Unexpected rebuild
11-29-2018, 06:45 PM
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Unexpected rebuild 99 Z28, M6, 853 heads, long tubes, lid and filter, unknown tune, stock cam, underdrive pulley, stock 10 bolt and gearing
Unknown mileage as speedo was unhooked when I bought car last year. Previous owner said it’s around 170k. Various leaks and internal wear are in line with that. Developed very noticeable squawk puttsing around town. Ruled out accessory drive so figured it was lifter. Upon tear down found 1 lifter tray cracked and allowed 1 lifter to rotate sideways. Just ruined the roller on the lifter and corresponding lobe on cam. Cam journals and bearings don’t show any signs any trash went thru the oil (engine ran maybe 15 mins total trying to track down noise). I haven’t had a chance to remove main or rod caps to look at those. When parked engine had excellent oil pressure so hoping bearings are all clean.
Future plans have been accelerated, didn’t plan on rebuilding for a couple years. Being realistic with myself I am shooting for 400hp at crank, to wheels would be bonus. Daily driver when weather is nice, can’t say I wouldn’t go to the drag strip a couple times of year, but street would be 90% of use.
I am confident i could open up the heads w hand porting. Just can’t decide on opening up the 853s or if I should brave the cold and rip some 5.3 heads out of a truck and open those up. Drawback there is machining for 2” intake valve. Looking at cams but I think I should know which heads I am going to run (to know compression) before I pick one. With cam, better flowing heads, and the long tubes I think it makes sense to look into a used LS6 intake manifold as well. After work is complete would take it to a good tuner.
Just looking for some advice on head selection so I can move on with putting it back together.
Thanks
Unknown mileage as speedo was unhooked when I bought car last year. Previous owner said it’s around 170k. Various leaks and internal wear are in line with that. Developed very noticeable squawk puttsing around town. Ruled out accessory drive so figured it was lifter. Upon tear down found 1 lifter tray cracked and allowed 1 lifter to rotate sideways. Just ruined the roller on the lifter and corresponding lobe on cam. Cam journals and bearings don’t show any signs any trash went thru the oil (engine ran maybe 15 mins total trying to track down noise). I haven’t had a chance to remove main or rod caps to look at those. When parked engine had excellent oil pressure so hoping bearings are all clean.
Future plans have been accelerated, didn’t plan on rebuilding for a couple years. Being realistic with myself I am shooting for 400hp at crank, to wheels would be bonus. Daily driver when weather is nice, can’t say I wouldn’t go to the drag strip a couple times of year, but street would be 90% of use.
I am confident i could open up the heads w hand porting. Just can’t decide on opening up the 853s or if I should brave the cold and rip some 5.3 heads out of a truck and open those up. Drawback there is machining for 2” intake valve. Looking at cams but I think I should know which heads I am going to run (to know compression) before I pick one. With cam, better flowing heads, and the long tubes I think it makes sense to look into a used LS6 intake manifold as well. After work is complete would take it to a good tuner.
Just looking for some advice on head selection so I can move on with putting it back together.
Thanks
11-29-2018, 07:30 PM
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Sounds simple enough to me. Can stock injectors handle 400 or would I be on borrowed time with those? From what I can see in the intake runners on the head they were all spraying well/evenly.
I know the 853 heads are frowned upon. I know the 243 are a better casting and people love them. What in particular lends them to flow so much better? Runner cc or shape? Finish? I wouldn’t mind sitting down and doing my best for 25-30 hours working with the 853s. The only ‘good’ thing I can say about these in particular is they don’t have the pry location cast in to them. I guess I’m just wondering what area of the 853 would need the most attention to get it to flow equal to or even a little greater than a STOCK 243.
Dont mean to come across as cheap. I enjoy taking things I already have and making them better. I have no problem spending the $ where necessary.
thanks for the quick response!
I know the 853 heads are frowned upon. I know the 243 are a better casting and people love them. What in particular lends them to flow so much better? Runner cc or shape? Finish? I wouldn’t mind sitting down and doing my best for 25-30 hours working with the 853s. The only ‘good’ thing I can say about these in particular is they don’t have the pry location cast in to them. I guess I’m just wondering what area of the 853 would need the most attention to get it to flow equal to or even a little greater than a STOCK 243.
Dont mean to come across as cheap. I enjoy taking things I already have and making them better. I have no problem spending the $ where necessary.
thanks for the quick response!
11-29-2018, 07:47 PM
#4
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The best porting on heads nowadays is done CNC, as it is repeatable forever. Hardly anyone hand ports anymore.
11-29-2018, 08:21 PM
#5
Sounds simple enough to me. Can stock injectors handle 400 or would I be on borrowed time with those? From what I can see in the intake runners on the head they were all spraying well/evenly.
I know the 853 heads are frowned upon. I know the 243 are a better casting and people love them. What in particular lends them to flow so much better? Runner cc or shape? Finish? I wouldn’t mind sitting down and doing my best for 25-30 hours working with the 853s. The only ‘good’ thing I can say about these in particular is they don’t have the pry location cast in to them. I guess I’m just wondering what area of the 853 would need the most attention to get it to flow equal to or even a little greater than a STOCK 243.
Dont mean to come across as cheap. I enjoy taking things I already have and making them better. I have no problem spending the $ where necessary.
thanks for the quick response!
I know the 853 heads are frowned upon. I know the 243 are a better casting and people love them. What in particular lends them to flow so much better? Runner cc or shape? Finish? I wouldn’t mind sitting down and doing my best for 25-30 hours working with the 853s. The only ‘good’ thing I can say about these in particular is they don’t have the pry location cast in to them. I guess I’m just wondering what area of the 853 would need the most attention to get it to flow equal to or even a little greater than a STOCK 243.
Dont mean to come across as cheap. I enjoy taking things I already have and making them better. I have no problem spending the $ where necessary.
thanks for the quick response!
katech charges 500 for a Cnc port work. But then again a stok 243 flows more and can get them for $300 all day.
11-29-2018, 08:31 PM
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Agreed CNC is the for sure way to go. I have read quite a bit of everyone’s experiences on here and other forums. Im still up in the air which way to go. Originally was sure I was going to pick up some 5.3 heads and go that route for the compression boost. But machining for the intake valve kind of turned me off that idea. And it seems milling the stock heads may hurt flow somewhat.
Back to the cam-112 or 114 lsa matter? Choppy doesn’t bother me, but not a necessity. Would rather not have a lopey idle to the point the ecm is hunting for the right rpm, weak brake vacuum, ac controls messing up, etc. Hopefully tune can take care of that? And looking at the dyno graph it’s not a very smooth climb. Is that common among the aftermarket cams aimed to meet this goal? Would rather move the power band down than up. After the long tubes is off road Y with SLP loud mouth. Anything past 6k is quite harsh (I don’t mind but neighbors in the next county might)
Back to the cam-112 or 114 lsa matter? Choppy doesn’t bother me, but not a necessity. Would rather not have a lopey idle to the point the ecm is hunting for the right rpm, weak brake vacuum, ac controls messing up, etc. Hopefully tune can take care of that? And looking at the dyno graph it’s not a very smooth climb. Is that common among the aftermarket cams aimed to meet this goal? Would rather move the power band down than up. After the long tubes is off road Y with SLP loud mouth. Anything past 6k is quite harsh (I don’t mind but neighbors in the next county might)
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11-29-2018, 09:27 PM
#9
99-00 fbody LS1's have 26# injectors. New ~ 450 whp was possible with the stock system. Injectors were static and spraying with intake valve closed.
My 99 TA made 418 whp and ran that way for 15 years & 130,000+ mile. However the stock fuel system definitely wasn't able to support that in the later years. The car "woke up" with a new Racetronix fuel system probably because the old stock fuel pump couldn't maintain the pressure at higher rpm.
I wouldn't trust a 99-00 LS1 stock fuel system in a 20 year old car to be able to support a good heads and cam package. New better fuel pump, filter and bigger injectors will help make sure the car makes good hp & keeps making good hp in the years ahead.
As Mavn said I skip the hand ported heads. You'll really have no idea what you've got unless all 8 ports are flow tested. There are a lot of good CNC probably and a few exceptional ones. You might get lucky and find a good set of ported used 5.3's with 2 inch or better valves or used ported243's on the classified section. Some 5.3's were prone to crack so be careful with getting a used 5.3 heads either ported or unported.
Looking forward to you'd build.
My 99 TA made 418 whp and ran that way for 15 years & 130,000+ mile. However the stock fuel system definitely wasn't able to support that in the later years. The car "woke up" with a new Racetronix fuel system probably because the old stock fuel pump couldn't maintain the pressure at higher rpm.
I wouldn't trust a 99-00 LS1 stock fuel system in a 20 year old car to be able to support a good heads and cam package. New better fuel pump, filter and bigger injectors will help make sure the car makes good hp & keeps making good hp in the years ahead.
As Mavn said I skip the hand ported heads. You'll really have no idea what you've got unless all 8 ports are flow tested. There are a lot of good CNC probably and a few exceptional ones. You might get lucky and find a good set of ported used 5.3's with 2 inch or better valves or used ported243's on the classified section. Some 5.3's were prone to crack so be careful with getting a used 5.3 heads either ported or unported.
Looking forward to you'd build.
11-30-2018, 10:00 AM
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Based on consensus I guess I’ll keep my eyes peeled for a set of 243/799s. Maybe I can make some table lamps out of the 853s🤔
With cams that have lift around the .600 range would there be any benefit to milling the 243 heads? Or am I making more work for myself with cutting reliefs?
With cams that have lift around the .600 range would there be any benefit to milling the 243 heads? Or am I making more work for myself with cutting reliefs?
11-30-2018, 10:24 AM
#11
Based on consensus I guess I’ll keep my eyes peeled for a set of 243/799s. Maybe I can make some table lamps out of the 853s🤔
With cams that have lift around the .600 range would there be any benefit to milling the 243 heads? Or am I making more work for myself with cutting reliefs?
With cams that have lift around the .600 range would there be any benefit to milling the 243 heads? Or am I making more work for myself with cutting reliefs?
You can mill your 243's .030 and still run that cam and have PLENTY of clearance.
11-30-2018, 04:53 PM
#13
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Whichever combo you pick,, it has to be tested by hand on the block, once you change cams.
Don't need the crank in, but you put the cam and valve train & heads in/on,, and check the valve sweep on every single one.
Some will say not necessary but I've been burned twice with "stock" heads with different pocket heights,, and not just a little off..
Example I did my 4 cylinder jeep head, had to cut 6 of the 8 spring pockets for a Clay Smith .560(IIRC) lift cam. YMMV..
Don't need the crank in, but you put the cam and valve train & heads in/on,, and check the valve sweep on every single one.
Some will say not necessary but I've been burned twice with "stock" heads with different pocket heights,, and not just a little off..
Example I did my 4 cylinder jeep head, had to cut 6 of the 8 spring pockets for a Clay Smith .560(IIRC) lift cam. YMMV..
11-30-2018, 05:15 PM
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I have been accused of being pretty **** upon reassembly. I can add this to the list.
on the suggested cam selections I will be a little more specific for the goal. If I had a choice between 400hp at a relatively lower rpm with more power down below and 425hp at a higher rpm with less low end, I’m going to pick the first. The 18 year old in me hates mid 30’s, more reasonable me.
Not saying the needle won’t see above 6k rpm couple times a week. I just don’t need an uber aggressive setup and go overboard at the expense of reliability.
thank you all
on the suggested cam selections I will be a little more specific for the goal. If I had a choice between 400hp at a relatively lower rpm with more power down below and 425hp at a higher rpm with less low end, I’m going to pick the first. The 18 year old in me hates mid 30’s, more reasonable me.
Not saying the needle won’t see above 6k rpm couple times a week. I just don’t need an uber aggressive setup and go overboard at the expense of reliability.
thank you all
11-30-2018, 05:52 PM
#16
Our high lift asa and milled (.030) unported 243s made 430/420 on a 99 m6 ta.
We also carry all of the rebuild/rering/reseal parts for the best price out there. Mix and match.
Our high lift asa cam and pac beehive springs are also on sale for $499 as well.
Great price, one stop shop, and everything you need. It has a 110 lsa so it has a very aggressive idle but will also peak a little sooner and give you much more useable power! Seems like exactly what you want.
We also carry all of the rebuild/rering/reseal parts for the best price out there. Mix and match.
Our high lift asa cam and pac beehive springs are also on sale for $499 as well.
Great price, one stop shop, and everything you need. It has a 110 lsa so it has a very aggressive idle but will also peak a little sooner and give you much more useable power! Seems like exactly what you want.
12-08-2018, 01:44 PM
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Went around to multiple junkyards today and the only 243 heads to be had weren’t for sale. They didn’t want to part out a good engine🙄. I found a few dozen 862 or 706 castings on 5.3 however.
I can get whatever heads I can find at LKQ for $50 each. So with being able to get a set of 862 or 706 for $100 would it be worth to go that route and use the savings to install the 2” intake valve in them? Or wait patiently for a 243 head engine to roll in and pray no one beat me to it (they would be $50 each too)? Would have to then pay to get the 243 heads milled...
I can get whatever heads I can find at LKQ for $50 each. So with being able to get a set of 862 or 706 for $100 would it be worth to go that route and use the savings to install the 2” intake valve in them? Or wait patiently for a 243 head engine to roll in and pray no one beat me to it (they would be $50 each too)? Would have to then pay to get the 243 heads milled...
12-08-2018, 02:47 PM
#18
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Look for 799's as they are identical to 243's and are in most pickups with a Gen IV 5.3.
12-08-2018, 03:03 PM
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I forgot to mention my search was for 799 and 243. Everything that SHOULD have had them was already picked over.
I know there are some for sale all the time but if I can get a pair for $100-200 local I would rather do that than $400-500 shipped. But I may have no choice!
I know there are some for sale all the time but if I can get a pair for $100-200 local I would rather do that than $400-500 shipped. But I may have no choice!
01-02-2019, 10:03 PM
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Got some 243 heads out of a 2007 Tahoe. Are the stock rockers the same between these and the stock 99 853 heads? Also I plan on an ls6 Intake. The 243s came with different steam tube and block off blocks. Will these work with the ls6 intake? Assuming the stock ls1steam tubes will not work with the flat bottom ls6 intake?
thank you
thank you