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Gray marine/Detroit Diesel

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raycarlyle1

New member
Hello
I'm looking for any information you can provide on a Graymarine/Detroit Diesel. It is in an oldcoast guard 30 foot boat built in 1958. and now owned and run by the seascouts. It is a 6-71 with the model #671RA48A and a serial #6A34647 are stamped in the block. I'm trying to find out if the if the currentinjectors are the right ones and if the full load rpm's are set right. itcurrently has HV7 injectors and the full load rpm's are set at about 3400. Everything I know about these engine tells me the full load should be about 2300.Any help would be greatly appreciated
 
If it's got 2 valve heads then the HV 7 looks right. 4 valve head would use an N 60 for the same fuel delivery.

I agree with marv that the timing for the HV 7 is 1.460 and the full load speed is 2300 rpm. At 3400 rpm, you are in "comeapart" territory and should easily be experiencing valves floating, springs breaking or worse. TURN IT DOWN!

Also, if you need injector parts, it appears there are still some available. This guy has a nice list.

http://www.dpausa.com/pdf/detroitdiesel.pdf
 
UPDATE: Got a hold of hand tach. Checked rpm on engine and found that someone had installed the wrong tach. Rpm at the engine was half what the tach read . Going to replace the tach , injectors and do a tune up on the old girl. Thanks everyone for the great information and advice
 
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