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ethyl
02-20-2011, 02:41 PM
3 years ago I had the 350 chevy in my 18 classic rebuilt using new 10:1 pistons, pushrods, lifters, roller rockers but reused a pretty radical ( can't recall the specs) Comp Cams cam which was checked and in good shape. She was running in the upper 60s with a 23 inch Merc cleaver. I had to replace the outdrive and opted for a SEI after market unit. Since the change I can't get the rpm up with the 23 inch prop and the engine just does not seem as perky. I am wondering if I should have used a fresh cam or if the problem is with the outdrive switch. The engine has always had a very "lumpy" idle and this seems to be unchanged. I hate to pull the engine again just to inspect the cam. Any thoughts? Thanks in advance for any replies. John

mrfixxall
02-20-2011, 04:42 PM
3 years ago I had the 350 chevy in my 18 classic rebuilt using new 10:1 pistons, pushrods, lifters, roller rockers but reused a pretty radical ( can't recall the specs) Comp Cams cam which was checked and in good shape. She was running in the upper 60s with a 23 inch Merc cleaver. I had to replace the outdrive and opted for a SEI after market unit. Since the change I can't get the rpm up with the 23 inch prop and the engine just does not seem as perky. I am wondering if I should have used a fresh cam or if the problem is with the outdrive switch. The engine has always had a very "lumpy" idle and this seems to be unchanged. I hate to pull the engine again just to inspect the cam. Any thoughts? Thanks in advance for any replies. John


The sei drive uses a 1.4? ratio vs a 1.50 which is what your merc drive should have been..i dont think that would cause a big issue,i know the fuels we are using are chit..try looking over your air bleeds in the carburetor to make sure they are not plugged up..check the timing, that would make it a pooch if it was retarded to much..could also be a restricted fuel line,check the screen at the end of the fuel pick up in the tank..i did away with mine and just let the inline filter catch any crap..

ethyl
02-20-2011, 05:36 PM
M.M., thanks for reply. The SEI unit is a 1:5 according to what I ordered and the info sent with the unit. I will inspect the fuel intake. I have been setting timing @ 8-10 btdc. Will recheck. Start with the simple possibilities. Take care.

mrfixxall
02-20-2011, 05:59 PM
M.M., thanks for reply. The SEI unit is a 1:5 according to what I ordered and the info sent with the unit. I will inspect the fuel intake. I have been setting timing @ 8-10 btdc. Will recheck. Start with the simple possibilities. Take care.

check the timing @ full advance also,,if you have a 22 degree module then you only have 28-30 degres of timing in the engine..read your module part number.if it reads v8-22 then its a 22 degree module,thats if you still the merc set up.that would mean you dont have enough timing in the engine..
run premimum fuel only now adays,you just dont know what your getting for fuel,93 has les alchol in it them the 87 and 89 fuels.

poorboy
02-20-2011, 08:59 PM
Are you sure the old outdrive was a 1;50 unit? If the rpm drop started after the installation of the after market unit then maybe you had a 1;64 unit before. can you post the rpm you were turning and what you are turning now. The gear ratio of the old unit if it retains the original gears is stamped on the left side of the upper housing. If you are sure the ratio's are the same and nothing is found with what Mr fixxall suggested then maybe time for a compression check. dropping one cylinder can change your wot rpm by as much as 600 rpm.