MArch 2004 - Studebaker Overhead valve Six cyinder engine - ------------------ Its not a great engine, being a conversion of the flathead done in a hurry it seems without sufficient pre production testing. But the head cracks can be welded. I have three OHV 6's and havent had any problems with the heads cracking. -------------------------------------------------------- I have had lots of exposure to the OHV six. First off, the engine is not that much different from the '59-'60 flathead from the deck down. Items such as the pistons, crankshaft and rods are virtually identical. The heads were prone to crack and Studebaker knew this. Subtle changes were made in the area between the valves, which is the area most prone to show cracks first. Typically burned valves were also an issue, caused by carbon flaking off in the combustion chamber, caused by excessive oil consumption. This carbon would get between the valve face and seat, which would start the whole process. There are other weak links in this engine, other than just cracked heads. Carburation was always an issue, with both the AS and RBS carburetors. They tended to run rich and load up, especially when cold. The heat transfer tube for the choke, inside the exhaust manifold tended to crack in one of the dimples, allowing exhaust to enter the choke stove. Pistons were changed in '63 which included a longer skirt to reduce piston slap. These skirted pistons tended to develop cracks in the corner radius of the skirt. If the skirts broke off, the piston cocked in the bore, cracking the cylinder. I have seen two that failed in that manner. The '59-'62 pistons without the skirt are generally the better way to go during an overhaul on a '63 or '64. The piston slap issue was of more concern beginning in '59 when the wrist pin bore was positioned lower than the '58 and prior Champion sixes. The pistons lost some of their stability in the bore as a result. The oil drain-back holes in the pistons tended to get plugged with carbon, leading to excessive oil consumption early on. The '64 used a set of piston rings unique to that year. The '39-'63 used the same ones. ----------------------------------------- According to DD's Studebaker six book, the later heads were worse because the engineers added more metal where there was too much already. ---------------------------------------------------- At one time someone had written a complete article about the OHV 6 cylinder heads, in Turning Wheels. (Perhaps someone with an index can look it up.) As I recall he mentioned Studebaker had added more metal in the area between the valves, and in the writer's opinion it made matters worse. I had heard a story at one time that mentioned the U.S. Goverment stopped using the Zip-Vans earlier than originally anticipated, due to the short supply of replacement cylinder heads. I had owned twelve different cars with these OHV sixes and all had similar problems. I do recall the heater hose came out in a different spot on the '64 head. Perhaps it came off of the front, and the rest off of the rear. As far as being slow, they were much quicker than the flathead they replaced. Had it not been for the inherent problems, I had always felt they had more than adequate power. Compared to a '59 with flathead six and automatic, an OHV with automatic was a rocket in comparison. At Bonneville they ran one for days on end at around 100 MPH. I believe Paula Murphy was the principle driver of the six cylinder Commander. This was during the Granatelli speed trials. ------------------- I have never owned a car with the ohv 6, but I have a friend who has one that he has driven for years. The car will cruise down the interstate at 70mph with no problem and has adequate pep around town. The only thing the owner of the convertible for sale seems to have right however is that the engine does not need to be lugged at all. These engines do have a bad reputation and it is mostly deserved, but taken care of, driven with care, they can last for a long time. Joe Roberts ---------------------------- I have had just as many with cracked heads on automatics, as I did on sticks, three on each. This idea of it being lugged will crack heads is bull. You cannot effectively lug an automatic. Poor coolant maintenance, low coolant level, deposits from hard water and burned valves will crack a head before anything else. From my experience the OHV 170 will need work when they get into the 50 to 80K range. Usually rings for sure, and sometimes valve work. I have never had any problems with the lower end. Many times the ring lands of the piston get worn and will be out of tolerance at about the same time. The cylinder bores never wore all that much and would take at least one fresh ring job. KK --------------------------------------`