Cam Lift Question 4.3LX

[AShipShow]

I was reading another thread that gave the lift and duration specs of all the early 4.3 auto motors and it looks like 92-95 Vin W cam was by far the best as far as lift goes. My question is, is there any risk with too much lift throwing that cam in when I do a vortec head swap? Thanks!

 

[gm280]

jross827. It really all depends on where they publish their cam's lift and duration from. The most common reference is lift is at 0.050" and duration the same. But other cams can be published at different lift points. So when comparing one cam to another, see what that lift is referenced from. It really does make a huge difference when making comparisons. Secondly, you can get too high with the lift. Even if the valve to piston clearance doesn't come into play, you still have spring compression to figure in and consider. If the lift is too high, the valve springs can compress and bind and that is never a good thing. So the entire cam, lifters, valve spring setup has to be considered. Also you need to understand that more lift has to be balanced with the work the engine is designed to do. Let me state a very important statement that I had to learn the hard way, "more is not always better". More lift and duration doesn't simply equate to more HP or engine power. If the engine isn't designed for a certain RPM range or application, simply changing parts to get there isn't the answer. When you change one part of the engine, it effects everything else. And it everything else isn't designed to work with that performance part, you don't get more HP or performance. I now understand that. :facepalm:

 

[Scott Danforth]

Marine cams are a different animal than a car cam.

Most RV cams are Marine Grinds - lots of low-end torque, no upper RPM operating range of 1500-5000 RPM.

I did a search a while back for aftermarket V6 marine cams and came up with nothing. the factory grinds are the only ones I was able to find.

what is your goal with going after a cam swap on a V6

one thing to note: most marine cams for flat tappet max out at 268 degrees of duration for a wet exhaust and about 270 degrees for a roller cam with moderate lift. This is to prevent reversion.

 

[AShipShow]

This is the info from the other thread, they were all measured the same.

Cam specs, from S10 Planet:

Factory 4.3L Cam Specs
* '96-'00, VIN W, w/ balance shaft
- Lift (I/E) - .415/.429
- Dur @ .050 (I/E) - .191/.195

* '93-'96, VIN Z, w/ balance shaft
- Lift (I/E) - .376/.402
- Dur @ .050 (I/E) - .183/.193

* '92-'95, Vin W, w/ balance shaft
- Lift (I/E) - .432/.440
- Dur @ .050 (I/E) - .208/.208

* '91-'93, ZR9/Z79, Syclone/Typhoon
- Lift (I/E) - .351/.386
- Dur @ .050 (I/E) - .179/.195 (Ductile)

* '90-'91, VIN Z, Astro/Safari
- Lift (I/E) - .403/.450
- Dur @ .050 (I/E) - .202/.213 (Steel)

* '87-'94, Vin Z, w/o balance shaft
- Lift (I/E) - .351/.386
- Dur @ .050 (I/E) - .179/.195 (Ductile)

That thread also stated that the 92-95 Vin W motors had 10 more hp than the Vin Z of the same year. Just curious if anyone else around here has tried running this cam and noticed any difference. The numbers definitely show a more aggressive profile so it would make sense... That being said, I totally agree with the above statement, just because the numbers look better doesn't mean it will perform better, I'm no engineer (actually I am) but not for engines lol... Just seems like if I'm swapping heads, it might be worth throwing this cam in.

 

[Scott Danforth]

your typical marine motor has more output than the truck version. reference 190hp for the truck and 220hp for the marine motor with vortec heads

the Z motor is a non-vortec cam, the W motor is a vortec and balance shaft

your best bang for buck on a V6 is the vortec heads and a 4 barrel intake. there are stroker cranks out there, however at $3k each, not worth it. FYI, for about what you are spending on the V6, you could get a V8

 

[Rick Stephens]

FYI, for about what you are spending on the V6, you could get a V8

I cannot imagine 10HP difference in cams would be detectable on the water.

Going to a 5.7 instead of the 4.3 has some truly obvious benefits. Add 40-100HP. Get rid of the balance shaft which costs 15HP to turn. Lower cost for components. HUGE choice of components.

 

[AShipShow]

I already have a 4bbl carb since I have the LX engine, so if i do the vortec swap I really only need to buy the heads and intake manifold... Ive already called around and found heads for 50 bucks for the set, and ive found a performer intake manifold for 250... I have a hard time believing I can do a V8 swap for under 300-400 bucks...

Since I already have the 4 barrel carb, do you think I will still see a noticeable increase with the vortec heads?

 

[AShipShow]

Going to a 5.7 instead of the 4.3 has some truly obvious benefits. Add 40-100HP. Get rid of the balance shaft which costs 15HP to turn. Lower cost for components. HUGE choice of components.

I totally agree with you, I'm just afraid of the sticker price for a different ratio outdrive.

And my block doesn't have a balance shaft I have an 89 block and heads that I've "marinized"

 

[Rick Stephens]

With Vortec heads you'd have the same engine I am running. And it kicks A... I mean butt! I got 12 hours on it yesterday with a (actually employed) race mechanic buddy of mine, he was impressed at how smooth it runs, no balance shaft and all.

Can't disagree with your price thoughts on the V8 when you throw in an outdrive. However, if I was looking to do that upgrade, I'd find a donor boat with the V8 I wanted and drive to go with. I did that and completely paid for my upgrade to the 4.3L from a 3.0L after selling the old 3.0L motor, the outdrive and trailer out from under the donor boat. A lot of others have posted the same thing. A little luck comes into the game as the drive has to actually stand up to use, hard to know with a donor. But starting with all the parts is the key to financial happiness.

 

[AShipShow]

I think I'm in between what I wanna do, my boat is 20' so it's on the large side for a 4.3 but it's definitely not bad right now, I really would just like to have a better holeshot without having to prop down and watch my rpms... It would be nice to find a prop that doesn't over rev and still gets me in plane quick... Obviously a v8 would do this but the budget would probably be in the 1k range of I'm lucky, but I'm not sure if the vortecs heads would make a huge difference since I'm already running the 4bbl carb and no balance shaft...

Gahh I'm not sure what to do... Either way, it would be a winter project so I'll have to be happy for now.

On another note, I did a lot of reading about cams today and have a much better understanding. To me it sounds like for marine purposes a similar to stock duration would be best, however more lift is better, makes me think the 96-00 cam would be the better bet. Its similar duration to the cam I'm running now but a good bit more lift.
I'm actually curious what the specs are on the marine cam... Maybe ill pull it from my old block and measure it!

 

[Scott Danforth]

if you really want to swap the cams, call the cam companies.

 

[Scott Danforth]

the mercruiser cam has a valv lift at .290 @ 0.050 and an exhaust lift of .296 @ .050 per manual #25

 

[AShipShow]

Wow! That cam has a lot of lift. Well, I guess that makes sense since that is for the Vortec motor with the better flowing heads. The cam I'm currently running only has .234 Intake/.257 Exhaust (89 truck motor)... The marine cam, which is still in my old block looks like it has .269 Intake/.273Exhaust which is a pretty significant increase over my current cam. But now I'm thinking if I do the vortec head swap, I should look into the cam you just listed.

 

[gm280]

If you want to verify any cam, you can use a degree wheel and a dial indicator and verify all the cam's specs to make certain you are getting what they publish. I did that with every cam I ever installed and most were pretty darn close. The most off was 1/4 degree. And the lifts were within 0.001" or so. So even with a used cam, you can check each lobe to see if any are worn too far before using it. JMHO