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Originally Posted by airjunky
(Post 4246481)
The zz grind is outside the gm marine grind box has a idle rumpity rump similar to hp500 ,if you have closed cooling you may be able to manipulate the idle water dump.to the minimum ,otherwise its going to be close if you want to put it together and forget it ,I did a zz dump at the tips cmi headers with 3rd overflow never reversion lots of idling and it was complicated .everybody will know its not a 502 mag when you start it .did I just read your zz502 went 2 seasons with cast manis and no problems ? You have aluminum heads on that ?
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If your on to something here , I'm game . So far I have a zz 502 hooked to merc exhaust that has lived unscathed as is and you want to upgrade to the next stage cast aluminum dry joint risers and your wondering if this will introduce new issues with the reversion bullet that you somehow dodged . Nah . It won't . Just watch your water flow to exhaust at idle make sure the water exit and drop is right and now is the time to ask how warm those cast manifolds were getting on a long idle while while listening to that rumpety rump .if you had some rust clogged barely flowing Manis and didn't notice cause you had some aluminum head friendly closed cooling system with the deluxe triple dump exchanger yea your potentially going to put your engine in danger with what should be the right upgrade .it will sound better and make more power .but keep a close eye on it and make sure those new manifolds are not getting hot from the or a lack of water flow
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Gotcha , thank you
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I guess you are sure it is zz502 cam? I bought a nova with twin 350's. LT 1 hot cams supposedly. But flat tappett motors.
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Originally Posted by dereknkathy
(Post 4247421)
I guess you are sure it is zz502 cam? I bought a nova with twin 350's. LT 1 hot cams supposedly. But flat tappett motors.
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Well keep us posted on the uncorking of your crate motor , if its not sucking water back at idle with merc centers and captains call thats what most would call a miracle unless your idleing at 1200 and crashboxing the drive or starting in gear .should pick up some notible power with exhaust upgrade .gotta be running full closed cooling on that bad boy to get this far . Just watch your raw water exchanger dump flow rate and you will be golden
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Will do , I'm going to go for it ... Currently idle is set at 750 with raw water cooling . Thx for all the help . How can I adjust my raw water dump rate ?
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I've run that cam in a 489 with stock 496 exhaust and silent choice, idle at 700rpm. No signs of reversion, and ran an O2 sensor in the riser all year. Just keep your initial timing low, and you'll be fine.
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Originally Posted by HaxbySpeed
(Post 4249606)
I've run that cam in a 489 with stock 496 exhaust and silent choice, idle at 700rpm. No signs of reversion, and ran an O2 sensor in the riser all year. Just keep your initial timing low, and you'll be fine.
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I prob wouldnt fiddle with it , other than maybe a off season leakdown test especially since you have the manifolds off just to confirm its all good .sometimes with lots of hp and water requirements you can have 2 exit ports to exhaust to control mani temps and rubber parts meltage , the extra goes through a 3rd line overboard .time consuming to dial but some motors can really floood the exhaust with the outbound water .heat exchanger styles with big cams in lighter boats benefit most it seems
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