Hi all,

The new 440 I've just built has Edelbrock aluminum heads. The headers bolts I was using in my old cast iron heads are from tti, and are 1" long. With the lock washer, that leaves about 7/8" of thread. The header flange and gasket take up about 7/16", so that leaves only about 7/16" thread going into the head.

I've measured the depth of the holes in the new heads, and they're about 1-1/4" from the surface of the header flange (or 13/16" deep from the head surface). So, I could easily go up to 1/2" deeper with my bolts, and not bottom out. That would be 1-1/4" to 1-1/2" header bolts.

Should I go longer, or are my current bolts sufficient? Thanks for any advice.

Roger

I think the old rule is at least the diameter of the fastener thread engagement which would be 3/8".I would feel better with at least 1/2" myself.The only thing is some headers won't let you get a longer bolt in because of tight bends.

i use studs in the edelbrock heads. works good, gives full thread contact and I don't worry about working those alum threads.

I always thought that 1 1/2 times the diameter was needed for full torque. with alum i'd want more than that.

On some cars with some heads you have to use bolts and some of them won't take longer ones unless you start those bolts with the header flange push away from the heads
the Hooker headers I bought and use on my engine run stand are that way on the second bolt back from the front on both heads
I have found that using header bolts with smaller wrench size heads on them make it easier to install them with a open end wrench, IE a 5/16 bolt head size tightens easier than a 7/16 bolt head size does

From Edelbrock



I wouldn't worry about it.

I appreciate the input, guys. And, I had forgotten about the helicoil inserts! These bolts are probably fine. Thanks!

Two things to think about. I always use Remflex gaskets on my Mopars these days. I've had great success with them and their collector gaskets are reusable 90% of the time. They also only require a relatively low amount of torque to tighten, although I do re-torque them until they hold without needing further re-torqueing.

Second, use a good quality anti-seize on your bolts and wipe them lightly with a cloth after application to remove the excess. Aluminum is susceptible to galling, especially if you use stainless steel fasteners, with also always require anti-seize on them to avoid galling.

The heads have helicoils in the exhaust bolt holes.

Stainless steel helicoils.

You are not screwing your stainless fasteners into aluminum.

I would use studs and not bolts

I use the bolts TTI sent with the headers. No washer. 3/8 head, 3/8 X 1.

my preference as well. i believe ARP makes 12 point nuts with a small head size if you need them. much easier to get nuts started on studs in tight bends than bolts [relatively speaking].

I've used the Mr. Gasket 3415 header studs on a few engines now with good results. Both steel and aluminum heads.

They have two thread sizes on the stud with a smaller 5/16 thread sticking out to make header installation and nut clearance much easier.
I usually buy better grade 8 nuts to replace the ones included with the studs.
I don't believe they are currently being made/sold new but they do show up occasionally on e-bay.

They do, they were easy to find but of course when I went to order no body had them in stock. Used all ARP stuff when putting the manifolds back on my 2.2, spendy but much less frustration using all reduced head size hardware.

Ah, even more important to use anti-seize on the bolts then. Stainless steel into stainless steel is generally prone to galling.

As someone who is forced to work with stainless fasteners, these are very wise words. I've had stainless nuts gall on stainless bolts threading them together by hand.

absolutely been there, done that [many times,-you would think i would learn not to even try by hand without anti-seize !], got a t-shirt AND a sticker !
anti-seize is your friend with stainless !

One thing to add here is headers also hold up most of the exhaust system.
The engine moves around and most of our exhaust systems does not want to twist with the engine, loading the header bolts.

+1 on Studs

But a few bolts in tight places dosent hurt, last 360 i had was cup/allen head bolts all the way through, pipes are easy to get past with a long hex drive instead of sockets and extensions