58 Chevy Truck Exhaust 2
Yanked the old mufflers and tubing out, the cans and pipe are all in very good shape actually,
cut out the old mufflers, they just got too loud over time, so will try these new ones....
The new cans are the same size as the old ones, should be an easy swap....
With this low rpm baffle setup it should be quiet when around my neighbors, but will have to
see at what throttle setting/rpm the "trap door" will open and let it straight through....
Cut the old cans out at the bells, up close to the body, but left enough of a stub on the cans
so that they can be easily reused. They are SS and still in good shape, if somebody wants them....
Had to carefully slice the welds and peel off the old muffler bells from the pipes....
Ground the welds down smooth, got one tube in, it fits nicely....
Took an hour or so, cleaned up all four pipes and fitted them to the new cans....
And stuck 'em back up under the truck, there are three hangers for the pipes/mufflers on each side,
everything matched up quite well...
There were cutouts right behind the headers before, but these new headers are longer, think I'll just leave
the cutouts out for now, just connect the old pipes to the new headers directly, at least for now....
Everything's a bit loose under there right now, as I get everything lined up I'll tak weld here and there,
then pull it out to finish weld, clean up, and paint with hi temp black....
And make sure the outlets line up nicely with the notches in the bed steps....
The original front and rear pipes off of the old mufflers are in good shape,
so just cleaned them up a bit, and as the new mufflers are the same dimensions
as the old ones, it all fit up quite nicely....
The end of the headers uses a bell and spigot style of flanged connection,
decided to use the pieces Hedman supplied to bolt up to the headers.
This gap is to be filled with a wye for cutouts, and it's a fairly tight fit,
so will start trimming a bit at a time until I get the fit I want....
The wye for the cutouts I trimmed as short as possible,
and also trimmed the bell connector down as short as I could
and still be able to weld it onto the wye....
This is the second wye, cut the bell adapter,
but decided to wait until the first one is done before I cut this one...
It took about two more trim jobs before I got the front section of exhaust pipe,
the bell adapter, and the wye to all fit the way I wanted....
Tack welded the front and rear pipes to the muffler while under the truck,
and did a trial fit, all good....
Hung the pieces in a tree and painted them with VHT flat black exhaust paint...
Now to do the other side exactly the same way, then work out the electric cutouts....
Bad hand injury, my baby quietly sits and waits for me....
Probably another 2 months.....
UPDATE:
Managed to get my cutouts fitted and welded up:
Painted 'em with VHT black and bolted 'em up, and fired up the rig, and.....
OOOOOF, those Dynomax VTs are way, way too loud at idle and just cruising !!
The so called "valves" are not staying "closed" in my application at idle and above,
so they are way too loud. I either need a stronger spring on those "valves", or a manually
operated "valve" that I can keep closed via a cable under the dash, for example, or
with a solenoid operated "valve" (trap door is a better term I think) to keep them
closed when I need to keep the truck quiet.
Discussed it with a tech rep at Dynomax, they suggested installing an "H" pipe
between the two sides ahead of the mufflers to even out the exhaust pulses a bit
and keep them from rattling the "valves" open and shut at idle.
It might work, but it would still be loud when the VTs open up!
I've also learned from this tech rep that I ordered the wrong mufflers, there are
apparently two different springs available, a softer spring in muffler #17157, which
are the mufflers I have, and are meant for smaller displacement motors, and there is a
stronger spring available for larger displacement motors under part #17957, which are
the mufflers I should have ordered. An H pipe would still be recommended to keep
"valves" from rattling from the exhaust pulses.
A good buddy has had good luck with the Flowmaster 70 series mufflers behind his BBC,
a nice rumble while cruising, and if I wanna make noise, I'll install the elec. cutouts
and open those!!
So I'm considering having to crawl under the truck again,
pull out the Dynomax mufflers, and install these....
The case on the Dynomax VT's is 14" long, these Flowmaster 70's are 22", let's see
how good a job of making them fit I can do....
More Later
