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I am putting the heads back on my engine right now and the head bolts I had were pretty old so I got some new ones from a local machine shop. PBM, he said they use them pretty regularly. I wasn’t haven’t any issues until I got to the 65lbs torquing. Only on the short bolts on the exhaust areas when I started the 3rd rotation of 65lb torquing it suddenly felt way easier and I stopped. I’ve stripped plenty of bolts in the past. I thought it may be my torque wrench so I switched to another and kept going in the sequence and when I got back to another short exhaust bolt the same thing happened. Am I over torquing these? Right now they are just at 55 on the exhaust bolts all the rest I was able to bring up to 65lbs no issue.
It’s not much but all of the new bolts are just slightly shorter than the old bolts. All of the new bolts have TY 10.9 stamped on their heads. They didn’t come with washers, so I used the ones from the old bolts. Was I not suppose to do that?
I’m gonna call them in the morning when they open cause I’m gonna be posed if I just stripped out 2 of the headbolt hole’s because of some **** bolts.
With aluminum heads, you really should have a washer under the special bolt head. The washer keeps any bolt head from gouging into the soft aluminum material.
The washer also takes up some of the over-all length. So, your bolts are just barely grabbing the top few threads in the block. I hate to say it, but you may have ruined some of the bolt holes.
I know they are pricey, but you really need to get a set of ARP head bolts for SBC. They come in the proper length, and come with the much-needed washers and come with an ARP lube for the washers to help achieve the specific torque specs. Then you only need to apply thread sealant to the bolts.
I think I would pull the heads back off. Run a thread chaser through the questionable holes. Your head gasket should be ok, but if it looks crushed you can not re-use it.
If your new ARPs refuse to torque to full specs, ARP sells same diameter, same thread count but a pinch longer than stock length.
Note that the short gray bolts are missing a good quarter inch of threads on the end. I would trash can them.
A shorter bolt, plus a washer, would result in less thread engagement for the 65ftlb spec.
less threads for the same torque value. Just a thought as to why it would strip.
if I remember correctly, factory cast iron heads do not use washers, aluminum heads use hardened washers
With aluminum heads, you really should have a washer under the special bolt head. The washer keeps any bolt head from gouging into the soft aluminum material.
The washer also takes up some of the over-all length. So, your bolts are just barely grabbing the top few threads in the block. I hate to say it, but you may have ruined some of the bolt holes.
I know they are pricey, but you really need to get a set of ARP head bolts for SBC. They come in the proper length, and come with the much-needed washers and come with an ARP lube for the washers to help achieve the specific torque specs. Then you only need to apply thread sealant to the bolts.
I think I would pull the heads back off. Run a thread chaser through the questionable holes. Your head gasket should be ok, but if it looks crushed you can not re-use it.
If your new ARPs refuse to torque to full specs, ARP sells same diameter, same thread count but a pinch longer than stock length.
Note that the short gray bolts are missing a good quarter inch of threads on the end. I would trash can them.
And that is exactly what I was afraid of. I did apply oil between the washer and the bolt but I didn’t notice the length difference until after I felt the give. Is it possible that I didn’t ruin the bolt holes and it will still hold the 65lb torque?
Im gonna pull the bolts tonight and take them back tomorrow.
Exactly. It's a poor mans version of a tap. It does not actually cut any metal. It just cleans the threads. Has a hex end that fits a socket.
Maybe Harbor Freight in your neighborhood has a set. Usually 4 or 5 sizes in a kit. That may save your block from getting Heli coil.
Summit sells the ARP head-bolt kits and free shpg over $99. I believe the bolt kit is around $135. The special washer that comes with ARPs is a concave design. It fits the shank of their bolts perfectly.
Are your block threads ok? IDK But I think what you could do is, with the heads off, install a few of the short ARP bolts with a spacer the same thickness equivalent of the cyl head bolting flange. Maybe use several washers. Slowly torque down some bolts and see how they react to 65 lbs. Just don't bottom out the threads. You can't break ARPs but the blocks first few threads are injured. Go slow.
By the way. is 65 what Edelbrock recommends? Seems low to me, some aluminum heads torque to 75 - 80.
With any luck your new bolts will grab lots of threads farther down in the bolt holes.
Exactly. It's a poor mans version of a tap. It does not actually cut any metal. It just cleans the threads. Has a hex end that fits a socket.
Maybe Harbor Freight in your neighborhood has a set. Usually 4 or 5 sizes in a kit. That may save your block from getting Heli coil.
Summit sells the ARP head-bolt kits and free shpg over $99. I believe the bolt kit is around $135. The special washer that comes with ARPs is a concave design. It fits the shank of their bolts perfectly.
Are your block threads ok? IDK But I think what you could do is, with the heads off, install a few of the short ARP bolts with a spacer the same thickness equivalent of the cyl head bolting flange. Maybe use several washers. Slowly torque down some bolts and see how they react to 65 lbs. Just don't bottom out the threads. You can't break ARPs but the blocks first few threads are injured. Go slow.
By the way. is 65 what Edelbrock recommends? Seems low to me, some aluminum heads torque to 75 - 80.
With any luck your new bolts will grab lots of threads farther down in the bolt holes.
I just pulled the head back off, it is definitely the short bolts. The top of the threads on the block were a little rough. I’m gonna clean them up so the thread lock doesn’t dry. Tomorrow I’m gonna take those bolts back and let them know what happened. I know they don’t have any arp in stock, which sucks. But there is a local fastener/bolt shop in town, they are really good guys and reputable. I might bring the arp bolts over there, explain the situation and see if they have any arp or equivalent that are tad longer that will hold on to deeper threads. I can see there are a lot of threads that were not used.
Yeah, 65lbs is what the instructions say, gives the specific pattern and you do it in series 40-55-65lbs.
Im gonna try putting a few washers on one of the arp bolts tonight and testing the threads, just to see if utilizing a longer bolt will hold up to 65lbs.
What are the ARP longer version bolts? I a bolt in with washers and they held torque, even if it felt like it barely wanted to hold lol
you could also use the head bolts that edelbrock recommends for those heads, edelbrock part number #8550
summit has them in stock.
they are manufactured by ARP.
Get rid of those.....as mentioned, bad idea for aluminum heads and now that you think the bolts you have now are going to strip.......what is the only solution? Nobody is going to be able to give you any insight short of replacing them with a known quality set.
The reason you have to use a bolt like the ARP is so the bolt shoulder twists into the washer while the washer remains stationary.....for aluminum head this is important to prevent galling and to setup for foolproof torquing.....
Maybe your block has has heads on and off it 10 times......and the thread peaks are getting shallow......maybe the bolts are just ****......
I bought the set you have reboxed by Enginetech for a 350 I just did with cast iron heads and they were fine...BUT.....I had a previously used set that I tried to use and they started to feel like they were going to blow away as you described......so I just went new. FYI.
Couldn't agree more. Trying to save time or money on something as important as head bolts is false economy.
take the time and spend the money on the good stuff.
Blown head gaskets will definitely not make your day.
This is just not a place to cut corners.
I don't have any personal experience with Edelbrock's aluminum heads, but I thought that I heard something a LONG time ago, when Edelbrock first introduced their heads, that you had to use their bolt set with their heads. The reason being that the heads are "thicker" in a couple of places, compared to the GM heads, so the Edelbrock spec'd bolts were longer, to accommodate this difference, and allow proper thread engagement. Then again, maybe my mind is playing games.
The other thing to keep in mind, is the "head bolts" don't thread into the heads, they thread into the block. Therefore, you want to be careful that you don't strip the bolt holes in the block. that will be a PITA to deal with....
I don't have any personal experience with Edelbrock's aluminum heads, but I thought that I heard something a LONG time ago, when Edelbrock first introduced their heads, that you had to use their bolt set with their heads. The reason being that the heads are "thicker" in a couple of places, compared to the GM heads, so the Edelbrock spec'd bolts were longer, to accommodate this difference, and allow proper thread engagement. Then again, maybe my mind is playing games.
The other thing to keep in mind, is the "head bolts" don't thread into the heads, they thread into the block. Therefore, you want to be careful that you don't strip the bolt holes in the block. that will be a PITA to deal with....
I believe the BBC heads have their own bolts like you say.......but the small block heads take the same old ARP SBC set as any other head......I installed a new set in 1999 and there was no special parts required.......I believe that set is 135-3601.
EDIT: the SBC pt# is 134-3601.
Jebby
Last edited by Jebbysan; Apr 28, 2023 at 10:00 AM.
I have seen your thought process several times on this forum. "I will just go up the street and buy some local hardware."
90% of the time this plan fails. Local hardware may not be grade 8, quality fasteners designed for SBC heads. I don't know why people do that all the time. Maybe they don't have a credit card or don't like to order over the phone or on the net. But regardless, you have a nice build going on there, keep it nice and do this right.
ARPs can be in shpd fairly fast. Faster than having to do this all over again because of a head gasket failure.
As I mention earlier, ARP has about any length bolt you need for those heads. Should you order custom size, quarter inch longer? IDK. If that is the case, you will have to go through ARP directly. I have done that before, and the cost was a little higher than Summit for custom sizing.
I believe the BBC heads have their own bolts like you say.......but the small block heads take the same old ARP SBC set as any other head......I installed a new set in 1999 and there was no special parts required.......I believe that set is 135-3601.
EDIT: the SBC pt# is 134-3601.
Jebby
At least my mind isn't TOTALLY shot....I did, sort of, remember something about the special bolts.....
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
most aluminum heads are thicker than the cast heads so there is material to remove to change the chamber volume. If you go to the head manufacturer website they should provide the ARP part number you need. As for the holes stripping, after numerous torguing of the heads, the threads will stretch and they will strip. After many blocks of dealing with this I bought some go-nogo thread checkers. they have 2 thread profiles. One is normal and the other side slilghtly over sized. if the oversized threads go in more than a turn or two they are stretched and should be heli coiled. You can buy used thread checkers from reputable resellers on Ebay. the price is worth it. My 69 427 block required quite a few new threads. zero had issues afterward.
green is good
red is bad
this is very bad
I clamped a tap guide to the block surface and bought a ratcheting tap handle....super expensive but worth every dime
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
I dont have a pic of my thread chaser set but they are inexpensive. I suggest chasing every single threaded hole in the block after you clean it just so you cont have any issues with any bolts. Every single bolt will go in with your fingers and a tiny bit of lube after that. If they dont there is an issue with the bolt or its cross threaded.
I only use ARP 12 point head studs. You only put them in hand tight.
To prevent stripping the aluminum head I use 5/16 ARP header studs. Very easy to install the gaskets and headers. Felpro metal gasket
header bolts have smaller wrench heads that give more flexibility in tight spots. Do you find that you miss not having that with the studs and nuts on headers?
To the OP: if you felt the bolts already “give way” when torquing, it’s over. Don’t muck about any
more, pull the heads and chase/repair the threads as outlined above. Otherwise you will just continue to chase the problem.
PBM Headbolt Kit Stripping?
