Exhaust Manifolds are different?

unclebrad

unclebrad

Active Member
Hi guys.

This is a two-part posting.

I am getting close to finishing my 348 to 409 engine swap in my '55 truck. (1963 QA engine with the addition of dual quads, but I may eventually go to an original single carb setup.)

It has been a bit more of a job that anticipated, especially since I also swapped the 350 trans to a 700r4.
And it has taken longer and cost more than anticipated. But that is just part of the deal, right?

Anyway, I only have about 20 items left on my list! WooHoo!

I have the 348 exhaust manifolds bolted up temporarily, because the 348 down-tube flanges don’t fit the 409 manifolds. I’ll use the 348 manifolds to drive the truck over to the muffler shop, when the time comes.

Part 1:
As I was double-checking things, I noticed that the LH and RH manifolds have some differences that bothered me:

- LH Outlet is just over 2 – ½” (correct for this manifold, according to the 348-409.com numbers)
IMG_7780.JPG


- LH Outlet has bevel or chamfer. (unknown whether this is correct, but I don’t think a donut gasket is used.)
IMG_7779.JPG



- RH Outlet is 2 - 7/8 “ (smaller than spec for this manifold, according to the 348-409.com numbers)
IMG_7784.JPG


- RH Outlet has no bevel or chamfer.
IMG_7778b.jpg


My first question then, is:
Are these differences by design, or is something amiss?


Part two
Based upon the information posted on 348-409.com, the manifolds I have are not the right ones for this engine.

What I have:
Exhaust# 3814682
Year used: 1963
Model: Passenger car
Engine: 409
Horsepower: 340
Side: right
Outlet: 2.54
Notes: Center dump design. 1962 manifold has casting dates, 1963/64 do not.

Exhaust# 3814683
Year used: 1963
Model: Passenger car
Engine: 409
Horsepower: 340
Side: left
Outlet: 2.526
Notes: Center dump design. 1962 manifold has casting dates, 1963/64 do not.

What I should have:
Exhaust# 3822925
Year used: 1963
Model: Passenger car
Engine: 409
Horsepower: 400,425
Side: left
Outlet: 2.54
Notes: High performance, rear dump design. Also used on the 427 Z-11.

Exhaust# 3822926
Year used: 1963
Model: Passenger car
Engine: 409
Horsepower: 400,425
Side: right
Outlet: 2.526
Notes: High performance, rear dump design. Also used on the 427 Z-11.


My questions about this are:
Does any of this matter?
What are my options?
What are your recommendations?
 
our1962

our1962

Well Known Member
Supporting Member 2
When your looking at the thread, you'll see there is 1' of no thread on RH side, that is where the spacer goes and then the outlet of the spacer takes the same doughnut gasket as the left side.

Yes by design.
 
unclebrad

unclebrad

Active Member
Thanks. Very enlightening.

About the left manifold and the steering box - As I said, I have the 348 manifolds bolted up, and the left manifold seems to clear the box nicely. It appears to have very similar dimensions as the 409 manifold, but I guess I had better actually bolt on the 409 manifold to see what's what.

Hadn't planned on changing out the steering box. Guess this could be another of those unanticipated thing that just goes with the job. I don't suppose it would be too much to hope that the guy who put in the 348 raised the mounts a bit for clearance?

Here is what it looks like with the 348 manifold...
IMG_7786.JPG
 
4

427John

Well Known Member
You may want to check the temp of the steering box the next time you take it for a extended drive in town just to make sure its not getting hot,if its cool enough that you can hold your hand on it your golden,if not you may want to wrap that part of the manifold.
 
unclebrad

unclebrad

Active Member
Excellent. Thanks!
55Brodie - The RTV is temporary to seal the exhaust while I drive to the muffler shop. Then it all gets replaced.
59apachegail - I'll try to get mount measurements tomorrow and post them.
 
unclebrad

unclebrad

Active Member
Here are some photos and a drawing with a bunch of measurements for the engine mounts.
-The drawing isn't perfect but will get you there if you check the measurements against your truck and engine.
-The one photo with the tape measure appears to show 5 7/8" but I think there was some distortion. It was closer to 6". It was the same on both sides.
-I put a yardstick across the frame in front of the pulley so that you can see where the engine sits. (The yardstick is about 1/4" thick.)
- Two pics shows a view straight across the yardstick to the pulley. You can see that the pulley nut is about 1/2" above the yardstick.
-The other view is lined up with the front edge of the pulley and you can see that the pulley is about 1/4" back from the front flat of the crossmember.
-The rest of the pics are of the driver's side mount in place.
Hope this helps!
Engine Mount drawing 1.jpgIMG_7850.JPGIMG_7851.JPGIMG_7853b.jpg

IMG_7841.JPGIMG_7844.JPGIMG_7845.JPGIMG_7847.JPGIMG_7849.JPG
 

Attachments

  • Engine Mount drawing 1.jpg
    Engine Mount drawing 1.jpg
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59apachegail

59apachegail

Well Known Member
I was worried how I was ever going to get 409 exhaust manifolds to clear my steering box after seeing the nightmare Don had with his. The pics, measurements and drawings are great!

Thanks a lot Unclebrad!
 
J

JJA

Member
Hi, good job with the manifolds and the pics are very helpful for comparison. The clearance you have looks to be good to go.

Also, the motor torques and pulls away from the steering box when you step on the gas and the RPM goes up so you should be A-okay.

Thanks for sharing,

-Juan in Virginia.
 
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