General Michael Speeder exhaust

[124spiderman]

Hi, can anyone tell me what benefits are achieved by fitting a Michael Speeder exhaust muffler to a 126? Apart from the sound, is there any significant change to engine performance.
I've just purchased one from EBay and hope to fit it to my 650(126) engined 500.

 

[gt alex]

Hi great question I just bought one and will be fitting it in a month after I do some other repairs. I am already using a bigger carburetor but hope to do a dyno test before I change the exhaust and then after. I hope noise level is normal but a better sound less like a lawn mower.
I will post some pictures as well.

 

[gt alex]

Just fitted the speeder exhaust to day I didn't do a before dyno cause I thought it would be no trouble to swap it back, but after a exhaust bolt braking off and drilling it out and tapping it for 10mm, I am not keen to change it again to soon.
After cleaning the gasket surfaces I have opted to use hi temp silicon in place of the gaskets.
I tightened all parts just enough to hold the parts firm but not tight so they can self align once the whole system was on with all bolts just nipped up. then I tightened in this order.
1 the bolts holding the elbows to the system.
2 the muffler bracket bolts.
3 finally the elbows the head.
Unfortunately because of rust in the fuel system it will be a couple of days to get running again, I have sealed the tank inside and out and have the fuel sender soaking in rust remover.
I have taken the opportunity to fit a 10mm fuel return fitting to the sender.

 

[gt alex]

Ok so no dyno test my wife was not happy with the sound so I have been side tracked trying to make it quieter.
The sound level when first installed was ok but within 1 hour of driving it was louder and after 5 hours too loud to hear the radio when going up hills or pulling a few revs.
I tried a baffle on the exit with no real success so next was muffler surgery.

When new a fiber optic camera down the pipes showed the became perforated once inside the muffler and then continuing around a bend the camera could not go round. There was also signs of white fluff (fiberglass packing) coming through the perforations.

Suspecting the fiberglass had already blown out I cut a hole and repacked it with stainless steel wool scrubbing pads. I only had about 10 but tightly packed it best for sound absorption.

 

[gt alex]

The result is good, it is now about the same sound as when first fitted.
Next I will remove the db killer that came in the tail pipe and replace it with a packed straight through insert. And at the same time make sure the packing i have already inserted can not block the internal entrance to the tail pipe.

 

[gt alex]

Re:Exhaust bolts on head coming loose

Hi, I am very happy with the speeder exhaust but the bolts on the head keep loosening despite repeated re-torqueing and using lock tight. All other bolts have stayed tight.
After a spirited 3 hour round trip average speed 90 kmph to the gold coast on sunday I fount the bottom bolt of the rear exhaust manifold sitting on the engine mount.
When i tried to refit it the thread stripped gone.
All the head exhaust bolts have been re torqued at least twice since fitting the new exhaust but this had been a problem since we have owned the car.

What have others done to fix this???

I am thinking thread inserts and studs not bolts.

I would love to here want others have to say

 

[Toshi 975]

The original design which goes right back to the early Fiat 500s is a disaster waiting to happen. The steel bolts are exposed to the atmosphere on the far inner end which is impossible to get at. They rust away on that end so when you remove the bolts that hold the elbows to the head they will damage or strip the soft aluminium thread or even worse seize up then the bolts shear off. I have got about 8 cylinder heads here awaiting repairs because of this problem. Sounds like you have got a repair job on your hands as well. You can use stainless bolts but my prefered option is to fit high tensile studs so once fitted they never need to be removed then to protect the outer end of the stud I use stainless dome nuts.

 

[gt alex]

Thanks for the reply.
Sounds like studs are the go.

The other thing I was thinking may be a contributing factor, is the muffler brackets flexing?, I can't see flex but if there was no movement I think the bolts on the head should have stayed tight.

Should I be adding extra bracing to hold the muffler rigid?