nm9stheham
Well-Known Member
Well sure.... that's how they came up with the classifications of 1/4 Midget, 3/4 Midget, right? LOL
Camshafts, idle quality, driveability and LSA-REAL WORLD EXP and OPINION
- Thread starter RAMM
- Start date
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The GM Vortec marine engines run 9.4 to 1 compression, so that is what I aimed for, making sure I had good .040 quench. Would I be better off going up to a .050 quench and lowering the compression to 9.2? At the fuel docks it's usually 93 and sometimes 89 Octane. I plan on keeping some good Octane boost on board in case it's an issue at unknown docks. I'm running Volvo drives and they use a cone clutch so that should also help with shifting around the docks.
Yes I plan on breaking them in out of the boat then tuning them on the dyno. Hoping to drop them in the boat and running the snot out of them right away. I'm sure it won't happen that way lol
GeorgeH
Well-Known Member
Yes, my stock merc 5.7 claims 9.4. Gas docks serve up ethanol free... Most run at 160ish degrees so that helps
OK....try this one
408 stroker
9.9ish cr
LD340 or RPM intake
Heads undecided but 270+ flow @ .550 with closed chambers
1 5/8 x 3" headers
904 a/t with 2700 stall
3.55s
Power brakes. ( I've run PBs with 8"s of idle vacuum to my satisfaction....)
Mostly street with 3-4 track days per year
I want to go roller (solid or hydraulic)
3600 lb Fastback
Did I leave any vitals out ?
408 stroker
9.9ish cr
LD340 or RPM intake
Heads undecided but 270+ flow @ .550 with closed chambers
1 5/8 x 3" headers
904 a/t with 2700 stall
3.55s
Power brakes. ( I've run PBs with 8"s of idle vacuum to my satisfaction....)
Mostly street with 3-4 track days per year
I want to go roller (solid or hydraulic)
3600 lb Fastback
Did I leave any vitals out ?
yellow rose
Overnight Sensation
Your headers are way too small, and probably too long. Skip the hydraulic roller cam and go solid. Probably not enough stall. You can't spend enough on a converter.
Solid was my inclination and I figured the headers might be too small. I can change that.
I have mulled over W2s for heads or maybe IMMs EQ magnums ported.
I could go Eddy but Im not fond of the look on a motor. I like a stock sleeper look... ( I hate to admit Id do something just for cosmetics..)
So if I stay under .600 lift how would you spec out a cam ? Solid roller.....
I have mulled over W2s for heads or maybe IMMs EQ magnums ported.
I could go Eddy but Im not fond of the look on a motor. I like a stock sleeper look... ( I hate to admit Id do something just for cosmetics..)
So if I stay under .600 lift how would you spec out a cam ? Solid roller.....
Number one, with that tiny engine the headers aren't too small unless you plan on spending a lot of time over 6,000 rpm. Number two, tough to pick a cam when you don't know what intake manifold and heads (intake and exhaust flows for certain) you are going to run. Oh, bye-the -bye, I'm just asking for the information for others, because I have no intention of designing a cam for you.
LD340 or Perfomer airgap (listed in post)
W2's or IMMs (my mistake ... they are Indy's) ported to flow in the 270 range @ .550 intake ...195 exhaust (listed in post)
I would consider any recommendations on heads...
leaning away from the W2's because of expense although I have run them before with fantastic results...
W2's or IMMs (my mistake ... they are Indy's) ported to flow in the 270 range @ .550 intake ...195 exhaust (listed in post)
I would consider any recommendations on heads...
leaning away from the W2's because of expense although I have run them before with fantastic results...
roccodart440
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If you like the sleeper look, check into what Nick Scavo does to his heads.
this would be one of my under educated choices...
Lunati Part Number: 40200732LK
LSA relative to lift and duration to meet the goals I set forth .
Lunati Part Number: 40200732LK
- Advertised Duration (Int/Exh): 273/279
- Duration @ .050 (Int/Exh): 243/249
- Gross Valve Lift (Int/Exh): .578/.585
- LSA/ICL: 110/106
- Valve Lash (Int/Exh): .016/.016
- RPM Range: 2800-6800
- Includes: Cam & Lifters (#72420-16)
LSA relative to lift and duration to meet the goals I set forth .
o1heavy
1974 dart sport
Any thoughts on this stick
yellow rose
Overnight Sensation
Really? It's 400 plus inches. It needs a 1.875 tube about 30 inches long and the cam to match it. That 1.625 tube is for dead stock stuff or Comp eliminator. There really is no in between.
yellow rose
Overnight Sensation
I would install it at 102 and let it go. If it seemed light on bottom end, put it in at 100.
o1heavy
1974 dart sport
I'm not seeing the lca Not trying to look like a dumb axx but
Just my experience on our dyno testing small block headers on a 423.5 ci LA engine to 6,500 rpm. I realize it wasn't much of an engine as it only made 601 HP on 91 octane.
What cam were you using ?
yellow rose
Overnight Sensation
I couldn't see it either, but if you add the intake centerline and the exhaust centerline together and divide by two you get the LSA. I also didn't see where Crane said to install it, but the late closing LSA could use some advance.
Intake max lift at 103 degrees after top dead center = 103 ICL. They want it 5 degrees advanced on a 108 LSA. (103 + 113)/2 = 108
Our custom designed solid roller we had Comp Cams grind for us. It's not one I would call out for power brakes. I design all the cams for the engines we build.
I was busting your chops....
I didnt think you would reveal the grind and it most likely wouldn't be the right choice for my build .
So.... is there a profile for a build like I described that would allow for a milder idle and vacuum yet still make use of the head flow in the upper rpms ?
Or does one have to tolerate a lumpy idle and low vacuum in an engine like this?
That is the whole point of this thread isn't it ?
I didnt think you would reveal the grind and it most likely wouldn't be the right choice for my build .So.... is there a profile for a build like I described that would allow for a milder idle and vacuum yet still make use of the head flow in the upper rpms ?
Or does one have to tolerate a lumpy idle and low vacuum in an engine like this?
That is the whole point of this thread isn't it ?
Lustle
Well-Known Member
The torque should be more and at a lower RPM. I'll post charts below.
With a tighter LSA you should have more torque at lower rpm. Might not be more OVERALL torque, but just more at a lower rpm. For example (and im pulling this outta my butt) 112 LSA might have 200 ft lbs at 3000 RPM, the 106 will have 200 ft lbs at 2600. It will at least make the same torque, just lower. But generally tighter LSA cams make more overall torque as well. It just all gets moved earlier and ends sooner.
While YR may have his problems with these articles. They give you a general idea of tight vs loose LSA. With the tighter LSA cams you can see how while they generally make more power/torque, it's earlier in the power band. You can also see how they fall off sooner. The crane article is especially good at showing this.
Look at the 104. Peaks torque between 5100 to 5200. While the 110/114 pull to 5400. Horsepower it's very evident. With the 104 plateauing at 6600-6700 then falling off. The 110 falling at 6900. The 114 still going flat at 7000.
That's part of why they chose it. 110 is the middle of the road and does offer a great compromise between max power and streetability. BUT it's also easier to mass manufacture cams when they are all ground on the same LSA core. Easier for mass production and such.
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SLOPAR72
Well-Known Member
Call Rhodes lifters....... They have obviously figured it out..... Then everyone can debate Holley's and Carter AFB's which is far more entertaining lol.......
JW
JW
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