Author Topic: Headers for a 1970 Deville convertible  (Read 259 times)

Offline grantatx

  • Posts: 30
  • Name: G. Scanlen
Headers for a 1970 Deville convertible
« on: October 02, 2017, 09:50:27 PM »
Hi All,

Finally found a nice '70 Deville convertible to bring home. The exhaust manifolds are pretty much shot and I'd like to go with headers. I've seen a few offerings out there - Sanderson, MTS and cad500parts.com. Also the cheapie block hugger headers on Ebay for around $100, but looking at them though I doubt they'd fit even though the sellers say they do. Has anyone had success fitting headers to a '70 Deville convertible without modification and if so what brand/model were they?

Thanks in advance,

Grant

Offline chrisntam

  • Posts: 1279
  • Dallas, Texas
    • CLC Member
      CLC Member #29206
  • Name: C. Jessen
Re: Headers for a 1970 Deville convertible
« Reply #1 on: October 03, 2017, 06:41:19 AM »
My understanding is that the chassis is different on a convertible than a coupe or sedan.  I can't answer if they would fit or not or how difficult to install or a good brand.

How do you intend to use the car?

I got my car about 3 yrs ago and also toyed with the idea of headers.  I spoke to MTS, they asked why I wanted headers, told them for better air flow through the motor, performance, etc.  They advised that the manifolds do pretty well and just add dual exhaust if I wanted.  I had them build the motor, 10 to 1 compression, mild cam, mild port work on the heads, electronic ignition, etc.  I do regret the compression choice, it forces me to use premium fuel and it's not a race car.......

I did not install headers, I'm using factory manifolds and am glad I made the choice I did.  I had my manifolds ceramic coated, they still look new after 3 years (as they should).

I've come to find out that these Cadillacs are better cruisers than performance vehicles.  The main reason is weight, approx. 5000 to 5500 pounds.  The motor is plenty powerful, more than enough for what I need.

I recommend you make it a dependable cruiser and get a lighter car if you want to go fast.

Additionally, from the factory, there were no gaskets between the heads and manifolds.  If you have a leak, be sure the exhaust hasn't eaten away the mating surfaces.  MTS supplied the gaskets, nary an exhaust problem since.

That's my $0.02.  Kind of a long reply and I didn't even answer your question...............

And since you just got the car and are new to the forum, please post pics!
1970 Deville Convertible  MTS 507
Dallas, Texas

Offline cadillacmike68

  • Posts: 1226
  • Still finishing up this 1968
    • CLC Member
      CLC Member #15823
  • Name: M Santos
Re: Headers for a 1970 Deville convertible
« Reply #2 on: October 03, 2017, 07:51:40 AM »
^^^

There are very few chassis differences b/w the Coupe and Convertible, especially up front. I don't think there are any forward of the firewall.

I would second the idea of adding dual exhaust.

The convertible had a curb weight of 4,600 lbs not 5,000-5,500 lbs, but still it's not a lightweight.  These case had great acceleration for their day, but they can't compare to the 5 or 6 sec 0-60 cars that are around today.

As for your high compression, just add some 110 octane race fuel to the tank.  It will rocket down the road without knocking.
Regards,
"Cadillac" Mike
Current:
1968 DeVille Convertible
1996 Fleetwood Brougham
2009 STS NorthStar Platinum ed RWD
2011 CTS PRemiun ed Sedan RWD
Past:
2008 CTS Premium ed Sedan AWD
2005 CTS Hi-Feature Sedan RWD
2000 ElDorado ESC Hard Boot Convertible
1995 Fleetwood Brougham
1973 Sedan DeVille
1970 Fleetwood Brougham
1969 DeVille Convertible

Offline "Cadillac Kid" Greg Surfas 15364

  • Posts: 2814
    • CLC Member
      CLC Member #15364
Re: Headers for a 1970 Deville convertible
« Reply #3 on: October 03, 2017, 09:50:43 AM »
Grant,
The easiest thing of course would be to replace the manifolds.  They are however getting pricey.  The headers MTS sells will fit your car and any good muffler shop can make the connections.
http://www.500cid.com/_p/prd1/3511124991/product/headers%2C-1968---1976-deville

What I have shown here is my MTS headers which I've modified for performance to help my 5000 pound '73 Coupe deVille get into the 12 second neighborhood. The main reason I am showing them is to show how VHT paint looks and lasts.  The paint on the original (upper 1/2) of the headers is several years old, and the lower half where modifications have been made to incorporate electric cut-outs and extend the headers to "long tube" is fresh/. Very little difference. Point being, the ceramic coatings sold as an extra are not necessary unless you like "pretty".

I suggest calling MTS and talking to Paul about your needs.
If you want to go with original manifolds, I've got the pair off my '73.  PM me.
Greg Surfas
Cadillac Kid-Greg Surfas
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline George D. Mukalian CLC # 10047

  • Posts: 40
    • CLC Member
      CLC Member #10047
Re: Headers for a 1970 Deville convertible
« Reply #4 on: October 03, 2017, 02:08:17 PM »
I purchased exact fit headers for my 1969 Convertible.
I had no issues with them.
Attached is the company I bought them from.

George
George D. Mukalian
CLC #10047

Offline grantatx

  • Posts: 30
  • Name: G. Scanlen
Re: Headers for a 1970 Deville convertible
« Reply #5 on: October 03, 2017, 09:53:36 PM »
Thanks guys for all your responses, they're all very helpful!

The manifolds on the car at the moment are in bad shape and causing leaks at the join between the manifold and pipe, so rather than try and find good used ones for big bucks I figured I'd just go down the header route provided I can find some that are a direct fit. And it sounds like both MTS and Sanderson do make direct fit headers so I'll give them a call.

I'll definitely be going dual, I guess 2 1/2 all the way back. At the moment the car is going to be a cruiser but next year I'd like to build up a fresh engine and warm it a little.

I'll definitely post some pics soon, just struggling with a turn signal replacement tonight!

Thanks again!

Offline grantatx

  • Posts: 30
  • Name: G. Scanlen
Re: Headers for a 1970 Deville convertible
« Reply #6 on: October 14, 2017, 12:09:11 AM »
Hi All,

I ended up purchasing headers from Sanderson, the CAD700 model. installed them tonight and they look and fit great! And what a sound!

I needed to unbolt the engine mounts on both sides (one side at a time) and jack the engine slightly to tilt it so I could get the headers between the block and chassis. The passenger side went in from underneath the car, driver's side from the top.

Thanks everyone for all your input!

Grant

 

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