Hot Rod Forum banner
1 - 12 of 12 Posts

·
Registered
Joined
·
354 Posts
Discussion Starter · #1 ·
I have always re-torqued heads after a couple of heat cycles. These were always cast iron heads. Now I've built a 351W with aluminum heads and I'm hearing re-torqueing heads went out with bellbottoms. It only makes sense to me that there's going to be some stretch and set in everything and re-torqueing the heads addresses those changes.
 

·
Registered
Joined
·
15,298 Posts
I always retorque aluminum head’s never did iron as it’s more thermally stable and a stiffer material. Aluminum is much more thermally active and will plastic flow when enough force is applied to its restraining fasteners. The no-retorque is actually an advertising ploy by gasket makers who are making a claim that no retorque is needed for their set it and forget it gaskets. I’m skeptical.

Not that I’ve found problems but I always use hardened washers between bolt head or stud nut. I’s careful not to have lube between washer and aluminum part but to have a little grease between the washer and the bolt head or stud nut. This allows fastener rotation against the washer but not washer rotation against the part being secured. Now just to be sure everybody’s on the same page I talking aluminum here and specifically aluminum head’s to iron blocks and aluminum intakes to aluminum head’s, though aluminum head’s are potentially the bigger issue.

Bogie
 

·
Registered
Joined
·
4,709 Posts
Another thing to be careful of and I would have never have thought of this but I read an article that with newer modern aluminum heads that the surface of them are finished so good that over the area of where the washer goes under either a bolt or stud head that the washer if being an ARP has such a smooth finish on it that along with the head having such a smooth finish as well, that if you go to torque them down that sometimes the washer will not be able to grip enough on the bottom of it and can end up causing your to over torque and strip out the threads on the block. The link is below.

Also another thing I like to do as well a few times is retorque the intake manifold as well after several heat cycles and I have been surprised on just how loose things can actually get. I have not redone my heads before but this time I am actually going to do that bit just to make sure with everything.

 

·
Registered
Joined
·
354 Posts
Discussion Starter · #4 ·
Another thing to be careful of and I would have never have thought of this but I read an article that with newer modern aluminum heads that the surface of them are finished so good that over the area of where the washer goes under either a bolt or stud head that the washer if being an ARP has such a smooth finish on it that along with the head having such a smooth finish as well, that if you go to torque them down that sometimes the washer will not be able to grip enough on the bottom of it and can end up causing your to over torque and strip out the threads on the block. The link is below.

Also another thing I like to do as well a few times is retorque the intake manifold as well after several heat cycles and I have been surprised on just how loose things can actually get. I have not redone my heads before but this time I am actually going to do that bit just to make sure with everything.

Interesting article. Now I'm worried I have too much tensile load in my fasteners (ARP). I found a wide range of "recommended" torque specs for a 351W. I erred on the higher side and torqued the heads to 110 lbs. ft. I believe I'm going to leave it alone.
 

·
Registered
Joined
·
4,709 Posts
On my small block chevy, ARP calls for 80 foot pounds for there studs and I did that with my last build but heard and read some folks even with brand new blocks torqued them to that big of an amount which normally I have read about 70 to 75 ftlbs for the ARP stuff and they pulled the threads out of the block. My current build was done at 80 ftlbs but wow it seemed quite a bit more then what it normally feels like. This time around on my new build in the works I am going to just go 70 ftlbs on everything as that what the machine shop did with a set of ARP studs and a torque plate when they did the final hone on my Dart shp block. I don't want to go way past that as I don't know for sure but am no expert but I don't know if it would affect the stretching of the cylinder bore or not.

I read aluminum heads does not need as much torque on them vs iron heads and read some folks who questioned ARP on that spec for mine and ARP said they could do 70 if aluminum and 75 if iron and it should still be ok if using there lube is which I use. In the past it was only 75 and somehow they changed to 80 in the last few years. I think 80 for me is a little bit to much and stock is only 65 with TTY bolts and with ARP bolts its 70 ftlbs with iron heads. I have read some folks did it only at 70 ftlbs and was just fine.
 

·
Race it, Don't rice it!
Joined
·
8,813 Posts
Meh….I keep thinking about all those thousands and thousands of heads going out the factory doors and engine machine shops all over the country that don’t get checked by the end user.
so many of them actually I haven’t seen or heard of anyone having issues because they didn’t recheck head bolts. Even all those with warranties returns because of loosening head bolts and spitting gaskets.
Oh wait, it seems like that’s not actually a problem since the days of bellbottoms.

Truth is the gasket technology has gotten so good that they are more compliant then they used to be.
 

·
Registered
Joined
·
202 Posts
This thread just made me start a new thread on head bolts vs studs. Re-torquing bolts on newer cars would appear to be very labor intensive as so much has to be removed to get to the bolts. I don't remember if this was done back in the 50's and 60's but we never had a new car.
 

·
Registered
Joined
·
442 Posts
First thing is you have to realize there are thousands of variations between the parts combos being used by builders. A guy building a 350 Chevy with a mild cam and some double hump heads and 10:1 compression is going to have different needs than a guy building a turbo engine..........so the amount of torque you want to use is going to vary. Further there are different types of head gaskets that are going to seal differently and react differently to heat cycling. There really isn't any one answer to this question. Now as to whether I want to go with what some guy on the internet reccomends or what the bolt and gasket manufacturers reccomend, thats a pretty obvious conclusion to me. Personally, this internet guy sees nothing wrong with retorqing after some heat cycles, but I'm usually too lazy to do it if everything is working OK.


Something you should realize is that torqing as done by us amatuers is not a perfect technique. What it does is put you in an area that should produce a satisfactory result.
 

·
Registered
Joined
·
4,709 Posts
The last few builds I have had done was with a set of felpro 1003 composite head gaskets and I used ARP studs on them and one was with a set of head bolts from ARP, and I did not retorque them and they never had a problem. The only thing I have had to retorque was the intake manifold as it seemed to loose a bit of torque after a few heat cycles. I torqued it to 25 ftlbs and when I went to redo them it seemed to be a bit loose and I got maybe a 1/4 of a turn at the most but its been so long it might of been a little bit less then that. With iron heads it seems the intake stayed tighter vs with it being on aluminum heads.
 

·
Registered
Joined
·
225 Posts
I usually just torque in steps then check final torque a little bit later before the thread sealer sets. Found if I chase the block with a thread-chaser(I like the arp one) the head bolts felt more consistent when I pull the heads later.

Made vid bout that washer article, actually just prepped some washers for my aluminum ebay heads. I bought a few diff brand head bolt washers to compare, just not got round to making the vid I'll prob this winter. I find little stuff like that interesting LOL

 

·
Registered
Joined
·
202 Posts
I always retorque. Just pull the valve covers and do it after a few miles or heat cycles. However, how do you retorque? I first break the bolts, nuts on studs loose then bring them back up. When I say break loose I mean just enough to over come the initial static friction. Usually only takes a slight amount of twist on the wrench. Then I bring back to the original torque. The initial torque to start a bolt when it is not moving is higher than the actual torque on the bolt. So if you are torqueing to say 70 ft lbs and you put a torque wrench set to 70 on the bolt, the bolt will not move but may not be actually at 70.

I am sure many will disagree with this but this is how I do it. Maybe this is old school and head gaskets are better today than years age. But think of it this way - can it hurt.
 

·
More for Less Racer
Joined
·
20,926 Posts
Alwill923, I do it the same way. Follow the torque sequence pattern starting with the center of the heads, crack loose and retorque each bolt in sequence one at a time.

But I don't do a heat cycle....just let the assembled short block sit a day to allow the the gasket and bolts settle in, then do the cold retorque.
SBC usually 1/16 turn or a hair more ends up on the long bolts, the short outer row below the exhaust ports not quite as much.
 
1 - 12 of 12 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top