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  #1  
Old 10-05-2009, 11:57 PM
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Default Do head bolts REALLY need to be replaced w./ gasket change?

Hey all. Just came across a parts store saying that "head bolt changing recommended...Perma-torque-Severe-Duty". These were for Fel-Pro gaskets and a few other manufacturers too!

My question is do I REALLY need to repace them and why? Are they weak/flimsy as O.E.M. factory head bolts? I'd like to save money, but if you all think I should replace them, let me know. This motor supposedly has 170K on it, and the engine seems to be given an oil bath. I guess due to the head gasket rupturing, although so much oil seems bizarre to put it mildly!?

Anyone know what or why someone needs "Perma-Torque sever duty" head gaskets in the first place?- I mean, I'm not going to run the Mint 400, or the Baja 1000, just normal duty back woods cruising, but mostly on pavement...

Thanks for your time!
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Old 10-06-2009, 12:46 AM
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Well first of all, I always recommend replacing head bolts. From the stress of all of the heat cycles, firing, and torque, head bolts are the last thing you want to fail. They are like $12 a side if I remember correctly, and its good insurance. Some vehicles actually use 'torque to yield' bolts, meaning that they are torqued until the point of maximum stretching. These bolts can only be used once, and will fail if torqued again. These are usually torqued by inch/ft lbs, and then the final tightening is done with an angle gauge.

As far as the head gaskets, perma torque head gaskets are head gaskets that will not need to be retorqued once they have been run after the initial startup. It is usually necessary to retorque head gaskets after they have been initially run, and the permatorque gasket eliminates that need. You dont need to use them, but they are nice.
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Old 10-06-2009, 01:02 AM
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You should make sure to run a tap through the block where each head bolt goes in no matter if you buy new ones or not. You want to change the head bolts do to all the corrosion in the threads and since head bolts have also been know to stretch over time. You can reuse them if you must but they need to put through a die and cleaned at the very least. make sure to use thread sealant on all head bolts. Permatex #2 is what I is called for in the clymer book. I personal have always used Fel-Pro gaskets they seem to hold up better than others for me go pick up a set then coat them with copper head gasket spray doing 3 even coats on each side and stick them on the block I guarantee the gaskets wont slide at all.
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Old 10-06-2009, 01:20 AM
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Originally Posted by antything2 View Post
You should make sure to run a tap through the block where each head bolt goes in no matter if you buy new ones or not. You want to change the head bolts do to all the corrosion in the threads and since head bolts have also been know to stretch over time. You can reuse them if you must but they need to put through a die and cleaned at the very least. make sure to use thread sealant on all head bolts. Permatex #2 is what I is called for in the clymer book. I personal have always used Fel-Pro gaskets they seem to hold up better than others for me go pick up a set then coat them with copper head gasket spray doing 3 even coats on each side and stick them on the block I guarantee the gaskets wont slide at all.
Thanks anything2! I sometimes forget to tap out the old rusty bolt hole threads in the block-- LOL! Alot of us re-use the Mopar head bolts, but probably shouldn't... My Grandmother was from Bonne-Terre. Small world eh? I'm from Boonville,MO. Good ole' Dan'l (Boone), huh?!

Never used that copper gasket spray, but will give it a shot. I've always used Fel-pro too, for foregin and domestic. Even on the bi-metal motors the Toyota hemi's...{ 4-M, 6-M, and 7M ones}, they never blew out on me. None better (imo). Thanks again!
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Old 10-06-2009, 07:23 AM
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yes, you want to replace them. When head bolts are torqued they are supposed to stretch. They are only made to stretch once. if you reuse them you have a good possibility of one of them snapping which will cause big problems.
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Old 10-06-2009, 11:23 AM
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Quote:
Originally Posted by antything2 View Post
You should make sure to run a tap through the block where each head bolt goes in no matter if you buy new ones or not. You want to change the head bolts do to all the corrosion in the threads and since head bolts have also been know to stretch over time. You can reuse them if you must but they need to put through a die and cleaned at the very least. make sure to use thread sealant on all head bolts. Permatex #2 is what I is called for in the clymer book. I personal have always used Fel-Pro gaskets they seem to hold up better than others for me go pick up a set then coat them with copper head gasket spray doing 3 even coats on each side and stick them on the block I guarantee the gaskets wont slide at all.
you should never run head bolts through a die. not all die's are top quality, and can actually make the minimum minor diameter smaller, causing the bolt to become alot weaker. if you must reuse head bolts, your best bet is to clean them using a wire wheel on your bench grinder-follow the threads around the diameter of the bolt, never go side to side (ie; left to right, right to left) as you can actually "fold" the peak of the thread over, greatly affecting the proper torque reading.
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Old 10-06-2009, 01:13 PM
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I'd also recommend against using the spray on the head gasket. Most modern head gaskets are designed to be used dry. The dowel pins should hold the gasket on there fine without any sliding.
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Old 10-06-2009, 09:21 PM
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I only use high quality snap-on tools and do as I was told and taught by my father and other mechanics who do this for living. Head bolts should be replaced but if you don't have the money they can be reused and not all head bolts are the same some are not made to stretch on the first torquing but a set like that runs about 100 bucks from Raceware or ARP but they are well worth the money if you plan on building an engine and have to to pull the heads again any time soon like I did . I had my heads done by Tim,s Auto performance in Farmington Mo and that is how he recommed to put them back togaether with spray and said that my head bolts where good to go since they had only been torqued once and ran very little prior to having the heads ported and polished. I also recommend that everyone buy a clymer manual for there blazer if they don't have one it should be a big help to any one with questions like this. It is more convenient than the web since its right there and covers almost all trouble shooting problems that you can think of. Has all specs and complete tear down of everything but the transmission.
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Old 10-06-2009, 10:00 PM
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Quote:
Originally Posted by antything2 View Post
I only use high quality snap-on tools and do as I was told and taught by my father and other mechanics who do this for living. Head bolts should be replaced but if you don't have the money they can be reused and not all head bolts are the same some are not made to stretch on the first torquing but a set like that runs about 100 bucks from Raceware or ARP but they are well worth the money if you plan on building an engine and have to to pull the heads again any time soon like I did . I had my heads done by Tim,s Auto performance in Farmington Mo and that is how he recommed to put them back togaether with spray and said that my head bolts where good to go since they had only been torqued once and ran very little prior to having the heads ported and polished. I also recommend that everyone buy a clymer manual for there blazer if they don't have one it should be a big help to any one with questions like this. It is more convenient than the web since its right there and covers almost all trouble shooting problems that you can think of. Has all specs and complete tear down of everything but the transmission.

The spray is meant to be used on 100% metal head gaskets which are what is used in many racing applications. The metal gaskets are good for high cylinder pressures such as boosted applications or other high performance applications. The perma-torque gaskets are designed to be used dry it should even say so on the box.
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  #10  
Old 10-07-2009, 12:19 AM
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I would NOT run a tap through the bolt holes in the block because the tap actually removes metal in the block leaving it larger and now the bolt will fit loose. what you should do is run a thread chaser in there to only CLEAN the treads and not enlarge them like a tap does. i have been down this route before so know from past experience. summit racing and jegs both sell a thread chaser kit for about $14 buck....

and yes you can reuse the head bolts. you can use Napa gasket remover(by Permatex) in a spray can and it will disolve any crap on the bolt threads with ease....
Old 10-07-2009, 12:19 AM
 
 
 
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1979, 350, 43, blazer, bolt, bolts, change, chevy, gasket, head, olds, replace, replaced, reuse, sealer, silverado, thread


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