Build Thread: 376ci Iron Block
04-01-2012, 10:06 AM
#21
ahh,you did open them up to 90% of the valve diameter then.just that and the right VJ really wakes up the flow,more than most people realize(or some porters will admit to).but of course you already know this.
i'm saving up for my next toy,and my plan is to build a 6.0 and do basically what your doing.OEM heads,but with the right supporting mods.for somebody on a budget,the money is better spent on quality internals and machine work.the way i see it,why spend money on heads that flow way more air than needed for the HP goals.some very smart people have said you need just enough airflow to support your target HP,and no more.what's the ICL of your cam?IMO,most people go too big on the cam with too wide of a lobe seperation.better to go smaller with a tighter LSA to let the overlap to get the intake charge going.
i'm saving up for my next toy,and my plan is to build a 6.0 and do basically what your doing.OEM heads,but with the right supporting mods.for somebody on a budget,the money is better spent on quality internals and machine work.the way i see it,why spend money on heads that flow way more air than needed for the HP goals.some very smart people have said you need just enough airflow to support your target HP,and no more.what's the ICL of your cam?IMO,most people go too big on the cam with too wide of a lobe seperation.better to go smaller with a tighter LSA to let the overlap to get the intake charge going.
Last edited by KCS; 06-26-2013 at 06:12 PM.
04-01-2012, 06:00 PM
#22
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considering your cubes and bore size,i don't think it's too bad.of course thats just going off the specs at .050 lift.too lazy to do the math right now,but that cam would be like a mid to high 220s duration on a 346ci motor.depends on what you want to do with the car.going by your dyno #s id say it's a good street/strip cam.i bet the idle sounds bad ***..
06-16-2013, 09:08 AM
#24
UPDATE:
This last Thursday the engine developed a slight tick. The tick quickly turns into more of a hammering sound. Pop the driver side valve cover and find that one of the rocker arms puked its bearings out, and when I say puked, I mean the violent puke like you ate some bad sushi and drank a bottle of Visine. It basically exploded out the sides.
So, this engine is done. I replaced the rocker arm and will just flush the oil a few times and see how long it lasts while I build the new engine. I have most of the hard parts to build a 347ci LS1. Definitely investing in a trunion upgrade next time.
This last Thursday the engine developed a slight tick. The tick quickly turns into more of a hammering sound. Pop the driver side valve cover and find that one of the rocker arms puked its bearings out, and when I say puked, I mean the violent puke like you ate some bad sushi and drank a bottle of Visine. It basically exploded out the sides.
So, this engine is done. I replaced the rocker arm and will just flush the oil a few times and see how long it lasts while I build the new engine. I have most of the hard parts to build a 347ci LS1. Definitely investing in a trunion upgrade next time.
06-23-2013, 09:25 PM
#28
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But I disagree on the motor being done. Even if all of the needles are not accounted for I still believe that the issue is not as big as its made out to be.
Magnetic drain plug is your friend in this situation.
We accounted for 56 of the needles in our 408 and thus far no issues. At the moment
06-23-2013, 09:32 PM
#29
Well, the trunion spit out the bearings, but also wore a lot of fine metal grit into the engine. You can see one side of the trunion is worn pretty badly in the photo. I had planned on new heads, intake, clutch, and headers this summer anyways so now I might as well just pull it out and replace the rings and bearings as I'm 100% sure they have all kinds of crap imbedded in them.
06-23-2013, 09:51 PM
#30
If you dont mind, can you post before and after measurements/pictures of your narrowed connecting rod crank journal bearings? That is wild, never thought of doing something like that before.
Thanks again for the ride along with the build process a year ago.
I also agree the motor is not completely done. Best to disassemble and assess from there. Might take extra time and consideration but it will allow you to better make the call. Worst comes to worst - you already have your backup plan in action
Thanks again for the ride along with the build process a year ago.
I also agree the motor is not completely done. Best to disassemble and assess from there. Might take extra time and consideration but it will allow you to better make the call. Worst comes to worst - you already have your backup plan in action
06-23-2013, 09:55 PM
#31
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Not arguing with anyone but I will disagree again on the crud being embedded.(your rebuilding anyways)
A good filter and oil should do it's job as far as the crud goes.
But anyways good luck with the next build,glad to see you can afford to throw money it for another build lol.
We call ourselves PBR. Poor Boy Racing lol
A good filter and oil should do it's job as far as the crud goes.
But anyways good luck with the next build,glad to see you can afford to throw money it for another build lol.
We call ourselves PBR. Poor Boy Racing lol
06-23-2013, 10:05 PM
#32
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Well, the trunion spit out the bearings, but also wore a lot of fine metal grit into the engine. You can see one side of the trunion is worn pretty badly in the photo. I had planned on new heads, intake, clutch, and headers this summer anyways so now I might as well just pull it out and replace the rings and bearings as I'm 100% sure they have all kinds of crap imbedded in them.
06-23-2013, 10:44 PM
#33
If you dont mind, can you post before and after measurements/pictures of your narrowed connecting rod crank journal bearings? That is wild, never thought of doing something like that before.
Thanks again for the ride along with the build process a year ago.
I also agree the motor is not completely done. Best to disassemble and assess from there. Might take extra time and consideration but it will allow you to better make the call. Worst comes to worst - you already have your backup plan in action
Thanks again for the ride along with the build process a year ago.
I also agree the motor is not completely done. Best to disassemble and assess from there. Might take extra time and consideration but it will allow you to better make the call. Worst comes to worst - you already have your backup plan in action
243's with LS3 valves.
10-23-2013, 10:01 AM
#35
UPDATE:
Finally! I have a clutch on the way. I decided on a SPEC stage 1 single disc with a billet steel flywheel and new GM slave cylinder. SPEC says its rated to 599ft-lbs of torque which should be plenty. Also picked up a Comp Trunion upgrade, FAST intake and throttle body, and OBX 1-3/4" headers and Y-pipe I wanted to try out. I also picked up Proform cast valve covers which I think I will have hydrodipped in carbon fiber with "PONTIAC" in orange to match the block.
I have been working on a new set of heads too. I started with a set of 862's I had laying around and popped out the old 2.02" diameter seat inserts and installed some Melling 2.170" diameter seats. This is my R&D head before I cut into the 243 heads which will actually go on the engine. The first valvejob I cut for the 2.165" valve went 281CFM @ .700" with basically just a bowl blend that I did in a hurry.
Got another valvejob cut with a shallower bottom cut (on the right) to see of that helps pick up the numbers. Haven't opened up the throat yet or blended anything in yet, but I will get the head back on the Flowbench once I do. Hoping to have new dyno numbers and track times before the local drag strips close for the winter.
Finally! I have a clutch on the way. I decided on a SPEC stage 1 single disc with a billet steel flywheel and new GM slave cylinder. SPEC says its rated to 599ft-lbs of torque which should be plenty. Also picked up a Comp Trunion upgrade, FAST intake and throttle body, and OBX 1-3/4" headers and Y-pipe I wanted to try out. I also picked up Proform cast valve covers which I think I will have hydrodipped in carbon fiber with "PONTIAC" in orange to match the block.
I have been working on a new set of heads too. I started with a set of 862's I had laying around and popped out the old 2.02" diameter seat inserts and installed some Melling 2.170" diameter seats. This is my R&D head before I cut into the 243 heads which will actually go on the engine. The first valvejob I cut for the 2.165" valve went 281CFM @ .700" with basically just a bowl blend that I did in a hurry.
Got another valvejob cut with a shallower bottom cut (on the right) to see of that helps pick up the numbers. Haven't opened up the throat yet or blended anything in yet, but I will get the head back on the Flowbench once I do. Hoping to have new dyno numbers and track times before the local drag strips close for the winter.
10-24-2013, 02:55 PM
#37
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UPDATE:
Finally! I have a clutch on the way. I decided on a SPEC stage 1 single disc with a billet steel flywheel and new GM slave cylinder. SPEC says its rated to 599ft-lbs of torque which should be plenty. Also picked up a Comp Trunion upgrade, FAST intake and throttle body, and OBX 1-3/4" headers and Y-pipe I wanted to try out. I also picked up Proform cast valve covers which I think I will have hydrodipped in carbon fiber with "PONTIAC" in orange to match the block.
I have been working on a new set of heads too. I started with a set of 862's I had laying around and popped out the old 2.02" diameter seat inserts and installed some Melling 2.170" diameter seats. This is my R&D head before I cut into the 243 heads which will actually go on the engine. The first valvejob I cut for the 2.165" valve went 281CFM @ .700" with basically just a bowl blend that I did in a hurry.
Got another valvejob cut with a shallower bottom cut (on the right) to see of that helps pick up the numbers. Haven't opened up the throat yet or blended anything in yet, but I will get the head back on the Flowbench once I do. Hoping to have new dyno numbers and track times before the local drag strips close for the winter.
Finally! I have a clutch on the way. I decided on a SPEC stage 1 single disc with a billet steel flywheel and new GM slave cylinder. SPEC says its rated to 599ft-lbs of torque which should be plenty. Also picked up a Comp Trunion upgrade, FAST intake and throttle body, and OBX 1-3/4" headers and Y-pipe I wanted to try out. I also picked up Proform cast valve covers which I think I will have hydrodipped in carbon fiber with "PONTIAC" in orange to match the block.
I have been working on a new set of heads too. I started with a set of 862's I had laying around and popped out the old 2.02" diameter seat inserts and installed some Melling 2.170" diameter seats. This is my R&D head before I cut into the 243 heads which will actually go on the engine. The first valvejob I cut for the 2.165" valve went 281CFM @ .700" with basically just a bowl blend that I did in a hurry.
Got another valvejob cut with a shallower bottom cut (on the right) to see of that helps pick up the numbers. Haven't opened up the throat yet or blended anything in yet, but I will get the head back on the Flowbench once I do. Hoping to have new dyno numbers and track times before the local drag strips close for the winter.
10-24-2013, 05:15 PM
#40
I'd rather not say exactly, but I'll tell you the top is steeper than 35, the seat is 45 degrees x .040" wide, and the bottom is steeper than 60 on the intake. The exhaust is shallower than 60. Both have a 75 degree bowl cut underneath blended into the throat.
The big valve head I think I'm going to run the exhaust cutter on the intake too and mix it up with a 70 and 75 so as to make the transition less abrupt.
The big valve head I think I'm going to run the exhaust cutter on the intake too and mix it up with a 70 and 75 so as to make the transition less abrupt.