really do anything other than help during assembly.
Certainly an important question - why did you blow a head gasket?
I would "fix that" in all kinds of ways no mechanic or machinist would ever recommend, because the "right thing" would be to have the head resurfaced and block decked again. No way I'd do that without doing a full rebuild, so I'd do "other things".
Right between cylinder 7 and 8.
I will take it to the machine shop and have them deck and resurface it again.
That area seems to be caused because people like using the air tools with the 3M buffer. All it takes is ruining one before you learn to leave that tool in the tool box.
The dowel pins don't really do anything other than help during assembly.
Maybe for a Ford where it does not matter too much but I've seen some engines that were not designed with dowels and the head can shift a fair amount before it gets torqued. Not good when you have a timing belt.
Dowels are even more important with the trans to block mounting. As far as I am concerned, all dowels should be used and are important.
I did some reading, I am worried about decking the block again, mainly because the top of the piston to the top of deck is a very close tolerance, it should be without the first time it was decked .023". I imagine the machine shop will have a solution. But I am thinking that the pistons will have to be decked to prevent it from protruding from the block. Has anyone ever heard of this method?
As far as I know decking the heads again will not be an issue. Besides a little bit more compression which I won't complain about.
How high do the pistons come up?
my engine the pistons stick above the deck by .002 after decking the block, my heads were cut .030 to decrease combustion chamber volume. If you are not familiar with engine building, I would suggest grabbing a good book, it will help you understand and talk intelligently to the machinist. The machine shop will know how much is acceptable but you really need to research some so you understand the other variables involved like compression, push rod length, valve piston clearances.
Sorry I didn't get back sooner, I was under a time crunch to get the engine out of my truck since we had a storm coming in.
I will clean up piston 1 and get a set of calipers on it and see what the clearance is.
I will also take some dimensions and info off of the valve train. I am not running a crazy cam, stock rockers. As I was taking off the heads on the engine I knocked over the box that all the pushrods very neatly in order and then went everywhere so I have some stock size ones coming here soon.
The cams intake lift is .478 and exhaust is .485. Intake opens at 17 BTDC and closes at 57 ABDC, Exhaust opens at 67 BBDC, and closes at 11 ATDC. Duration is 210 and 214 at .050". Its the comp cams 35-255-5.
Do you guys recommend some good literature on engine building? When I rebuilt it a couple of years back, I just used the Ford shop manual, and some online resources. I have heard that desk top dyno is a good resource, but I never pulled the trigger on it.
I have seen the different head gasket thicknesses, the ones I saw were .044 and .039 compressed.
Its been a little bit over a year since I had this apart, a lot of this will start coming back to me when I start doing some more research.
So actually I just did some research for the pistons I had put into the engine are actually decked at .020. Their height is 1.752" compared to the regular 1.774".
Good news, dropped the block and heads off. They said that they can fix them.
I tore the engine down today and was wondering if anyone knew about the key that goes into the crankshaft. There is a keyway in the timing gear, and the harmonic damper, however there is a gap between the key and the keyways, like the key isn't tall enough. Is this normal? I wouldn't think it would be normal to have a key that is too short.
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