Help with Bad Boat
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Joined: Apr 2010
Posts: 10
Help with Bad Boat
Hi Folks!!
I ran across your forum researching upgrades for my 350 jet boat engine. I would love to hear from anyone using Dynosim5-pro for engine design. I’m using this for cam and other part comparisons. I would also like to talk with anyone using Edelbrock or big block heads on the small block. Before you guys waste your time telling me stuff I already know, I’ll give you a rundown on what I have. I made a mistake with the cam selection and it is not the best available according to the computer.
1970 Olds 350 355.4 CID, F1 block decked to .013, 1970 N crank std, stock rods, Speedpro flat tops, all oil mods {oil restrictors and restricted pushrods}, Stock 8 heads 78.2CC 1.879 1.622 valves, Comp roller rockers fully adjustable, Edelbrock performer manifold, Hardin Marine through hull exhaust {no headers} Holley 4150 750CFM. Crower 56903 cam straight up 289/300 214/224@.050 .475 .498 lift 112LCA 108 ICL{very close to the Edel RPM Cam}. Compression is 9.03 Quench distance is .052
According to the HP curve for the jet pump the engine is delivering about 270 HP and tops out at 4350 RPM. The curve does not account for torque and the limited RPM is probably due to the torque curve dropping off. I would like to use the Edelbrock Heads for a couple of reasons, reduced weight, eliminate buying bigger valves and the cost of head porting, no cross over port filling. I’m already using an electric fuel pump and know about the clearance problem. I hope doing this upgrade will yield the following.
RPM Heads reduced to 76CC 9.54 Compression, quench distance .041, Edel 7111 Manifold port matched, tweak the Holly, Comp Cams XE274H 274/289 230/236@.050 .520 .523 Lift 110 LCA{LS} 106 ICL{Intake Centerline}
The Computer says 369HP@5000 434Ft@3500 with a very nice torque curve from 2500 to 4500 rpm. This “I hope” will push the boat into the 70 MPH never never land area. I’m currently in the 60 MPH wannabe area. The biggest problem with this engine is the limited Exhaust options. The wet exhaust is very large {2-½ inch} but probably will not provide any scavenge effects. This is reflected by the computer numbers, which you guys may find low for this configuration. I’m a little concerned about the piston to valve clearance with the E heads. I read that the stock valve angle is 6 degrees and know the Ebrock is 18.
Hope I didn’t bore you all to tears, any comments would be welcome {wish I dumped all this cash in a BB}
Thanks airmale
I ran across your forum researching upgrades for my 350 jet boat engine. I would love to hear from anyone using Dynosim5-pro for engine design. I’m using this for cam and other part comparisons. I would also like to talk with anyone using Edelbrock or big block heads on the small block. Before you guys waste your time telling me stuff I already know, I’ll give you a rundown on what I have. I made a mistake with the cam selection and it is not the best available according to the computer.
1970 Olds 350 355.4 CID, F1 block decked to .013, 1970 N crank std, stock rods, Speedpro flat tops, all oil mods {oil restrictors and restricted pushrods}, Stock 8 heads 78.2CC 1.879 1.622 valves, Comp roller rockers fully adjustable, Edelbrock performer manifold, Hardin Marine through hull exhaust {no headers} Holley 4150 750CFM. Crower 56903 cam straight up 289/300 214/224@.050 .475 .498 lift 112LCA 108 ICL{very close to the Edel RPM Cam}. Compression is 9.03 Quench distance is .052
According to the HP curve for the jet pump the engine is delivering about 270 HP and tops out at 4350 RPM. The curve does not account for torque and the limited RPM is probably due to the torque curve dropping off. I would like to use the Edelbrock Heads for a couple of reasons, reduced weight, eliminate buying bigger valves and the cost of head porting, no cross over port filling. I’m already using an electric fuel pump and know about the clearance problem. I hope doing this upgrade will yield the following.
RPM Heads reduced to 76CC 9.54 Compression, quench distance .041, Edel 7111 Manifold port matched, tweak the Holly, Comp Cams XE274H 274/289 230/236@.050 .520 .523 Lift 110 LCA{LS} 106 ICL{Intake Centerline}
The Computer says 369HP@5000 434Ft@3500 with a very nice torque curve from 2500 to 4500 rpm. This “I hope” will push the boat into the 70 MPH never never land area. I’m currently in the 60 MPH wannabe area. The biggest problem with this engine is the limited Exhaust options. The wet exhaust is very large {2-½ inch} but probably will not provide any scavenge effects. This is reflected by the computer numbers, which you guys may find low for this configuration. I’m a little concerned about the piston to valve clearance with the E heads. I read that the stock valve angle is 6 degrees and know the Ebrock is 18.
Hope I didn’t bore you all to tears, any comments would be welcome {wish I dumped all this cash in a BB}
Thanks airmale
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