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Header Bolts on Hemi Head

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zupanj

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I fitted my tti headers to the engine the other night. The engine is fitted with 426-1 Indy hemi heads. The bolts supplied were 1" long and when I tightened them, they bottomed out before the header was tight against the head. There was maybe as much a 1/4" of space between the header flange and the bottom of the bolt head. So I measure the depth of the holes on the exhaust ports and they are 1/2" deep, the header flange is 3/8" and the gasket will be something, maybe 1/8". That adds to 1" and I can't figure out what is going on. I call Indy and they say 3/4" bolts will work fine and that the holes are tapped to 1/2" depth. I call tti and they can't figure out how that can be. The guy says he has a head in front of him and he never heard this before, then says 3/4" bolts would probably be OK. I come home last night with calipers I borrowed from work. The flange is 3/8", the holes are 1/2" deep, it makes no sense. Then I crawl down and look into the hole with a bright light. I looks like the threads only go in about 3/8" so that explains why the 1" bolts bottomed.

So here's the question. Would you use 3/4" header bolts to put the headers on or would you tap the bolt holes to be able to use 1" bolts. I can't see that the 3/4" bolts can have much bite, maybe 5/16" and that's my concern. Will that be enough. Threading the bolt holes can be a bit tricky and will delay the project but now is the time to do it if it needs to be done. So what do you guys think? By the way the 383 used 3/4" header bolts. I need to measure the flange on those headers tomorrow.


Jack
 
ACME A12

ACME A12

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Okay gents, someone with some wide valve cover experience needs to step up here and help our buddy Jack out... I myself can't do it as my most intimate experience with a hemi head engine was simply riding in the back of a pick-up with a derelict 392 in route to its new home...

No idea on tapping the bolt holes, whether or not they're wet, or even anything on the anti-seize question posted in your other thread.

Time to circle the wagons, muster the troops, raise the flag...you get the idea... George, where the hell are you...?

ACME
aka Wedge Guy Only...
 
Big John

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Sounds like the holes aren't tapped deep enough. It happens.

I would get a bottoming tap and re-tap the holes. The bottoming tap is just what it sounds like... a tap that cuts the threads to the bottom of a blind hole. You have the thread started, which would be the hard part for you to do with the engine in the car. Just take your time and use a tapping fluid (even kerosene would work OK with aluminum in a pinch) and tap a half turn at a time, backing off a 1/4 turn to break the chip.

Oh.. and get a good tap from a industrial supplier, not some Chinese POS from the local Harbor Freight.
 
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Big John said:
Sounds like the holes aren't tapped deep enough. It happens.

I would get a bottoming tap and re-tap the holes. The bottoming tap is just what it sounds like... a tap that cuts the threads to the bottom of a blind hole. You have the thread started, which would be the hard part for you to do with the engine in the car. Just take your time and use a tapping fluid (even kerosene would work OK with aluminum in a pinch) and tap a half turn at a time, backing off a 1/4 turn to break the chip.

Oh.. and get a good tap from a industrial supplier, not some Chinese POS from the local Harbor Freight.
Click to expand...
John is right on all accounts with this one........... :thumbsup: And no I'm not just sucking up........
 
Big John

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Hoosier Bird said:
[quote="Big John":1q8bd3l3]Sounds like the holes aren't tapped deep enough. It happens.

I would get a bottoming tap and re-tap the holes. The bottoming tap is just what it sounds like... a tap that cuts the threads to the bottom of a blind hole. You have the thread started, which would be the hard part for you to do with the engine in the car. Just take your time and use a tapping fluid (even kerosene would work OK with aluminum in a pinch) and tap a half turn at a time, backing off a 1/4 turn to break the chip.

Oh.. and get a good tap from a industrial supplier, not some Chinese POS from the local Harbor Freight.
Click to expand...
John is right on all accounts with this one........... :thumbsup: And no I'm not just sucking up........[/quote:1q8bd3l3]

:gives secret Toolmaker handshake:
 
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Hoosier Bird

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Big John said:
[quote="Hoosier Bird":1hc9uwjf][quote="Big John":1hc9uwjf]Sounds like the holes aren't tapped deep enough. It happens.

I would get a bottoming tap and re-tap the holes. The bottoming tap is just what it sounds like... a tap that cuts the threads to the bottom of a blind hole. You have the thread started, which would be the hard part for you to do with the engine in the car. Just take your time and use a tapping fluid (even kerosene would work OK with aluminum in a pinch) and tap a half turn at a time, backing off a 1/4 turn to break the chip.

Oh.. and get a good tap from a industrial supplier, not some Chinese POS from the local Harbor Freight.
Click to expand...
John is right on all accounts with this one........... :thumbsup: And no I'm not just sucking up........[/quote:1hc9uwjf]

:gives secret Toolmaker handshake:[/quote:1hc9uwjf]

:flag:
 
george68hemirr

george68hemirr

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zupanj said:
I fitted my tti headers to the engine the other night. The engine is fitted with 426-1 Indy hemi heads. The bolts supplied were 1" long and when I tightened them, they bottomed out before the header was tight against the head. There was maybe as much a 1/4" of space between the header flange and the bottom of the bolt head. So I measure the depth of the holes on the exhaust ports and they are 1/2" deep, the header flange is 3/8" and the gasket will be something, maybe 1/8". That adds to 1" and I can't figure out what is going on. I call Indy and they say 3/4" bolts will work fine and that the holes are tapped to 1/2" depth. I call tti and they can't figure out how that can be. The guy says he has a head in front of him and he never heard this before, then says 3/4" bolts would probably be OK. I come home last night with calipers I borrowed from work. The flange is 3/8", the holes are 1/2" deep, it makes no sense. Then I crawl down and look into the hole with a bright light. I looks like the threads only go in about 3/8" so that explains why the 1" bolts bottomed.

So here's the question. Would you use 3/4" header bolts to put the headers on or would you tap the bolt holes to be able to use 1" bolts. I can't see that the 3/4" bolts can have much bite, maybe 5/16" and that's my concern. Will that be enough. Threading the bolt holes can be a bit tricky and will delay the project but now is the time to do it if it needs to be done. So what do you guys think? By the way the 383 used 3/4" header bolts. I need to measure the flange on those headers tomorrow.


Jack
Click to expand...

jack....i havent heard too many good things about indy....customer service and there machine work is terrible....if i were you i would do what big john said and get as much thread as possible and make it work....my heads are stage v...by hansen..top self stuff
 
ACME A12

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Big John said:
:gives secret Toolmaker handshake:
Click to expand...


Aha, I thought so...

...you two probably know who was REALLY behind the Kennedy Assasination too... :lol:

:jester:
ACME
I love a good conspiracy theory...
 
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Hoosier Bird

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ACME A12 said:
[quote="Big John":2y5x6xkl]
:gives secret Toolmaker handshake:
Click to expand...


Aha, I thought so...

...you two probably know who was REALLY behind the Kennedy Assasination too... :lol:

:jester:
ACME
I love a good conspiracy theory...[/quote:2y5x6xkl]
And maybe you haven't noticed but I have only 3 words above my Avitar.............. :devil:
 
ACME A12

ACME A12

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Hoosier Bird said:
[quote="ACME A12":17vvdyb6][quote="Big John":17vvdyb6]
:gives secret Toolmaker handshake:
Click to expand...


Aha, I thought so...

...you two probably know who was REALLY behind the Kennedy Assasination too... :lol:

:jester:
ACME
I love a good conspiracy theory...[/quote:17vvdyb6]
And maybe you haven't noticed but I have only 3 words above my Avitar.............. :devil:[/quote:17vvdyb6]


Well, before you shoot my car just remember that she's named after a Stripper and not a Deer... :D

:jester:
 
69hemibeep

69hemibeep

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:jester:
Bambi - the other kind of sweet meat...[/quote]
:lmao: :lmao: :lmao:
 
Z

zupanj

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I'm around George but just a little frustrated. Talked to a lot of people on the headers. Some say use 3/4" bolts but most say to tap the holes. I know a guy from my car club who is a machinist and he is coming over this week to help tap the bolt holes. I expect I can do it but he is pretty experienced and I don't want to screw it up by cross-threading or something. I am usually very careful but sometimes I push ahead when I shouldn't.

Decided to use a mechanical fuel pump because I want a semi-stock look. The block was not machined far enough into the block to allow the ears of the fuel pump to seat. Also there were a couple of "steps" where the cutting tool didn't go completely even with the surface. What a crappy bunch of machine work. I love Mopars but I was under no illusions about their quality. Anyway I have been grinding on the fuel pump ear and the block some but haven't got it seated right quite yet. I picked up a couple of grinding stones for my dremel and hope to finish tomorrow.

This is a lot easier to do on the garage floor than in the car!
 
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zupanj

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No it's a Mopar block. I've been told by several people that the Mopar blocks require a lot of machining to be right but the fuel pump surprises me a little.

Jack
 
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