Tecumseh engine head bolt question

[johhnyx]

Hi
I have an older Tecumseh H60 (6HP horizontal) engine. I had to pull the head gasket to change it, and several of the head bolts were rusted severely, so they got mangled upon removal.

Now you know since the head is flat, I just assumed when I took them out (and I was cursing the rusted ones anyway) that they were all the same, so I didn't pay any attention to what bolt went where.

I went to the outdoordistributors dot com web site and used their online parts diagram. It lists the following head bolts, (item 36 on their list) but does not list quantities or locations:
650697 5/16-18, 2 1/2
650695 same, 2 1/4, Grade 8
650694 same 2"

So, interestingly, the 1st and the 3rd numbers are about a buck each at outdoordistributors or jackssmallengines, but the middle one is two bucks. It was the only one listed as a Grade 8.

My questions to any Tecumseh expert:
1. Do they use all the same bolts, or do I need to measure the depth of each tapped hole in the cyl block?
2. If they are mixed, why?
3. Should I use the Grade 8 for all of them?
4. Why the price difference if they're all grade 8?,etc.

This engine if probably from the late 60s, an Ariens snowblower. I have no idea if it's original or they ever worked on it. It was running when I got it, but I had to take it apart for various reasons.

Thanks for any help,
John

[HayZee518]

look for six notches or lines in the head of the bolt. the lines or notches indicate the amount of torque in ft-lbs. I believe 6 notches is 600 foot lbs. so when you check the torque specs on your specific engine, I think you'll be right in the ball park.

[johhnyx]

look for six notches or lines in the head of the bolt. the lines or notches indicate the amount of torque in ft-lbs. I believe 6 notches is 600 foot lbs. so when you check the torque specs on your specific engine, I think you'll be right in the ball park.

Thanks for the reply, but that isn't really what I was asking.
I was talking about choices of length, and whether I would have to try to measure each hole depth now that I've mixed up their locations and busted a couple of bolts. Perhaps I wasn't completely clear.

BTW, six lines on a SAE bolt head indicate grade 8; they are two above the number of lines, i.e. 3 lines=grade 5.

For a 5/16-18 dry torque, I'd suggest about 25 foot-pounds max. Times 12 to convert to inch-pounds would be 300 inch-pounds. I don't know where you'd get a 600 foot-pounds bolt. Maybe some space-age material!

[HayZee518]

yeah, I would check the depth of the block and subtract a quarter inch.
2 5 7 8 SOCKET HEAD CAP SCREW
I.D. Marks No markings 3 lines 5 lines 6 lines Allen head
Material Low carbon Medium-carbon, tempered Medium-carbon,
quenched & tempered Medium-carbon, quenched & tempered High-carbon, quenched & tempered
Tensile strength (Minimum) 74,000 psi 120,000 psi 133,000 psi 150,000 psi 160,000 psi
Bolt Dia. Thread per inch Dry Oiled Dry Oiled Dry Oiled Dry Oiled Dry Oiled
1/4 20 4 3 8 6 10 8 12 9 14 11
1/4 28 6 4 10 7 12 9 14 10 16 13
5/16 18 9 7 17 13 21 16 25 18 29 23
5/16 24 12 9 19 14 24 18 29 20 33 26
3/8 16 16 12 30 23 40 30 45 35 49 39
3/8 24 22 16 35 25 45 35 50 40 54 44
7/16 14 24 17 50 35 60 45 70 55 76 61
7/16 20 34 26 55 40 70 50 80 60 85 68
1/2 13 38 31 75 55 95 70 110 80 113 90
1/2 20 52 42 90 65 100 80 120 90 126 100
9/16 12 52 42 110 80 135 100 150 110 163 130
9/16 18 71 57 120 90 150 110 170 130 181 144
5/8 11 98 78 150 110 140 190 220 170 230 184
5/8 18 115 93 180 130 210 160 240 180 255 204
3/4 10 157 121 260 200 320 240 380 280 400 320
3/4 16 180 133 300 220 360 280 420 320 440 350
7/8 9 210 160 430 320 520 400 600 460 640 510
7/8 14 230 177 470 360 580 440 660 500 700 560
1 8 320 240 640 480 800 600 900 680 980 780
1 12 350 265 710 530 860 666 990 740 1060 845

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[mrcaptainbob]

Head bolts....

Jack's Small Engine is a great place to work with. Give them a call and tell them your dilemma. They're sure to help. You can also join this Yahoo group and post there. Lots of help available.
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