31 replies to this topic

[claysummers]

Bloody hell, that’s a shame. I wonder if one of the no1 rod bolts got over torqued, partly because it is what I did recently, managing to shear the shaft on assembly. I was reusing factory fasteners because that is what the machine shop advised.

At the least you will have been very lucky to avoid damage to the block and crank.


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[73SUNBURSTEXYOUWON]

That's the funny bit, this engine is super mild. 30tho over, cam was a 666 from crow and the head was a YT 161 with standard YT valves. So I'm completely starstruck as to why it's gone boom. Was just taking it round the block 50kmh.

Disclaimer this was my first time rebuilding an engine at all, so chances are I #@$^%& something up.

So, trying to understand this, as all are.
And noting this is your 1st rebuild. But what a learning curve this is.

Is that cam - Crow 666, solid or hydraulic? Lifters to match cam? Were the lifters new? Were the valve springs pressure rated to match cam? Was the rocker geometry at full lift checked - No binding? Push Rod lengths, was that correct for Head/Block combo?

Lots of questions.

As well as, torquing your bolts... were all torqued to recommended specifications...checked and double checked, witness marked along the way? Is your torque wrench within calibration, not over or under?

Food for thought.

Jaso.

[Ice]

So, trying to understand this, as all are.
And noting this is your 1st rebuild. But what a learning curve this is.

Is that cam - Crow 666, solid or hydraulic? Lifters to match cam? Were the lifters new? Were the valve springs pressure rated to match cam? Was the rocker geometry at full lift checked - No binding? Push Rod lengths, was that correct for Head/Block combo?

Lots of questions.

As well as, torquing your bolts... were all torqued to recommended specifications...checked and double checked, witness marked along the way? Is your torque wrench within calibration, not over or under?

Food for thought.

Jaso.

Clearances are also an important details when rebuilding an engine in fact its crucial 

[FNQ]

Hi avoidev,   The tear down , post engine failure , is really important to try and make sense of what happened, maybe what broke first etc - although it is painful, it is always better getting a good diagnosis, - so you can be sure you are not going to put it together just to happen again. The chaps above are offering good advice to what to look for etc. If you can get another set of experienced eyes on it , it would be worth while. ( checking torque of remaining rods etc)

 

If your head has been recoed, check the oil galleys are all free - Also could the clever people please advise how /which way oil gets up to the rockers? (to check also)

 

and finally in my "mini - BMC type" engine the OEM pushrods are still used by many because they are the failsafe - soft enough to bend when things go wrong but good enough to last years and years of abuse if nothing goes wrong - I have no commentary on Crow pushrods - but wondered others thoughts on this.  Good luck with the rebuild

[avoidev]

Pictures of the damaged nut for those that are curious.

 

https://freeimage.host/i/hXUsoJ

https://freeimage.host/i/hXUPta

 

Now that I've had a good look, its not as bashed up as I remembered. However to me it's pretty clear cut that the nut came off and probably jammed up the cam. The only way it could've received that impact if there wasn't a bolt there...

 

 

Bloody hell, that’s a shame. I wonder if one of the no1 rod bolts got over torqued, partly because it is what I did recently, managing to shear the shaft on assembly. I was reusing factory fasteners because that is what the machine shop advised.

At the least you will have been very lucky to avoid damage to the block and crank.


Sent from my iPad using Tapatalk

 

 

Anything is possible, the torque wrench I was using wasn't recently calibrated and It was just a backyard rebuild. Was trying to build something fun. I've had another look and there is very minor damage to the block, and similar to one of the counterweights on the crank.

 

 

So, trying to understand this, as all are.
And noting this is your 1st rebuild. But what a learning curve this is.

Is that cam - Crow 666, solid or hydraulic? Lifters to match cam? Were the lifters new? Were the valve springs pressure rated to match cam? Was the rocker geometry at full lift checked - No binding? Push Rod lengths, was that correct for Head/Block combo?

Lots of questions.

As well as, torquing your bolts... were all torqued to recommended specifications...checked and double checked, witness marked along the way? Is your torque wrench within calibration, not over or under?

Food for thought.

Jaso.

 

Hey mate, you are not wrong about it being a steep learning curve. As much as I'm bummed out by this I'm keen on building another.

 

Now to answer your questions, the 666 cam was hydraulic, lifters were correct for the cam too, however they weren't new and neither was the cam.

 

Were the springs pressure rated to match I have no clue, they are the double spring setup that YT would've fitted with the 161 originally. From what I had read on the net that was the correct length pushies for a 202 block with a 161 head.

 

 

Clearances are also an important details when rebuilding an engine in fact its crucial 

 

100% couldn't agree more, checked everything I could with Plastigauge when I replaced the cam, crank and big end bearings.

 

Hi avoidev,   The tear down , post engine failure , is really important to try and make sense of what happened, maybe what broke first etc - although it is painful, it is always better getting a good diagnosis, - so you can be sure you are not going to put it together just to happen again. The chaps above are offering good advice to what to look for etc. If you can get another set of experienced eyes on it , it would be worth while. ( checking torque of remaining rods etc)

 

If your head has been recoed, check the oil galleys are all free - Also could the clever people please advise how /which way oil gets up to the rockers? (to check also)

 

and finally in my "mini - BMC type" engine the OEM pushrods are still used by many because they are the failsafe - soft enough to bend when things go wrong but good enough to last years and years of abuse if nothing goes wrong - I have no commentary on Crow pushrods - but wondered others thoughts on this.  Good luck with the rebuild

 

Thanks FNQ, I honestly appreciate all the info you fellas are giving me here. I'm keen to give the whole thing another crack. I'm gonna get the ol W&B torque wrench checked/calibrated this time and double, triple, quadruple this time. Just gotta build up the cash stack again and then I'll be doing rebuild 2.0

Edited by avoidev, 15 June 2022 - 01:48 PM.

[73SUNBURSTEXYOUWON]

Avoidev,

Good on ya mate, get back on the horse and try again. Enjoy

Ive been in a similar position many years ago (teenage years), a first rebuild on an Austin 1800 Land Crab engine... for whatever reason, too long ago to remember, the engine failed...(oil pressure).

[warrenm]

That nut has had a hard hit.