Engine Ground Bolt

[Caman96]

My buddy mechanic lent me his distributor wrench for my truck. When I looked at it, it was 1/2”, I told him everything I researched said it was 13mm. He insisted it would work and it was his GM distributor wrench. It would not fit period! He laughed and said lookout… let me try. NOPE, wouldn’t work. I grabbed my 13mm wrench, fit perfectly, although a PIA to use a typical wrench.

 

[Nad_Yvalhosert]

My buddy mechanic lent me his distributor wrench for my truck. When I looked at it, it was 1/2”, I told him everything I researched said it was 13mm. He insisted it would work and it was his GM distributor wrench. It would not fit period! He laughed and said lookout… let me try. NOPE, wouldn’t work. I grabbed my 13mm wrench, fit perfectly, although a PIA to use a typical wrench.

1/2" technically is 12.7mm

I've got one of those old SAE distributor wrenches. Wish I could find a metric one...

 

[454cid]

My buddy mechanic lent me his distributor wrench for my truck. When I looked at it, it was 1/2”, I told him everything I researched said it was 13mm. He insisted it would work and it was his GM distributor wrench. It would not fit period! He laughed and said lookout… let me try. NOPE, wouldn’t work. I grabbed my 13mm wrench, fit perfectly, although a PIA to use a typical wrench.

Yes, every so often I find a 13mm fastener that's too big for a 1/2" wrench.

 

[Schurkey]

I've got one of those old SAE distributor wrenches. Wish I could find a metric one...

54 hits on eBay. Prices vary considerably. Here's four random 13mm samples:
www.ebay.com/itm/125419491133?hash=item1d33958f3d:g:2fgAAOSwGC9i0vPL&amdata=enc%3AAQAIAAAA0AAsUQqS%2BSk9RiCBAqycRZyng7jgoQvX%2BDM9lieATbSQwd%2BmfWRC5O4pxErTafy8qpyY%2FRAsU6t1YUKotHDhu%2BoTylJs1HrADL3Yt75xffumIbW2Z2ig8aNYZdu9sQ%2BkbKOPseHTYMh1T038UNzd6VQGluFXYGdaCkq%2Bv%2B0ImLepRDkeBimbqchlb4%2Bx%2FmTKO1AmDEil%2Bp625yfhP2WzmMul4LXt7kwB914XnIVP8tuJ0eFwAJ6NJGzXwQ%2B0H3nqqoza2P1t5qMYlWs421ribRA%3D%7Ctkp%3ABk9SR-y-4cW_Yg

USED, SNAP ON TOOLS "13MM" DISTRIBUTOR WRENCH, PART#S8704 | eBay

SEE PICTURES FOR ALL CONDITION DETAILS.

www.ebay.com

www.ebay.com/itm/266089362012?hash=item3df429725c:g:R7oAAOSw-bhi1Zem&amdata=enc%3AAQAIAAAA0FAbACEydRZ%2BCOvJAoseXNEOu3Yop%2FoDwSf5%2Botqx6t9mvHUgqboLK2SSFRQYypJC4cVzy67eFtTsdNda30c1qM7ycYThEmMyw0KwiUFHQ0HjMTgznw1JJW5mG%2BnDyKQl3%2BmbmFmY63HP4Jo42crJO5DE8tG7rog4e7bn3Gg4OPVYgg6863adWu6f8uRf2RfCbEIDCr%2BTc9m%2FO7stYTWBkJk76yknjeaihHm%2FzaIWwn%2FK1hJ1yTv3qnxRem%2FkJIqO%2BzyhACcU8j5A60y4M%2FhLZk%3D%7Ctkp%3ABk9SR-y-4cW_Yg

Snap-on Metric 13mm S87C4 Distributor 12-point Wrench Made in USA | eBay

Find many great new & used options and get the best deals for Snap-on Metric 13mm S87C4 Distributor 12-point Wrench Made in USA at the best online prices at eBay! Free shipping for many products!

www.ebay.com

www.ebay.com/itm/275630876097?epid=658653305&hash=item402ce165c1:g:yE4AAOSwwctjyCxQ&amdata=enc%3AAQAIAAAA0G4eO2Phz5kLnXG4470cMpv1eKafzjezLGhbGQugyr%2BOOB6%2FIOKdEK%2FUc5pekoAWFIy2EHOm61vCX%2BupX53hwEN8QKhKnMWKNHruR0ElatuPnl0s3vLzdpVTpQZM3ql78lDSfTZ2eEvYYruuRX5BWBsCdMyDgcpkbvBwEZ2zBaaZI2V9TSW%2BgYnc4Q59HTF%2BKNMZHftsNBvySLY5s9QcHYvZQIIJPElQqh0z1O%2Fmh%2FwlJ7Uw8aFxWa7apgTW49pQfJaabCSQTuvM3GEZrO1lNYg%3D%7Ctkp%3ABk9SR-6-4cW_Yg

Kent Moore Tool J-29828-a 13mm Distributor Wrench USA for sale online | eBay

Find many great new & used options and get the best deals for Kent Moore Tool J-29828-a 13mm Distributor Wrench USA at the best online prices at eBay! Free shipping for many products!

www.ebay.com

www.ebay.com/itm/393995582604?hash=item5bbbf77c8c:g:sOgAAOSwl1diN1o8&amdata=enc%3AAQAIAAAA8Fzpca3KkUoxWZpiSeSYDIH50bxX5PaCRSSjVUZ1YCQdvTyzbqgxo06snE%2FA1pCybzMwUB24ijGmQaaAVta2hn73WUilWcN%2BGLPaaT2AZTzyUDMX2jcVVO0nZBsQlz1ejjt2ApkEzF7%2F3e92lPzlFqMtmZc37KbfSyr%2BWxxRNQ3jXw8eyM5CSsEFhFkGxJaYbG4658tuniMpDipkvBmFMgNmQ2kWjvuF7aWZk6woYiLgs4WhnXYfCrOU4pNQr%2Fn4ZM9YhML%2B%2BgUOqxgbKbm2Y0HKkinEiLamHurRpnCVVZO1Hqfi4OqAz6ukFJ%2BI1LY3Lw%3D%3D%7Ctkp%3ABk9SR-6-4cW_Yg

Vintage ** MAC *** 13MM Fine Metric Distributor Wrench S179 x 12 Pt USA | eBay

Part Number x Point S179 x 12 Point. Allied is Mac Allied Tools founded in 1945 in Akron, Ohio. This item has the fine condition. Product of USA.

www.ebay.com

 

[Martin Evans]

54 hits on eBay. Prices vary considerably. Here's four random 13mm samples:
www.ebay.com/itm/125419491133?hash=item1d33958f3d:g:2fgAAOSwGC9i0vPL&amdata=enc%3AAQAIAAAA0AAsUQqS%2BSk9RiCBAqycRZyng7jgoQvX%2BDM9lieATbSQwd%2BmfWRC5O4pxErTafy8qpyY%2FRAsU6t1YUKotHDhu%2BoTylJs1HrADL3Yt75xffumIbW2Z2ig8aNYZdu9sQ%2BkbKOPseHTYMh1T038UNzd6VQGluFXYGdaCkq%2Bv%2B0ImLepRDkeBimbqchlb4%2Bx%2FmTKO1AmDEil%2Bp625yfhP2WzmMul4LXt7kwB914XnIVP8tuJ0eFwAJ6NJGzXwQ%2B0H3nqqoza2P1t5qMYlWs421ribRA%3D%7Ctkp%3ABk9SR-y-4cW_Yg

USED, SNAP ON TOOLS "13MM" DISTRIBUTOR WRENCH, PART#S8704 | eBay

SEE PICTURES FOR ALL CONDITION DETAILS.

www.ebay.com

www.ebay.com/itm/266089362012?hash=item3df429725c:g:R7oAAOSw-bhi1Zem&amdata=enc%3AAQAIAAAA0FAbACEydRZ%2BCOvJAoseXNEOu3Yop%2FoDwSf5%2Botqx6t9mvHUgqboLK2SSFRQYypJC4cVzy67eFtTsdNda30c1qM7ycYThEmMyw0KwiUFHQ0HjMTgznw1JJW5mG%2BnDyKQl3%2BmbmFmY63HP4Jo42crJO5DE8tG7rog4e7bn3Gg4OPVYgg6863adWu6f8uRf2RfCbEIDCr%2BTc9m%2FO7stYTWBkJk76yknjeaihHm%2FzaIWwn%2FK1hJ1yTv3qnxRem%2FkJIqO%2BzyhACcU8j5A60y4M%2FhLZk%3D%7Ctkp%3ABk9SR-y-4cW_Yg

Snap-on Metric 13mm S87C4 Distributor 12-point Wrench Made in USA | eBay

Find many great new & used options and get the best deals for Snap-on Metric 13mm S87C4 Distributor 12-point Wrench Made in USA at the best online prices at eBay! Free shipping for many products!

www.ebay.com

www.ebay.com/itm/275630876097?epid=658653305&hash=item402ce165c1:g:yE4AAOSwwctjyCxQ&amdata=enc%3AAQAIAAAA0G4eO2Phz5kLnXG4470cMpv1eKafzjezLGhbGQugyr%2BOOB6%2FIOKdEK%2FUc5pekoAWFIy2EHOm61vCX%2BupX53hwEN8QKhKnMWKNHruR0ElatuPnl0s3vLzdpVTpQZM3ql78lDSfTZ2eEvYYruuRX5BWBsCdMyDgcpkbvBwEZ2zBaaZI2V9TSW%2BgYnc4Q59HTF%2BKNMZHftsNBvySLY5s9QcHYvZQIIJPElQqh0z1O%2Fmh%2FwlJ7Uw8aFxWa7apgTW49pQfJaabCSQTuvM3GEZrO1lNYg%3D%7Ctkp%3ABk9SR-6-4cW_Yg

Kent Moore Tool J-29828-a 13mm Distributor Wrench USA for sale online | eBay

Find many great new & used options and get the best deals for Kent Moore Tool J-29828-a 13mm Distributor Wrench USA at the best online prices at eBay! Free shipping for many products!

www.ebay.com

www.ebay.com/itm/393995582604?hash=item5bbbf77c8c:g:sOgAAOSwl1diN1o8&amdata=enc%3AAQAIAAAA8Fzpca3KkUoxWZpiSeSYDIH50bxX5PaCRSSjVUZ1YCQdvTyzbqgxo06snE%2FA1pCybzMwUB24ijGmQaaAVta2hn73WUilWcN%2BGLPaaT2AZTzyUDMX2jcVVO0nZBsQlz1ejjt2ApkEzF7%2F3e92lPzlFqMtmZc37KbfSyr%2BWxxRNQ3jXw8eyM5CSsEFhFkGxJaYbG4658tuniMpDipkvBmFMgNmQ2kWjvuF7aWZk6woYiLgs4WhnXYfCrOU4pNQr%2Fn4ZM9YhML%2B%2BgUOqxgbKbm2Y0HKkinEiLamHurRpnCVVZO1Hqfi4OqAz6ukFJ%2BI1LY3Lw%3D%3D%7Ctkp%3ABk9SR-6-4cW_Yg

Vintage ** MAC *** 13MM Fine Metric Distributor Wrench S179 x 12 Pt USA | eBay

Part Number x Point S179 x 12 Point. Allied is Mac Allied Tools founded in 1945 in Akron, Ohio. This item has the fine condition. Product of USA.

www.ebay.com

For 25 bucks minimum, I'll srick with the PITA 13mm combination wrench.

 

[SuperSpore]

I could’ve sworn the frame to head bolt was 13mm when I just replaced that ground strap.

You must be registered for see images attach

thanks for the picture... I wonder if this is the oem location? Because on my 90 that cheesy grounding strap is on a bolt further towards the center of the head. And based on feel it's a bolt that threads into the head, not a stud with a nut. Regardless, yours is a more accessible location. Hmmm, *scratches chin*.
Good pic tho, I can't pull that off. =-)

 

[Caman96]

thanks for the picture... I wonder if this is the oem location? Because on my 90 that cheesy grounding strap is on a bolt further towards the center of the head. And based on feel it's a bolt that threads into the head, not a stud with a nut. Regardless, yours is a more accessible location. Hmmm, *scratches chin*.
Good pic tho, I can't pull that off. =-)

Just hold your phone back there and have flash turned on. It’s a good way to get a visual of what you’re working on, then go by feel.

 

[SuperSpore]

Just hold your phone back there and have flash turned on. It’s a good way to get a visual of what you’re working on, then go by feel.

Sir, you're assuming I can operate a cellphone!
...For sure, I'm working on that now.

 

[evilunclegrimace]

thanks for the picture... I wonder if this is the oem location? Because on my 90 that cheesy grounding strap is on a bolt further towards the center of the head. And based on feel it's a bolt that threads into the head, not a stud with a nut. Regardless, yours is a more accessible location. Hmmm, *scratches chin*.
Good pic tho, I can't pull that off. =-)

It is in a different place on the early trucks, it is also a short 3/8x16 threaded bolt. On the later trucks it is a 3/8x16 stud that threads in to the head with a 9/16 hex and a metric 8x1.25 thread that takes a nut to fasten the strap to the haed.

 

[SuperSpore]

It is in a different place on the early trucks, it is also a short 3/8x16 threaded bolt. On the later trucks it is a 3/8x16 stud that threads in to the head with a 9/16 hex and a metric 8x1.25 thread that takes a nut to fasten the strap to the haed.

Yes I just finished taking it off you're correct.
For our googlers looking for help:
On a 1990 350 the ground straps from the frame to engine head and the one from the firewall (under heater core hoses) to engine head are secured to a 14 mm bolt on passenger side head, between head and firewall. If you have big hands, you may have to remove a bracket (for plug wire holders?) also on the head and in the way, mounted with two additional 14mm bolts. Access to the ground strap bolt is precisely blocked by the transmission dipstick tube. At least that will help you located it, lol.
Btw, 14 mm is the size of the head of the bolt. It is not thread size/pitch.
Most efficient tool to remove would be a ratcheting swivel wrench.
You can do it with a standard wrench, but you'll be unhappy for a few minutes. =-)
Hope this helps someone.