94sylvan

Ryan, did you ever dyno that engine? Just curious as those are the heads I am using for this engine. Do you think there was anything to gain with putting 1.6's on the exhaust or did the grind have enough duration even with wet exhaust? I'm going to start with the 600 edelbrock carb I have from my current 383 setup. Depending on where it drops off on top end, I'm putting together a 750 DP Holley to try as well.

SB

iTrader: (1)

Time will be better spent with the Holley.


Ryan's 1984 Hammond Challenger MKII V2150 ran 80.5mph with that motor.
http://www.speedwake.com/forums/107-...tml#post681072

94sylvan

I know SB, but I only have a 30 gal. fuel tank My boat is very close in weight and dimension to that Challenger and I would hope a more efficient hull. Wow! Wasnt expecting those kind of numbers!!! I'm at 62 now with 340 hp.

Ryan00TJ

iTrader: (8)

Never dyno'd. I always liked the GPS dyno. The 1.'6s on the intake were per Bob M's advice. The XM276HR is perfect for a Marine 350. In a 383 with AFR heads it will idle like a dream and have great midrange punch. IMO, if your after top end power it and a 600 carb will be disappointing. If set on the XM276 then 1.6's all around will not hurt. My HP750 and 234/240 cam made the 383 a real top end screamer.

94sylvan

Ryan, reviving this post for a little more advice. Maybe Trash and SB can chime in as well please. Finally ordering parts for motor so I can get it to the machine shop. Definitely going with the 276 comp cam. I'm needing advice on static compression ratio with this cam. My choices in d dish pistons put me at 9.35:1 or 9.77:1 with close to ideal quench. Do I play it safe or will that result in a lazy engine in the lower rpms?

SB

iTrader: (1)

That engine will not be lazy with the lower of the two compression's in your 383 with that cam.

Ryan00TJ

iTrader: (8)

I agree. Truthfully, I don't believe you would feel the power difference between the two ratios on the water. Running alum heads, I always shot for 10-1 static. When tuned right they ran great on 89 marina fuel. A 9.7-1 alum head SBC tuned right should be fine on marina 89 fuel. If you can't source 89, shoot for the lower compression and go boating.


I ran AC FR2LS @ .050"gap in mine. There a step colder than what AFR recommends. Holley 750HP 78P, 88S 2.5PV, 87-89 octane, 36* Timing 10.18-1 static.

SB

iTrader: (1)

Great info. As a note, those ^^^^ plugs are no longer.