So I have my marine 383 running and will lake test it soon. I have been doing some reading and comparing different scenarios on which way to jet, rod and spring my Weber WFB.
The Weber is off the same castings and design of the Carter AFB and Edelbrock model #1409.
This same carb is used in stock Mercruiser 454 engines that turn 4500 RPM with a bigger set of jets & rods etc.
The carb was born with a 1997 Mercruiser 350 Mag engine which is a roller block 9.4:1 Chevy with a fairly conservative lift & duration. I'd guess it's whatever roller block & cam Chevy made in 97 with stainless head gaskets and brass core plugs.
I have bought an Edelbrock carb tune kit and checked the lengths of the rods. They match which is a happy surprise because Mercruiser uses a tall rod cap and an extra length piston with a helper spring. I don't have proof it will work but one marine expert that I am familiar with has done a similar move from one 4.3 to another later better one. He only needed a step up spring change.
I have info on three different 350's and as many 454's as to rods, jets and springs.
My new 383 has 9.85:1 static compression, 7.9:1 dynamic. It has a Comp CS 268XFI HR-13 cam. Which has .570/.565 lift, 218/224 duration @.050, 113 lobe separation and is installed at 109 degrees intake centerline.
The heads are Dart iron Eagle SS with the little runners (165 cc) for torque. On top there are Scorpion aluminum self aligning rockers.
It has Comp short travel lifters and beehive springs. Quench distance is .040. The bottom end is unremarkable except that there are some TRW forged pistons in there with marine ring gaps. It has clearance for the 3.75" stroke crank, and there's a Cloyes double roller timing set.
Don't flame me for exhaust, it has a reversion resistant extra height stainless riser system with EMI aluminum exhaust manifolds.
Thing sounds nasty on a stand!
I have tried to optimize this to breath to about 5200 RPM which I won't hit often since the lake I use has a speed limit.
The boat is fairly heavy, 4000+ lbs, with a deep 22 degrees deadrise hull. So the engine will be under load all the time.
I'm looking for some input on jetting etc.
I am not very interested in a dyno run. And there are not marine tune guys around here any way. I suppose I could spend for an AFR kit. But I'm thinking I will use the Edelbrock process to get it close.
Since it is going to be under load when running I'm thinking for a start I'm better off fat on fuel. Maybe a little less than the 454 settings. I'd rather ruins some spark plugs than pistons.
What do you say?
The Weber is off the same castings and design of the Carter AFB and Edelbrock model #1409.
This same carb is used in stock Mercruiser 454 engines that turn 4500 RPM with a bigger set of jets & rods etc.
The carb was born with a 1997 Mercruiser 350 Mag engine which is a roller block 9.4:1 Chevy with a fairly conservative lift & duration. I'd guess it's whatever roller block & cam Chevy made in 97 with stainless head gaskets and brass core plugs.
I have bought an Edelbrock carb tune kit and checked the lengths of the rods. They match which is a happy surprise because Mercruiser uses a tall rod cap and an extra length piston with a helper spring. I don't have proof it will work but one marine expert that I am familiar with has done a similar move from one 4.3 to another later better one. He only needed a step up spring change.
I have info on three different 350's and as many 454's as to rods, jets and springs.
My new 383 has 9.85:1 static compression, 7.9:1 dynamic. It has a Comp CS 268XFI HR-13 cam. Which has .570/.565 lift, 218/224 duration @.050, 113 lobe separation and is installed at 109 degrees intake centerline.
The heads are Dart iron Eagle SS with the little runners (165 cc) for torque. On top there are Scorpion aluminum self aligning rockers.
It has Comp short travel lifters and beehive springs. Quench distance is .040. The bottom end is unremarkable except that there are some TRW forged pistons in there with marine ring gaps. It has clearance for the 3.75" stroke crank, and there's a Cloyes double roller timing set.
Don't flame me for exhaust, it has a reversion resistant extra height stainless riser system with EMI aluminum exhaust manifolds.
Thing sounds nasty on a stand!
I have tried to optimize this to breath to about 5200 RPM which I won't hit often since the lake I use has a speed limit.
The boat is fairly heavy, 4000+ lbs, with a deep 22 degrees deadrise hull. So the engine will be under load all the time.
I'm looking for some input on jetting etc.
I am not very interested in a dyno run. And there are not marine tune guys around here any way. I suppose I could spend for an AFR kit. But I'm thinking I will use the Edelbrock process to get it close.
Since it is going to be under load when running I'm thinking for a start I'm better off fat on fuel. Maybe a little less than the 454 settings. I'd rather ruins some spark plugs than pistons.
What do you say?