502mag cam change or hp upgrade questions
#11
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There ya go, what Gimme Fuel said.
Regardless of which path you follow, I would (and did) get a qualified marine engine machinist/mechanic who you can trust to do the build. Poke around here on OSO and on other hi-perf boat sites and you find way too many horror stories from simple rebuilds to wicked mods that went south, and caused guys a ton of grief, and allot of $$. If it were me I'd do a good solid rebuild for now then save up for a hp build down the road.
Regardless of which path you follow, I would (and did) get a qualified marine engine machinist/mechanic who you can trust to do the build. Poke around here on OSO and on other hi-perf boat sites and you find way too many horror stories from simple rebuilds to wicked mods that went south, and caused guys a ton of grief, and allot of $$. If it were me I'd do a good solid rebuild for now then save up for a hp build down the road.
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The 502 Mag carbureted had flat tappet cam, Webber carb (quadrajet style), dual plane manifold, non adjustable rockers. The carb HP500 had hydraulic roller cam (significantly larger), single plane manifold, 800 Holley, roller rockers. I would check your specs for the 502 MPI roller cam, I think they are 224/224 duration at .050 at about .318 lobe lift, could be wrong though. Good luck.
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last thing.... i knnow guys and buddies of mine that race cars and do high performance stuff that run different ratio lifters on intake vs exhaust
any theories on that
any theories on that
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im sorry boat1 but i dont think your numbers are anywhere near correct a lot of people have been throwing the number around but it doesnt make sense.... 115 separation would suck the water right in
here is where i get my specs from!
http://www.perfprotech.com/store/art...fications.aspx
im going to call merc and see what they say personally
here is where i get my specs from!
http://www.perfprotech.com/store/art...fications.aspx
im going to call merc and see what they say personally
#17
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im sorry boat1 but i dont think your numbers are anywhere near correct a lot of people have been throwing the number around but it doesnt make sense.... 115 separation would suck the water right in
here is where i get my specs from!
http://www.perfprotech.com/store/art...fications.aspx
im going to call merc and see what they say personally
here is where i get my specs from!
http://www.perfprotech.com/store/art...fications.aspx
im going to call merc and see what they say personally
#18
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All of this information about cams has been covered many times. You can do a search of this site and find all of this out. If specs are posted by RMbuilder or YoungPerformance you can take that as fact.
#19
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so....factory cam is 227/211 at .050 and 342 lift on both
there is no way i can go one small step up? maybe a bit bigger on exhaust size or possible use the stock cam and go from 1.7ratio rockers to some nice billet 1.8:1's
just get a few ponies out without touching the ecu
there is no way i can go one small step up? maybe a bit bigger on exhaust size or possible use the stock cam and go from 1.7ratio rockers to some nice billet 1.8:1's
just get a few ponies out without touching the ecu
The previous owner of my boat upgraded the exhaust to EMI with long runners and a Keith Eckert breather without a recal on the ECM......gained hardly anything (so he claims).
With changing the rocker ratios, the biggest increase you will see is just from going from stamped to roller rockers. That is usually around 14 (+/-) hp on dyno just from reducing friction. That little bit of added lift won't do much.
There is a rule of thumb to be considered when you are gonna build an engine. What ever you think you are going to spend......double it and that will be a more realistic final cost. There is nothing cheap about upgrading a BBC and especially a MAG EFI version.
There is not a single part on my 540 that I have not modified or am in the process of modifying. You are almost better to find a second block and piece together a whole separate motor and take your time on it if you want big power. That way you have your stock one as a back up to keep you on the water.
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technically now that you mention it i could run a fuel pressure regulator like my buddy does on his turbo charged 318ci dart.... super simple it runs off of vacuum vs boost and they make them for na applications and a afr gauge isnt alot of work.... im going to do some more looking into this... i was also hit up by a guy on here from cmd marine (the power commander company) and they are dropping a piggy back system for factory merc efi this march at the la boat show and he sent me a bunch of info.... seems pretty easy and itsnt too costly