525SC jetting
06-28-2006 | 03:32 PM
#1
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From: LOTO 31 mm
525SC jetting
Wanting to know what jets people are running. My new 1050 Holley came with 88's in all four corners and the Merc service manuel states 98's in all four corners. I am sure merc runs them on the fat side. Also Holley does not list a 98 jet as far as I can tell. I am also going to run the stock pulley for now.
06-28-2006 | 10:58 PM
#2
Charter Member # 55
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From: Omaha/LOTO
Re: 525SC jetting
Rich, mine still had the 98's in it when I took it apart. It had a smaller pulley when I got it and still does. I put in a 731 cam and increased jetting to 102's all around. Its a little on the rich side, but rich = safe.
Mine ran great with the 98's, but I did have the smaller pulley. I would think you could safely run 95's with the stock pulley.
Mine ran great with the 98's, but I did have the smaller pulley. I would think you could safely run 95's with the stock pulley.
06-29-2006 | 07:18 AM
#3
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From: On A Dirt Floor
Re: 525SC jetting
Note: Be careful comparing same type carbs but with different list/part #'s to each other. Bleed holes, boosters, emulsion circuits, etc,etc can be different, thus leading to different jetting and etc.
Power valves on Dominators are typically the high flow power valves since their pvcr (power valve channel restriction) is larger and thus able to flow more fuel than a standard power valve can.
I worked on a pair of 525SC's that had chillers installed and next step up in boost. Baseline tested with the stock 98's and then went to 102 jets squared, picked up some power, and then went to 104's which again picked up a little more performance. I kept it here since everything read fine and worked terrific.
I also used the secondary idle speed screw to open the secondary throttles a touch so that I could back down the primary throttle blade position a touch, making the idle mixture screws more sensitive. This provided a steadier idle that didn't surge as it was doing before I touched it.
Power valves on Dominators are typically the high flow power valves since their pvcr (power valve channel restriction) is larger and thus able to flow more fuel than a standard power valve can.
I worked on a pair of 525SC's that had chillers installed and next step up in boost. Baseline tested with the stock 98's and then went to 102 jets squared, picked up some power, and then went to 104's which again picked up a little more performance. I kept it here since everything read fine and worked terrific.
I also used the secondary idle speed screw to open the secondary throttles a touch so that I could back down the primary throttle blade position a touch, making the idle mixture screws more sensitive. This provided a steadier idle that didn't surge as it was doing before I touched it.
06-29-2006 | 11:45 AM
#4
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From: LOTO 31 mm
Re: 525SC jetting
I better check to see what power valves in has then. I have the same cam as you have in mine Griff. Guess I need to order some jetts since my kit only goes up to 99 on size.
06-29-2006 | 11:46 AM
#5
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From: LOTO 31 mm
Re: 525SC jetting
Originally Posted by SB
Note: Be careful comparing same type carbs but with different list/part #'s to each other. Bleed holes, boosters, emulsion circuits, etc,etc can be different, thus leading to different jetting and etc.
Power valves on Dominators are typically the high flow power valves since their pvcr (power valve channel restriction) is larger and thus able to flow more fuel than a standard power valve can.
I worked on a pair of 525SC's that had chillers installed and next step up in boost. Baseline tested with the stock 98's and then went to 102 jets squared, picked up some power, and then went to 104's which again picked up a little more performance. I kept it here since everything read fine and worked terrific.
I also used the secondary idle speed screw to open the secondary throttles a touch so that I could back down the primary throttle blade position a touch, making the idle mixture screws more sensitive. This provided a steadier idle that didn't surge as it was doing before I touched it.
Power valves on Dominators are typically the high flow power valves since their pvcr (power valve channel restriction) is larger and thus able to flow more fuel than a standard power valve can.
I worked on a pair of 525SC's that had chillers installed and next step up in boost. Baseline tested with the stock 98's and then went to 102 jets squared, picked up some power, and then went to 104's which again picked up a little more performance. I kept it here since everything read fine and worked terrific.
I also used the secondary idle speed screw to open the secondary throttles a touch so that I could back down the primary throttle blade position a touch, making the idle mixture screws more sensitive. This provided a steadier idle that didn't surge as it was doing before I touched it.
06-29-2006 | 02:02 PM
#6
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From: Omaha/LOTO
Re: 525SC jetting
Mine idles like an efi. Idles at 800 in nuetral and 650 in gear. Has a very little 50-100 rpm surge when the air is cool. Its a little cold blooded at initial start up, buts thats it.
If you're running the stock pulley, I would probably just start with the 98's and 99's. I also had to order separate jets in the bigger sizes at like $7 a set. I don't know what PV's were in mine, but I just used the standard 6.5's off the shelf when I replaced mine while it was apart. I'm sure I could drop a size or two on my jets, but it runs fine, so I figure why mess with it.
If you're running the stock pulley, I would probably just start with the 98's and 99's. I also had to order separate jets in the bigger sizes at like $7 a set. I don't know what PV's were in mine, but I just used the standard 6.5's off the shelf when I replaced mine while it was apart. I'm sure I could drop a size or two on my jets, but it runs fine, so I figure why mess with it.
