Head bolt torque settings?

[glennkil]

Whoops!! Left my manual (cd anyhow) at work. Can somebody please advise the correct torque settings for the head bolts on a 1972 25 HP Evinrude. Thanks for your assistance.

 

[glennkil]

Re: Head bolt torque settings?

Joe Reeves advised the follwing and I'm not going to second guess him only ask for clarification. 96 to 120 is a big range? Somewhere in the middle?<br /><br />Torque the head bolts to 96 to 120 inch pounds in the following sequence.<br /><br />9..10<br /><br />5...6<br /><br />1...2<br /><br />4...3<br /><br />8...7

 

[glennkil]

Re: Head bolt torque settings?

Sorry Joe, now I do have to second guess you because at 30 ft lbs the bolts felt like they we going to strip the threads out of the head and at 40 one did. ARRRRRRRGHHHHHHHH!!!!<br /><br />Surely this 90 odd foot pounds is WAY too high for an aluminium head and block.<br /><br />What do I do now???

 

[glennkil]

Re: Head bolt torque settings?

No!!! How dumb can I be!!! Inch pounds are not foot pounds. Any wonder they were tight.. The torque wrench I have is in foot pounds...<br /><br />What an idiot!! Hope I can get the thread re-tapped for a slightly bigger bolt. This or helicoil?? Either way I'm obviosly not going fishing this weekend.

 

[R.Johnson]

Re: Head bolt torque settings?

The easy route is the heli-coil. About the only place for a Ft/Lb wrench is the flywheel, and pinion gear nut on an outboard.

 

[willamettejeff]

Re: Head bolt torque settings?

Or just divide the inch/lbs by 12 to get ft/lbs I believe.

 

[glennkil]

Re: Head bolt torque settings?

Yep, 10 ft lbs is a far cry from the 30 that I had the head smashed down to. Heaven knows what damage I have done. Wonder if it is possible to pull the bores out of shape? I tried the bolt with the stripped thread without the washer and it grabbed up nice and tight at the right torque setting. Not ideal but I can live with it. The engine fired up first pull and I idled it for 15 minutes without problem. I cleaned out the water jackets in the block and head, checked the water tube, thermostat and impeller (new). If this thing overheats on the next trip I am going to convert it into an Evinrude 25 boat anchor.

 

[Walker]

Re: Head bolt torque settings?

If a stripped bolt caught by removing the washer then you have an infintesimal amount of thread holding it. Best go ahead and helicoil it now to save headaches later.

 

[Paul Moir]

Re: Head bolt torque settings?

Ft/lb reading torque wrenches are very commonly uselessly inaccurate at 10 ft/lbs. Get an inch/lb reading wrench and do it properly.<br />Helicoil is you're best option to repair the thread, because you won't have to drill the head to fit a larger bolt and also because you won't have to recalculate the torque value for the new thread pitch and diameter so you can get the clamping force right. If the bolt lets go after it's on the 2000 or so lbs of force the head sees at full throttle, exhaust gasses will leak into the cooling passages and cause an overheat.

 

[glennkil]

Re: Head bolt torque settings?

I agree the helicoil seems the best way but is it possible to install it without removing the head.? Is there enough clearance through the bolt hole in the head to get the tap through? I have already run the engine and don't want to replace the head gasket which is close to $50 over here.

 

[OBJ]

Re: Head bolt torque settings?

Glenn...you will need to drill an oversize hole and then thread it for the helix coil. I don't see any way around doing this without removing the head.<br /><br />Maybe on of the other guys will have a different point of view.

 

[glennkil]

Re: Head bolt torque settings?

Thanks for your advice OBJ. I feel like such a "num nuts" for doing this! Too used to torquing up iron heads on big V8's. You know the type that you stop when your elbow goes "click".<br /><br />If I have to remove the head gasket which at least shows no problems at idle what is the chance that I can re-use it? It is a black shiny type with the sealant probably being the shiny part of it. Can I reuse it by applying permatex on the faces?

 

[OBJ]

Re: Head bolt torque settings?

I would not advice reusing the head gasket Glenn. Once the ring is "crushed", reusing it will probably end up with a leak.<br /><br />And don't feel bad about the torquing.....we all make mistakes.....I striped a plug once once cause I can't cypher numbers on a torque wrench yet......happens.

 

[glennkil]

Re: Head bolt torque settings?

Hmmmmm, good point and I wonder just how crushed it is after smashing it down to three times correct tension and the backing it off?

 

[OBJ]

Re: Head bolt torque settings?

It's gonna' be......real flat......we (in the USA) say something like "Flatter than a pancake". I would suppose it would be flatter than that....

 

[Paul Moir]

Re: Head bolt torque settings?

I think we all hate giving bad news.

 

[glennkil]

Re: Head bolt torque settings?

Actually Paul bad news would be that I distorted the head or bores. (any chance I did this?)

 

[Paul Moir]

Re: Head bolt torque settings?

I don't think so. Since the bores are open deck, I really don't see how distorting the bolt holes can affect them.<br />The head is pretty tough but it's worth checking for warp. It's not unusual for them to be a little out and require surfacing. Surfacing, if necessary, should be done by hand so you remove the bare minimum of material to make it flat. Outboards normally don't take kindly to compression bump ups.

 

[glennkil]

Re: Head bolt torque settings?

Helicoil in stripped thread, checked head for flatness, torqured correctly. Water passages cleaned and thermostat and water pump checked. <br /><br />It flies!!! Thanks guys.. Ran it for 20 minutes yesterday at 75% throttle and it didn't miss a beat. Ran for 30 seconds or so at full throttle but I ran out of balls before the engine did. (only a small boat and it sure feels fast with this thing screaming its brains out over your shoulder) My 18 month old son sat up in his seat with the wind in his hair yelling out "BOAT, BOAT, BOAT!!)<br /><br />One quick question though, does the slow speed circuit have any effect on high speed operation? When operating at high speed is mixture a composite of both low and high speed circuits or just the high one? <br /><br />Thanks<br /><br />Glenn

 

[OBJ]

Re: Head bolt torque settings?

Your gonna get a little from the low speed jet (tube) Glenn....but the main flow will come from the high speed jet. Once the throttle plate cracks open, your taking fuel from the high speed jet.<br /><br />AND...on behalf of my trusted partners in crime her on forums.....congrats on a good job.....ENJOY!!