Hey everyone. Yes I know arp recommend 100lbs torque on them but do you guys actually torque it to 100 or more or less? I put together a lot of engines and after some years when I disassembled couple of them I found out cracks on the block from head bolt hole to the coolant passage. 2 engines that were torqued to 100lbs on 625 head bolts had cracks and another 2 engines that were torqued to 90lbs on l19 bolts does not have cracks. All engines had similar power on them and I am wondering if 100 lbs torque is too much for that block. I found out that there is a lot of distortion on the bore itself when torqued to 100lbs. I am wondering how far I can go with power/boost/timing on 625 bolts torques to 90lbs instead of 100lbs. Thanks!!

 

100ftlbs. Make sure you have the correct oversized nuts and washers. Generally what ARP supplies isn't big enough. Washer should be almost same diameter as the register in the head. And make sure the washer registers are machined flat.

If you have blocks cracking you have other issues. L19's will do 1000whp with proper setup/install, and good tune up.

 

Yes I do use oversized nuts and washers all the time. What other issue would you say it is if 2 blocks cracked at exactly same spot that has been torqued to 100lbs with 625 custom age bolts???. The funny think is those cracks does not do anything wrong being there. No head lifting no problems. I would never know that cracks are there if I would not disassemble the engine for refresh. Regular person that the engine was build for would never ever know about those cracks being there. I talked to Roni from Jrp performance and he did also noticed a lot of those cracks on his engines during disassembly, and he put them back in service with no negative results, so I strongly believe this is something about torquing it to 100 lbs. There is so much flex with that much torque applied and also there is a lot of flex pushing a lot of boost. So I think those 2 things combined causing that issue. I strongly believe that 1/2 fill concrete might be a solution for this because block will not flex as much on high boost but I am still considering to torque all new builds to 90lbs instead 100 lbs

 

I've never cracked a block around the head stud hole.

Are you chasing the threads in the block, and making sure the hole is 100% dry with no liquid at the bottom? Are you over lubricating the stud (too much lube gets caught in the bottom of the hole, and its not compressible, so it makes a bunch of pressure in there when you torque the stud)?

Are you leaving the stud just finger tight in the block prior to torqueing the nut like ARP says to?

 

Yes studs are finger tight and I always chasing the threads and always 110% dry no liquid at the bottom. I usually put just tiny bit or nothing lube on the side that going to the block. The cracks are not in thread itself, they are on the top of the block going from head stud hole to the water jacket ( hair line crack). I have picture somewhere so I will send later. I also talked to the class one machine shop ( known shop in illinois for 4g63 engines) and his answer was:
Those 63 blocks just dont like a high torque stud and high boost very long. I have seen a 4g63 blocks with 625 studs and 40 to 50 lb boost that split these in a few days after I put them together.

 

Who said that? Because I've never experienced this.

 

You probably never pushed them to this limit. Terry from Class One machine shop said that. He is located in freeport IL and he has been around 4g63 since they start making them.He was building 4g63's for rally for many years. Also Roni from Jrp performance in california experience those cracks and I did also.

 

Yeah. Don't mind me. I only have like several currently running around at 40-50psi and 800-1000 wheel horsepower. Good luck with your build, bud.

 

Dont take me wrong I am not saying you dont have 800-1000whp engines I am just saying that those cracks are pretty common and I believe that it is happening from all of combined 100lbs head studs plus 40-50 psi boost and a lot of timing and high compression, so in cylinders there is so much distortion that something has to give. Would they not crack if the tune would be softer maybe but It is weird that non of my builds cracked block on 90lbs torque but they did on 100 lbs and all of them has very similar tunes and has been tuned by myself. My next builds will all have 90 lbs torque on 625 head studs and I hope it will be enough to not lift the head and not crack the block. Have a good one.

 

I would not deviate from torque procedure the fastener manufacturer specifies. Going lower will result in less stretch and less clamping load.

The reason some blocks crack and others don't is likely due to core shift more than anything. Easiest thing to do is grind the crack out and weld in new material before the block gets decked.

 

I know some people don't like to weld cast iron but it can be done by experience welder. I might try to do that to be honest.

 

So i did a headgasket on my evo 8 today and notice the exact issue your talking about. hear line cracks from the head stud holes going to the coolent passage. the reason i did my headgasket was because i have a coolent pressure sensor and i notice my coolent pressure raising. My coolent temp is always normal never overheats. I figured i go ahead and change the gasket just to be safe. iam pushing 45psi and timing is by no means soft. my headstuds were torque to 100ft lbs. I have now torqued them even higher to 110ft lbs. i notice my headgasket compromised just a little in between the layer between cylinders 3 and 4 exhuast side, right where the M1 is stamped on the gasket. The top and bottom layer of the gasket is good but somehow inbetween the layer u can tell its been compromised. the head is also Copper O-ringed. Using the evo 9 headgasket. Ive look to make sure the cracks dont go through the coolent passage. So far it doesnt seem like it but i guess ill find out once i get it running in a day or so. Btw also using Arlington machines Oversized washers.

 

I strongly believe that those cracks happen from block flexing on high boost/power applications. Look like arp 625 studs and high clamping is trying to prevent block from flexing and block is cracking. I have never crack any block on l19 studs (90lbs) but I did a couple on arp 625 (100lbs) I am currently testing my personal evo now with arp 625 (95lbs) and block is 1/2 concrete filled. I believe that concrete will prevent block from flexing and it will not crack on those common places. Couple months ago I was testing one block with cracks. I torqued this block to 85lbs first on ne headgasket and I was driving the car for 2 weeks on lower boost (up to 30psi) no problems whatsoever no coolant disappearing nothing, than I re torqued the head to 95lbs and after another 2 weeks of driving it was low on coolant.I immediately knew why but for testing purposes I re torqued the head to 105lbs and after 4 days of same work-home trips it was low on coolant. Conclusion is that when cracks are there that block is basically garbage unless you lower clamping torque and power. Check you center layer of the head gasket. If its wavy it means you were lifting the head under boost.

 

With head studs doesn't matter if its 150hp engine or 3500hp Diesel engine. I have always put the studs in and back them off a 1/4 to 1/2 turn which relieves the chance of pressure cause by the stud driving further into the block like a nail setting tool as you torque the nut down.