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Good afternoon I was wondering if anyone could help me with a question I have on a 1953 303 rocket engine I purchased. When I bought my 1951 super 88 it has a original 1951 303 mounted to a hydromatic transmission. When I bought the car the motor was seized. I was lucky enough to find a free spinning 1953 303 engine and was told it was also bolted to a hydromatic but when I recieved it, it was not it had a set up for a manual transmission with clutch and pressure plate. I know that the cranks are different because of the center drilled out in the manual engine for the pilot. Will I be OK just removing the 1953 manual flywheel and pressure plate set up and installing my 1951 automatic flywheel in its place? I was not sure if there was a difference in the cranks or flywheels from 1951 to 1953? Thank you for your time.
The Hydra-Matic also used a pilot bushing . The same one that manual trans used .
Everything will fit OK .
Your biggest problem will be to get the Hydra-Matic separated from the "frozen " '51 engine . The engine must be disassembled somehow so that the crankshaft can be rotated so that all thirty or so bolts on the torus cover can be accessed .
Last edited by Charlie Jones; Apr 23, 2020 at 04:36 PM.
What Charlie said, this sometime works if you have the engine out of the car and heads removed and engine is upside down. The issue is being able to rotate the assembly with the seized pistons. Sometimes you can disassemble as many rod and main bearings and find the piston/ pistons that are stuck and drive them out with force using a wood block and a 3 # hammer. If the seized piston are on the rods that you can't get to the nuts because they are hidden you are in for a very had time. That is why I try not to buy any seized engines from first generation Oldsmobiles unless they are very cheap. Best of luck and keep us updated on your progress....... Lost in the fifties... Tedd
Thank you Charlie and Tedd so much I sure appreciate all the info. You guys have been very helpful! I was very lucky and after soaking for months and months I was able to loosen everything up enough that I did get the motor to move enough I was able to separate the Hydromatic from the seized motor and am in the process of driving out the pistons in the seized motor as we speak. It was funny I could get the motor to turn using a pry bar on the flywheel but that was it no other way and once I took the engine apart everything was spotless inside no scoring on cylinders or anything? Cam spun freely? Some pistons are coming out easy others not so much but even the bad ones are not scored. Thanks again for the info!
Thank you Greg! Iam very excited about my new 51 olds! Iam the second owner of this car and it only has 62,000 original miles but had not moved since 1972. Its heart breaking for me not to use the original engine which I still might! I now have all the pistons out and everything seems like brand new minus the rings and pistons?? But I now have this 53 engine that seems to be working just fine with a few more test we will see. Than you again to everyone for all the helpful info and excitement in my project.
Glad it worked out as good as it did. There are no matching numbers on this early era Olds so if mine I would just rebuild the best of the two and not worry about it. You did good getting it unstuck.... Tedd
Glad to see you were successful in separating engine and trans .
While the system of " matching numbers " was not used in the 50's there were numbers on the block and heads that are different between '51 and '53 .
There are also a number of minor differences between '51 and '53 engines . Things like compression , cam timing , and rocker arm ratio .
The '53 engine had more horsepower .
There is a discussion on the H.A.M.B. of these numbers and a link to it here ; https://www.jalopyjournal.com/forum/...elated.149650/
You should be able to check compression or cylinder leakdown on the engine stand with the '53 engine . If the numbers are within 15 percent of each other you may consider it good to install . Then you can drive and enjoy the car .
However , I would keep the '51 engine just in case you , or a future owner , want to re-build it .
Thank you so much Charlie that is great information! I did check the compression roughly because of no intake or anything on the engine and I had 40 PSI in every cylinder exactly minus two of them! The others were at like 15 PSI and the other was zero. I discovered that the one with zero the lifters are not pumping up and Im suspecting maybe the same with the other or a valve not seating good? I know that this is a rough test but I just wanted to see if the cylinders were even close? Any other ideas how to check things at this stage with it on my stand with no intake or exhaust manifolds?
Thank you very much Charlie I sure appreciate it. Im finding I might have to go through the new engine a little more than I thought anyhow! Im getting a little nervous stuff Im seeing like loose head bolts , a couple broken bolts here and there, washers missing? Id rather work on it on the stand than in the car. I also believe that my 1951 heads even though less compression are in far better shape then the 1953 heads. Would the 1951 heads work on the 53 engine? I know the compression would be less but not worried about horse power probably using the original 2 barrel intake as well anyhow. Thanks again for everyone's help!
The '51 heads will fit on the '53 block .
The rocker arm ratio changed in '52 so the pushrods and rockers will be different .
An old " hotrod " trick was to use '52 thru '55 rockers and pushrods on a '49 thru '51 engine to increase valve lift .
If you do use the '51 heads , you may still want to use the '53 rockers and pushrods .
Thank you Charlie for that tip that will be perfect! Im excited to get something running and in good shape to put it back in my 51! Thanks again for all the tips!!
