Head Bolt Check

[FreeBeeTony]

I keep hearing about head bolts "stretching".<br /><br />Is there a way to check them? How about if I measured them with calipers? Would I be able to tell?<br /><br />The only reason I am concerned is that I didn't find a "blown" head gasket but I was definitly "eating" anti-freeze in one of my cylinders and, the only thing I did find was that the bolts on that side didn't seem tight enough.<br /><br />Could they have stretched? Or maybe they weren't torqued properly to begin with.<br /><br />That's why I am wondering if I can check them to see if they are any good..........

 

[TilliamWe]

Re: Head Bolt Check

I am sure that there are specs somewhere,and you can measure them. Or you could but one new one, of each of the three lenghts, then compare your old ones against them.

 

[Zamboni]

Re: Head Bolt Check

Far more likely they were not properly torqued, correct sequence etc...need to go back at them as the gasket compresses. Another possibility is low grade washers were used...many mechanics don't realize when they use a crap flat washer with a grade 8 fastner it will just dish or actually compress causing failures.

 

[FreeBeeTony]

Re: Head Bolt Check

There weren't any washers.............

 

[KaGee]

Re: Head Bolt Check

Tony if there is any question at all I'd put a new set on. You're not talking that much money.<br /><br />Oh, and I don't believe there are any washers on SBC head bolts, as far as I know.

 

[rbezdon]

Re: Head Bolt Check

Tony, definately no washers on the head bolts and for the same reasons your are asking I bought a new set of bolts when I did my head gasket and of course, I got a bad bolt in the new set. Broke right off when I went to applt y the final torque. My point is, you cant know 100% you have perfect bolts BUT, there an awful lot of SBCs out there running fine so just get a new set (about $35) and hope for the best.

 

[Destin]

Re: Head Bolt Check

If you buy new head bolts I would recommend ARP high performance head bolts. They apparently provide 25% stronger clamping force than stock. If you go to http://www.arp-bolts.com/ and download their 2005 catalog, they have some interesting technical articles on bolt stretch, torqueing with and without assembly lube, and the proper installation of head bolts. JEGS has them (PN 070-134-3601) for 49.99 plus 9.99 handling with free shipping. They also have ARP assembly lube 6.99 and ARP thread sealer 8.49.<br /><br /> I bought an ARP Head Bolt Set for my 5.7L Chevy (haven't installed them yet). An instruction sheet cam in the box. My stock bolts are supposed to be torqued to 65 ft-lbs. <br /><br /> The following are the instructions that came with my kit:<br /><br /><br /> Automotive Racing Product Tel: (805) 339-2200<br /> 1863 Eastman Avenue Fax: (805) 650-0742<br /> Ventura, CA 93003<br /> <br /> <br /> INSTALLATION METHOD FOR HEAD BOLT KITS HIGH PERFORMANCE SERIES<br /> 170.000 Psi 7/ 16-inch Diameter<br /> To ensure proper thread engagement and accurate torque readings, clean and re-tap. If necessary<br /> ALL threads in the block<br /> [2] Clean and inspect all hardware prior to installation. Look for obvious defects or shipping damages.<br /> plus proper fit, length and dimension.<br /> [3] a. IF cylinder head bolts protrude into the water jacket, lubricate the threads of the bolts with<br /> ARP Thread Sealer.<br /> b. If cylinder head bolts protrude into blind hole, lubricate the threads with ARP MOLY<br /> ASSEMBLY LUBRICANT or a 30wt motor oil.<br /> [4] Install cylinder heads and check for binding or misalignment.<br /> [5] ARP recommends using the ARP MOLY LUBRICANT or at the very least, a good quality Moly<br /> Lubricant as opposed to motor oil. This is due to higher friction on the bolts as well as<br /> inconsistencies in the clamping force of the fasteners when motor oil (or low quality lubricant) is<br /> used.<br /> PRELOAD (TORQUE) RECOMMENDATIONS:<br /> [A] Torque values are based on 75% of the fasteners yield strength. Use the manufacturers torque<br /> sequence but do not use the engine manufacturers torque specs. Torque the bolts to 65 ft lbs for<br /> ARP MOLY ASSEMBLY LUBRICANT (or ARP THREAD SEALER) or torque to 85 ft lbs with 3Owt<br /> motor oil.<br /> [D] Due to the heat expansion rate of ALUMINUM, It is recommended that the torque should be 60 ft<br /> lbs with ARP MOLY ASSEMBLY LUBRICANT (or ARP THREAD SEALER)

 

[Scaaty]

Re: Head Bolt Check

Tony, all bolts stretch. Thats whats makes them work. Some newer applications are 'Torque to Yield" and are onetime use only. Buy only the ARP bolts..period. Nice post Destin....

 

[FreeBeeTony]

Re: Head Bolt Check

So maybe I should just go with what I have.......<br /><br />Depending on the weather I amy try to install heads tomorrow!

 

[Friz]

Re: Head Bolt Check

Companies also sell "Bolts that never need retorqueing" and "head gaskets that never need retorqueing". Don't believe it. All SBC heads need to be retorqued at least twice to ensure that the gasket has compressed all it will compress and that the bolts will not stretch any further.<br />Replace the gaskets and/or bolts, torque to specs, heat up the engine, let it cool, retorque, repeat.

 

[Buttanic]

Re: Head Bolt Check

Re-torqueing head bolts after running the engine is not necessary if proper assembly instructions are followed. The shim type head gaskets do not need to be re-torqued. The procedure for composition type gasket is to torque them to specs, allow 10 minutes for gasket to compress, loosen one bolt at a time 1/8 to 1/4 turn and re-torque to spec. Only on race engines is it a good pratice to re-torque after a heat cycle. You would have to remove the manifolds and valve covers and whatever else that would be in the way and would be a lot of unnessary work and expense (new manifold gaskets). Do use harden washers under the bolts available at NAPA. I don't feel new bolts are necessary. Bring them up to spec in 3 to 4 steps

 

[FreeBeeTony]

Re: Head Bolt Check

Thanks Buttanic.......so after I torque, I loosen each bolt, one at a time, and then retorque to spec.

 

[Friz]

Re: Head Bolt Check

I disagree with Buttanic.<br />I have been building Chevy motors for over 20 years. Stock, mildly modified, heavily modified, they are all the same.<br />Torque your heads as prescribed by the manual. Run a heat cycle and retorque. You don't have to loosen them, if the bolts have stretched or the gasket has compressed, they'll move. Retorque in the order that the manual prescribes. Depending on gaskets and bolts, you may only have to do it twice. If the bolts do not turn on the second torque cycle, you are good to go.<br />On a SBC, you don't have to remove the exhaust manifolds. All the head bolts are under the valve cover.

 

[Bt Doctur]

Re: Head Bolt Check

Better check again,Fritz. there is a set just under the spark plugs on GM heads.

 

[Buttanic]

Re: Head Bolt Check

I don't know what SBC's you work on but the short bolts are under the exhaust manifolds where the spark plus are. You don't re-torque them. What's the point of doing just those under the valve covers. There are ten's of thousands of SBC's running in boats and cars that have never been re-torqued after a heat cycle. Re-torqueing is fine if you have the engine on the dyno sitting out in the open and only have to pull the dyno headere to do it but if he has to put it in the boat to run it it may be a major job to pull the water cooled manifolds to get at the lower row of bolts and it's just not necessary. Plus the valve covers may not come off with the manifolds in place.

 

[Don S]

Re: Head Bolt Check

Ya Gotta Love It, ..... Valve job by committee.<br /> Choose the answer that most suits your frame of mind for the day, and go for it.<br /><br />Another possibility is follow the OEM (Mercruiser) service manual (TO THE LETTER) for your engine. You did say you bought one, use it!<br />No fancy head bolts, torque to specs, with clean bolts and threads, use sealer, and they work. Use the OEM gaskets, set things to OEM specs and it WILL work.<br />Right now, I see a couple of thousand more posts to get the heads and manifolds back on, then on the first test run, it's going to go 3200 rpm and no more. Then we will be in place for another summer of fun.<br /><br />The SBC does not use ONE TIME ONLY head bolts.<br />They do not have washers.<br />They do not need retorqued 2 or 3 times.<br /><br />Geeezzzz Tony, all you are doing is making the job more difficult with all the questions when you have the answers in your BOOK.

 

[FreeBeeTony]

Re: Head Bolt Check

Don........I appreciate your knowloedge and agree with it. I am just looking for a little more info.<br /><br />Yes, I have the manual and read it almost every night and am going to follow it......I heard rumors about this bolt stretching and wanted another opinion..........that's all. I didn't want to go through this whole process and have another problem.<br /><br />And BTW.......thanks for the vote of confidence, it's really appreciated.........<br /><br />Are the long nights getting to you up there? Or is it the days.........

 

[KaGee]

Re: Head Bolt Check

Don gives the final word! <br /><br />I just wanted Friz to know we are working on Marine Engines... not auto. <br />

On a SBC, you don't have to remove the exhaust manifolds. All the head bolts are under the valve cover.

BtDoctur already pointed out the obvious. On my engine, you cannot remove the valve covers without first removing the exhaust manifolds. So, is there a trick to that that I've overlooked? <br /><br />Tony, <br />Everything Don said is the same that is in my OMC manual. The ONLY thing I did different, based on reccomendations of the headgasket manufacturer was to progressively torque the bolts i.e I torqued them in order to 30, then to 60 and then to spec.

 

[Friz]

Re: Head Bolt Check

My bad on the bolt location. I don't know what I was thinking about at the time.<br />Since I'm not very experienced on marine engines, I didn't consider the water cooled manifolds, either.<br />But I will stand on my experience with retorqueing the heads. Do it, don't do it, it's your motor, but I always will.

 

[FreeBeeTony]

Re: Head Bolt Check

Don does not have the final word.........he just thinks he does!