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New straight six from Mazda

2639 Views 24 Replies 11 Participants Last post by  LouJC
Seems Mazda is following in Chryslers footsteps. Maybe there is hope for ICE engines yet .
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Probably the worst example of V6 vibs was the old GM 90* V6s before they fitted the split journal crankshaft, (pre-1977) that made it better, but finally they added the balance shaft around '92-93 or so, that brought it up to a tolerable level for automotive use. I have a pre-balance shaft 4.3 in a boat with the split journal crank and the vibs aren't noticeable due to the soft engine mounts and fiberglass/wood composite structure but if you watch it you can see it trying to lift the front of the engine up & down. If I ever repower it I will get a late model 4.3 with the balance shaft and Vortec heads.
The old inline 6 in our Jeep on the other hand is very smooth.
Engineering Gas Auto part Machine Nut

here's the old 4.3 with the even fire crankshaft but no balance shaft, on the later models you'd see the balance shaft above the tin retainer for the roller lifters
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The final chapter in the old cast iron GM 90* V6 design was written by of all companies, Mercruiser, what they did was design their own version of the latest GM 4.3 V6, with a bigger bore, same split journal crankshaft, same balance shaft, updated cylinder heads, and modern engine management, if you look at the parts breakdown you'd swear they bought the old tooling from GM when they stopped making the cast iron V6s. Still all cast iron, used in sterndrive applications. I guess they thought the old GM engineering was good enough!
GM version used by Mercruiser:
Genuine Mercury Marine parts, large inventory, fast shipping. CYLINDER BLOCK AND CAMSHAFT (

Mercruiser's own "new" V6:
Genuine Mercury Marine parts, large inventory, fast shipping. Cylinder Block, Camshaft, Crankshaft, and Balanceshaft (

the parts for this new engine from Mercruiser are MUCH more expensive than what GM charged for theirs!
Merc's price for a new long block is about 9 grand, you could buy GM's version brand new for less than half of that when it was still in production (I think 2014 was the last year they built them).
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Well those of us with Chevrolet V8s small block or big block did the points without pulling the distributor because reinstalling it was a bit of a nuisance. Take an old seat cushion lay it across the air cleaner and lay on top of the engine. The later Delco points set ups had the points & condenser mounted on a single plate & there was the Allen adjustment that allowed you to get it close so the engine would start & then set it with the engine running with the dwell meter. Back then this was one big advantage that GM V8s had vs FoMoCo & Mopar. While Chevy, Pontiac & Olds had the distributor in the rear, Buick & Cadillac the distributor was right up front. Very easy…until we got HEI in 1975. This were good but the modules could fail with no warning but again very easy to replace.
My old boat with the 1988 Chevy 4.3-4bbl has a Prestolite points distributor with mechanical advance. Very simple easy to maintain. If I repower I might try an electronic Delco EST marine unit.
About 1974 or so the points failed on my 1965 VW Beetle 1200 and I changed the points on the side of the road on the way home from college. Always carry spares lol!
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