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View Full Version : Jet sizing for a SC525 motor



2dasand
07-11-2007, 01:06 PM
Anybody have any info for the jet sizing on a Mercury SC525 with a dominator (the later versions)? Just want something to reference to.

cfm
07-12-2007, 03:37 AM
I've had a few apart and here are my notes on these engine's. Special note is on total timing. Rev engine until timing stops advancing and then set total.
I have found that total is at approx 4200rpm.
454cid
7.5:1 compression
rectangle heads
Holley Dominator 1050 carb - jetted 98 square + 6.5 high flow (not standard one's)power valves front and rear.
177 supercharger
AC Delco MR41T spark plugs - gap .035"
35° Total timing - typically reached at 4200rpm
Premium fuel required. Merc suggests min 92 octane
And following hyd flat tappet cam:
Merc 400 / 420 / 425 / 525SC
Crane Part#132561 Grind # H-228/312-2S-14 T1.2
Duration at .004" : 298°, 296°
Duration at .050" : 228°, 236°
Lift with 1.7 rocker: .530", .551"
LSA 114°LSA
ICL 109° ATDC , ECL 119° BTDC

MACHINEHEAD
07-12-2007, 08:38 PM
You have PM j Pre menstral jetting

2dasand
07-13-2007, 10:55 PM
What a wealth of info you are! You should be in Engine Masters magazine! Oh wait....maybe you are! :D