This a great thread with a ton of good info. One thing that puzzles me is why the need for large oil lines to the filter block and cooler? The hole passage from the block is small. Currently i'm using the Merc 575 SCI set up on my 871 540's. I am also using the large style HP6 Wix filter. Anybody see any issue with this set up? Also anybody use the Kendall GT motor oil 20-50W?

there is no genuine need. the majority of the time people do it because they look zoomy and because of mythology and folklore. unless you are running extremely long lines the area of your lines need be only that of the largest internal oil galley of the block.

in a nominal set of conditions any good quality motor oil will do the job just fine. when you get into extreme duty like some of the big blower motors on here typical street grade oils might lack some of the additive components required to make them live a long time . like anything else there is no " one size fits all " answer. your oil line , oil, oil filter and everything else will be specific to your motor and what it needs. a box stock 502 mag will run for 20 years with the oil lines it comes with and your 20 =50 kendal but one of smittys monsters will require bigger , more and tougher everything else to live.

I think this has been brought up before but when I sized my lines at -12 vs -10 the main reason was the restriction in the fittings, I tried to keep every fitting's id at a minimum of 1/2", some of the -10 stuff although 1/2 inch or so on the hoses had smaller fittings when it came to 90's /and adapters that were neccesary for clearence. When I prep a block any time I assemble a motor I take a hard look at id of main oil passages too and how they line up with adapters. If I see a oil gallery that can be bored or blended to help with flow I go after it.
Kendall GT used to be considered a good racing oil years ago from what I have been told by the older racers but it was sorta green back then, had a ton of ZDDP, nowadays it isn't anything all too special but I wouldn't be afraid to run it, Smitty

thanks. The 575 SCI lines are only #8 AN. I have 871's but i guess with the big filter and large Canton pan, i've never had an issue with to high oil temps. 212 is about it. granted i don't run hard for very long.

So what if any of these relief valves will I need to change for a 1979 Mark3/4 engine. Not sure which it is. I think its a mark 3 454

Great, Great, Great, Great info here..... this should be a must read everybody......... I have a lowly 7.4L Gen 6 that has been bumped up with a magnum cam and ported oval port heads with big valves and a tune..... I notice that every time I cruise over about 3,500 rpm, the oil pressure will steadily start to drop somewhat and i assume it is from the temp increasing. Normally idle psi is at 40 but hot is 18-20.... Running presure normal cruise is about 50-60 and hot it drops to 40-45......This is acceptable for sure and I am running a Melling HV oil pump. I am thinking about removing the center oil restrictor and hopefully I have a 30LB outer restrictor? I will get a larger (longer) oil cooler installed with an adapter to run -10 or -12 lines. I think this is cheap insurance and a must mod for just about any big block engine....... It is not expensive or complicated to do. I will also install an oil temp gauge and think a water pressure gauge is a good idea as well. I am all about preventive maintenance here after blowing my first rebuild so I want to do everything I can to increase the longevity of my engine...... TBF

I know this posting is from 2005. What is the best artical/thread about this zz502 marine installation. I just bought a boat and it has the zz502 engine and he said its is marinized . just wanting to double check what i can and do upgrades if needed

I'm going to install the freeze plug on the recommendation of this thread but I can't find a 20 mm plug. The closest one is from napa and it is 20.29 mm. Will that work

tmbl52, I have linked my thread which addresses what plug will fit the bypass hole. A 13/16 plug will fit, but you will have to grind or turn down the height to get it to fit flush with the block.

http://www.offshoreonly.com/forums/g...ot-bypass.html

Thanks