edlebrock 4 barrel manifold broken bolt

[Scott52]

An Edlebrock 452 manifold was included in extra parts that came with the car. It has a broken off bolt. I was wondering what the hole is used for. Also I don't remember removing a broken bolt from Aluminum so any hints would be appreciated.

[tubman]

That's in the heat riser passage from the exhaust system. It looks like a hole got put into it, and someone tapped the hole and put a bolt into it to plug the hole. There isn't supposed to be a hole of any kind there. The only thing I can think of is that someone at some time decided they wanted to run an automatic choke and put the hole in there for a tube to supply heat to an automatic choke. When they found out it didn't work, the decided to plug it. If you have access to someone who is good at welding aluminum, I'd have it welded up. If you're cheap like me, I'd just clean it up and patch it with a high quality aluminum epoxy. There's really no pressure there so it would probably work fine. (Make sure what you use is intended for high temperature use.)

It looks like whoever had it modified it for a PCV system instead of a road draft tube as well.

[51 MERC-CT]

If that is a view of the drivers side of the manifold and it's not a distorted view, the carb mount surface is backwards of what it should be and the angle does not look right.
Looks more like it was meant for some special application like a boat.

[Scott52]

That view is of the passenger side and please double check me. My advancing age and dyslexia can confuse me. The top view photo shoes the side with the broken bolt is the passenger side. I never noticed the plane of the carb surface was not parallel with the block surface. Some reason for that?



As far as the broken bolt, I may just leave it alone if it is blocking a hole that was put in later by someone.

[marko39]

My offy manifold has a similar hole plugged with a bolt.

[JSeery]

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Engines normally mount at an angle to the ground and the carb mounting surface is angled to level the carb. Because most engines mount at about the same angle the manifolds come with this machined into them. In some special applications more or less angle may be required and the carb base machined to a different angle. An extreme example would be an engine located backward in a boat.

[Scott52]

I guess I never noticed carb angles and I am going to look more closely at my other cars and cars in general.

[tubman]

Don't 8BA manifolds have a 4 degree tilt down in front and the pre '48's have none?

[51 MERC-CT]

Originally Posted by tubman

Don't 8BA manifolds have a 4 degree tilt down in front and the pre '48's have none?

Can't say about the pre- 8BA's but all the 8BA's I have seen have the 4 deg. angle.

[cadillac512]

Originally Posted by tubman

Don't 8BA manifolds have a 4 degree tilt down in front and the pre '48's have none?

Correct. I milled my 8CM Merc manifold flat to use in the '41 Merc.


Terry