Engine rebuild, now no compression
#25
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How did you assemble them wrong? Sucks to hear. If thats the case then that is for sure your problem. Bent valves surely won't hold compression. Just when I thought the Miata's were safe from bending valves. I've had bad luck with bent valves. They do usually come in large numbers in situations like yours. If one goes, so do the rest. Both times I've dealt with them I bent 14 of 16 and 15 of 16.
PS, a lot of aftermarket valves come with longer stems for cams with a smaller base circle.
PSS, how do the valve seats look in the head? I know when I did my head, the seats and valves were for sure not going to work if swapped around, or the seats wouldn't have worked with new valves unless I had them machined. Don't know if you took this into account or not.
PS, a lot of aftermarket valves come with longer stems for cams with a smaller base circle.
PSS, how do the valve seats look in the head? I know when I did my head, the seats and valves were for sure not going to work if swapped around, or the seats wouldn't have worked with new valves unless I had them machined. Don't know if you took this into account or not.
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I would imagine not much. Looking at the head with it off the block with cams at maximum lift, the valves stick out a fair amount past the deck. Pistons at TDC aren't very far below the deck of the block, with the little valve "cups" on the piston face. Couldn't be more than 1/4'', at least I wouldn't think. My head is machined ~.030'' and the block deck another .005'' so I am probably not far from being able to bend valves with some over revving action and valve float.
I would think an HLA that was assembled wrong and is locked up would possibly cause contact.
I would think an HLA that was assembled wrong and is locked up would possibly cause contact.
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If you would. I'm curious to know. Like I said, I recall that the bottom edge of the valve stuck past the deck of the head by probably 1/4'', and the pistons aren't that far below the deck of the block. It can't be much at all.
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If its off in that pic, its just a tooth off on the exhaust. Remember, 19-teeth between the cogs contacting the belt. He also could have swapped or have the gears out 1/3rd. The lobes look fine in that pic to me.
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Its been nearly a year for me since doing a timing belt, but from what I remember it looks correct. Or is that 180* out of time? Stupid of me to not know, but doesn't the crank turn clockwise? Been a while since I looked at the engine honestly. If it does turn CW, doesn't that mean the exhaust valve will be open on the down stroke, and intake open on the up stroke? Lobed would need to point inward. Unless it rotated CCW, in which case that is correct.
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Yeah, I got that part but I think that the letter "I" should be at the four o'clock position on the intake side and the letter "E" should be at the eight o'clock position on the exhaust gear. I was trying to remember and I think he may have them backwards.