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Manifold Spreaders

blublaz

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Hey I'm replacing my motor. The old exhaust manifolds will not come close to lining up with the holes on the head. Is the manifold spreader a real tool? And where do I get one?
 
Yes, it is a real tool and they work. Any auto parts store should have them or be able to get them easily. They usually run about $15.00-$20.00.
 
I don't know if its that I just watched a confusing movie or confusing posts tonight but wtf? I've never heard of a "manifold spreader" and seeing as manifolds are made of cast iron and could not be spread without cracking and being ruined then NO. There are exhaust expanders. I have a few examples of them, they are great tools you can get at any auto parts store. Whats up with your manifold that it won't line up? What is the manifold you are trying to use off of? What is the motor from? The only thing I can think is you are trying to use a Small Block manifold on a Big Block, beyond that all small block chevy's should have the same pattern on the heads, plus or mine one bolt hole on the very end(front end on the driver's side head).
 
It's a manifold from a 305 that's going onto a 350 block. One side went on like it was new out of the box, the other side doesn't line up at all. It's about a 1/4" off. We can get 5 of the 6 bolts installed.
 
somebody just had this here awhile back.. for some reason i think it was Southernspeed or another of our euro counterparts... maybe they'll chime in...
 
Did a search after this post and yes, there is such a monster. It's so bad that if we were to get this manifold on the #8 plug would NEVER come out......
 
is it the very last bolt on the driver side that won't go? Like I said I've seen heads with 2 holes at the end of the driver's side head. I seem to remember a difference in 305 manifolds now that I think about it, can't place what it is though.
 
i believe this is what your looking for...


18030.JPG
 
I've got exhaust manifolds off of Vortec motors (1996+) that won't fit because the manifolds have "shrunk". Could get all but one bolt in for engine break-in. I had some older ones as well, and one of them wouldn't bolt up either. Has nothing to do with the 6 vs. 7 bolt head pattern either. The over plug manifolds have the same problem as the under the plug design.

Notice that on some of the under the plug style manifolds GM cast them with reinforcing pieces between the runners to prevent this problem from happening.

Yes the spreaders do exist, and they work, but it's a good excuse to go with headers.

I was looking at the manifolds and it looks like there is plenty of meat on the rearmost or frontmost bolt hole to drill it out one size larger, but again, headers if cost permits, just make sense. :)
 
learn something new all the time. I think I get it, do you have to heat the manifold when you spread it?
 
I have never used spreaders, but I suspect no. I doubt even an oven gets hot enough to make the cast iron "pliable".

It seems odd that the bolts don't shear off because of the shrinkage, but perhaps that is the reason bolts sometimes break off in the heads when you try to remove them?
 
old mechanic trick is to drill out the small holes to the bigger hole size and thay will drop on no problem. this will alow for the spread of the manifold over time.
 
Headers are nice, but another day:frown1: Never thought about drilling the holes out. Definately easier, make warble a few others out as well. It was a fight just to get 5 bolts on.
 
The spreaders are made by Lisle tools and available at most parts stores. I think they'd work very well if you only need to stretch it a hair.
 
A few tricks....

I used a 1/2 inch bolt about 3 inches long and a nut,and a peice of 1/2 inch pipe to make my own spreader,it worked ok--just screw the nut on the bolt,slide the pipe over it,place the whole shebang in between the manifold bolt castings,and use two wrenches to "unscrew" the bolt and spread apart the manfold--you might have to grind the pipe and bolt head concave to keep it from slipping off too easy..

One manifold I had was "shrunk" like that,it was in the winter during a motor swap--I had my wood stove going,and my friend suggested putting the manifold in the stove,on the hot coals--about ten minites later,I fished it out with a poker,and using my welders gloves,was able to get the bolts started without much difficulty!--I never can figure out how the bolts dont snap if they expand and contract that much....:confused:
 

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