Stroking an HP500 to a 540.
 

Can anyone tell we what this would entail? I have a pair of HP500's that need to come apart to have the CAM bearings replaced. Is stroking the motor a good option at this point? I've just replaced the Heads, Intakes, Cams & Ignitions so I'd hate to see all this go to waste. I was planning on replacing the carbs this winter anyways but I was told that I might be able to release some extra HP by stroking the motors to 540's...

Re: Stroking an HP500 to a 540.
 

new crank, and probably a new cam for the cubes.

Re: Stroking an HP500 to a 540.
 

Check out http://www.speedomotive.com/
I bought a 427 stroker kit for my Bronco a few years back.
Very knowledgeable

Re: Stroking an HP500 to a 540.
 

You'll need your block clearanced, line honed, bored and decked. New crank and pistons, possibly a new cam. Why put it back together with the same pistons and not bore it? If you've got it apart you might as well go all the way. Go with a solid roller while you're at it too, that's good for a couple of more ponies. Now you're talking a 548 stroker with a big solid roller cam, 700hp should be easy to get at that point.

Re: Stroking an HP500 to a 540.
 

Care to give a guess on the cost for doing this? The CAMS are the 731 right now and the lifters were changed to solid roller at the first rebuild.

Re: Stroking an HP500 to a 540.
 

I'm having one done now buy a builder here in town, I think I'm looking in the 9k range with head and carb work as well. Thats all new internals, new pan, port work on the heads with all new hardware. He swears by Comp stuff and won't use any one elses. I may do a crank trigger too. This is for a blower application though, maybe your pistons and rotating assembly could be a little cheaper? I would say you should be in the 5k range with just doing the bottom end????

Re: Stroking an HP500 to a 540.
 

No offense BadKachina, but I wouldn't touch a solid roller with a ten ft pole. If you just love taking the valve covers off I guess it doesn't matter. The difference in power should not be that much.

Yes, you can get more RPM and power but at what cost ? Ask others on this site what they think of solid roller cams.

Re: Stroking an HP500 to a 540.
 

It looks like all your previous upgrades are matched toward a mild upgrade of the hp500. Stroking it to a 540 will require changing most of the same stuff you did already to achieve maximum benefits from the ci increase.

You said you replaced the heads.....with what heads???????They may work well or may not depending on what you have.

The 731 is only a slight increase over stock. You will need more cam for a 540. Also, I highly doubt you have solid roller lifters with that cam. No reason to go with a solid roller unless you want to spin more than 5800rpms or so. Plenty of hyd rollers will make plenty of HP. There is also no reason to replace the stock carbs on your current set up.

Personally, I would look into supercharging before stroking it. A lot more HP to be gained vs the $$$ spent.

Re: Stroking an HP500 to a 540.
 

Worst case scenario is you have to adjust your valves every season.
Ever notice that when you first launch your boat it runs it's fastest? I've heard that with hydraulic roller, you'll get less lift as your oil gets aerated and hotter later in the day. The understanding I had was that as you drive around, and your oil gets bounced around in the pan, it gets more air in it, which lets it compress in the lifters. You end up bleeding off 3 or 4 mph later the day. How much would each of us pay for 3 or 4 mph? I could be wrong, maybe someone will chime in. Maybe I'm wasting my time putting a solid roller in?

Re: Stroking an HP500 to a 540.
 

Whipple's hp500 set up isn't cheap either. You probably would gain more hp for the buck but what kind of reliability would you have? You would end up going through the motor anyways in shorter period of time. Your clearances, comp ratio and cam aren't set up for a blower. Just my .02 but build it strong first and if you want to put a blower on it, set it up that way from the get go.

Re: Stroking an HP500 to a 540.
 

The heads are the Dart Iron Eagles, Intk: 308cc / Cham.: 119cc / Int/Exh: 2.25/1.88. You are correct I am not running a solid roller. As for the carb. One of my carbs was rebuilt but doesn't respond well. Was told that a replacement was probably necessary at some point, so i was planning on swapping them both out. If I only need/should replace one then that's all I'll do. As for the CAM, I went with the 731 (Hardened, copper). because i was talked out of the 741. Was told too much risk for reversion. With only 20 hours on them, I'm sure I could find a buyer.
I don't have a ton to spend, (maybe $7000-10000) for both and I really don't want to move above pump gas. I'd just like to see mid to upper 70's, with rock solid realibility.

Re: Stroking an HP500 to a 540.
 

Why do you need new cam bearings??????? and how do you know the cams are not damaged as well?????? Used cams are not an easy sale. Not worth the risk to most people.

You could run a pair of 250 SC's at low boost(4#) on pump fuel and still be very reliable. Talk to Nickerson about your carbs either way you go. They can be flowed for more CFM's and rebuilt right. Probably have to go with Dominators if you go the SC route.

Re: Stroking an HP500 to a 540.
 

While we don't know for sure we are pretty certain that the cam bearings are shot. Started to get metal flakes in the oil and pressure was dropping. Motors just were dropped off today for the initial teardown. Never got to any copper in the oil so i hope we caught it in time. Only 20 hours since the last rebuild and most of that was break in time.

Not really thinking about supercharging. I just want to be able to push about 600-700HP with realiable motors. Start & Go. I spent most of this year laying in the damn engine compartment instead of enjoying it with my family.

Re: Stroking an HP500 to a 540.
 

Since you are rebuilding already, the only items that are going to increase your cost are a new crank, longer rods and clearencing the block. If you are on a strict budget, Eagle stuff works well but needs to be checked carefully. The 731 cam is too small for this build.It's smaller than a 500 EFI cam. A 741 would be the minimum cam I would use. If you don't mind a lumpy exhaust a 651 would be best and make a lot of power. Both of these will probably revert with a stock exhaust. If you have Gil or CMI exhaust, a set of dry tailpipes would take care of that problem.

Re: Stroking an HP500 to a 540.
 

I just reread 20 hrs since last rebuild. :eek: Don't go back to the same guy unless he's doing it for free. It's probably more than just the cam bearings if you have flakes in the oil. No reason a 500 or 540 can't be reliable if the guy putting it together does a good job.

Re: Stroking an HP500 to a 540.
 

I agree. :D

Re: Stroking an HP500 to a 540.
 

He's doing it at no cost and he doesn't care if I replace components or not. He is a full machine shop so he can work the block if need be. I'd just pay for that, but I'm not sure I want him doing the work since we had troubles last time.

Re: Stroking an HP500 to a 540.
 

sounds like a job for JC Perf !!!

Re: Stroking an HP500 to a 540.
 

If there's anyone serious about helping out on this, let me know. We can get you these motors. I just want the motors broke in on a dyno so i don't have to deal with this crap again.

Re: Stroking an HP500 to a 540.
 

You'll hear a TON of different options and opinions on here---many of them good. At least you have some good aftermarket heads---JimV can really do a good number on some porting for you without having them fully ported---just another option. I would stick with a hydraulic roller cam/lifters as well----set it and forget it!

Here's some added stuff that should be mentioned. Supercharging vs. stroking---it can be difficult to decide what you want to do with all the options that are available. Superchargers = more wear/tear and maintenace. There's reliabillity in cubic inches and there is great power in supercharging. It comes down to what YOU are willing to spend and sacrifice.

Either way you go, power upgrades usually require a domino effect with components and it could cost you more than what you were originally planning and if you try to "cheap out" too much by cutting too many corners without doing the project the right way the first time then you will ultimately loose. With a budget of only $7,000-$10,000, you will spend roughly half of that with 4.25" cranks, pistons/pins, and 6.385" rods. Cams, lifters, rings, bearings, gaskets, etc, are all extra on top of that. Then you have the labor of all the machine work, and professional assembly, and even head porting, and dynoing. It can all add up quick!

Do yourself a favor and take your engines to someone who KNOWS what the heck they're doing with the budget you have---someone who has an awesome reputation/track record with marine engines and knows what it takes to make them survive. Someone in your area if you can.

I don't know how much you really know---just trying to give you some awareness. Do lots of research and watch out for the wolves in sheep's clothing!

Re: Stroking an HP500 to a 540.
 

Would Jim get to pick the color of the duct tape since his boat is red,white and blue or is it just a standard grey on all of JC's engines :evilb: . :D

Re: Stroking an HP500 to a 540.
 

I know enough to be dangerous but I am by no means a gear head. Understand how an engine runs but wouldn't trust myself to rebuild a weedeater. I only know of one engine builder in my area and he's not all about marine. He's all about drag racing and that's not what I want.

Re: Stroking an HP500 to a 540.
 

And BTW... I appreciate this board for all the knowledge it shares... it always gives me a 360 degree perspective on what is happening. Keep it coming guys. Peon's like me depend on you for motor wisdom!

Re: Stroking an HP500 to a 540.
 

Hey Jim,

700hp w/ those heads is not obtainable unless you use a very aggressive solid roller cam. You will need at least a 310 dart or afr, probably 325's. You can get at least 600hp out of just 510's w/ hydraulic roller camshaft and would be able to use your parts (less the pistons & camshafts.) Consult a professional builer for your needs. FREE is not the answer. Spend the money ONCE. We have all had the "friend deal before". It NEVER works out in the end. You are going to at least need heads, cams, pistons, rods and carbs to make 700hp. Hope everything works out for you, welcome to the boating world, the HARD way. Whippled it you cheap bastard. I know a whipple dealer on smith mountain, just kidding.

Re: Stroking an HP500 to a 540.
 

Ran the 741 cam on a blown HP465 502 motor for a few yrs with no problem of reversion. Standard Merc/Gil exhaust with silent choice.

Re: Stroking an HP500 to a 540.
 

Sell the 502's build two tall deck 540 motors and their will be no question of thier reliability.
The Tall deck blocks will out live the short deck ones and be money better spent . While at it build 555's with the 3/8 stroke cranks. The parts will all cost the same, except for the blocks, and hopefully you buy the Darts, for a litle more and have some really great tough motors, It's worth it in the long run.