Are 2-1/2 inch Head Bolts OK ?

[RTR]

Had a blown head gasket on a 50 model 8n tractor and found that the head has severe pitting inside and has marks where a valve has contacted it before so Im gonna buy a new aftermarket head from Tisco. Engine runs perfect other that the oil mixing with coolant in radiator and Vice Versa.

My question is that the original head bolts seem fine but I would rather replace them. I cant find the original size of 2-3/8 long and our bolt bin at work has GR 5, 2-1/2 bolts. Ive heard of using flat washers to make up the longer bolt length but would rather not use flat washers in fear of messing up the torque of the head bolts. Will the extra 1/8 inch of length in the bolt mess anything up? I notice that several aftermarket sites sell the bolts (assuming 2-1/2 long) and dont mention any disclaimers.

 

[TheOldHokie]

(quoted from post at 22:47:04 04/25/22) Had a blown head gasket on a 50 model 8n tractor and found that the head has severe pitting inside and has marks where a valve has contacted it before so Im gonna buy a new aftermarket head from Tisco. Engine runs perfect other that the oil mixing with coolant in radiator and Vice Versa.

My question is that the original head bolts seem fine but I would rather replace them. I cant find the original size of 2-3/8 long and our bolt bin at work has GR 5, 2-1/2 bolts. Ive heard of using flat washers to make up the longer bolt length but would rather not use flat washers in fear of messing up the torque of the head bolts. Will the extra 1/8 inch of length in the bolt mess anything up? I notice that several aftermarket sites sell the bolts (assuming 2-1/2 long) and dont mention any disclaimers.

It won't matter. Trim them with a hacksaw or cutoff wheel on 4" angle grinder if it keeps you awake at night. Lay off the washers.

TOH

 

[lha]

I found some correct ones at an industrial supply in a small Town near my home. When I asked if they were grade 8,but he said that
they were harder as they were made for big stuff. If you plan to cut them off,thread a nut on,then it will clean the threads when
you remove it.

 

[Ken-Ark]

They should all go into the water jacket . Check to see if you have clean threads deep enough . The space below the end of the old bolt may have had a calcium build up and baked by the heat of the exhaust ports . If you run out of clean threads you can crack the block when you torque the bolts .

 

[RTR]

(quoted from post at 00:16:04 04/27/22)
They should all go into the water jacket . Check to see if you have clean threads deep enough . The space below the end of the old bolt may have had a calcium build up and baked by the heat of the exhaust ports . If you run out of clean threads you can crack the block when you torque the bolts .

Ok good to know. I'll use Grade 5 bolts, 2-1/2 inches long without the washers.

 

[8NChris]

The bad thing about going long into a coolant jacket is the exposed threads will tend to build up corrosion. Removing will force the fatter threads through a smaller hole. You risk breaking the bolt when removing. From a washed up auto technicians point of view it was not uncommon to break bolts or crack a boss in that scenario. When one broke one off in my own 8N last year I was sorta paranoid about cracking the thin boss in the corner. When the welding trick twice failed I played it safe and drilled out the bolt. This was on a 226, the two blind hole bolts came out fairly easy compared to some of the others.

 

[ASEguy]

When bolts go through coolant jackets, and are close to the same size, your only real concern is thread engagement. If the threads are similar length in the right places, use them. Manufacturers usually make the bolt holes a little deeper than needed anyway. A washer is fine. Don't cut graded bolts because they are coated to resist rust. Most manufacturer's require lubricated threads, so make sure to use a thread sealer on any bolt that goes into a coolant passage. I use the small tubes you can purchase from auto parts stores. I would also use a thread chaser in the block holes to clean them up prior to reassembly. Hope this helps.

 

[ASEguy]

As stated, measure the holes if they are blind. Corrosion develops because the antifreeze additive package is worn out or not using distilled water to mix/add to coolant.

 

[TheOldHokie]

(quoted from post at 14:05:09 04/27/22) The bad thing about going long into a coolant jacket is the exposed threads will tend to build up corrosion. Removing will force the fatter threads through a smaller hole. You risk breaking the bolt when removing. From a washed up auto technicians point of view it was not uncommon to break bolts or crack a boss in that scenario. When one broke one off in my own 8N last year I was sorta paranoid about cracking the thin boss in the corner. When the welding trick twice failed I played it safe and drilled out the bolt. This was on a 226, the two blind hole bolts came out fairly easy compared to some of the others.

The OEM bolts and studs all go into the water jacket. That extra .125 inch wont change much.

Standard procedure for removing any through fastener that is subject to corrosion is to back it out in stages - loosen a half turn then tighten a quarter to clear corrosion caught in the threads. Repeat until fully out. Just cranking on them will almost always break them. Using the staged method success rate on OEM studs is probably around 75%..

TOH.

 

[8NChris]

Your explanation backs up what I said. Thank's

A little extra effort initially will just about do away with the 25% failure rate.