Cam and valvetrain longevity....??? low duration high lift...
#1271
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So I wonder what happens IF they regrind a cam?? Is it "re-heat treated"? Heres a story of a cam I had a fiasco with at one time, NOT MK'S FAULT, I built a 540, MK spec'd the cam, said I would make 950 hp on dyno, got to dyno at Crocketts, fired up motor, ZERO oil pressure at anything below 1000 rpms BUT would jump to 45-70 psi at 1100 rpms up, Crockett said lets pull er off, you screwed something up on this motor building it. I made the judgement call to go forward (cut filter open, clean as a whistle), set idle at 1100 for now, we are on dyno, dont want to do this twice, I will figure out my idle oilin problem at home when we are done. Tuned, made our number, everything was good except idle oil pressure,
Got motor back to my shop, pissed around testing all kinds of stuff, found with intake manifold off I had TONS of oil blowing around top of lifters when they were in right spot. Turns out this merlin 2 block I had had fairly short lifter bores and they had a massive radius at top that allowed lifter band to enter it allowing oil to blow out with no resistance (morels), this was back in like 2005 I think and they just wasn't alot of info on what worked and didn't work at time. Pulled cam out, sent it back to Cam motion and they reduced base circle either .050 or .100, re-installed cam in motor, had great oil pressure, ran that motor for a little over 100 hours before upgrading it another 170 hp or so, cam looked perfect when it came out, saving it to go back in that POS merlin block one day, so if cam was already cut from a core with a certain range THEN reduced even just .050 all the way around it either had to be cut thru the heat treat or re heat treated to last 100+ hours ran at 185/190 seat and 460 open with morels to still look like new??
Got motor back to my shop, pissed around testing all kinds of stuff, found with intake manifold off I had TONS of oil blowing around top of lifters when they were in right spot. Turns out this merlin 2 block I had had fairly short lifter bores and they had a massive radius at top that allowed lifter band to enter it allowing oil to blow out with no resistance (morels), this was back in like 2005 I think and they just wasn't alot of info on what worked and didn't work at time. Pulled cam out, sent it back to Cam motion and they reduced base circle either .050 or .100, re-installed cam in motor, had great oil pressure, ran that motor for a little over 100 hours before upgrading it another 170 hp or so, cam looked perfect when it came out, saving it to go back in that POS merlin block one day, so if cam was already cut from a core with a certain range THEN reduced even just .050 all the way around it either had to be cut thru the heat treat or re heat treated to last 100+ hours ran at 185/190 seat and 460 open with morels to still look like new??
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#1272
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tim,did bob m tell you that the valvesprings would last 400 hrs?i am asking because on some builds i did with cams from bob pretty close to yours i was told&expected way less.even mercury marine,s fabled hp500 needs springs replaced at 250 hrs and a valve job should also be done at that time.what valvesprings do your engines have.
Hot Rod Series Springs are designed to offer the engine builder and hot rod enthusiast a mild upgrade and replacement for their hot rod.
241* Lobe, 680 lift, basic valvespring, 250 hours, seems like alot to ask. Merc engines went that long, but they also had easy cam lobes, most in the 590-630 lift range, and didn't exceed 5200rpm.
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#1273
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Hey Eddie.
So, the advantage of a 55mm is still worth it even in a relatively low RPM marine application?
Is the main advantage the better geometry with the larger base circle?
Also, what are you using for cam bearings on the 55mm stuff? Roller of Babbitt, is what I'm wondering, not so much manufacturer?
So, the advantage of a 55mm is still worth it even in a relatively low RPM marine application?
Is the main advantage the better geometry with the larger base circle?
Also, what are you using for cam bearings on the 55mm stuff? Roller of Babbitt, is what I'm wondering, not so much manufacturer?
The addition of the 55mm and .904 is beneficial on any engine really. It's certainly not needed on something with a small to moderate cam, but it sure can't hurt. The only downside to it is cost, not that it's really that much. The acceleration rate is slowed, the contact area is larger, spreading out the load over a larger area. The wheel and axle are larger, making them stronger. Also, when opening the lifter bores to .904, you can correct the geometry. I don't care which block you use, none of the lifter bores will be perfectly perpendicular to the cam. They are pretty close in both the Merlin and Dart blocks and in 99.9% of the applications, you would never know or have an issue. The GM Bow tie block is another story. I've seen where those had to have bushings installed instead of steel on steel since boring to .904 would not clean it up. The bores were off so bad that just cutting to .904 would not allow the cutter to touch everywhere. We had to open them even more and install bronze bushings in order to correct them and run a .904. Again, you would more than likely never have an issue due to lifters bores being off slightly. However, if you are boring them out to run .904 lifters anyway, you would be a complete fool to not correct them. The valve train is by far the weakest link on a BBC, so anything you can do to help it out is a step in the right direction.
Eddie
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#1274
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to be honest mid 70's would make me happy with this hull, I had 420's boat was fun... but knew 70 ish the hull came alive for running rougher waters and still not totally taking out drives (running it right helps) then I had the chance to buy a boat that had them 565's making 600 hp, knew I could buy it and sell of the rst, keep power and make money still... so I did, then that got a little messed up with some issues they had that I fixed, like was fun running 73 all the time, then 2 seasons later I toss a rod, then find Bob, he promises me 700HP spinning existing props to 6000 puts me at 78-80 mph, far stretch but numbers say so, I figured it would do 75-76, daily, then the rest is history... that being said....
I love my boat, a gun may be in future but still no speed demon, its paid for, I could take a ,loan and go buy a TS if I wanted a payment, I pick and chose money things in life, mostly pay cash for toys and most things I have, so this is what I can afford without stretching, if money is there I spend it, if not I lay low and don't do much like last winter..so I left it. Here we are now, it needs addressed so I will address it, I don't really want to go broke and reinvent the wheel, but will change a few things and get better results, and reliability of not touching them I hope for a bit, speeds? well anything over 73 will make me happy, if I was that concerned about all out speed I would have not gotten a Mistress or maybe not even a Cig, I love what I have and old boats in general, one reason being even at 75-80 in a Mistress is doing well, and in the $$ area I can afford to play with while living life, family, other toys and so on... Kinda like Joe, I wanna keep playing with it to gain speeds here and there, to learn, and say wo that slug ran what?? this mess is not my fault so I must just fix it... when done we see what it does, if I decide I want more boost will be next, but that's also not the best thing on TRS, so who knows what future holds, with friends having cancer and things like that I literally live one day at a time, you never know guys....I deal with the NOW not what ifs or laters...
I love my boat, a gun may be in future but still no speed demon, its paid for, I could take a ,loan and go buy a TS if I wanted a payment, I pick and chose money things in life, mostly pay cash for toys and most things I have, so this is what I can afford without stretching, if money is there I spend it, if not I lay low and don't do much like last winter..so I left it. Here we are now, it needs addressed so I will address it, I don't really want to go broke and reinvent the wheel, but will change a few things and get better results, and reliability of not touching them I hope for a bit, speeds? well anything over 73 will make me happy, if I was that concerned about all out speed I would have not gotten a Mistress or maybe not even a Cig, I love what I have and old boats in general, one reason being even at 75-80 in a Mistress is doing well, and in the $$ area I can afford to play with while living life, family, other toys and so on... Kinda like Joe, I wanna keep playing with it to gain speeds here and there, to learn, and say wo that slug ran what?? this mess is not my fault so I must just fix it... when done we see what it does, if I decide I want more boost will be next, but that's also not the best thing on TRS, so who knows what future holds, with friends having cancer and things like that I literally live one day at a time, you never know guys....I deal with the NOW not what ifs or laters...
At this point Tim you need to ask yourself will you really be happy with a low 70mph boat that cost 3 times what you planned to get it there???? At the time your build made sense and if everything worked out you could have enjoyed the reliability for years and saved your money. But things have changed.
I would take some time to carefully consider upgrading boats, or adding forced induction.
I honestly believe you will not be satisfied unless you hit 80mph next.
Seriously
I would take some time to carefully consider upgrading boats, or adding forced induction.
I honestly believe you will not be satisfied unless you hit 80mph next.
Seriously
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#1275
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At this point Tim you need to ask yourself will you really be happy with a low 70mph boat that cost 3 times what you planned to get it there???? At the time your build made sense and if everything worked out you could have enjoyed the reliability for years and saved your money. But things have changed.
I would take some time to carefully consider upgrading boats, or adding forced induction.
I honestly believe you will not be satisfied unless you hit 80mph next.
Seriously
I would take some time to carefully consider upgrading boats, or adding forced induction.
I honestly believe you will not be satisfied unless you hit 80mph next.
Seriously
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Was gonna look into that gun no power on eBay but since I have to rebuild upper half of my engines because Bob sucks I can't buy it... Thx Bob Madara!
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#1279
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Heres a thread I had started about tims combo, in another forum. If anyones interested.
http://www.speedtalk.com/forum/viewt...hp?f=1&t=47746
http://www.speedtalk.com/forum/viewt...hp?f=1&t=47746
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