: '70 Deville headers



BluEyes
04-01-05, 01:41 PM
anyone out there have headers on their big-block Caddy?

I've been looking at the headers that MTS makes (http://users.elknet.net/mts/page44.html). They look pretty nice, but it looks like I'd have to change the exhaust pipes to hook up. How well do these headers work in the real world? Worth the $350?
Also, anyone have a '68-'70 with them who knows what modifications are needed to clear?

davesdeville
04-01-05, 06:31 PM
I know Sanderson also makes headers that fit, in fact MTS might just resell those... I think the modification just requires you to move one primary using a mallet to clear something. I personally plan to use Monte Carlo BBC headers adapted to Caddy flanges to save a bit of money, the flanges are $70 from Flash and the BBC headers are $150. They're 2" primaries which will cost a bit of power unless you get up into some real power where you'd need 2".

BluEyes
04-01-05, 06:49 PM
Are the sandersons supposed to fit up to the stock exhaust pipes?
Figured the modification was just a minor tweak with my BFH.

So, the Monte's headers clear the Caddy suspension okay? I've noticed those upper a-arm mounts are really close... Sounds like a much better solution, cost-wise.
Except for the pipe spacing, I wonder what about using something like 1 3/4" Small Block Chevy headers...

Also, what is the best solution for what seems to be a BB Caddy problem of shearing the exhaust manifold bolts? The rear bolt on both sides on my car was broken when I got it, and a spare set of heads that I just grabbed from the junkyard was just as bad.

djcwardog
04-02-05, 02:37 AM
I looked at the MTS page as well. I would want to know who runs the mid-length headers like you tagged or the full-length ones like Cad Co sells for about a grand. I wonder how much power you get over stock from just the mid-length headers? Are the stock ci pieces that crappy? If I put headers on a car (either my 1973 Corvette or the Caddy I expect to buy this summer) I will likely want full length tubes and the ability to spec out the primary tube diameter. I think 2" is a bit big for the street unless it is a killer motor. Otherwise, loss of low rpm power and response.

davesdeville
04-02-05, 03:15 AM
I don't know if they'll fit to the stock exhaust but I don't see why you would even bother with headers if you're going to bottleneck it all up with the stock 2 or so inch single (unless it's radically differant between a 70 and a 75.)

Flash saw a 10hp/15ft.lb. increase with some sanderson which were 1 7/8 primary and 3" collector, those were block huggers but you get the idea. Smaller primaries would've been a bit better. I'm only going with the big 2" ones because I'll be spraying it pretty hard.

I got the idea of using the Monte Carlo headers from the four grand cadoo article - I'm going to talk it over with the people at Cad Co beforehand though. It would probably behoove you to call MTS or Cad Co and ask if they know - if they want to sell you flanges (which they do) they'll tell you.

BluEyes
04-02-05, 11:00 AM
I haven't measured yet, but I think my stock '70 exhaust is at least 2.25", maybe 2.5". Yes, stock is single, but I'm pulling the exhaust off another '70 soon, and plan to splice it onto the stock y-pipe, giving me duals with a crossover pipe! I'll have the stock mufflers for now, but a pair of turbo muffs will find their way under there eventually.

As for the stock manifolds sucking. The drivers side one isn't that bad, but the passengers side is terrible. Just about the definition of a 'log' manifold. One common tube that all the ports dump into, and the exit to the pipes at back. Flow might not be too terrible, since it is reasonably large, but there will be no pulse tuning whatsoever.

I hadn't noticed that reference in the 4K Cadoo writeup, very nice. Considering how big this car is, it is really suprising how little room there is under the hood in some places!
Heck, if the Monte headers are longtubes, that sounds even better, and worth doing some hacking to hook up. Longer tubes should improve my lowend torque even more. Yesssss, more torque, ahhhh...