XCAV8

LAKE EFFECT-- thx for the flywheel info, i have the bell housing mounted starter... how mush was that flywheel ??, i was thinking of the zz502 but i was worried about detonation with the 9.6....So when changing to an 8 quart oilpan did you have to adjust the oilpump sump????

Pat McPherson--Yes i was thnking of going with the closed cooling, i am also considering going with the 435hp 502's.... trouble is he doesn't have any in stock...

Kidnova

Lake Effect, with only 35 or so hours mine hasn,t stood the test of time yet. But when I put it away for the winter, the ZZ was running as smooth as a sewing machine, except for the rumble when I opened the switchables, and heard the cam lope

I'm installing an oil temp gauge this spring to monitor the oil temp. What water temperature do you run at, and what temp thermostat do you have? Mines running about 170* to 175* Not much fluctuation regardless of speed. I think my thermostat is 160*.

HARRISONMIRAGE

That picture in the link is an iron head peanut port motor with a 6 quart pan(probably a tow truck special if it's a 502).It definatly will not make 500 horse but will have lots of low end torque.Pick up a copy of GM's performance parts and engines from a local dealer and that will explain all the motors to you.Of course GM will not recomend any of these motors for marine use.

HARRISONMIRAGE

ZZ 502 update.I bought one of these motors, did a total teardown and discovered many problems.I had a faulty block and tight valve guides.The changes I made were torque hone block,deck for proper quench,loosen piston pins,balance rotating assembly,regrind cam and mod timing sprocket for a 112 lsa and 110 atdc ilcl(originaly the cam was 104 atdc ilcl wich is quite advanced for marine use),install ferrea exaust valves,pro magnum steel roller rockers,RPM air gap,800 4150 holley,8 quart pan and I think thats it.I had closed cooling already so head rot is not a concern.I modified my short stainless marine risers to be dry to the tips(about 3" from transom).Upon firing this motor I discover it had a bad reversion problem if let idle below 800 RPM.Its easy to check with stainless marine manifolds with the dry joint.Shift the riser and look in the manifold.The only way water can get in there is from reverrsion or a crack.I think lots of people have reversion and don't know it.I installed a high idle selenoid wich I engage when warming the boat up and make sure I give her a good blast before shut down to clear the manifolds.I was a little disapointed after modifying my cam and manifolds to avoid reversion I still had a healthy dose of it.I woud be careful with this cam or any other cam with overlap @.050 and wet exhaust.I am happy with the performance.Its in a 25'7" 24* 5000#boat and with a 23 mirage plus I am geting 65 mph @ 5500 rpm.Light on fuel with just me in the boat I can get 68mph @5800 rpm.I just instaled a oil temp gauge and my temps are to hot.I am 240 at 3500- 4000 cruise but if I get onit it rises to 275 realy fast.I just ordered a big 3" cooler from edie marine that I am going to instal this weekend.It doesn't look like it is going to be very easy to shoehorn in.I will keep you posted on my new temps.Curious on where you guys are with your jetting.I'm 96 front 86 rear with a 6.5 pv.I was richer than this and just started cautiuosly leaning her out with positive performance gains.It is a bit rich at idle but runs good every where else.I get a bit of transom soot with extended idling but its very minimal.I find it very hard to get colour on the plugs so I'm going to run her like this for a while til its broken in.Last word of caution on modifiying the zz cam.You can only mod the intake lobe and only by a small amount or the lifters will fall in the guide plate with stock gm lifters.

Kidnova

HARRISON, Your oil temp is high. I ran the small oil cooler from my old 7.4 last season and don't trust it which is why I'm putting the oil temp gauge on.

My ZZ is in a 23 Nova that I think weighs in at around 4200 lbs. Speed on gps is 68.5 with a Mirage Plus at 4750 rpm, and 70.5 gps with Mirage 25 {non Plus} at about 5075 rpm. I had Throttle Up lab the 25Plus to get the rpms up around the 5200 rpm range so hope to see a little more top end this season

Reversion: Last season I ran the stock Merc stuff with Imco Sound Advantage. I never pulled a riser to check for reversion. I'm no mechanic so I rely on others, along with "trial and error" for my info. I read in Dennis Moore's book that the ZZ cam was ok/safe as far as reversion is concerned. But many dispute that.

I also keep the idle on the high side in no wake zones, the marina, etc. I've ordered a set of Revolution Marine exhaust manifolds that I hope will arrive early next week. The Revolution risers have a steeper pitch down to the tips than the stock Mercs. They also have a small reversion "dam" cast in to them. I'm hoping this will help with any reversion problems.

Jetting/carb: Last season I ran the carb that came on the engine, Holly 850 with vacuum secondaries {automotive}. I sent the carb to Nickerson to have it marinized. When I spoke to them before shipping the carb, they advised that the automotive carb as it came with the ZZ would likely run a bit on the lean side at mid to high rpm. Again, I'm not a mechanic so I'm not sure what all Nickerson will do to it. But they told me re-jet, rework the throttle shafts, and install J tubes.

I'll let you know what jets Nickerson installed when I get it back. Also, please post your temp after you install the new oil cooler.

Sorry to be so long winded here

LAKE EFFECT

XCAV8, I bought me flywheels from Don Carter at Offshore Performance in Ft Myers in 1998, when I put these motors in. They came off of new 502's that were going into air boat applications(I think Don was selling the motors for Bravo use?). Dont remember all the details, but he sold them for $50 each. You would have to call him(offshoreperformance.com). If the flywheels aren't available no longer, this would be your plan: Buy a GM manual trans flywheel(around $100 in '98),knock or press off the starter ring, put the ring in an oven,and knock it back on(sounds crude but thats what Don told me when I bought them). As far as the oil pans go, I didn't know about them in '98, back then in plugged the GM dipstick hole and welded a pipe plug adapter in the bottom of the pans, and used the 454 dipsticks that came with the mercruiser 330 pans. It would be a safe guess that the pans are the same depth(easy to check), then you could tack weld the pick up to the oil pump for extra safety. Another safe guess would be going to Mercury and buying a dipstick/tube to put in the 8qt pans, the dipsticks that come with the ZZ's are automotive, and wouldn't work for me. As far as the 9.6 compression, I'm not so worried about it, the aluminum heads have to help, plus I run the motors pretty cool.


Kidnova, I'm running a 3" by 18" oil cooler, with the 6qt pans, GM PF35 filters, and mercruiser remote oil filter mounts mounted above my tranny's(all 5/8 hoses) I use Gaffrig gauges for my oil temps, the senders read from the oil filter mounts on the output of the coolers. Under normal cruise(3600 to 4000rpm) the gauges read just above 140 degrees, at extended WOT they read above the 200 degree mark, but always maintain under 230 degrees. Keep in mind I'm reading on the output of my coolers. I was told a good cooler can knock off 50 degrees. so worst case I'm pushing 250 to 260 degrees. I have run this boat pretty hard, and the oil temps always level off no matter how long I keep it at WOT. Last season I switched to crossovers on my cooling systems, I was happy with the Mercruiser setup, but was looking for more HP. With the Merc setup,140 degree stats, the gauges read just above 130 degrees, after a hard run I would get a hot soak up to 150 degrees. I'm still playing with the crossovers though, there from Eddie Marine, The crossovers have a bypass hose(3/8) from the crossover to the t-stat housing, and your suppose to run stats, but I kept on getting to much of a temp swing with them in(up past 150 on its way to 180). I'm now running restricters in place of the stats, but can't get enough temp in the motors, I going to a smaller opening this season trying to get back to the 120/130 degree range.

HARRISONMIRAGE, I purchased my ZZ's in '98 when they first came out($4800), pulled the pans,welded my oil pick ups on, screened the block, installed Iconel exhaust valves with a wider grind on the seats(you were right about tight valve clearances,my head guy wanted more clearance too, and wider seats to promote better valve cooling) As far as reversion goes, it is tough to detect, thats one reason for the Iconel valves(as many times as I have checked my plugs, I haven't seen any signs of water). Other then roller rockers,and shorter pushrods(to get better roller tip/valve contact) I have 350 hrs on mine with no problems other then using some oil(which I think is a 502 trait). Heres my setup: 88 Formula 311(8300#), 8 clutch 72C B/W trans, TRS drives spinning inn, 25p Mirage Plus props(Merc lab finished), '98 IMCO Powerflow manifolds w/raised risers(3" taller to mate with the transom)(help reversion?),modified Silent Thunder swim platform, Victor jr intake(gasket matched), 850 Street Demon,Holley blue pumps,Fram water separators/filters,crossovers,Mobil synthetic oils(motor,trans,drives), Merc Thunderbolt IV ignition with MSD 6AL boxes,MSD wires/Rapid fire plugs.

Jetting/Timing, I played with jetting alot when I first started using this setup but got the best performance with these specs: 82/83 jets on the primary,90/91 jets on the secondaries, 5.5 powervalves(I boat on the west end of Lake Erie,the temps fluctuate up here from 50/60's to 80/90's during the season,so I usually go up and down in jetting during the year). I use vacuum gauges to play with powervalves and found on this setup, the top of the primaries is at 3800/4000rpm, and vacuum is at 5 to 6 inches, so I try to get the powervalves to open here to prevent a lean condition on the top of the primaries. Timing set at 32 degrees total (went up and dn 2 degrees and seem to get the best speed at 32)

Performance, The boat planes with no effort, cruises at 51/52mph at 3600rpm, 56/57mph at 4000rpm, top speed is always above 75mph with most any load, and I have seen 78mph on my Magellan GPS, and 79/80 on the Gaffig GPS speedo with a light load and dangerous trim settings. WOT rpm is between 5300/5400rpm. With the drives set pretty deep from Formula, the boat gets a good prop slip ratio.

Sorry for the rambling, Ill be back tomorrow.

LAKE EFFECT

I forgot about the GM roller lifter topic. According to Crane, the max lift on GM roller lifters is .570 of a inch.I guess when you go beyond .570, the lobe centerline gets smaller so the GM lifter would fall out of the lifter guide. I priced the cams I wanted from Crane; lifters $450, cam $350 x 2 + rebuild = next years tax return. I hope I can get 425 hrs!!

HARRISONMIRAGE

Lake efect,good to here the hours you are getting.I bought a new merc pan for mine.I started modifying a gm 8 quart truck pan but it turned in to a dogs breakfast so I just baught a new merc pan.I got my fly wheel from GM for 110$ with ring gear.On my oil pump I made a brace that is tack welded to the tube and bolts to the pump housing.I am a bit anal about this as I had a pickup brake off once.My oil temps are on the remote filter housing so I'm basicly reading pan temps.My setup runs up to 3900 on the primaries and i still have 9-10" of vacuum.Once the secondaries open I can run into the high 4's until the vacuum drops to 6.5" where my power valve opens.I am very leary to lean out as my plugs are clean and I only get transom soot with extended idle.I find I have more sucsess jeting by perfomance increase or decrease and transom soot at different opperating ranges.What are your thoughts on oil temps after the cooler.I am mostly concered that the oil hits boiling to burn water off and that the oil does not get overheated.That is why I put the sender on the hot side.My motor pulls strong vacuum at idle wich I think ads to the reversion.Open pleniums like the hp 500 dart manifold pull less vacuum so the cylinder has less vaccuum while both valves are open.I started a thread a while back that I got little response to with regards to the overlap at less lift.These zz cams have almost 300* of duration at .006 lift.This is good for valve train life as the valves are lowered slowly on to the seats but I think the strong vacuum signal and both valves being open at lift under .050 is still a contributing factor to reversion. I have run comp 224/234 on 110 lsa wich gives 9* overlap at .050lift and had less reversion with a short riser silent choice setup than my zz cam with 7*overlap and long risers.The comp cam has a lot less duration at .006.One way I have noticed to tell if there is a reversion problem is when you rev the motor after extended idling and a lot of steam comes out it usualy is the water pooling in the manifolds burning off.If I get 350 good usage hours I will be happy.I am pretty satisfied with what I got bang for buck.It took a bit of effort but I have a pretty custom motor.Back to the compression ratio queston at the start of this thread,all of the big blocks with JE pistons have a small dome(maybe 3cc's max).The different comp ratios come from different head chamber sizes.8.75:1 withh 118 cc heads,9.5:1 witth 110 cc heads and mine is hitting 10:1 with the block being decked.It shouldn't be a problem with proper quench an aluminum heads.GOt to go sleep these beers off and get ready for work in the AM.

HARRISONMIRAGE

I took the boat for a rip saturday and at 3500 I just hit 210.It takes about 10 minutes to get there.At full throttle 5350 (tach was reading high on dash)I hit 225 after a few minutes and it seemed to stabilize.I don't want to bag on it too much as it is pretty new still.These temps are on the filter mount so the oil going in the engine is probably a lot cooler.I don't know how much temp the cooler drops.How did you make out with your carb jets.