New headers = Can o' worms

[68ChargerAG]

So, I decided to install headers for the first time... man, I hope they are worth it.

Anybody ever have the old exhaust manifold studs break off flush with the heads. Yep, I had one break off on each head. The rear most stud on both sides.

After mangling one of them by trying to drill blindly into it and use an Easy-Out (which didn't help in the slightest, only proved to ream more of the bolt and head material out), I finally ended up having to remove both heads to get at the bolts correctly to drill them out and re-tap the holes. :edgy:

Now I'm waiting on $60 worth of new gaskets to put it all back together.

Man... what a disaster!!!!! :sad:

 

[Meep-Meep]

I have felt your pain!! Sounds like you got it under control.

Hopefully you have a hot cam to take advantage of the headers.

 

[68ChargerAG]

I have felt your pain!! Sounds like you got it under control.

Hopefully you have a hot cam to take advantage of the headers.

I hope so too. I can't remember the specs right now, around 0.475 or 0.48 lift I think. But I read an article in Mopar Muscle Magazine where they did a 383 build with very similar specs to mine and saw very good HP gain with headers over the stock HP manifolds... so I figured that I should go for it. We will see... :grin:

 

[70BEE&500]

Exhaust studs

I removed my headers for a project last fall. I got the front two studs out fine and then came the rears. What a pain! It must be the angle and poor amount of room to work in that makes the job hard. After several soakings of penetrating oil, I was able to back them out but they put up a fight. I chased the threads and installed header bolts from Jegs when I reinstalled the headers. No more studs!

 

[68ChargerAG]

Yes, I would say to all that are planning this project in the future... take 70BEE's advice and use lots of penetrating oil etc and be very cautious with the rear studs.

I wasn't putting much torque on them either. I was putting much more torque on some of the front ones and they didn't break. I figure that the rear bolts must get brittle from the higher temps or something, and just ready to go. There is no way that I should have been braking the studs with the amount of torque I was putting on them.

 

[Meep-Meep]

I hope so too. I can't remember the specs right now, around 0.475 or 0.48 lift I think. But I read an article in Mopar Muscle Magazine where they did a 383 build with very similar specs to mine and saw very good HP gain with headers over the stock HP manifolds... so I figured that I should go for it. We will see... :grin:

That's about what I ran in my 383. Worked great!!

 

[69 Runner]

Hope you didn't get headers with 2" tubes..........

 

[69HEMICORONETR/TCONV]

Hope you didn't get headers with 2" tubes..........

You can say that again ! :yes: I tried those.............once.

 

[68ChargerAG]

Hope you didn't get headers with 2" tubes..........

No, not 2" tubes, I read that going too big with headers will actually cause worse flow in a moderately built engine due to excessive heat loss and turbulent flow inside the tubes. If I recall correctly, they are 1 7/8" tubes... which I hope isn't still too big. If anything I did want to err a bit on the big side instead of too small and being worse than the stock HP header manifolds that I had.

I am also going with a 2 1/2" exhaust instead of 3" for similar reasons.

Also, I looked up the cam spec (from prev comment) and it is 0.470 lift. Comp Cams recommended not going higher for street driven car, but I would like to put true 1.5 or 1.6 ratio rockers on there some day which would add a bit to that.

This is all based on what I have read over the years for building "performance with economy", I don't really have that much experience with all of this.

 

[69 Runner]

I had 1.75" tubes on my 69 383 Super Bee. Worked great. But according to an engine analyzer program I used to have I should have been running 1 5/8" to compensate for the drop in torque through the mid-range. Most all big blocks with headers have that drop.

 

[Meep-Meep]

Your exhaust valve size plus about 1/8" to cover the boundry layer is a good rule of thumb, so I'd say you are good. I wouldn't bother with the high ratio rockers, but would use the Crane or Isky iron adjustables with the 3/8" push rods. I think those ratio out to a C hair over 1.5 anyway. I degreed my .455" and .509" MoPar cams and the lift came out to .462" and .517" respectively.

Keep the 2.5" pipes all the way out.

 

[68ChargerAG]

OK, great. Thanks for the advice guys. :beerchug:

 

[68ChargerAG]

Wow... this just gets more and more fun! Got left one in by taking just about everything out of the engine bay and lifting the engine 2", now can't get the right one in for anything. Looks like I have to remove the torsion bar to get it in there. Aaaaahhhhhh!!!

Can't find the tool to rent anywhere, looks like I will have to try to make a tool myself to get it out.:edgy:

Anyway... this is all part of the fun, right?:black_eye: