Mercruiser 470 3.7 timing-chain & also bore limits - 03/02/10 02:05 PM
I am building a 3.7 Mercrusier. As most of you know this is a 4cyl derivation off the Ford 460, [whereas the 3.0/181 is a variantion of the GM Iron Duke/ChevyII 4cyl).
I am looking for answers on two questions-
1/ Can you put a 4.44 bore (.080 over) in the factory cast in liners? As far as I know, no test exists to separate what the thickness of the cast-in liner is vs the aluminum of the block. Basically bore it and shine a bright light looking for "shadows". My block (and I am "land-locked" so it's the one I would prefer to use, rather than having another shipped in) is already at 4.39 and has deep scratches in one of the bores. I think .050 will clean it up. I'd like to know if
anyone has experienced boring one or more of these stock blocks to .080 over.
2/ A tech copy that Phil sent me from a 1999 newsletter mentions the timing chain used by the writer is one for a "Line bored Windsor".
Now, that statement gives me more questions than answers. I am not clear as to whether that means just the chain, because the cam "pulley" is definitely a lot more like a Small block Chevy, so obviously you can't swap on a Windsor set. Something a lot of people don't know is a Windsor chain and a SBC chain are identical. Maybe it's a Chevy Cam gear and chain with a Windsor crank gear? or Maybe the cam gear is unique to these motors?
The factory set-up is a chain with a really added-on looking sliding tensioner. By going with a chain for a "line bored"- so 10-20 thou shorter (5-10 thou per side), do you eliminate the need for that tensioner?
Furthermore I am interested in going with a wet-style belt drive, such as the Comp 5100. I feel anything that can be done to eliminate the harmonics of a big four, should be done, and that this may help.
Pics of this item, here: http://www.summitracing.com/parts/CCA-5100/?rtype=10
I am looking for answers on two questions-
1/ Can you put a 4.44 bore (.080 over) in the factory cast in liners? As far as I know, no test exists to separate what the thickness of the cast-in liner is vs the aluminum of the block. Basically bore it and shine a bright light looking for "shadows". My block (and I am "land-locked" so it's the one I would prefer to use, rather than having another shipped in) is already at 4.39 and has deep scratches in one of the bores. I think .050 will clean it up. I'd like to know if
anyone has experienced boring one or more of these stock blocks to .080 over.
2/ A tech copy that Phil sent me from a 1999 newsletter mentions the timing chain used by the writer is one for a "Line bored Windsor".
Now, that statement gives me more questions than answers. I am not clear as to whether that means just the chain, because the cam "pulley" is definitely a lot more like a Small block Chevy, so obviously you can't swap on a Windsor set. Something a lot of people don't know is a Windsor chain and a SBC chain are identical. Maybe it's a Chevy Cam gear and chain with a Windsor crank gear? or Maybe the cam gear is unique to these motors?
The factory set-up is a chain with a really added-on looking sliding tensioner. By going with a chain for a "line bored"- so 10-20 thou shorter (5-10 thou per side), do you eliminate the need for that tensioner?
Furthermore I am interested in going with a wet-style belt drive, such as the Comp 5100. I feel anything that can be done to eliminate the harmonics of a big four, should be done, and that this may help.
Pics of this item, here: http://www.summitracing.com/parts/CCA-5100/?rtype=10
