Head bolts for an EM1 engine
 

I need to replace the head bolts on my 1980 Honda Civic Wagon. It has a 1.5L EM1 engine. Apparently, it uses bolts called torque to yeild which have to be replaced once removed. Anyone know where to find some, or maybe there is some suitable substitution out there? Thanks!

Re: Head bolts for an EM1 engine
 

The bolts on the early Hondas are reusable but a back up is to replace them with grade 8 equivalent metric studs. The key to using the original bolts is to re-torque often during the first 10,000 miles.

Are you doing a complete rebuild or did a head gasket blow?

Re: Head bolts for an EM1 engine
 

Sorry for resurrecting an old thread, and also for a very late response. And thanks for the reply GrumpyOne. :)

So back when I posted my original question, the engine was getting rebuilt, and the mechanic was having difficulty finding new head bolts. He eventually found some for a different engine, though I never was able to find out which one.

Since then, my head gasket has developed a small leak. Seems I'm losing coolant into the oil. Maybe a stop leak product will work, but I'm thinking I'll eventually have to replace the head gasket. Replacement studs sound promising. I don't mind re-torquing every now and then. It's easy enough to get to them.

Re: Head bolts for an EM1 engine
 

If you replace the head gasket, I would re-use the bolts that you have or better yet, the originals if you still have 'em. Studs are a last resort as the grade 8 equivalent material is not readily available. Be sure to copper coat, (spray), the gaskets prior to re-assembly.

BTW, how did you make out with the carbs that I sent you a few years ago?

Regards,

JT

Re: Head bolts for an EM1 engine
 

I got some replacement parts from the incomplete one already, and the complete one, I'm using as a reference to make sure all the linkages get put back right on others.

My original carburetor is now only good for parts. the cover has broken in several spots now, so I can't use it. I've been using another carb on the car for the last 3 years or so, and it's working well. I think the jets may be too small, but I haven't had a chance to look into it yet. I've never played with jet sizes before, so that will be something new.

I've also got a carburetor off a parts car that is all rebuilt and ready to go if it's ever needed. And I recently found another one from a fellow who swapped out with a Webber. So I now have 6 carburetors in total. Eventually, I'll rebuild all the ones that can be, and save them for either when I need them, or in case someone else does.

The original head bolts are long gone, but I could scavenge some from a parts car. Supposedly, it's engine is seized, but I haven't gotten around to confirming that yet. So if I were to go with studs, I'd be looking for grade 8 fastener steel. I'll have to look into that. I'm pretty clueless as to what those classifications mean. I probably won't be doing any disassembling until this summer though, so I have time.

Re: Head bolts for an EM1 engine
 

Grade 8 vs the other
EZ Bolt Grade Markings | GTSparkplugs

it is always the dilemma, grade 8 will brake and grade 5 will stretch or is it myth?

also from the head bolt makers
https://www.arp-bolts.com/p/technical.php

The grade 8 bolts you may use for everything else are not the right alloy for head retention, they do not retain the propper clamping force after they are tightened. Buy a set of ARP bolts of better yet studs and don't worry about it

from
https://www.fordmuscleforums.com/thr...-bolts.415217/

Re: Head bolts for an EM1 engine
 

Thanks! My email notification for this thread ended up in my spam folder, so I just now found it. I've checked out ARP's website. They don't have anything that will fit my car listed, but it looks like I may be able to ask them for a custom set. Trouble is, the M10-1.25 size seems to be quite rare. Also, since I haven't pulled any out yet, I don't know how long they'd need to be.

At the moment, I'm testing out the engine after the current head bolts got re-torqued. And I still haven't gotten around to checking the condition of the engine in my parts car. But I will keep ARP in mind if and when I do get hold of a head bolt that's been removed from the engine. :)