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MGB Engine rebuild, then...

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My mechanic friend will not allow me to re-use any nuts or bolts except for non-stressed external ones such as alternator brackets and the like. It's cheap insurance. I hope you can find a used block in good condition - should be more than a few in view of the large number of MGB's in this country. Good luck.
 
Rut said:
Well, the consensus between Hap and the machine shop is rod bolt failure. Michael, the machine shop owner told me about stress cracks in failed fasteners and what to look for...sure enough the bolt fit his description with a shiny area surrounded with a darker area. This picture does not show the end of the bolt, but it's the little $astard on the left! The rod bearing looked good as far as wear was concerned, so the oil dilution was not the cause. I thought I went ARP fasteners throughout, but reused the rod bolts...kicking myself a little harder after that discovery and it won't happen again!
Rut
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Too late now and not trying to sound sarcastic, but that was my first thought when I asked if you used new rod bolts. When you relieve the pressure on an old bolt that' been exposed to heat, cold and stress over a period of time and then reuse it, the internal structure of the steel changes when it's re torqued' Expensive lesson, but don't feel real bad, most of us have been there at one point in time. Another thing, I never use head bolts/studs a second time either. PJ
 
Guys,
Yep, this one is fully on me...lesson learned! I'm looking at an engine and I'm away for my manual, books, etc. and need help deciphering this code. I want an engine with a forged crank and later connecting rods, is this it?
18V673Z-L4499 with a head code of 12H2923 and a block code of 12H3503.
Thanks, Rut
 
What a lucky mutt I must have been when I rebuilt several B and Spridget engines reusing the rod bolt and nuts without a failure. The engines were thrashed by autocrossing and spirited road driving so fate was extraordinarily kind to back then!
I'm glad Moss has a sale going as this time I'm getting all new hardware for my 1275 build after Rut's experience.
 
Oh Im so glad you posted about this. While unwrapping the long block from my machinist I noticed what looked like the original hardware. I just got back from his shop with confirmations they were reused. Bummed I have to open it back up and he's not excited at the thought. However, because you posted for other to learn you saved my new build. THANK YOU! He said he saw nothing wrong with them. Why take a chance though. Cheap insurance.
 
Not all the original bolts will go bad, but my very expensive experience makes me wish I had used ARP rod bolts or at least new stock rod bolts...very cheap insurance. My second engine is at the shop now with the rods, pistons, cam bearings, and ARP hardware ( with proper 45* bevels ground on the cam side). I can't wait to get elbow deep into this rebuild since I enjoyed the first one so much! Next is the Bugeye 1275 followed by the TR4a engine...I'm a very excited and happy camper!
Rut
 
Way to have a good attitude. I think my next build will be a mid 90s 1.5 civic motor. Had a lot of luck with the last one I ran and we want a gas sipping "family car" I just want the B to be running. No more engine work. I will be so glad when this wiring is done to. I think Im just going stock on the hardware. I only went out .20 on the bore and shallow dish nothing crazy.
 
Rut said:
Not all the original bolts will go bad, but my very expensive experience makes me wish I had used ARP rod bolts or at least new stock rod bolts...very cheap insurance. My second engine is at the shop now with the rods, pistons, cam bearings, and ARP hardware ( with proper 45* bevels ground on the cam side). I can't wait to get elbow deep into this rebuild since I enjoyed the first one so much! Next is the Bugeye 1275 followed by the TR4a engine...I'm a very excited and happy camper!
Rut
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He said he saw nothing wrong with them. You can not see the internal structure of a piece of metal without magnafluxing it. Hard to believe a machinist would do that. The structure of those bolts change over time. Some get away with it and some don't. I wouldn't take a chance for the price of 8 bolts. PJ
 
Gray_Cat said:
What a lucky mutt I must have been when I rebuilt several B and Spridget engines reusing the rod bolt and nuts without a failure. The engines were thrashed by autocrossing and spirited road driving so fate was extraordinarily kind to back then!
I'm glad Moss has a sale going as this time I'm getting all new hardware for my 1275 build after Rut's experience.
Click to expand...


We often used to rebuild street engines with existing rod bolts, back when stock ones were hard or impossible to get in a reasonable time frame and we never had any blow ups related to that. I think I still have a spare engine under the bench that I built over night to get it back in the race car for a Sunday race. Didn't have any rod bolts. Used Grade 8 bolts. Lasted just fine, although I wouldn't recommend it.

That was just bad luck, Rut.

Everyone should beware of something that wasn't an issue in the old days. There are a bunch of Chinese bolts floating around properly marked as to grade - you can buy what you think are performance bolts and get grade 5 or less. Let the pros do the worrying for you and buy from a reputable source, in most cases ARP.

I keep seeing people going cheap on bolts, after market connecting rods, pistons - playing Russian (or rather Chinese or in some cases Indian) roulette with their engines.
 
Hey guys, a little to this party. A s Bill said people rebuild engine every day reusing the OEM rod bolts. I remember when Rut and I started getting his engine rebuild kit together, we talked about ARP rod bolts, but his rods has already been resized, and I informed him if he did use ARP rod bolts he would need to resize them again, the decision was made to move on with the OEM ord bolts. Now I sue ARP in every build i do, mostly because that is what is expected of me and my builds, and I want to no chances on such a part. With that being said, this is extremely rare failure for a street engine, but as we can can all attest to, it can and eos happen.

The one thing I can say for sure is Rut had a wonderful attitude about all this, he enjoyed the process of the rebuild, and while I'm sure he did not have to want to do it so soon again, he went into this with a very positive attitude,and that is really the best thing you can do.

I think what we learned from all this, ARP rod bolts while pricey can end up being a bargain in the long run. FWIW, I ahte early MGB 5 main rods, what a heavy piece of crap, Rut this go around is using later straight MGB rods, a much better, and lighter design.
 
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