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Broken/chipped starter bolt whole

 
krunchw
I love my Chevy Chevette!
Posts: 7
Joined: 07/11
Posted: 07/28/11 12:00 PM

I have a stock sbc 350, the starter bolt hole on the ear of the block is broken off but some threads (3/4 remain) still remain in contact (bolt will tighten). The motor gets 3-4 good turns/firing before the starter slips and disengages from the fly wheel, very frustrating!! I have tried shims, new starters, new/longer bolts, and lock tight on the threads with no luck.  Does anyone have any other ideas on how to fix this issue  without getting it welded? (168 tooth flywheel/stagger bolts alignment)  

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waynep7122
Everything in my driveway’s a Chevy
Posts: 556
Joined: 08/09
Posted: 07/28/11 04:48 PM

chevy blocks up through 81.. are drilled at the starter mount for 3/8 -16 bolts..

chevy blocks from 82 are drilled for 10MM x1.5 bolts..

using metric bolts in a block that has SAE threads will split the block almost every time...  the metric bolts are 0.020" larger...  so it's like splitting firewood..

how tight do the starter bolts fit in the housing...  tight like this.. where the Knurls fit...  or loose...


Chevystarterboltfit


do you have this bracket to support the brush end of the starter motor..????

Chevystarterbracket




~~~~~~~~~~~~~~~~~~~
this is a 3510 starter.....    notice the larger solenoid...  these if they are assembled correctly should fit the 3/8 starter bolt knurled section ....

3510Starter


~~~~~~~~~~~~~~~
this is the 3510M starter for the 10MM metric bolts..   notice the short solenoid...

3510M Metricboltholes  

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pepsi1
Big Block power for the win
Posts: 940
Joined: 03/11
Posted: 07/28/11 04:53 PM

Question: are there two different bolt patterns on the engine block? If there is you maybe in luck. The only thing is this: You will have to buy a new Jegs or Summit mini starter, a 153 tooth flywheel.  Many of the mini starters have bolt patterns for a 153, and 168 tooth flywheel. (NOTE: SOME OF THE VERY NEW 350 BLOCKS DO NOT HAVE MULTI STARTER BOLT PATTERNS, SO CHECK ON THAT SITUATION FIRST.

Install the flywheel and adjust the mini starter to the correct spacing. Now I don't know
which will be cheaper to fix, but the labor will definetly be a plus for the starter way  

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krunchw
I love my Chevy Chevette!
Posts: 7
Joined: 07/11
Posted: 07/28/11 05:10 PM

I believe the 350 is 1985 possibly an 86 block  

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krunchw
I love my Chevy Chevette!
Posts: 7
Joined: 07/11
Posted: 07/28/11 05:15 PM

My block does have the 2 bolt patterns, but i think the bolt hole that is chipped may be the one that the 153 starter will still have to use.  

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waynep7122
Everything in my driveway’s a Chevy
Posts: 556
Joined: 08/09
Posted: 07/28/11 05:16 PM

you might since you are working under the car..  read the large 3 digit casting numbers usually between the freeze plugs

if they are not there.. they are on the back of the block behind the heads right were the bell housing bolts on...  visible from above...   if you have a LONG neck..

please verify which bolts you are using..

do they have six strips on the head...  or numbers like 10.9 or 12.9....


oh... which bolt hole is broken...

there are 3....    2 parallel to the back of the block... one inboard.. one outboard.. and the third is closer to the front of the block...


Starterboltpattern1  

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krunchw
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Posts: 7
Joined: 07/11
Posted: 07/28/11 05:39 PM

My bolts fit loose around the knurled part (does this mean I should try the metric bolts?), and I'd say that I'm running the 3510M starter based on your pictures. I don't have the bracket support, will that be in any parts store?  

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krunchw
I love my Chevy Chevette!
Posts: 7
Joined: 07/11
Posted: 07/28/11 05:50 PM

the starter bolts Im using, one has a "C" on the head and the other has and "M" with some sort of symbol on it. the bolt hole that is broken is the outboard one ( bottom in this image)  

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waynep7122
Everything in my driveway’s a Chevy
Posts: 556
Joined: 08/09
Posted: 07/28/11 07:16 PM

can you identify the numbers on the side of the block????

can you identify the head bolts...  you will need a 3/8 open end wrench and a 10MM open end wrench...



with the bolts out.. stick the open end wrench around the threads...

which one fits tight?????  the 3/8 wrench or the slightly larger 10 MM wrench..????

are the bolts adorned with metric markings???   10.0.. 12.9 on the top....

or do they have stripes ?????

Bolt Nut Markings SAE And Metric


now...   which ones fit properly IN THE BLOCK???????   by hand....

like i said at the beginning ..   putting a metric bolt into the sae threaded block.. will split the end right off like you have done..

if you use an SAE bolt in a metric block.. it may NOT hold when the starter engages..  there is a tremendous amount of pressure when the starter kicks in...  

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krunchw
I love my Chevy Chevette!
Posts: 7
Joined: 07/11
Posted: 07/28/11 07:45 PM

I cant seem to find the numbers on the block (engine is a bit dirty) kind of hard to see. My bolt head looks like the one in the first row/second column (no numbers, just lines with a "C" in the middle; and the 3/8 wrench fits tighter than the 10mm... however, these bolts do fit into the well  

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krunchw
I love my Chevy Chevette!
Posts: 7
Joined: 07/11
Posted: 07/29/11 05:27 AM

Waynep, i purchased a new 3510 s starter, along with the SAE bolts.... bolted up the new starter, bolts and shim, cranked it up and the engine fired smoothly with no grind or disengagement!!! Thanks for the help  

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deano419
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Posted: 07/29/11 01:42 PM

i was told  metric bolts wont work in a standard bolt hole.........if its coming losse that would be my guess???  

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pepsi1
Big Block power for the win
Posts: 940
Joined: 03/11
Posted: 07/29/11 04:37 PM

Did you say you can get a bolt to go thru the threaded hole and see it come out the other side, and the bolt is coming loose? If you can get a piece of threaded rod longer then the bolts your using, so you have many threads coming thru on the other side. You will need enough bolt threads to put a flat washer, lock washer, and a nut on that end. Now do the same on the good end of the starter, and pull them as tight as you can. If the starter makes noise try shimming it on the outboard side only. This can be a temporary fix. How did the block get broken? I'm curious.  

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waynep7122
Everything in my driveway’s a Chevy
Posts: 556
Joined: 08/09
Posted: 07/29/11 07:21 PM

the outer starter bolthole is usually what breaks when a metric 10MM starter bolt is threaded into a sae  threaded block.. the only changes between the 81 and 82 are the starter bolts threads... all the other threads are SAE..


the metric bolts are 0.020" larger in diameter...

the holes in the block are counter bored..  so the threads start about 3/8 of an inch down the hole.. perhaps even half an inch.. i have not measured them ... this is just enough to allow a metric bolt to start...    when the larger knurled section reaches the counter bored area... it gets pulled into the slightly too small hole and splits it open...

this is usually done with an air impact... OH.. that bolts a little tight.. let me drive it in with an air impact....  and  BOOM.. block busted...

my first experience with this was on a gm diesel truck motor... the shop i worked in swapped the starter.. and managed to crack the block...  the previous starter bolts were torn up.. so the tech.. if i could call him that .. grabbed some out of the used bolt bucket...  after attempting to repair the broken block..   holding it up with a muffler bracket.. drilling and tapping the block at an angle above and welding the new bolt to the bolt threaded into the side of the block ..

they ended up replacing the WHOLE diesel V8 motor..  

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