Manifold washers

-
eestatic

eestatic

Well-Known Member
Joined
Dec 2, 2012
Messages
320
Reaction score
16
Location
Texas
I've "fitted" my '92 Dakota manifolds to my 318 in my 65 'Cuda after machining .250 off of flange face for fitment clearance.

Do I need to use a washer of sorts..on any of the bolts, ya think?

The 273 had a particular type of washer, iirc..
 

Attachments

  • IMG_1778.jpg
    38.2 KB · Views: 296
I put washers or flanged bolts on everything especially if tit tightens into cast or aluminum. I think you get a more even torque and they stay tight longer.
 
Stock - they had thick, conical washers on the nuts/bolts. That was to spread the load on the castings. I would use them. Your flanges look pretty thin. I'd really be worried about cracking those.
 
69_340_GTS said:
Stock - they had thick, conical washers on the nuts/bolts. That was to spread the load on the castings. I would use them. Your flanges look pretty thin. I'd really be worried about cracking those.
Click to expand...

Yes, I am concerned also and was curious to the the load distributing characteristics of the conical washers from the 273 over a flat washer. I figured best to put those at the thin spots and possibly flat washers on the long bolts.
 
The Machinist felt comfortable with the thin spots...
 
Would you mind posting as many pics as possible of you exhaust manifolds on the engine. I couldn't quite make out the casting numbers. Do you know if these are the large hole (2 1/8") magnum manifolds??
Please post more pics of both sides and casting numbers...the more the better for everyone!!!

thanks,
Treblig
 
Yes they are the large manifolds off of a '92 Dakota. I'll post some pics soon..
 
The conical washers are intended to make up for the difference in expansion between the cast manifold and steel bolts. Without them, the bolts will eventually work harden and snap.
 
eestatic said:
Yes they are the large manifolds off of a '92 Dakota. I'll post some pics soon..
Click to expand...

Have you had time to get those pics?? Also the manifold casting numbers. If you made any other modifications please let us know. As for the conical washers, they are designed to distribute the load in a circle around the bolt head. Without the conical washer the bolt head would apply pressure directly to the hole in the manifold increasing the chances of breaking the hole area. A regular flat washer doesn't distribute the load in a circle away from the hole.
If you look closely at the conical washers you'll see that they only contact the manifold along a small area (in a circle) around the hole. When installed correctly there is minimal pressure on the hole itself.
Treblig
 
Treblig said:
Have you had time to get those pics?? Also the manifold casting numbers. If you made any other modifications please let us know. As for the conical washers, they are designed to distribute the load in a circle around the bolt head. Without the conical washer the bolt head would apply pressure directly to the hole in the manifold increasing the chances of breaking the hole area. A regular flat washer doesn't distribute the load in a circle away from the hole.
If you look closely at the conical washers you'll see that they only contact the manifold along a small area (in a circle) around the hole. When installed correctly there is minimal pressure on the hole itself.
Treblig
Click to expand...

I disagree on the washers being used to protect the castings rather than the bolts themselves.
Those conical washers only show up in two places...Slant Sixes (three positions) and the SB. In both cases the fasteners are only 5/16s.
Exhaust manifolds that use 3/8 bolts and studs use standard flat washers.
The conical washers are intended to expand and contract along with the undersize bolts.
 
It's good to use washers whenever possible as it helps distribute the load from the bolt to the part better.

However, in some cases you need to make sure that the washer OD is not too big where it will interfere with it seating, like would probably happen on the center exhaust port where there is little clearance room for a washer in the picture in post #1...
 
whitepunkonnitro said:
I disagree on the washers being used to protect the castings rather than the bolts themselves.
Those conical washers only show up in two places...Slant Sixes (three positions) and the SB. In both cases the fasteners are only 5/16s.
Exhaust manifolds that use 3/8 bolts and studs use standard flat washers.
The conical washers are intended to expand and contract along with the undersize bolts.
Click to expand...


Any washer would expand and contract, that's a physical property of any metal. A flat washer will expand and contract and so will a conical washer. The big difference is that the conical washer only makes contact on it's outer diameter thus putting the force of the torque (bolt head) on the outer edges of the washer. By putting all the force (torque) on the outer edge of the washer you don't put pressure on hole area. Since most manifold gaskets crush to some degree they allow the manifold ears to flex (bend) into the gasket where the bolt exerts pressure. We all know that cast iron will only bend so much before it breaks. So by distributing the load (torque) to the outer edge of the washer you don't press on the hole area and cause it to bend into the gasket. It's just like pushing a car....if you push a cart using a pointed ice pick you'll push a hole through the body before you actually make the car move. But if you you push with the force distributed over a large area (both hands) the car will roll without any damage to the body. In the same way the conical washer will press the whole manifold ear against the gasket, not just the hole area. Maybe the conical washers have a dual purpose. One may be to distribute the load more evenly and the other may be to decrease the surface area of contact to allow for expansion???? That would make sense because if the washer only touches the manifold on it's outer edges it can expand and contract more easily (less surface contact). I know one thing for sure...those ears will break, especially if you're using gaskets.

treblig
 
iam just trying to help. do NOT NOT use cal plated blots on ext system. the cad plate can come off and jam the threads. but DO use anti seize compound on all plain bolts.
 
Treblig said:
Have you had time to get those pics?? Also the manifold casting numbers. If you made any other modifications please let us know. As for the conical washers, they are designed to distribute the load in a circle around the bolt head. Without the conical washer the bolt head would apply pressure directly to the hole in the manifold increasing the chances of breaking the hole area. A regular flat washer doesn't distribute the load in a circle away from the hole.
If you look closely at the conical washers you'll see that they only contact the manifold along a small area (in a circle) around the hole. When installed correctly there is minimal pressure on the hole itself.
Treblig
Click to expand...

Here ya go..only mods were to shave off flange


So don't use cadmium for bolts?

Which ones require sealant on threads for coolant?
 

Attachments

  • Dodge Dakota manifolds 001.jpg
    32.2 KB · Views: 166
  • Dodge Dakota manifolds 002.jpg
    34.2 KB · Views: 158
eestatic said:
Here ya go..only mods were to shave off flange


So don't use cadmium for bolts?

Which ones require sealant on threads for coolant?
Click to expand...


The front and back bolts on both sides!!


DID YOU SHAVE THE FLANGES ON BOTH SIDES (L & R)????
treblig
 
Yup..250" off of both sides. Probably could have went less..~.200" but at the time I was extrapolating w/measurements it appeared I would need that amount.

I ended up using one shim under under driver mount approx. 3/16" for insurance but may have been ok with out it...
 
eestatic said:
Yup..250" off of both sides. Probably could have went less..~.200" but at the time I was extrapolating w/measurements it appeared I would need that amount.

I ended up using one shim under under driver mount approx. 3/16" for insurance but may have been ok with out it...
Click to expand...

I guess you could have removed less than .250 if you had been willing to grind a little off the manifold or the steering box on the driver's side? If you had not removed anything off the passenger's side would the manifold hit the inner fender?? This info is greatly appreciated!!!!

Hope you don't mind all the questions but many A body owners (NOT ME) are always looking for alternative exhaust option, just like you.

thanks,
treblig
 
The passenger side was scratch-the-paint tight, about the thickness of the exhaust gasket clearance!

While extrapolating my desired clearance I felt .250 was needed at that time but now see .200 would be fine. I shortened my steering column tube & added a bearing at tube end and have about 3/8 clearance there. The steering coupler is a given, has to go. Probably about 3/8" clearance to steering box now w/shim under mount with no modifications to gear box.

Whilst jostling motor about I was cognizant of limitations of motor movement/placement due to fan interference with fan shroud and AC compressor to hood.

I recommend new motor mounts and center motor to desired position before taking manifold measurements, in retrospect...

Please feel free to question anytime!
 
You must log in or register to reply here.
-

Back
Top