I have a set of headers, I think I got the SS set. It does give off alot of heat. Is there a heat wrap that would help this? I always thought wrapping them would cause them to rust?? Is that true?
Tom
Tom
Thorley headers heat
- Thread starter Billygoat
- Start date
Correct, wrapping is not a good idea. Thorley offers ceramic coated which helps a bit with the heat, but headers don't help that much overall. OEM manifolds are still available from Cinnabar.
Try to better manage your igition timing and set the vacuum advance lines like they did on the 455 from 1970. The earlier 455's had the vacuum advance canister hooked up to manifold vacuum, and also make sure your mechanical advanced its working properly. The Olds exhaust manifolds are very thin and dont really contain heat like other thicker caast iron manifolds. I have headers and I didnt notice a differance in heat or sound when I switched to headers the same way that I did when I switched my SBC and LS engines to headers.
Other things to check are the muffers, if they are internally coroded they will restric flow and contain heat. Moving the mufflers to the back can also help keep the heat moving away from the front of the coach.
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Headers are going to put off heat just like cast iron manifolds do. They do cool off faster than cast iron. I like wrapping small parts of header tubes when we are worried about burning wires or things of that nature. Wrap does trap heat and can lead to cracking welds if they are really wrapped up.
I'd bet that you would probably notice a greater improvement with headers on a fuel injected engine vs. a carb engine (unless you are actually tuning the carb engine; checking plugs, needles and jets, timing etc). Most people arent.
They certainly wont hurt, but depending on what level of effort you put into the overall package, can help. If I have to pick stock manifolds or headers, I'd do headers every time
I'd bet that you would probably notice a greater improvement with headers on a fuel injected engine vs. a carb engine (unless you are actually tuning the carb engine; checking plugs, needles and jets, timing etc). Most people arent.
They certainly wont hurt, but depending on what level of effort you put into the overall package, can help. If I have to pick stock manifolds or headers, I'd do headers every time
i have an aluminum (flashing) heat shield mounted on inner fender.. which were melting and 7 inch vents just beneath the floor to exterior (gills) larry
I replaced the (other performance company) mufflers at the front (off my headers) due to a droning noise at cruise. If you can move them to the back (as suggested by @icsamerica), I think you'd definitely see less heat and noise. If you're doing it yourself, the front setup is easier to do, in my opinion.
Lots of V8’s will drone around 2200-2400 RPM with ‘performance’ mufflers. I still love the sound of foxbody 5.0 Mustangs with flowmasters.
I think that a 23 to 36’ exhaust system probably isnt the most efficient system out there. We are probably working towards a happy medium at the end of the day.
I think that a 23 to 36’ exhaust system probably isnt the most efficient system out there. We are probably working towards a happy medium at the end of the day.
I believe I might have that done. I have a pair of Maxflo mufflers right behind the engine that contributes to the heat I’m sure. I’ll just have my muffler shop move one of them to the back. I’ll guess I’ll have a spare muffler available when I need one.
I have Thorley headers and Magnaflow mufflers, 3.55 final drive. No droning problems.
That might not be a great idea. You probably should attempt to keep the backpressure the same on both exhausts.
If you have a muffler on one side but not the other AND you have not installed blockoff plates in the intake, the differential in pressure from one side to the other will drive tremendous amounts of heat through your intake.
With the blockoff plates it might be ok unless the pressure differential blows out the plates.
Well unfortunately my engine builders took out my block off plates and did not recommend then being used. They were saying it causes problems on start ups from stop lights and such. Anyhow, that was their take on it.
So at this point I have 2 magflows right behind the engine as the oem setup was. So are you saying its not good to go with a single muffler in the back?
Dick Paterson says he still has some of his stainless steel block-offs in stock. I's contact him for a set and his recommendation on intake gaskets to match.
It might run a bit rough on stone cold startup, But that soon clears as the engine quickly warms up.
your builders are used to building cars that only get driven on short trips. A GMC reaches operating temp by the end of the driveway. It's biggest problem is overheating the intake as it's running HARD for hours and hours.
Block off plates are highly recommended on a GMC, unless you drive short trips in the winter, a lot.
A single rear muffler is the best solution. with 2 mufflers 1 of them always flows better than the other and gets worse over time. This causes even more flow through the intake crossover and thusly more carb heat.
Even modern cars with 2 mufflers have them in back behind a single catalytic converter
Block off plates are highly recommended on a GMC, unless you drive short trips in the winter, a lot.
A single rear muffler is the best solution. with 2 mufflers 1 of them always flows better than the other and gets worse over time. This causes even more flow through the intake crossover and thusly more carb heat.
Even modern cars with 2 mufflers have them in back behind a single catalytic converter
A muffler on just one side will cause higher pressure on that side, and that will drive molten hot exhaust gases through the crossover which is cast into your intake manifold. They already get too much heat in normal OE configuration, I can't imagine how much flow you would get with one muffler on one side. It would be a lot of heat and the manifold would warp and crack very quickly.
Is the paint burned off your freshly painted intake manifold, directly over the crossover, yet?
Didn't I just read that he retired on the 21st? Would there be anyone else taking the reigns at Springfield Ignition?
I read that to mean you'll move one of the 2 existing mufflers to the back and you'll keep the other as a spare.
Please confirm as some are reading it another way.
Start up from stop lights...?
Yeah, that 600 pounds of iron cools down something fierce when I'm stopped for 4 minutes at a stop light.
Just a quick note regarding intake gaskets:
When I was by Jim K's place last summer, I mentioned to his tech that I had messed up my install due to the front seal slipping out of place and my not noticing it. He told me that "they never use those" and that silicone sealant is their choice. Seems that has become the go-to for sealing that area. My 4.3L boat motor (GM) replacement gaskets don't even include that one. RTV used their now (and lots of it).
Anyway, that will make it significantly easier to drop the manifold down when you have the manifold gasket (I used the tub tub style), sealant around the ports, AND sealant on the block off plates. Should be "one shot, one kill" as long as you line it up right when you "simply drop it in place".
I don't believe one of your present mufflers will fit in the back. There is limited space back there that requires a shorter muffler than the ones normally used in the front. Plus, you would probably want a 3" muffler in the back as opposed to the 2.5" that are usually used in the front position.
So, unless you happen to have a much different system than is typically found under the floor, you may just need to have the would system pretty much replaced. Maybe adding a resonator in the rear of your current system might get rid of the drone.
