Cam and valvetrain longevity....??? low duration high lift...
09-21-2016, 08:45 AM
#261
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The port volume is determined by the length of the port and Cross-Sectional Area (CSA). Matching the correct CSA to the engine’s demand is the key. The properly sized intake runner will create the right balance between airflow volume and airflow velocity, and it’s not always the biggest runner that wins.
“We usually recommend the smallest port volume with the highest efficiency,” “This means there’s good velocity through the port and the ability to fill the cylinder.”
The article is below and has some good key points. This also hits on how you build an engine combination that is matched instead of simply throwing cams at it.
http://www.onallcylinders.com/2015/1...ylinder-heads/
“We usually recommend the smallest port volume with the highest efficiency,” “This means there’s good velocity through the port and the ability to fill the cylinder.”
The article is below and has some good key points. This also hits on how you build an engine combination that is matched instead of simply throwing cams at it.
http://www.onallcylinders.com/2015/1...ylinder-heads/
09-21-2016, 08:50 AM
#262
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I may pull heads and intakes either way and send them to bills dad, check it all, clean ports up and match, if no issues seen that's good, see why can Kip thinks at that time if it's close or same put it together, if way off and benefits seem good I may change, cost me not much per engine to do that with heads and intakes, we talked the other night about it.
One thing i will be doing from now on, and did on my current heads, is check each and every spring. Each spring was taken out of the box, and put in the spring tester. Seat pressure checked, open pressure checked, and coil bind checked.
Out of 32 springs, sure enough, found one spring way out of spec.
If i was tim, if the springs check out ok, valves are sealing well, and visually things look fine, id prob leave the engines in, cover the boat, and save money for next seasons fuel fund.
When the engines get tired, yank em, then make some changes to the combo. Or, if you have valve leaking, or signs of valvetrain issues, yank them now. You certainly dont want to deal with any more failures that hurt the hard parts.
The area that a few builders using bobs cams and heads, had in common, were the exhaust valve seats being pounded into the head, and lobe wear issues. Pretty sure there were a couple broken scorpion rockers in there as well.
Really chitty part of that story was, even though a few of these builders, experienced the exact same issues as the others, when it was brought to bobs attention, he acted as if he had never heard of that happening. There was alot of tjme and money wasted at the builders expense, rather than trying to get together as a group, and find out WHY it was happening. If you were the builder, you'd be prettt pizzed when you find out others were having the same issues, and it was swept under the rug.
Out of 32 springs, sure enough, found one spring way out of spec.
If i was tim, if the springs check out ok, valves are sealing well, and visually things look fine, id prob leave the engines in, cover the boat, and save money for next seasons fuel fund.
When the engines get tired, yank em, then make some changes to the combo. Or, if you have valve leaking, or signs of valvetrain issues, yank them now. You certainly dont want to deal with any more failures that hurt the hard parts.
The area that a few builders using bobs cams and heads, had in common, were the exhaust valve seats being pounded into the head, and lobe wear issues. Pretty sure there were a couple broken scorpion rockers in there as well.
Really chitty part of that story was, even though a few of these builders, experienced the exact same issues as the others, when it was brought to bobs attention, he acted as if he had never heard of that happening. There was alot of tjme and money wasted at the builders expense, rather than trying to get together as a group, and find out WHY it was happening. If you were the builder, you'd be prettt pizzed when you find out others were having the same issues, and it was swept under the rug.
09-21-2016, 08:52 AM
#263
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I know first hand of similar issues ( north of the border ) that your referring to, but it was easier for them to pull it out, stand it in the corner with others like it, than argue & argue till blue in the face ( you need more spring pressure ) with the cam supplier.
Im done.......
Im done.......
09-21-2016, 08:53 AM
#264
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I had a shelf cam for my mistress and they made the 700HP as advertised, nothing crazy. Crane 741 hydraulic roller cam. And I sent you the other engine specs in the past
09-21-2016, 08:57 AM
#265
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We can talk about csa's, flow numbers, intake heights, compression ratios, and all thst until we are blue in the face.
What i find hard to argue with, is when all that was engineered into a build, and you simply yank that cam out, and swap it out, and see significant gains in power, with no other changes to the combo, that is what i find hard to argue about.
Articles on engine design are stemmed from real world testing, not the other way around.
What i find hard to argue with, is when all that was engineered into a build, and you simply yank that cam out, and swap it out, and see significant gains in power, with no other changes to the combo, that is what i find hard to argue about.
Articles on engine design are stemmed from real world testing, not the other way around.
09-21-2016, 08:57 AM
#266
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Chief engine didn't have any bob cams.... Might just be weak rocker arms!
09-21-2016, 08:58 AM
#267
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Dart Big M block, 9.0:1 static compression
Crane 741 hydraulic roller cam,
Crane roller lifters,
AFR 315 CNC heads with backcut Del West stainless intake valve, Del West inconel exhaust valves,
Isky (PSI) "Tool Room" springs,
Crower stainless rockers,
JE forged pistons,
Crower 4340 billet 6.386 rods,
Crower semi-lightweight 4340NT crank,
Victor Jr intake,
Holley marine 850cfm 4150 carbs,
MSD Pro-Billet Distributor
I ran this setup and they ran for 650+ HOURS, before one had a rod failure. I tested this with a 1" carb spacer with Dyno pulls. Made about 15 HP more, but just left it alone. No secret ingredients needed. You need secret ingredients to make 750-800 because it requires a lot of lift, and for duration and reliability, it is tougher to make it last.
Crane 741 hydraulic roller cam,
Crane roller lifters,
AFR 315 CNC heads with backcut Del West stainless intake valve, Del West inconel exhaust valves,
Isky (PSI) "Tool Room" springs,
Crower stainless rockers,
JE forged pistons,
Crower 4340 billet 6.386 rods,
Crower semi-lightweight 4340NT crank,
Victor Jr intake,
Holley marine 850cfm 4150 carbs,
MSD Pro-Billet Distributor
I ran this setup and they ran for 650+ HOURS, before one had a rod failure. I tested this with a 1" carb spacer with Dyno pulls. Made about 15 HP more, but just left it alone. No secret ingredients needed. You need secret ingredients to make 750-800 because it requires a lot of lift, and for duration and reliability, it is tougher to make it last.
09-21-2016, 08:59 AM
#268
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Yes, I really wish I copied your builds completely as they are the best combo I seen with proof of results, too bad I asked you Halfway into mine lol
09-21-2016, 09:00 AM
#269
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Exactly! Now Tim knows when to raise the red flag when someone is selling him parts. I am trying to point him in a direction of education. I'm sure he spoke to you about it before buying and surprised you didn't say STOP wtf is going on here.
09-21-2016, 09:01 AM
#270
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Talk to Zero Patience and Lock & Load, their chief engines had scorpion rockers at one time and all the rocker arms had hairline cracks in them after 150 hours. They switched back to crane gold wide body and never had a problem again. I have never liked scorpion rockers and will not use them, to many stories like this.
Chief engine didn't have any bob cams.... Might just be weak rocker arms!
Chief engine didn't have any bob cams.... Might just be weak rocker arms!
