HP500 rebuild...what next?
 

Here's where we're at: Rebuilding both Gen 6, HP500 motors with a new set of Dart Iron Eagle 308cc heads (Inconel Valves) Crane Cam 168731 (copper). Already has a new Dart Intake on both. The only 2 areas needing attention is Carbs (so far just stock Holly 800, jets supposedly replaced from size 70 to size 80 but this doesn't make sense) and Exhaust so far just stock GILS with a weird NRS exhaust tube.

The question is...what's next?
I have not replaced the original ignition and figured a new MSD (6M-2, MSD8560 & Soft Touch Rev Control 8768) was next for this. Won't this be necessary in order to get everything synced up correctly and to increase the rev limiter?
The Holly 800 I'd like to just keep but didn't know what problems I'm going to face or if a 900-950+ was necessary.
And as for the GIL, I know my choices is GIL or CMI and would prefer CMI, but I'd like to just get on the water this year and look at a winter project for exhaust. I'd like to have silent choice but do not want reversion. I'm not counting ponies just want the most out of a reliable set up. OSO has been great source of information... keep it coming.

Re: HP500 rebuild...what next?
 

I sent my carbs to laz. I think the 800 is plenty.

I switched to the crane HI-6M ignition. You can play with the rev limiter and its a better spark.

Re: HP500 rebuild...what next?
 

Crane ignition is the way to go.

Re: HP500 rebuild...what next?
 

Summit's Estimated ship date is 5/29. Anyone have a lead on 2?

Re: HP500 rebuild...what next?
 

I kept my Tbolt and switched to the V6 module and MSD rev limiter. No sweat, runs to 5800 and I still have the V8 module in the boat if something fails. Just need to change timing.

Re: HP500 rebuild...what next?
 

buy an add

Re: HP500 rebuild...what next?
 

The 800 should be plenty of carb. As for jet sizing, stock jets are not 70's and jetting is staggered. Here are the stock jet sizes.

Pimaries--port-81, starb-75
Secondaries--port-89, starb-93

Re: HP500 rebuild...what next?
 

Go to the Crane 741 cam. The 731 is smaller than some of the HP cams. The new HP 525 cam has the same lobes as a 741 except it is ground with a 114 lsa instead of a 112 lsa.

Re: HP500 rebuild...what next?
 

I almost begged for the 741. Crane told me the 741 is not for Gen 6. That only the 731 would work. I questioned it 3+ times and still received the same answer. Is crane wrong?

Re: HP500 rebuild...what next?
 

They changed the part no. I'm not sure what it is now. Do a search or maybe someone can chime in. Or use the new 525 cam. Again the part no has been listed here before, have to try a search.

Re: HP500 rebuild...what next?
 

The part no. for a mark 4, Gen 5 741 is now 139021. Have to use a cam button in a Gen 6 instead of the retainer plate. Maybe Crane can make one to fit a Gen 6.

Re: HP500 rebuild...what next?
 

Yep, they're wrong or simply misunderstood. I have three Gen6 502s all with 741s

http://www.cranecams.com/?show=brows...tType=camshaft

Re: HP500 rebuild...what next?
 

Its got a good chance of reversion with the 741 and gils. thats a big risk for not much hp.

Re: HP500 rebuild...what next?
 

The 741 will fit a gen 6. Dock holiday is running the 741 in his 500efi's.

Re: HP500 rebuild...what next?
 

But with CMI's :D

Re: HP500 rebuild...what next?
 

The 731 cam has bin replaced with the new Z-camprofile #139011. This cam act like a "bigger" cam caused to the new grind. Powerrange is 1600-5600 RPM and it pulls very strong al way up and idle is smoote 750-800 rpm

Re: HP500 rebuild...what next?
 

So can I assume that an HP500 with 731 & GIL'S may have less reversion issues than the same set up with a 741? It seems that a lot of reversion discussions are stemming around the 741. Of those who are running 731's vs 741's who's got a bigger reversion problem? And for those experts, in your opinion is the cause of the HP500 reversion issues mainly CAM related or Exhaust related? If you remove the water all together from the tailpipes I guess you'll solve the reversion problem, like cutting the head off a snake, but would a simple "less aggressive" cam change also do the trick?

Re: HP500 rebuild...what next?
 

Bob Lloyd whos opinion I trust and did my engines said the 731 would work with the gils. The 741 would work, but would need to change exhaust. I didnt want to spend the money on the exhaust.

The 731 isnt much of a performance gain over the stock carb'd hp500 cam, but every little bit adds up.

Re: HP500 rebuild...what next?
 

That is good news. I'm staying with the 731 and my GILS. For now. I'm just running out of time to get these engines back in. Adding the Crane HI-6M and a Crane PS92 coil. That combined with the new Dart Heads, Dart intake and upgraded valves, I'm hoping I've nailed the "Best performance for the reliability buck" Only thing left is to find dyno time the week before Memorial day.

Re: HP500 rebuild...what next?
 

I'm with Griff if the carb has not had the metering blocks modified the jet you have is going to be at least 25 hp off to what it has to be the numbers are as Griff mentioned try that you won't regret it we've done a lot of work on those carbs for years since we were racing Factory 1 AND 2 that's the best way to run that carb on that intake don't worry about the two front plugs being darker then the rest . Sincerely Laz Mesa

Re: HP500 rebuild...what next?
 

Lazaro:

So you're saying to replace my current set up with stock? Why would a "LARGE" engine builder write down that they "replaced jets in carbs, old size 70, new size 80"?

Re: HP500 rebuild...what next?
 

I've heard nightmares about the NRS system. Can you same FIRE. You have to watch running the higher lift cams with silent choice. This is a big cause of reversion.\\My $.02

Re: HP500 rebuild...what next?
 

NRS is coming off. Removing the Y pipe too. Just have to see "what" I'm going to be able to use to get it plumbed out the transom.

Re: HP500 rebuild...what next?
 

I don't get the Large engine builder part what I'm saying is that the carbs you're using I've done alot of testing with both in the water and on the dyno and from my work I'm saying the factory jet setting has been the best for power and fuel distribution with the Dart intake and the gm heads it doesn't make since why that jetting but it works. Best of luck to you Laz Mesa
P.S. When I give an opinion or advise on this forum or anywhere I mean it with good faith and good intentions so don't think because someone is a big or small guy in the business they can't take the time to help we're all the same today you may need help from me and tomorrow I may need help from you.

Re: HP500 rebuild...what next?
 

Laz;
You read me wrong... what I was saying about the LARGE DOG was, I'm finding all kinds of...well crap that these large dogs did to my motors in the past. From reusing gaskets, to silicone fixes, to recycling valves, to so called replacements, when the stock parts are still in place...so a receipt saying replaced jets in both carbs, old size 70, new size 80 scares me. What was really done, who knows, I'm just forced to make changes to both motors now, so i know what I'm starting with and I just want to get OSO advise so I have some feedback for my builder. For the record, I prefer the small dogs. More willing to help the small guy.

Re: HP500 rebuild...what next?
 

I'd have your tail pipes mofidied to look like a stock piep to a tip connected by a hose. Or you can go straight thru the transom will a TRS style with a wedge plate.

Re: HP500 rebuild...what next?
 

I'm using my 741's with CMIs, so I can't comment on the Gils. I love my Crane Hi-6M ignitions, but I can tell you I HATED my Crane coils (LX92s, I think) - lost at least one per season - sparks flying all over the engine compartment (NOT a good thing). I went to MSD Blasters and haven't had a problem since.