I am looking for some opinions on what to do next.

I am in the process of installing my rebuilt heads on my 75, L48. Here is where I am at:

Picked up new.038 composite gaskets (to allow for any variance in the heads or block).

Cleaned block surface with razor blade and vacuum.

Cleaned block threads. I used a tap (not a thread chaser, I know, I know, this may not be the best). Now I was VERY careful, went in only about 3/8 inch and never saw any metallic reminants on the tap, only left over sealant from the original installation. Then I ran a bolt into each hole to clean up any remaining old sealant.

Reused the head bolts, cleaned by the engine shop, sealed with Permatex 2, oiled the bolt heads with 30 weight oil.

During the installation, only 1 bolt turned into taffy. While doing the final torque (20, 40 and then 65 ft lbs) on the #5 bolt, I felt the bolt start to give way. I stopped and proceeded to the remaining bolts. All the other bolts on both heads went in with no problem and no sense at all of weakness or stretchyness.

I bought a set of Fel-Pro head bolts, replaced the #5 bolt and the new one went in great, felt super and that was that.

I was so impressed with the presealed bolts from felpro, I though, hey, why not replace all the old bolts.

So, I pulled out the #1 bolt from the other head. Put in the new bolt and then at about 65lbs, the bolt started to stretch. UG! How could a new bolt stretch! So, I put back in the old bolt and it tightened right up, with no problem at all. Surprising

That's when I went back to the auto shop, a local regional parts store with its own machine shop. They have been around for a long time; we are not talking autozone here. The guy there, who used to work in the machine shop was very surprised and said it must be the block. He suggests pulling everything off and reinstalling with all new bolts.

I called the engine shop that did my heads, (not the same shop at the part's store, but a reputable, race engine building shop), and he said that as long as all of your bolts are properly torqued, you are OK. In otherwords, although he can't explain why the new bolt twisted, if the old bolt is in there at the right torque spec, don't worry about it.

I borrowed another torque wrench from autozone to get a second opinion on my torque wrench (mine is a 15 year old Craftsman with the internal clicker, not a dial, and not a digital). The OTC wrench clicked out at about 70 foot pounds, so it is possible that my craftsman wrench is off by 5 lbs and the head bolts are installed at 70 ft lbs instead of 65. according to the manual, though, this should be ok.

So who to believe and what should I do?

1. Redo everything with new bolts - as per the parts store? (note, the parts guy felt so strongly in his opinion he said I could have the parts for a very good discount, so his motivation is not to just sell me more stuff)

2. Leave it - as per the racing engine shop, "everything is torqued properly, should be ok"?


FYI, here's a picture of the first bolt that stretched.

 

My choice would be purchase ARP bolts and install per ARP specs.

 

If you achieved good torque on those bolts I personally would leave them alone. The guy commenting that there was something wrong with the block doesn't make any sense to me. As long as it was the bolt or bolt threads that failed that doesn't indicate a block problem. Unless I am really missing something here. Myself, I tend to go overboard and when I built my 468 I used ARP studs top and bottom. But it was intended to be a very stout engine with full roller valve train, forged crank, forged pistons, etc. For a mild build your stock bolts at proper torque are fine. JMO but I would leave them be.

 

The quality of even most name brand parts can be questionable these days. Not like the old stuff.
Spend a couple bucks for the ARP bolts and feel confident.
A potential problem down the road will cost you more than the bolts.
The cheaper clicker wrenches screw up sometimes too.

 

Thanks guys, all very good points.

If price is any indicator, I see that ARP are better bolts. The FelPro bolts were only $23 for one set. Even thought they are made in the US, I too agree that the FelPro bolt failed and not the block.

I'm still on the fence as to what to do; I'll continue to research and seek out opinions.

Thanks!

Jamie

 

I've been thru this before a couple of times and the new cheepo bolts failed after a few month's.

 

One more request for opinions; tomorrow I am going to start buttoning it back up. Got the timing cover and oil pan back on today, looking good.

Thanks!

Jamie

 

Best advise has already been given.

Re-do with ARP bolts and know you're good to go.

 

3 votes for new ARP bolts, 1 for let it be. Looks like I'll get some new bolts.

Thank you.

Jamie

 

I have used ARP bolts many times , just make sure you prep the bolts properly and make sure your torque sequence is on , If you bring your torque wrench back to sears they will recalibrate it for you ...

 

I would be concerned with the bolt hole that turned to mush. You are using steel bolts into a cast iron bolck and threads. That mush feeling is usually the bolt threads pulling over the block threads.
They are softer than the bolt threads. When the new bolts torque to the proper spec. they had better and stronger threads. They bit better than the threads form the factory bolt.
I'd run a bolt into the hole in question and see how much lateral and vertical play there was. If that hole has more than the rest of the holes, I'd put in a Helicoil and not have any doubt.
If you don't know for sure, there will always be that doubt in the back of your mind. Doing it correctly is much better than guessing that it may be going to hold.
I've learned that, that maybe it will, or maybe it won't concern isn't worth it when you are in position to make the correction at little cost. I'm wondering why the machine shop didn't offer that suggestion?
IMHO

 

Redo everything , If you want to invest in ARP bolts, that would be cool But If you think your bolts are OK then Reclean, oil, seal and re-torque them down. If your not happy with how they torqued get the ARPS.
My 2centavos

 

I managed to read the whole thing. Even though they say made it the USA, they can be made anywhere and they can get around by various different means.

If a sleazeball wants to make money #1 he will find an cheap and easy way. #2 if the same guy is doing this he could give a crap and half if your $7,000 motor went up in smoke.

You wont see any serious drag or road course driver using anything but ARP bolts and studs and on a serious piece and with that in mind I wouldn't use ARP hadware on anything but an Premier Padmini or Hindustan Ambassador India Taxi.

Hopefully the bolt failure didn't cause any permanent damage to the head bolt hole

 

"I called the engine shop that did my heads, (not the same shop at the part's store, but a reputable, race engine building shop), and he said that as long as all of your bolts are properly torqued, you are OK. In otherwords, although he can't explain why the new bolt twisted, if the old bolt is in there at the right torque spec, don't worry about it."

IMO this is very good advice from a professional. If I were going to go with anything other than OEM I would (and do) use ARP hardware. For an L48 (very docile, low compression engine) I would not have bought the set of head bolts, I would have asked the machine shop if they had a good OEM bolt laying around to replace the one that failed. I fully expect they would have given you one. Bottom line is if you do decide to change them, use ARP, I would think we all agree on that.

 

Cast iron hole threads will give it up before the bolt thread. As soon as the first bolt didn't torque I would have suspected the hole threads. If that in fact is the bad part, just because the new bolt, OEM or ARP, held torque it doesn't mean thet it will forever.
If those hole threads are damaged to the point of giving up torque, they may fail you down the road (no pun).
I know other builders who have employees who impact wrench the core motors apart. Often doing the thread damage. I've let them go myself for the same reason. One of the reason I chase all threads before assembly, is to get a feel for the quality of the hole threads.
A helicoil restores the bite you are looking for, and being a steel thread will last as long as the engine.
IMO

 

he showed us a picture of the stretched bolt.

 

"During the installation, only 1 bolt turned into taffy" if this happens for any reason it it is time to pull the motor apart and start again.

Bob's auto-shop sells the blue thread repair kit it. I might work or I'll bet $100 it doesn't.

You need to find out what is wrong, it's either the thread's f'uped in the hole or bad 25cent head bolt.

Like the old commercial used to say " You's can pay me know or you can pay me later"

 

MotorHead is correct. Now is the time to make sure. Spend a little effort now or a bunch later. I'd run a good ARP bolt in the hole. It should have minimal lateral and vertical play.
If it runs in hard the edges of the hole threads may be pulled up a bit.
Putting one together and hope it works is when Murphy gets his foot in the door.

 

This seems more complicated than I thought (and hoped). I didn't do anything with the heads today. It's a lot to think about, so I thought I'd take the week to stew it over. I don't want to have doubts about the build this deep into the motor, so I'll probably pull the heads as most of you suggest, check the threads and reinstall with new bolts. Part of me feels this is overkill, but if I have the time and the $100, better safe than sorry.

Thank you for providing your comments and ideas.


I spent the day regreasing/rebuilding the steering gear. Good news there is that with only 35k miles, the tolerances in the gear were within spec and the old grease looked good. At least something went well.

 

cast my vote to pull em and go with some ARP'S