So, this is the first official engine that I'm rebuilding with my brother. It's a 302 small block that is going into a sweet little 52 Ford. I thought that I'd post some sweet little pics and take you on the adventure of last night. It all started a long time ago, in a galaxy far, far away..... Then reality set in and we broke a main cap bolt in the block!!!
The story behind the broken bolt is two problems. The first is that my brother believed the machine shop, and didn't buy ARP main cap bolts or studs because the machine shop (Cleggs Automotive for those of you in the area) told him to reuse the old ones. BIG MISTAKE. The second problem arises when two TOTAL FNG's believe the book when it tells us to torque the sum-bitch down to 100 lb/ft torque. Do we know what happens to bolts when we over-torque them children? That's right- They break. So Eff ol' bolts, and books that say the wrong thing. AND MACHINE SHOPS THAT DON'T KNOW THE DIFFERENCE!
Spirolocks just got thrown in the mix becuase let's be honest, have you ever tried to screw the little fetchers in? It took me about 15 minutes to get the first little bugger in, with each successive spirolock I got faster. So, by the time I finished with them I was able to put one in the piston in about 45 seconds. I also called my machinist (NOT the Clegg's automotive guru) and asked what his advice was. He was surprised I hadn't stripped the block. He also said a good rule of thumb is that 7/16 can really only take about 70 lbs/ft torque. Info that would've been good YESTERDAY! But, all of that aside, it was one of the BEST evenings of my life! It rings deeply in my loins. Deeply.
I had a feeling who the idiot was when reading this. The book torque is 60-70 ft/lbs. Man, you blamed EVERYONE else but who messed up. Glad you fixed it.
You're right. It was actually one of the most enjoyable evenings I've had in a long time. I guess a broken main cap bolt and difficulty with spirolocks is par for the course. Does anything really ever go easy? Probably not, and that's why we love it.
You obvoiusly looked up specs for the 351 which calls for 95-105 ft/lbs. You cannot swear in the title per the rules. You really need to slow down and read.
What makes you think you would have been better off torquing ARP bolts to 100 ft/lb. I don't think the machine shop led you astray. You should have been ok with the stock bolts.
Lets get this straight first. <TABLE border=0><TBODY><TR><TD>260, 289, 302</TD><TD> </TD><TD width=30> </TD><TD>351W</TD><TD> </TD></TR><TR><TD>Fastener Type</TD><TD>Torque Spec</TD><TD> </TD><TD>Fastener Type</TD><TD>Torque Spec</TD></TR><TR><TD>Main cap bolts</TD><TD>60-70 ft-lbs</TD><TD> </TD><TD>Main cap bolts</TD><TD>95-105 ft-lbs</TD></TR><TR><TD>Outer main cap bolts</TD><TD>35-40 ft-lbs.</TD><TD> </TD><TD>Connecting rod bolts</TD><TD>40-45 ft-lbs.</TD></TR><TR><TD>Connecting rod bolts</TD><TD>(40-45 ft-lbs. for 289 HP & Boss 302)</TD><TD> </TD><TD>Cylinder head bolts</TD><TD>90-100 ft-lbs.</TD></TR><TR><TD>Cylinder head bolts</TD><TD>65-72 ft-lbs.</TD><TD> </TD><TD>Rocker arms</TD><TD>17-23 ft-lbs.</TD></TR><TR><TD>Rocker arms</TD><TD>17-23 ft-lbs.</TD><TD> </TD><TD>Intake manifold bolts</TD><TD>23-25 ft-lbs.</TD></TR><TR><TD>Intake manifold bolts</TD><TD>23-25 ft-lbs</TD><TD> </TD><TD>Oil pump bolts</TD><TD>23-28 ft-lbs.</TD></TR><TR><TD>Oil pump bolt</TD><TD>23-28 ft-lbs.</TD><TD> </TD><TD>Cam bolts</TD><TD>40-45 ft-lbs.</TD></TR><TR><TD>Cam bolts</TD><TD>40-45 ft-lbs.</TD><TD> </TD><TD>Cam thrust plate bolts</TD><TD>8-10 ft-lbs.</TD></TR><TR><TD>Cam thrust plate bolts</TD><TD>8-10 ft-lbs.</TD><TD> </TD><TD>Harmonic damper bolt</TD><TD>70-90 ft-lbs.</TD></TR><TR><TD>Harmonic damper bolts</TD><TD>70-90 ft-lbs.</TD><TD> </TD><TD>Flywheel / flex-plate bolts</TD><TD>75-85 ft-lbs.</TD></TR><TR><TD>Flywheel / flex-plate bolts</TD><TD>75-85 ft-lbs.</TD><TD> </TD><TD>Pressure plate bolts</TD><TD>35 ft-lbs.</TD></TR><TR><TD>Pressure plate bolts</TD><TD>35 ft-lbs.</TD><TD> </TD><TD>Front cover bolts</TD><TD>12-15 ft-lbs.</TD></TR><TR><TD>Front cover bolts</TD><TD>12-15 ft-lbs.</TD><TD> </TD><TD> </TD><TD> </TD></TR></TBODY></TABLE>
You're probably right about the machine shop and the old bolts. Clegg's automotive is a great shop, and I'm stoked about the work they've done for the engine we've got. You're also right, that ARP bolts would've failed too.
I probably did just look at the wrong torque spec. I'll double check in the book that I've got. But, I also appreciate this post. I'll print it off so that I get all of the other torque specs accurate. Thanks
Probably not, they are rated for a much higher fatigue strength than stockers. But too much torque can also cause fastener failure as well as distort the item that is being torqued in the first place.
You might want to double check the torque specs on them rod bolts. It's correct for the 3/8 rod bolts, (BOSS 302 and 289 HI-PO) But the 5.0L 5/16's bolts are something like 19-24 ft lbs! Please double check!!
So, we spent the night last night scratching our newbie heads! The connecting rods have to match up with the radius on the rod journals! We knew that the rods where directional, it just took us a couple of tries to figure out why the rods were binding on each other and not seating correctly on the rod journals. We had to pull the spirolocks out with the wrist pins, flip the rods 180 degrees, and then throw the wrist pins and spirlocks back in and VIOLA! The big end of the rod has a radius that sits PERFECTLY on the rod journal. I'm so stoked it's finally coming together, just bummed they're all in the garage right now working on the engine, and I'm here at work pretending to work. He he he.
All you engine builders with experience are right. The book we referenced has a 351 build right after the 302, and we got the torque values wrong. It's a 100lbs for the 351, and 70lbs for the 302! DBL CHECK EVERYTHING!!!
Just to add something, you might also want to rethink the whole "sitting on the ground under an engine on a stand wile working on it" idea. Legs snap pretty quick when a shortblock lands on them
I've cleaned up loads of used engine hardware and never had issues with any of it, this includes basket case builds grabbing hardware from my spackle bucket stash. You did work through it, and you now believe that SUCCESS TEACHES YOU NOTHING. Good to screw something up and get a good schooling making it right. Bob
Don't know that I get this response. I do believe that I've learned a lot working through it.... That's why my brother in law, my uncle and my dad and I are out there turning the wrench rather than paying someone else to do it for us.
Small update. While I've been at work, they've finished installing the pistons, timing set, heads, rocker arms, and are now working on the manifold and carb. I wish I didn't have to work.
I learned that lesson the hard way. Not my leg, but my right thumb snapped pretty easy from the weight of the hemi.
I can't tell y'all how much I learned through this build! It was SO much fun! I'll post pics of the final assembly which included: Timing the Cam, Timing Set, Timing Cover, Dampener, Heads, Lash the Valves (we got all of them lashed and then looked at where they contacted the valve stem- didn't like the path, so we measured a push rod and lengthened it 3/16-1/4 over stock). Ordered new push rods 1/4 over stock, reinstalled roller rockers with the longer pushrods and they were BOMBER. Finished by modifying the pan, for the pick up, sealed that and the valve covers, intake manifold. AWESOME! Thanks for giving me grief for my mistakes, help with the torque values, and some good advice along the way. You Hamb Heads Rule!
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