Help decide what block
Help decide what block Ok here are my plan 347ci, 6.0 heads, Diamond pistons, Eagle rods, stock crank, custom cam, Turbo tech T60-1 kit. The plan for the car is a daily driver that is raced at local events (streets) and 3-4 times a year to the drag strip.
With that said I have had issues with my block since it spun a rod bearing back last year sometime. I have rebuilt it but it had to be line bored because of the crank getting bent. Ever since then the oil pressure has been lower than stock so I have decided to use another block for this buildup.
Right now I have a iron 5.3 block sitting in the garage ready to be bored and to put all of the goodies into. Im now having second thoughts on weather to go with the iron block and bore it to 3.905 or just getting another aluminum block and just have it bored to 3.905.
Can you guys help me make my decision? I have a limited budget so if you can see some pros in useing the bored iron block please chime in. Thanks.
With that said I have had issues with my block since it spun a rod bearing back last year sometime. I have rebuilt it but it had to be line bored because of the crank getting bent. Ever since then the oil pressure has been lower than stock so I have decided to use another block for this buildup.
Right now I have a iron 5.3 block sitting in the garage ready to be bored and to put all of the goodies into. Im now having second thoughts on weather to go with the iron block and bore it to 3.905 or just getting another aluminum block and just have it bored to 3.905.
Can you guys help me make my decision? I have a limited budget so if you can see some pros in useing the bored iron block please chime in. Thanks.
Originally Posted by MYTURBOT/A
Whats the oil press. on your 347 block? Me personaly i`d try to stick with the 347 or sell that 5.3 to buy a 6.0 block. How far over did they go on the line bore?
Why do you think I should go with the iron block? You really didnt say. I mean its really on about 60-65 lbs more than the alum. block.
An iron block is more like 105lbs difference. Do a search and you will see actual weights. The advantage the 6.0 iron block is the extra cubes, its cheap ($595 at gmpartsdirect.com), it IMO, it think its stronger than an alum block. Since I'm going turbo, I went with iron but I think an alum block can take the stress of FI. I just wanted something that was affordable and could live if I went with 15+psi of boost. Not saying alum can't. I think the extra cubes will make up for the added weight. If I was doing more road racing, I'd stick with alum.
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The reason your pressure is low is because your clearances are too wide. I`d take it back to them and have them do it right. line bore it .010 over and install .010 over bearings.(How could they take it back to stock specs. after removing material from the block) Sounds kinda shady. The reason that i would not advise going with the 5.3 block is because when you bore a block the cylinder walls get thiner. by the time you bore the cylinders out to get back to 5.7 liters, you have an extra 100lb of weight, cylinder walls that are weaker and the same CI you had before. Where if you started with the 6.0 block yes the cylinders will still be weaker but at least you`ll have more cubes then you started with to makeup for the extra weight. But you also have to figure that that little 60-1 turbo is huff`n to supply air for 346ci, strap it on a 372ci motor and that turbo will be about worthless IMO. After seeing people push 700rwhp with the aluminum block, It`s strong enough for my hp goals. The iron block is not worth the extra weight in a turbo application. (just my opinion) 
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Originally Posted by MYTURBOT/A
How could they take it back to stock specs. after removing material from the block) Sounds kinda shady. The reason that i would not advise going with the 5.3 block is because when you bore a block the cylinder walls get thiner. by the time you bore the cylinders out to get back to 5.7 liters, you have an extra 100lb of weight, cylinder walls that are weaker and the same CI you had before.
The 5.3 liter block is capable of being bored back to 3.905 per Wade at ARE. I also told him that I was going to be putting a turbo on the car and he said the thickness of the wall is still thick enough for a FI setup. He explained that they just finished a 5.3 bored for a twin turbo setup.
So you think just have my alum block bored to 3.905 run the over sized bearings and forgetting the 5.3 block?
.0021 is not too big. They explained the align bore process to you perfectly. You may be losing pressure through other areas. Typically, a cap is cut .0003" to .0004". Caps are retorqued, and align hone done to acheive stock bearing diameter. Simple process.
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silverchicken, I think you should just do a built 346 or 348, there a lot of us pushing 600+ with that motor and if you are doing a t60 then I think anything bigger will not work with that turbo. unless you go to like a 80mm
Originally Posted by scott ws6
silverchicken, I think you should just do a built 346 or 348, there a lot of us pushing 600+ with that motor and if you are doing a t60 then I think anything bigger will not work with that turbo. unless you go to like a 80mm
Im not sure where else I would be losing oil pressure. Where should I look when I take it out this time?
Correct me if im wrong but arent +1 bearings oversized by .001? If that is the case could I just get that set and lower my clearance to like .0011 and may cure some of my oil pressure issues? I think since im on the high side of the allowable bearing clearence and that is why its lower.
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If your current clearance is .021 then using a .010 over bearing will drop the clearance down to .011 When you order the bearings just tell them you want 10 over main bearings. If you look at the back of a stock bearing it`ll have STD. stamped in it meaning standard. The .010 over bearings will have .010 stamped where the STD was. After you install the new bearings Plastigause all your clearances again make sure nothing is to tight. I like to keep my rod and main clearances at the tight end of the allowable clearance. They also make somthing called shim stock for adjusting clearances it`s kinda like tin foil that you place between the back of the bearing and the cap or block to help tighten things up but thats kinda getto and i don`t recomend doing it unless you have no other choice. I did this on a 72 454 chevelle The customer did not want to do all the machining and stuff for the oversize bearing so he insisted we do the shiming last i heard the car was still running great so it does work.
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From: Downers Grove,IL
.002" is NOT to loose. Infact for a serious motor I think it's a bit to tight but probably fine.
You sure as heck don't want .001" IMO.
Are you using a 3/4 grooved main bearing?
I run .0025"~.003" on my 347. I use the 3/4 grooved fed-mog racing mains and tri metal rod bearings.
Oil pressure is lower at idle mainly because of the increased oil to the rods from the 3/4 grooved mains.
Try shiming your oil pump relief spring. I use a .145" shim in mine and 15/50 mobil1 oil.
Gives about 40psi at idle and 65 or so at WOT.
No shim and dino oil had me at 20psi idle hot with this motor.
Steve
You sure as heck don't want .001" IMO.
Are you using a 3/4 grooved main bearing?
I run .0025"~.003" on my 347. I use the 3/4 grooved fed-mog racing mains and tri metal rod bearings.
Oil pressure is lower at idle mainly because of the increased oil to the rods from the 3/4 grooved mains.
Try shiming your oil pump relief spring. I use a .145" shim in mine and 15/50 mobil1 oil.
Gives about 40psi at idle and 65 or so at WOT.
No shim and dino oil had me at 20psi idle hot with this motor.
Steve
Originally Posted by S_J_H
Are you using a 3/4 grooved main bearing?
I run .0025"~.003" on my 347. I use the 3/4 grooved fed-mog racing mains and tri metal rod bearings.
Oil pressure is lower at idle mainly because of the increased oil to the rods from the 3/4 grooved mains.
Try shiming your oil pump relief spring. I use a .145" shim in mine and 15/50 mobil1 oil.
Gives about 40psi at idle and 65 or so at WOT.
No shim and dino oil had me at 20psi idle hot with this motor.
Steve
I run .0025"~.003" on my 347. I use the 3/4 grooved fed-mog racing mains and tri metal rod bearings.
Oil pressure is lower at idle mainly because of the increased oil to the rods from the 3/4 grooved mains.
Try shiming your oil pump relief spring. I use a .145" shim in mine and 15/50 mobil1 oil.
Gives about 40psi at idle and 65 or so at WOT.
No shim and dino oil had me at 20psi idle hot with this motor.
Steve
This is going to be the third time tearing into the motor. Should I replace the main bolts or reuse the other ones?
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From: Downers Grove,IL
I have a friend who also installed these same bearings and had a big drop in oil pressure when hot from the stock bearing setup.
I just made a shim and installed it under the spring. About .145" did the trick.
Also switching from 10-30 dino oil to 15-50 mobil-1 made a big difference in hot oil pressure.
I just made a shim and installed it under the spring. About .145" did the trick.
Also switching from 10-30 dino oil to 15-50 mobil-1 made a big difference in hot oil pressure.
