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Discussion Starter · #1 ·
Alright Buick gurus let me run something by you I'm sure there is something I'm missing I have a Buick 455 that's bored .038 over (4.350 bore) I have an offset ground crank to give me a 3.950 stroke and utilize a 2.200 rod journal size....

I've been looking at some 7.1 inch Eagle rods for mopar with the proper rod journal size.....



And a set of these pistons for mopar




So I have a stroke of 3.950 a 7.1 inch rod and a 1.485 compression height piston with a deck height of 10.570 that should put me at .010 "in the hole"


Other than needing to get the big ends of the rods machined to the buick width of 0.925 would this setup work? I'm sure I'm missing something so I hope you guys chime in.
 

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I'm not a Buick guru, but know my way around stroker situations fairly well, so I'll throw up a couple considerations.

Once you narrow the big end of the rod, what about the bearings?? Can you get a narrower bearing??
Along with that, is there any beam offset to the big end you need to also account for??

Valve relief in piston....be prepared to re-cut those as it is unlikely the Buick and Mopar share a valve location and angle.

Will you have enough room in the crankcase for stroker clearance with the chosen rod to clearance the block or oil pan and not hit water or oil galley?


You gave us the rod link twice...no piston was linked.
I'm guessing ICON 842 or 828?
 

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Looks like you need to narrow the rod .083"....as long as there is room to not hit rod beam while cutting .042" off each side of the big end it should be fine.
Consideration might need to be made for whether this will take too much strength out of the big end cap to rod area that the bolt passes through.....might be better to trim the rod less or none and widen the rod journals on the crank??

Is the amount of beam offset the same or nearly the same between the Mopar 7.1" rod and the stock Buick??
I have no clue as to the stock Buick dimensions.
 

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Discussion Starter · #8 ·
I really don't know either I'm gonna do some more research on the subject before I purchase anything. Just thought I'd run it by you guys first I knew one of yall would realize something I didnt....if you come across anything let me know!
 

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Discussion Starter · #9 ·
Normally I'd agree with you 110% on cutting the crank vs the rods Eric but I've messed with quite a few of these Buicks through the years the stock nodular crank while strong you want to do the least cutting as possible on it because the block/main caps are weak the crank is a lot of the engines structure
 

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1979 Chevrolet Malibu 496-TH400-9" (cruiser). 1992 Chevrolet S10 355-700r4-7.625" (daily driver).
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I'm not advocating for this connecting rod. I just thought it could provide a potential answer as far as the big end width. It shows a 7/16 fastener and .900 width. From that, I would gather getting a wider rod machined while accomodating the 7/16 fastener is possible. No Buick experience here either.
 

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Discussion Starter · #12 ·
79 malibu you got me looking a little closer at the rods and I found these.....




My local machinist said cutting down the big end is no problem does it all the time. You have to get creative on these buicks because there isn't a wealth of speed parts available. I should have asked him this but maybe some of you guys will know....to create a "stroker" in these motors you have to offset ground the crank most commonly is changing the stock rod journal of 2.249 offset grinding it to the common big block chevy size of 2.200 and you basically get .050 more stroke....my question is and it may be an obvious answer but since guys "offset" grind these can I just do a straight up grind to 2.200? I'm not worried about increasing the stroke seems to me if you can take .050 off of "one side" then should be able to turn the whole thing taking .025 off "both sides" correct?
 

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You almost need to have rods an pistons as there are two ends to think about that being how high the rod and piston combination is in the bore at TDC and what clearance that provides to the deck as this plus the head gasket establishes the squish/quench clearance where especially with iron heads you want around .035 to .045 inch to maximize mechanical octane, that is getting the fuel you use to react as if it were 4 or 5 octanes higher than its pump rating. Really important feature to take advantage of when cylinder bores exceed 4 inches.

The other end is piston to counter weight clearance at BDC. When mixing rods and pistons this can get to be a problem so off set grinding .050 might make the difference between needing to trim piston skirt bottoms and/or counter weights for clearance which will affect balance.

This is potentially a bigger issue than the added stroke of offset grinding so you got to pass these dimension and clearance gates first.

Bogie
 
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