on buddy barry's 1988 r model mack, it has a miss at higher rpms. any ideas??? changed the fuel filters and did some basic checks. now i have to check valves and injectors. thansk KoO Published Author
i could not take it any longer and slipped out to buddy barry's shop and popped the valve cover off. then i ran the engine and it is the front 2 line on the pump that don't make much difference when the engine is running. so i when to the storage trailer and took the pump off the parts engine. on thursady i change the pumps and see if that makes a differnce. these pumps are like IH crawler pumps and just line up the marking gears (this has a flat gear)???? also how do you set the valves since the rocker arm has and adjust and so do the valves??? also how do you set the raocker arm that has the big end on it??? the tg on the engine says E6-350 serial number 6W0161 valve setting intake .016 exhaust .024 on a cold motor. also 3 days ago the phone tower here burnt to the ground so the nearest phoneis 300 kms away. they say it will be 2 weeks before we have phone services back plus, bank machines, interact, and internet. good thing i have my own high speed dish. the joys of living in the great white north. thansk KoO Published Author
King, if the R model mack is has a miss at higher rpm's check for broken or weak valve springs while you have the valve cover off.As far as valve adjustment ,from the pics you have a 4 valve head with a bridge on the two valves .Adjust the bridge so there is equal pressure on both valves.On any 4 cycle engine I have found that while rotating it by hand in the direction of rotation,I adjust one cylinder at a time.Have someone bar the engine over while you watch and adjust the valves on each cylinder.Adjust the intake valve when the exhaust valve is just starting to open.Adjust the exhaust valve when the intake valve is almost closed.set the intake at 11 thousandths and the exhaust at 21 thousandths of an inch.
check the camshaft. I had a few macks the past 20 yrs that developed a miss at high engine RPMs only to find the cam lobe was gone.
Adjusting the valves on a Mack with a Dynatard engine brake fitted is quite complicated and not easy to explain . I have added a link to a chap who has explained it quite well . http://www.justanswer.com/questions/1mos6-bigmart-tino85-1985-mack-valve . I would also be checking the cam lobes for lift with a dial gauge as Macks are renown for wiping lobes off .