Exhausted.

[phild]

Without going into boring detail I'm missing the front part of the exhaust on my '69 427/435. That is the downpipes from the manifolds and the heat riser valves. It looks like it would be sensible to replace the whole system from manifold back and I'm looking for suggestions and experiences with after market systems.

I've had a look at various suppliers systems and they all seem to be from the downpipes back but I desperately need a system with those pipes included.

Any ideas/suggestions would be gratefully received.

 

[CaptainK]

Could you go to a custom exhaust fabrication shop and get them to make an exhaust for your system?

 

[Roscobbc]

If 100% originality is your goal, then fine follow your path.......but for efficiency surely a pair of good quality headers would be the way forward?

 

[phild]

Not too worried about originality and a custom build is probably the way forward. My issue is that half the system (front pipes not the headers) is missing so I thought buying an after market system would eliminate the need to transport the car to a builder. I'm meeting the new restorer tomorrow so we'll, hopefully, work out the way forward then along with all the other stuff that needs doing.

Good news is that I'm due a tax rebate which will greatly assist getting the car on the road. My goal is to have it running for next years show season.

 

[Chuffer]

Not too worried about originality and a custom build is probably the way forward. My issue is that half the system (front pipes not the headers) is missing so I thought buying an after market system would eliminate the need to transport the car to a builder. I'm meeting the new restorer tomorrow so we'll, hopefully, work out the way forward then along with all the other stuff that needs doing.

Good news is that I'm due a tax rebate which will greatly assist getting the car on the road. My goal is to have it running for next years show season.

Nice to hear that Her Majesty`s Tax & Revenue Department is funding another Corvette back on the road ! About time the government spent our money on something useful !

 

[Roscobbc]

Being as I already had the underfloor Supercomps it was the opposite of what you need - i.e I had a twin 3" diameter 'X' pipe system made-up from the header collectors back - still cost me the best of £850 7 or 8 years ago. I had replaced the Hedman 1 7/8" od headers with the Hooker 2 1/8" od but running through 2 1/2" pipes and straight through mufflers. The difference using the larger tube pipes over 4500/5000 rpm was quite significant.
In your position I would source a set of quality ceramic coated headers and have the stock down pipes adapted to them. Surprisingly you might loose some underhood temperature with the headers.

 

[phild]

Being as I already had the underfloor Supercomps it was the opposite of what you need - i.e I had a twin 3" diameter 'X' pipe system made-up from the header collectors back - still cost me the best of £850 7 or 8 years ago. I had replaced the Hedman 1 7/8" od headers with the Hooker 2 1/8" od but running through 2 1/2" pipes and straight through mufflers. The difference using the larger tube pipes over 4500/5000 rpm was quite significant.
In your position I would source a set of quality ceramic coated headers and have the stock down pipes adapted to them. Surprisingly you might loose some underhood temperature with the headers.

Now that sounds like a good idea, under bonnet heat is a problem on a 427 even, as mine is, in standard tune.

Going over to see the restorer this afternoon to work out a planned schedule of works. A bit of good news is that we've found the new convertible top in a box hidden under some other stuff, so that's saved a fair old wedge of my hard earned.

 

[Roscobbc]

In the early days of owning my Vette with its L36 lump running hot there were a number of logical things I had to do to reduce temperatures but the surprising one was installation of headers and the significant reduction of underhood temperatures as I mentioned previusly. The only downside to this was the proximity of the collectors, specifically the drivers side one which was perhaps too close to the underside of the floor pan..........feet would get rather warm. And ceramic coated headers mostr certainly do further reduce underhood temoeratures and also stop that typical 'ticking' sound expericenced when running.
The people who did my exhaust system (Hayward & Scott) specialise in custom exhaust systems and headers for race and street vehicles - expensive, very expensive but you only buy once...........

 

[phild]

Decision made. We're going for trailering the car to a specialist exhaust builder so it will be exactly as I want and will be a perfect fit. Going for ceramic coating on the headers also. Having done some pricing analysis its going to be cheaper than importing a ready made system from the US which is a nice bonus.

We checked out the identification numbers for the gearbox and, good news, it is the correct one for the car so it remains matching numbers. As its already been taken apart and most of the internals have some rust/water damage it will be fully rebuilt as new so I'm pleased with that. I'm also surprised how reasonable the parts prices are for the box also, much cheaper than the ones I already paid for with the previous charlatan.

I'm now feeling much happier and looking forward to next year now I've got someone decent, CCM Vettes, and trustworthy doing the work. Tom Falconer popped in whilst I was there looking hale and hearty, was good to see him after some years.

Thanks for the advice and support chaps, much appreciated.

 

[Roscobbc]

Make sure the ceramic coat application on the headers is both external and internal for best sound, heat and corrosion protection.......

 

[HJG]

Sounds like a nice opportunity to convert to sidepipes!

 

[phild]

Make sure the ceramic coat application on the headers is both external and internal for best sound, heat and corrosion protection.......

Thanks for the tip, will do so.

 

[phild]

Sounds like a nice opportunity to convert to sidepipes!

I had thought that but there's too much work, and expense, with adapting all the other things to take them. Will go for standard exit and incorporate an 'X' pipe in the system.

 

[GiuG]

I resolve some heat problem with a Titanium pipe wrap (20£ or less), specially to the passenger side where the pipe run close to the starter. When I made around 100 miles, the car once off, refuse to turn on for 2 days! Because the starter shell expansion block the inside brushes. Till now, I don't have that problem any more.
The Titanium is different from the common wrap, he became after the first ride after installation a strong metal shield, and you don't have problem of moisture or tear up.

 

[teamzr1]

IMO,
Few issues using heat wraps
One is by trapping heat in also can cause welds to crack in that since the weld is thicker than the pipe there is a different rate
of expanding and contracting, causing the pipe to change quicker than weld and cause cracking
This is worse if pipe is made of mild steel

Other is water vapor can get trapped between wrap and pipe causing rust, as I found in one customer Corvette I was tuning


If the pipe is stainless steel, that metal wants to return to its original made shape that is flat, so trapping in heat could induce welds to crack

If engine does not have oxygen sensors or CATSs not too many issues that engine that do have them
as trapping in too much heat will affect them more and cause degrading sooner

Example of 1 customer's C5 Corvette was tuning the engine ran like crap, the fueling AFR was way out of wack and the front O2s reported wacky readings
Headers had been heat wrapped and made of mild steel, which as above the heat difference change caused welds no only crack but also break off
That caused outside cooler air to be sucked in and that forced the O2 sensors to report incorrectly to the PCM as what AFR, so it then was commanding wrong amount of time the fuel injectors be commanded on





I would limit the amount of heat wrap to be used, stainless steel transmits heat out OK
so would only coat the outside but not inside that could affect O2 sensors temps.