Can a High Torque spring damage a big block engine?

[CoolTrees]

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cooltrees
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[http://storage]
about an hour ago
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I have a 2005 yamaha G22A limo cart that I got with no history or engine. I just installed the VC 625 engine in it. It currently tops out about 25mph but at about 5000rpm (short bursts and I don't push it higher). I'm pretty sure that my rear clutch has an aftermarket high torque spring in it (probably put there cuz it's a limo). Can this damage my new engine through having higher RPM's?



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[CoolTrees]

I am reposting this under the Big Block section.

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[Dave in VA]

You shouldn't need a torque spring with the engine upgrade. If anything, that spring is probably robbing you of RPM and speed.

[slonomo]

The spring itself won't damage the engine, running the engine at high rpm can damage the engine.

I don't know what rpm the 625 is set up to run at, but the VC460 was prone to having the connecting rod "egg out" if you ran above 4000 rpm for long periods as there was no bearing. If there is a connecting rod bearing in the 625 then that shouldn't happen since it has pressurized oiling system.

Also the safe max rpm is determined by the valvetrain, in particular the valve springs. If the springs are weak you will get valve float which can cause a valve to bend or break.

A call to Vegas Carts will answer the max safe rpm question.

[raydhd]

The very early VC 460 had a cast aluminum rod. They changed to the ARC billet rod with shell bearings and the rev limit was some where in the low to mid 5000 rpm range. The even later VC 460 came with the VC produced long billet rod. This unit also has shell bearings and is good for somewhere in the low 5000 rpm range. In fact some racers are now using this rod with the upgraded 180,000 psi rod bolts from NRracing.

[sho305]

I think it would be worth your time to take that out and put a stock spring in. The big spring helps stock power cope with large tires or towing, it is not needed with a big block though I had a umax in with a clone and it worked fine. But the umax price went way up and a clone 420/460 likes to rev more, and the umax (yamaha) spring is about half way between stock and a huge spring. It is the utility spring and would work well in a limo. Again with a larger engine you really don't need it, and you can preload the stock springs more if you must have more rpm. Maybe bump up your preload one, instead of B-2 do B-3, etc. Less preload will give less rpm at part throttle but stock is pretty loose to start with, this makes them run low rpm and be quiet when not going up a hill or accelerating. A big engine has a lot more torque than stock engines so they don't need to rev more, and why you don't need one unless you are towing/working it really hard.

There should be a sticky or many posts here on how to swap them out, but stock springs can be pushed in by hand they are much easier to get on. If you have someone with little strength you don't need straps or tools to put them on. Extra hands can help though to get the nut started on. Don't lose the key when you take it off, meaning don't do it on grass lol.

[CoolTrees]

That makes a lot of sense. I just ordered a stock spring off Ebay and I'll give that a try when it arrives. I don't need it to be faster but quieter would be nice, it currently kinda roars through the neighborhood [emoji16].
Thanks everyone for your assistance and advice.
Can anyone point me in the right direction for learning to adjust the secondary clutch (B1,B2 etc... and what they mean)? Or will I know it when I see it, once I start taking it apart?

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[sho305]

It should be posted here someplace, I thought it was in the stickies. One side has 123(4 too, I forget) holes and other has a,b,c. A1 is lowest preload you turn it to next ramp when you install and you will see it turns barely 1/3 a turn. As you go up to a2, a3, b1, b2,etc it will need to be turned more and more tighter to engage the ramp and get the nut on the clutch. That pressure makes it down shift and run more rpm while cruising. It changes WOT rpm but not much, mostly part throttle rpm. So its quicker and peppy. Again with a big block you have way more torque now, you don't need it. You should be able to find the number or letter next to the hole in the casting, you may have to clean it good, and sometimes the spring wears them off in well used spots. Check the shoes while apart and replace if they need. Grease the moving sheave and check the seals on it.

If you run the stock setting on your cart it should cut rpm down when you go a steady speed, until you go pretty fast and the clutch runs out of shift. If you set it higher letter/number it will run more rpm closer to what it does now when you go a steady 10-20mph say. Either way it should rev if you floor it, and it may rev quicker with more preload because its already partly higher rpm. So that may better for off road or towing etc, not good for cruising when you want it to settle down and be quiet and use less fuel (as the stock setting usually is).

[CoolTrees]

Thank you so much! I had been googling it without much success in getting an explanation.

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[sho305]

I think stock setting for a G9 is B3 but don't quote me. I am sure it is posted here many places, not sure on a G22 but bet similar. If you set the ramps and spring together on a table and mark the outsides, then stick the spring in the next number then start again at next letter do the numbers again....with mine you could see it advance the preload a little with each setting. You can't see what it is doing when you put it together and turn it to the next ramp, but if you look at it close you will get it, it makes the spring wound tighter. Like I said its mostly part throttle rpm that it affects, it will run steady cruise speed lower rpm with less preload which is about stock setting, and more rpm with higher setting. Stock setting is plenty of rpm for a larger engine with more power. If you set it too low it can slip the belt, also remember the lawn engines like cart engines need to spin some to air cool so you don't want it to run super slow. It can also act sluggish to throttle with very little preload. The aftermarket spring does not have the tangs for the holes usually, and they are massive in size to make up for it, not adjustable.