41 buick straight 8 headers design ?

I have been threw 3 sets of straight eight 248 ci exhaust manifolds . They crack and break up ,now the exhaust leak isn't that bad at first . Then years later couple more cracks -- etc. . I have decided to make my own headers for the 1941 buick compound carbs original car . The flanges are coming from hells gates hot rods (off ebay) then ordered the shorty sbc weld up kit from speedway motors . Now comes the design process for me , did some doodling and came up with these couple designs . . I am wondering if there is a reason the original exhaust manifolds were 2 pieces or can I connect the entire length of the motor with 2 directional exhaust pipes . I am not looking for performance more for no exhaust leaks . I will be using the original compound carbs ,linkage, baffle flap on rear carb , and single exhaust too . On top of the single pipe was going to put heat riser tubes up to the intake too (like the original design is set up ) . If there are others on here that have custom headers on there straight eights all help will be appriciated . Thank you for reading .

 

I whould beleave that thay made the exhaust manifold in two peaces because of the heat expansion problem with a manifold that long. I whould make it a two part header think it whould hold up better and be eazer to make.

 

Hey kuhn, what size engine? 320 or 248? If it's a 248 and you wanna give it one more try with stock parts, I think I have a good exhaust manifold for you. I'm not too far away, over here in Capac, east of Imlay City. Welcome to the Hamb.

There's a member here that designed and built his own dual intake and exhaust for his Buick 320. I think it was a '49 thru '52 car. I can't remember who. Can anybody find the thread for the OP?

EDIT: I looked...couldn't find it. The build I saw may have been elsewhere on the internet.

 

Looks like this guy did exactly what you're planning.

 

I got my header flanges from "Hells Gate Hot Rods " delivered today fedex . pics of the group of stuff (pipes are sbc block hugger weld up kit from speedway motors) besides the main tube pipe I am thinking of that design still .

 

Make a pair of 4 into 1 pipes.

 

I am thinking that .2 pipe headers tied together to the single exhaust .

 

Hell's Gate made my manifold and supplied the exhaust flanges and I made my own headers....Good stuff!!

 

I love the clean look . Have you driven it much yet ,did you notice a difference in how the engine acts ?

 

I ve read the original exhaust had no gaskets.
They just used graphite IIRC between the head and the exhaust.
What happen now is every body use gaskets. So at first there s no leak, but the iron can t shrink / stretch and break.

 

That is a possibility , My car at one time had single carb and single log factory exhaust manifold .Who ever installed it put 3 sets of gaskets on it - that exhaust manifold broke severly after driving to a 1 hour away car show . I think it has to do with the wieght of the entire set up then being bolted together on the head it needs a back brace just as some people do to stand up . I have seen pics of braces fabbed up on straight eights . My original owners manual actually says to be aware of exhaust smells coming into the cabin area ,take to qualified dealership and have exhaust manifold inspected for cracks or leakage . Simpler times back then the manual also says if your car leaks water in to the back floor drill a hole in the floor so the water has a place to go - that was their fix .

 

In fact I had this information on teambuick forum, where many knowledge guy have good informations. This topic has been debated several times.
Bonus : the modern replacement gaskets are one piece, which for sure doesn t help to shrinkage ...
I would be funny to know how hot a head go, and how much the iron expand.
If my math are corrects, with a thermal expansion coefficient of 6 x 10^-6 po./po.*/ °F , lets say it s 70 F outside, and the head after running a while goes to 195 F, it s a difference of 125 degres, so 0,024 " (0.06 cm ) for the 32 " head of the 248.
It s not a lot, but may be enough to cause cracks.
Any expert ?

 

Here's Bryan Blake's 1936 Century. May be a little inspiration for you.

I'll be making a set for my Dad's 1952 Roadmaster with a 320 when I get back home. I'm going to go ahead and split it, I want to hear that 320 with duals out the back.

 

There's discussions of cracked manifolds on the ACAA pre-war Buick site. One poster had this posted:

Be sure to follow the instalation procedures faithfully on instalation of the manifold. The manifold must be able to slide on the gasket at the head attachment. Liberal use of graphite or moly antisieze on the gaskets is necessary. The Manifold mounting studs have a domed heavy washer That is supposed to allow the manifold is move. Don't over tighten the manifold studs!!! I polish the washer contact points so the washer can move on the surface.
Under exhaust heat, the manifold will expand. Cast iron can take high compression forces under heat expansion without problems. Upon cooling, if the manifold can't easily slide on the surfaces, it will put the manifold under tension forces and cast iron is terrible for tension strength.

Due to the inherent cracking problem on these manifolds, Buick eventually switched to 3 pieces exhaust manifolds.

I recommend that on old engines with rusted manifolds, that they be removed the gaskets properly lubed, all rust on the washers and locking surfaces be polished and the nuts be carefully lightly tighened upon instalation.

 

That is a attempt that I have not tried ,I will make sure the matting exterior surface is smooth and clean up those wedge blocks that hold the intake and manifold together on a single stud .I have in the past separated the gaskets it did seem to help . Thank you for the info and will apply the new knowledge for sure .

 

What a cool post about these wonderful inline 8's. Appreciate the pix posted by others with the set up. That yello racer would be a blast to hear tear up the drag strip. ~sololobo~

 

Bryan's yellow 36 sounds pretty damn cool. I'll try to remember to take a pic of the headers going in his Dad's black 36 Century LSR car. That set is really neat.

Have a listen. The Buick is pretty much all you can hear in this video, from the same day as the above pic.


http://youtu.be/YTi_1f36UI8

 

I've made several sets of headers for my flatheads and OHV's. I used the kits that are just a box of bends, flanges, a Sawzall, and a grinder. It's actually pretty easy except the joints where the pipes come together. Luckily I do a lot of sheet metal welding so filling with a MIG is something I'm familiar with. Like a couple of guys here said, I'd do two sets of four ports. Trying to tie eight pipes together would be a nightmare as sometimes four can be a challenge. The really neat set up on the running chassis appears to have been done with a pipe bender, something I don't have access to. Also, building headers is MUCH easier if the sheet metal is off the car.

The way the exhaust ports sit on this engine, would it be easier to find a couple of sets of sbc headers and cut them up? These things are rusting in garages all over the place, especially around circle tracker's places.

 

The cracking is likely due to an under-engineered part. Cast iron is a very stable metal, especially at these relatively low temps. However, a thin walled casting or one that is not designed correctly to cope with the stresses it is placed into will have failures. In modern race shops, it is common to circulate hot liquid through the water jackets to simulate racing temps while the block is being finish honed, and the difference between the bore size at room tempurature and 200° is less than .003". Since the head is cast iron on the Straight 8 and the manifold is cast iron, there expansion rates are going to be the same. I bet it just a poorly designed part to begin with, its common on other inlines to have this problem also.

 

I was sent this link today and thought it related to the topic:

http://www.hotrod.com/featuredvehicles/hrdp_1303_bombshell_buick_1952_super_rivera/photo_01.html#

 

I mentioned these earlier....

 

I love the fact that the old straight eights are not fading off because of bad exhaust manifolds , but getting reborn to new carbs intake combo's . I love the way my compound carbs act and I believe with a sealed exhaust system they are going to work even better . Any more buick guys out there doing mods to the straight eights to make them run smoother,better,and more reliable .

 

Of all the examples pictured, those are the only ones that take the middle four ports into one pipe and the outer pairs into another. As I believe Buick used the more common 4-4 crank configuration (rather than the rarer 2-4-2 configuration favoured by Packard) the result of this header pattern should be identical to a V8 rumble.

 

Having just picked up a '52 320 for my '35 chevy 3w coupe I'm very interested to see how your design turns out! here's a few pics of designs I've collected so far.


Nick Flores... do you know who's in the vintage pic? Seems like the exact set you've got!

 

Those look FANTASTIC! Sorry if I missed it, but is your motor a 248 or a 320?

 

That's my brother with the headers I welded up for his straight 8 powered '37 gas coupe in about 1961 or so; and they are now in the Phoenix area with some other parts of his.

 

I don't know the story on that header, They just kind of appeared one day. Its cool to see the old pic and hear some of their history. I'm sure either Dave had them stashed or somebody brought them down. Bryan is a member here and I've been trying to get him to post, he's been doing some neat-o stuff with his straight motor as is his Dad.

 

I'd buy one of those headers if it would fit in a 47 special? Cant tell if that's for the 320 or a 248/263

 

These are the pics of my engine now ,before I build my own header for the 248 straight 8 .

 

This is the design I am going to try to stick to . It is really close to the original dual exhaust manifold style . I just ordered my first tig welder too from Eastwood 200sx - it is on sale and free shipping this month . I have built headers in the past with a mig welder , just looking for a better job .Now I will get that better job .