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By any chance you didn't put the wrong spark plugs back in it. A hot plug will do it. My 2 cents JOHN
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Loose spark plug will also cause 1 cylinder to run lean.
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Originally Posted by mjb
(Post 2204109)
My engines where 1997's and they had the defect. I'm not sure when Mercruiser fixed the problem but I know it was after 1997. You have to be VERT careful when you open up the hole not to score the matting surface of the o-ring. I opened mine up as much as I could and still leave enough mating surface for the o-ring to seal well. Hard to give you any definitive measurements though. I'm guessing that I doubled the x-sectional area of the feed hole...but it's still smaller than the other 7 holes....but large enough to prevent a lean condition with my bigger cams.
Harry |
Originally Posted by Fenderjack
(Post 2204113)
By any chance you didn't put the wrong spark plugs back in it. A hot plug will do it. My 2 cents JOHN
NGK BR6FS |
Might not be THE problem, but isn't a 741 lift cam to big for a set of stock 502 heads. If you didn't lengthen the valves and strengthen the springs you might have had a bigger problem down the road.
I am actually asking the experts if I am right on this. have heard this from some local guys in the past. |
Originally Posted by jeff1000man
(Post 2204783)
Might not be THE problem, but isn't a 741 lift cam to big for a set of stock 502 heads. If you didn't lengthen the valves and strengthen the springs you might have had a bigger problem down the road.
I am actually asking the experts if I am right on this. have heard this from some local guys in the past. The only thing that is stock is the head it self cause I changed the springs, rockers and valves. Note that mjb is right cause I checked the fuel rail and on the no 7 outlet there is only a little hole that feeds the injector. Harry |
Originally Posted by mjb
(Post 2204109)
My engines where 1997's and they had the defect. I'm not sure when Mercruiser fixed the problem but I know it was after 1997. You have to be VERT careful when you open up the hole not to score the matting surface of the o-ring. I opened mine up as much as I could and still leave enough mating surface for the o-ring to seal well. Hard to give you any definitive measurements though. I'm guessing that I doubled the x-sectional area of the feed hole...but it's still smaller than the other 7 holes....but large enough to prevent a lean condition with my bigger cams.
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Originally Posted by D Harry
(Post 2204792)
Jeff,
The only thing that is stock is the head it self cause I changed the springs, rockers and valves. Note that mjb is right cause I checked the fuel rail and on the no 7 outlet there is only a little hole that feeds the injector. Harry |
Hard for me to say if 6.5mm is enough...that's only about 1/4" and still sounds pretty small. I did not drill mine. I used a dremmel tool with a long, slender grinding bit to open up the passage. I think you will be able to remove more material that way as opposed to a drill.
I do not think that there is an aftermarket fuel rail that will just bolt on to solve the problem. You may be able to get a later model mercruiser rail but I am pretty sure that the injectors on the MEFI 1's were different than MEFI 2's and I think the fuel rails are different...but I'm not sure of that?? I think your only quick bolt on option is to modify your fuel rail but maybe someone else in the know can comment. |
[QUOTE=mjb;2205023]Hard for me to say if 6.5mm is enough...that's only about 1/4" and still sounds pretty small. I did not drill mine. I used a dremmel tool with a long,
Mjb, OK, I'll try to a least get the hole about 1/2". But thanks to you I found the problem, cause I couldn't figure out what happened, Harry |
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