Have 7 exhaust manifolds with no cracks and good threads but all have drooped at #4 port. Anyone straighten manifolds or has the availability of reproductions rendered these scrap metal?
I think they are worth something. There are videos on how to straighten them using heat and a jig. I've never used a reproduction but I've heard they are not all that good.
I have made and used several sets of eccentric copper washers ( gaskets ), just turn them slightly to adjust as needed. They are easy to use and work well.
DON"T Scrap them. They are very easy to straighten.
Check out the videos first. Send to me second.
I have 2 manifolds I bought at swap meets cheap that were warped. I used one with the flat asbestos gaskets on one car and its works fine.
The other I straightened after making up a jig similar to the one that was used on a video by the Tulsa T club.
It was fairly easy to straighten and it works fine.
If you belong to a T club that has a jig and an oxy-acetylene rig Its economical to straighten one.
If you go to the trouble to straighten one use one that has good threads. Cost comes into play when you have to use your own oxy-acetylene because it does take more gas than usual to heat up the manifold and carefully straighten it.
I believe I would buy a new one as the cost of gas and making a good jig is about half or more the cost of a new one. It was for me anyway.
Its not something you would be doing everyday for the average T guy.
I bought a repro one and at the time they were about 100 bucks.
A new manifold is $85 plus freight. I have at least 2 dozen reproduction manifolds out on engines that I have rebuilt, no complaints. They bolt right up and the threads are great. I have a jig that is made for straightening them. If you are paying someone to fix it, probably cheaper to buy new. If you have a chunk of steel laying around and the oxy/acetylene at home it probably would be fun to fix them all.
To Richard: I have a Lang's reproduction and it's excellent.
Thanks John, good to hear the new ones are good.
I'm afraid I have to be on the other side of the fence. I'm sure straightening works well for those who have the resources. I found the replacements to be of what appears to be high quality and Snyders had tons of them right in the showroom. I took my old one to the scrap yard. As I threw it from my truck, it actually broke in half.
http://mtfctulsa.com/Tech/manifold.htm
http://dauntlessgeezer.com/DG82.html
http://www.mtfca.com/discus/messages/257047/312701.html?1348150760
We have done several in the Long Beach club with good result's. Kind of a fun process too, straightening them.
I used a Snyder's reproduction manifold on my 27 in 2010 with the one piece copper gaskets. Still good in 2015. More info below; http://www.mtfca.com/discus/messages/257047/318698.html?1351426017
Easy way to straighten them:
http://www.mtfca.com/discus/messages/331880/342833.html
Snyder's had a scratch/dent sale on manifolds a couple of months ago. The manifolds were perfectly serviceable - they just had some finishing marks that did not make them suitable for a show car (not an issue on doodlebugs). Markdown was half-price, so I bought two of them and put them on the shelf. Quality on the repro manifolds is great. But if you have 7 with good threads, it might be worth borrowing a jig and trying to straighten them.
Sure as hell wouldn't scrap them.
Tom in Austrailia, I also use the copper rings with the new manifolds as you do. I found out the hard way that it is easy to ruin those expensive copper rings if the manifold is not straight. I think it's important to torque the manifold nuts regularly. I use 30 ft lbs. Would doing so help prevent warping? Hard to say but, it can't hurt.
Ron, I bought a couple of those too. One came with a blow hole on the tailpipe flange & they cheerfully replaced it & said, "keep the bad one, too expensive to ship back for us to scrap!"
Hmm, great wall hanger art piece!
Ron, I bought a couple of those too. One came with a blow hole on the tailpipe flange & they cheerfully replaced it & said, "keep the bad one, too expensive to ship back for us to scrap!"
Hmm, great wall hanger art piece!
Sorry, dial-up mess caused double posting.
Dave in Ontario. Thank you for the heads up on re-tightening the manifold nuts. I'm driving the car in the next few days,so will check and tighten if necessary. They were very tight after I tightened them hot, last time. (But,it has been a while) Tom
No problem Tom. I tighten mine once a week and always to exactly 30 ft lbs which seems to feel just right. Sometimes a nut will move and sometimes not. Same idea as checking the demountable wheel nuts. My own weak theory is that keeping them torqued constantly with the solid copper rings locked in the port holes might make it impossible for the manifold to sag or at least for a longer time. I bet a lot of cars are running around with the nuts backed off a bit.