1954 Evinrude Head Gasket Replacement

FlyBoy1976 · #1 October 26th, 2009, 10:14 PM

I have been restoring a 1954 Evinrude Fleetwin 7514 7.5hp. I finally have made it back to the Power head and was replacing the head Gasket.

Now here is where my problem comes in the manual says I need 90 - 95 inch pounds on these bolts. When I tighten them I get maybe to 20 on my torque wrench and they seem to give way. And I may have just solved my own dilemma as my torque wrench is in foot pounds not inch pounds, which means I way over torqued the ones I put in. Can I just re-tap the ones I messed up or do I need to do something else to fix this now?

Thanks for any and all help.

bktheking · #2 October 26th, 2009, 10:17 PM

Are you saying you stripped the threads in the power head? Sounds like it if it called for 95 inch and you put 20 ft. You will probably have to drill them out and helicoil them with an insert. I've never done one, maybe one of the experts on here can explain.

samo_ott · #3 October 26th, 2009, 10:23 PM

Yep. Drill em and retap next size larger. You should be able to do it without heli coils. And the aluminum is soft and easy to so. 95 inch pounds / 12 = ~8 foot pounds. Not very tight at all.

stingertrey · #4 October 26th, 2009, 11:40 PM

This is really helpful i have been wondering what the correct torque on the head bolts

FlyBoy1976 · #5 October 27th, 2009, 02:04 AM

Thanks for the quick replies I will try to get that done tomorrow. It may be a bit of a pain, but doesn't sound to hard.

Just for clarification the bolts were 1/4 - 20, 1 1/2 inch so the next size to step up to I believe would be 3/8 - 20?

Thanks again for the help.

F_R · #6 October 27th, 2009, 03:56 AM

Quote:

Originally Posted by FlyBoy1976

Thanks for the quick replies I will try to get that done tomorrow. It may be a bit of a pain, but doesn't sound to hard.

Just for clarification the bolts were 1/4 - 20, 1 1/2 inch so the next size to step up to I believe would be 3/8 - 20?

Thanks again for the help.

Nope, the next size is 5/16-18. Or maybe a Metric? I'm not up on Metric stuff.

However, my opinion is that you should install Heli-Coils. By the time you drill the holes in the head out to 5/16" + clearance, isn't the material around them going to be mighty thin? With Heli-Coils, you use the original bolts. Besides, seeing 5/16" bolts in there would arouse an instant suspicion that a shade-tree has been working on it and will destroy the originality and value of the motor. Right now you have a classic motor of interest to restorers. Cobble it up and you will have just another pile of aluminum. If you are going to do something, do it right.

samo_ott · #7 October 27th, 2009, 10:14 AM

That's the other method. Personally I'm not that keen on heli coils. I find they pull out over time. But now you have 2 different options.

As for the 5/16" bolts? They can have the same head size so not noticeable. and usually there's lots of material around the bolts to drill out... anyway... Your choice... or maybe others will weigh in...

bktheking · #8 October 27th, 2009, 10:35 AM

Samo, then you haven't been installing them right. Helicoils are stronger than tapped threads and if done right will last a lifetime. If you are worried about it send the block into a reputable shop and have them installed.

jay mendoza · #9 October 27th, 2009, 06:04 PM

Be sure to drill out the holes on a drill press so they are straight. You can then either re-tap for 5/16-18, or Heli-coil inserts. Be sure to use a bottoming tap for the inserts so the treads don't have a taper at the bottom of the hole, that would cause the Heli-coil inserters to bet tighter at the bottom once installed and cause the head bolt to bind in the threads.

If you go with inserts the only drilling will be in the block. If you go for bigger bolts, be sure to clearance drill the head, and holes in the head gasket as well for the larger bolts. You may want to check and see if there is enough meat around the holes before you decide which way to go.

samo_ott · #10 October 27th, 2009, 08:33 PM

Quote:

Originally Posted by bktheking

Samo, then you haven't been installing them right. Helicoils are stronger than tapped threads and if done right will last a lifetime. If you are worried about it send the block into a reputable shop and have them installed.

That is quite possible! And the main reason I like to over drill and tap. It's easy and always works and relatively cheap.

bktheking · #11 October 27th, 2009, 10:00 PM

I agree, sometimes you can't and have no choice but to coil them, oil passages and water jackets and everything else can get in the way. Winter's coming, good ole Ottawa.

1946Zephyr · #12 October 28th, 2009, 01:19 AM

7 millimeter is .276 diameter, which won't give you enough thread. 8 millimeter is .315 so if you go out to a 5/16" that would actually be safer. You'll have to tap it out larger for a helicoil anyways, but you'll have steel thread inserts, instead of aluminum threads, so it'll actually be stronger and less likely to be seized up years down the road. Use the 640 locktite and they'll never come out in a million years. Just make sure that you let it set up for several hours before you put a bolt in it, incase some gets on the inside portion of the threads