Derrico Posted Tuesday at 02:17 PM Share Posted Tuesday at 02:17 PM Good morning forum members. I need to do a tune up on my B20 Magnadyne gas engine. What are the recommendations for parts, spark plug gaps and point gaps? Also oil and trans fluid and rear end fluid. My plan is to get it running so I can get it in and out of the shop with no problems and while at it feel confident it is ready to run. Thanks.....Frank 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74769-tune-up-for-a-b20/ Share on other sites More sharing options...
BOBWhite Posted Tuesday at 02:34 PM Share Posted Tuesday at 02:34 PM I once saw a spec book for one of those Magnadyne engine but I didn't pick it up unfortunately. Point gap should be around .015-.020 on most engine, a business card is what I use since it's just about the right thickness. I'm not even sure what brand of ignition Mack used Do you have any pictures of the engine? Lots of the small parts have to be cross referenced. 2 Quote Link to comment https://www.bigmacktrucks.com/topic/74769-tune-up-for-a-b20/#findComment-562208 Share on other sites More sharing options...
Popular Post mowerman Posted Tuesday at 03:08 PM Popular Post Share Posted Tuesday at 03:08 PM If you have not moved the engine, be sure to pull out all the spark plugs and shoot a bunch of mystery oil into the cylinders before you do anything and leave it. Sit for a week or so I believe ignition parts are still available from what I hear, good luck. 3 Quote Link to comment https://www.bigmacktrucks.com/topic/74769-tune-up-for-a-b20/#findComment-562212 Share on other sites More sharing options...
topo Posted Tuesday at 03:37 PM Share Posted Tuesday at 03:37 PM Do you have any idea what motor it has ? Quote Link to comment https://www.bigmacktrucks.com/topic/74769-tune-up-for-a-b20/#findComment-562216 Share on other sites More sharing options...
Derrico Posted Tuesday at 03:54 PM Author Share Posted Tuesday at 03:54 PM Hi topo, it has the 291ci. 107 hp. Quote Link to comment https://www.bigmacktrucks.com/topic/74769-tune-up-for-a-b20/#findComment-562217 Share on other sites More sharing options...
HarryS Posted Tuesday at 04:53 PM Share Posted Tuesday at 04:53 PM Looks like the plug gap is .030, timing is 4* BTC. The Mack Operation Manual does not give point gap but generic six cylinder should be around .020 and the dwell should be 31-35. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74769-tune-up-for-a-b20/#findComment-562219 Share on other sites More sharing options...
Popular Post D2Denny Posted Tuesday at 04:57 PM Popular Post Share Posted Tuesday at 04:57 PM Attached is a scan of the B Model owner's manual on tune-up specs for the gas engines. I still have it so if there are further questions, ask For the gear units the manual shows 90 wt mineral oil for all. I would use 80-90 wt stuff you find at tractor supply or Rural King. The B-20 has the CL-51 Clutch, TR-73 or TR-730 trans, FA-201 front axle, SG-34 steer gear, RAS-202 rear axle, CRS-89 carrier If I remember correctly the plugs in my EN401 were Champion H-10's. Your old line NAPA store will be able to look up the points and condenser and order them The EN-291 holds 9 qts of oil 4 Quote Link to comment https://www.bigmacktrucks.com/topic/74769-tune-up-for-a-b20/#findComment-562220 Share on other sites More sharing options...
Derrico Posted Tuesday at 06:16 PM Author Share Posted Tuesday at 06:16 PM Thank you D2Denny! a lot of good information, I'll get Tractor Supply & NAPA 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74769-tune-up-for-a-b20/#findComment-562225 Share on other sites More sharing options...
Popular Post D2Denny Posted 15 hours ago Popular Post Share Posted 15 hours ago Derrico: Was at local NAPA today. Asked about tune-up parts for your engine. Had some in stock and the rest a day away at distribution center. Distributer is a Delco and these are still pretty common parts. About $62.00 for all Distributer cap Echlin RR95 Rotor Echlin RR83 Points Echlin CS763A Condenser MPE RR174SB 5 Quote Link to comment https://www.bigmacktrucks.com/topic/74769-tune-up-for-a-b20/#findComment-562288 Share on other sites More sharing options...
Derrico Posted 9 hours ago Author Share Posted 9 hours ago Thank you again D2Denny, that helps! Great info, just what I needed! Quote Link to comment https://www.bigmacktrucks.com/topic/74769-tune-up-for-a-b20/#findComment-562303 Share on other sites More sharing options...
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