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Exhaust manifolds for 400 sb in 67 Chevelle

 
chevfella2
I love my Chevy Chevette!
Posts: 3
Joined: 09/09
Posted: 09/07/09 02:30 PM

My son and I are doing a complete restore on a 67 Chevelle. Floor pans have been replaced as well as all new sheet metal including quarters.

We're going to power the car with a fresh small block 400 mated to a rebuilt Powerglide.

What I'm trying to locate is where to buy exhaust manifolds for this engine that have two and half inch exhaust outlets that exit toward the rear of the engine. Rams horn manifolds will not work in a 67 Chevelle. We were going to use headers, but there are too many fit issues and I personally don't like them anyway. (Heat related headaches and exhaust leaks.)

I've posted this question in other Chevy forums (Chevy Talk etc.) and was overwhelmed by the lack of helpful responses or advice. I'm willing to scour salvage yards for the much needed manifolds if no aftermarket are available. I'd just like to know what specific cars I should be looking at if I have to go that route.

This engine really needs the 2 and half inch exhaust outlets to breath properly.

Any help would be much appreciated.  

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waynep7122
Everything in my driveway’s a Chevy
Posts: 556
Joined: 08/09
Posted: 09/07/09 04:54 PM

one question....    are you using 6 or 7 bolt patterns on the cylinder heads...   a lot of the exhausts that exit the rear have 7 bolt patterns...  where there is an extra exhaust bolt hole in the head a little farther back...

did you measure your frame to verify that you don't have cross member sag???
here is a frame dimension chart that might help..

http://www.imca.com/manage/uploaded/%5Bform-27%5Dgm_chevelle_frame_dimensions.pdf

when the cross member sags... there is not enough room for the headers..  the car sits lower...  even with fresh springs... and you cannot get the wheels aligned.. as you cannot take out enough shims to set the camber...    when you get to 0 shims and have to go farther... what do you ***  when the frame gets pulled back to the proper dimensions.. there is also room under the car for the collectors...

you should probably be looking at chevy pickups... 73 through 79... as they came with a rear exit angled and were 2and a half inch as i recall.. and used the 6 bolt pattern...

oOo__oOOo__oOo    a six bolt pattern
ooOo__oOOo__oOo  a seven bolt pattern on the head..
o-Oo__oOOo__o)o   a seven bolt pattern on the exhaust manifold...  see the missing hole...

newer chevys also had an 8 bolt pattern exhaust.. but lets not talk about that...
if you find 7 bolt pattern manifolds .. and you have 6 bolt patten heads... you can get from enginequest.com a 5/16 spacer plate to convert one side...



there is one problem... the right hand exhaust has a flat face... requires a spacer that usually includes the heat riser valve.. the other side of that spacer will have the correct taper for the donut gasket to fit into...

as just to top that off... i ran across the heat riser manufacturers web site a few months ago.. they have the spacers without the heat riser valve...      

here is a picture chart of some of the exhaust manifolds that are available...

http://www.stevensparts.com/CHEV%20EXHAUST%20MANIFOLDS.htm

i think that i might look at these...  you might also check out the various restoration parts suppliers... as they might have just what you are looking for....

Part # :1264R 305-350 1985-88 Truck Tubular

Part # :1265L 305-350 1985-88 Truck Tubular


if you were in the san francisco bay area.. i would say stop over to dorris auto wrecking in hayward... they have exhaust manifolds sorted by engine...  there are also engine core suppliers...   thousands of junk yards ...

i would also take a chain type exhaust tube cutter...  so you could just unbolt the manifold from the heads... and cut the exhaust pipe from below... that way you have a piece of pipe to replicate..  

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chevfella2
I love my Chevy Chevette!
Posts: 3
Joined: 09/09
Posted: 09/07/09 06:46 PM

It's a six bolt pattern for the heads. I thought about cross member gag. I'm a retired bodyman with thirty years experience with heavy collision repair.

Let me stop before going any further to thank you for your detailed help and quick response. I stopped visiting the other Chevy forums because I grew weary of checking for responses that never came. It's much appreciated I assure you.

Getting back to the frame sag, I don't believe that's the problem. I don't think the frame chart dimensions you linked to are correct for a 67 Chevelle. I'm quite positive of that. Here is a link to a more accurate dimension chart.

http://www.chevellestuff.com/tech/67_frame_dimensions.htm

If you compare the charts, you'll see there's more than a six inch discrepancy in the frame horn width measurements between the two charts, and I can tell you right now if I tried to spread this frame THAT much, I'd ruin it beyond imagining.

The fact is our frame measures dead on the money according to the frame chart I'm going by. In making diagonal-cross measurements, the frame measures perfectly square.

So though I'm aware of cross member sag and have dealt with it in the past, I don't think it's the problem with this car in regards to header fit. I honestly believe the headers are poorly designed.

I'll check out the link for the manifolds and may got to the salvage yards and try to scare up a couple of those 73 Chevy trucks you're talking about.

You've given me a starting place and I really appreciate it. Thanks.  

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85_trans_am
I have an SS396 tatoo
Posts: 252
Joined: 05/09
Posted: 09/08/09 09:28 PM

here is what you can do. Look at classic industries catalog they have a web sit as well. They have mantifolds and headers for the firebirds and trans ams with a 400sb. The 2nd gen firebird\trans am headers hugged the block a little more and made some room for the steering. just a thought.

hope I could help.  

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waynep7122
Everything in my driveway’s a Chevy
Posts: 556
Joined: 08/09
Posted: 09/09/09 09:54 AM

thanks for pointing out the huge difference in dimensions... i posted that link do to the single measurement between the upper control arm mounting brackets...    the other dimensions are for body fit and don't effect the cross member sag...

i guess i will have to order the 5 buck dimension chart off ebay and compare...

i spent a lot of years doing stuff under the hood.. not much in collision...   so i found out about the frame sag and how to fix it in my shop with the stuff i had laying around...  after i saw it fixed properly... takes me less than an hour.. including driving the car in  to do the repair... and alignment..    the frame shops i have sent people to... all want 600 to 800 bucks for that same hours work... they want to pull it with the towers.. instead of jacking it from below... as with the jacks you can control which side gets bent more.. by moving the jack toward that side..

best of luck with your search...    and your chevelle..


edit...

i went and looked at both dimension charts...    the imca chart has the later model frame horns... with spread in them...

i would say for anybody  to buy the exact frame dimension chart ... for their chassis... as there are year to year differences... any body remember the johnny cash song.. one piece at a time....  

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68scott385
I have an SS396 tatoo
Posts: 325
Joined: 07/09
Posted: 09/09/09 01:59 PM

all the little things we took out in my buddy's big lunch box, like nuts and bolts and all four shocks...

and the headlights, there was two on the left and one on the right and ya pulled out the switch all three came on...

love  that song  
68scott385 68scott385 68scott385

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