Exhaust

[IndyJimW]

Installed a Torque Tech GM G-body 2 1/2" Cat-Back Exhaust Kit with Walker Super Dynomax mufflers and a CATO-4116 Cat-Converter on my '87 Avanti. The converter was a direct bolt on for the OEM with a bigger outlet 4" compared to the OEM 2 1/2". The exhaust bolted up easily with only a couple of problems. I think the exhaust pipe is a bit too close to the passenger seat well, so I'm going to drop it back down and wrap the pipe at that point. Also the G-body exhaust exits further out to the sides then the Avanti, so I cut the pipes behind the rear wheels to exit. I am going to bend the pipe that is left and then bring them out the back later. I wanted a quiet system and with better performance and got both. The OEM cat was causing a problem of no power every now and then, the inside of the converter was coming apart and blocking exhaust flow. I will post some photos later.

[Charlie Kile]

Do you have any idea how this would work on an 84 with the original Lark chassis?

[IndyJimW]

Won't '87 uses a G-body frame and running gear.

[bob.lyle]

When I replaced the anemic 305 engine with a GM 330hp crate motor, I used Edelbrock's header-type system (dang it...I can't remember what they call it...some fancy 'exhaust system' name), but it's basically a set of headers made for the Monte Carlo that also have the air injector pipes on top of each cylinder tube.

I ground off those air pipes and welded them shut, then installed the headers. The biggest drawback is that they are actually a 2 into 1 type since the driver's side gets pulled over to the passenger side and is setup for only one exhaust.

I cured that by taking it to a custom exhaust shop and having them delete the crossover pipe and make it into true dual exhaust. They ran custom pipes all the way to the back but since it's an 88, they insisted on istalling a catalytic convertor on each side as well. It doesn't sound nearly as loud as the duals on my 78 coupe (without cat convertors) but it DOES sound good!

Too bad I never ran it for a timeslip before making the changeover...but mileage is up, acceleration is definitely up and the fun factor went WAY up! Nothing better than cruising with the top down, air in your hair and the sound of dual exhausts when you drop the hammer and watch people's eyes bug out as a bright red

Avanti leaves the stoplight with a growl and a squeal of tires!

Bob (c'mon springtime weather...I want to go cruising!)

[IndyJimW]

Edelbrock TES headers. I have been wanting to try them but was worried about underhood temperatures getting to high. So they work OK for you Bob? My 5.0L is still strong so I'm waiting, have a LT1 with a 700R4 that I will replace it with one of these days.

[SBCA96]

My 5.0L is still strong so I'm waiting, have a LT1 with a 700R4 that I will replace it with one of these days.

Have any questions with that LT1, give me a holler ... I am pretty versed in them.

Also I am doing a swap into a 78 Camaro which should be simular.

Tom

[IndyJimW]

Have any questions with that LT1, give me a holler ... I am pretty versed in them.

Also I am doing a swap into a 78 Camaro which should be simular.

Tom

Thanks for the offer. I have the donor car sitting out back and it runs so I shouldn't have too many problems. The only real problem I saw was that the A/C compressor would hit the frame, but I found an A/C bracket kit that moves the compressor to the drivers side of the engine.

[bob.lyle]

Well, this is Central Texas and temps here get near (and often over) 100 degrees during the summer, so there have been instances of being stuck in traffic and the engine temp climbing to 220+...but no serious overheating and no problems with heat under the hood that I have seen.

My 78 has block hugger headers and dual exhaust and it's no hotter or cooler on the firewall/floorboards than her convertible is, whether it had standard exhaust or the header system.

In fact, the headers seem to cool off faster than the cast iron manifolds, so residual heat has been less of a problem...but I have thought about installing some extra heat mat shielding under the carpet of BOTH Avanti. It seems to be an inherent problem, not something related to any particular exhaust system.

An electric fan would probably help that slight overheating in traffic problem on her convertible but I've been waiting to do that until we decide whether to convert to the new RamJet fuel injection setup that GM has recently released for the Vortec engines.

Decisions, decisions....trying to decide whether to convert to fuel injection or air bag suspension first.

Those dropped spindles on the front sure give it the old "Avanti rake" and make it look soooooooo good...but we're tired of dragging the exhaust at every hard dip in the road. New shocks haven't made much difference and if I have to replace the springs, I might as well just install the airbag setup and have it fully adjustable.

Bob

Edelbrock TES headers. I have been wanting to try them but was worried about underhood temperatures getting to high. So they work OK for you Bob? My 5.0L is still strong so I'm waiting, have a LT1 with a 700R4 that I will replace it with one of these days.

[IndyJimW]

Those dropped spindles on the front sure give it the old "Avanti rake" and make it look soooooooo good...but we're tired of dragging the exhaust at every hard dip in the road. New shocks haven't made much difference and if I have to replace the springs, I might as well just install the airbag setup and have it fully adjustable.

Bob

I've had no problems with my drop spindles causing anything to drag. Maybe I'm not driving it hard enough?

[SBCA96]

The only real problem I saw was that the A/C compressor would hit the frame, but I found an A/C bracket kit that moves the compressor to the drivers side of the engine.

Yes, that IS the single biggest problem, the other being the exhaust manifolds. The heads

are a "D" port, your current engine is most likely a "square" port. The location that the

manifold "dumps" on the LT1 is different then most early SBC apparently.

What A/C bracket did you decide to go with? The Corvette one has been discontinued,

and the aftermarket one I found was close to 1000 bucks!

Tom

[IndyJimW]

Yes, that IS the single biggest problem, the other being the exhaust manifolds. The heads

are a "D" port, your current engine is most likely a "square" port. The location that the

manifold "dumps" on the LT1 is different then most early SBC apparently.

What A/C bracket did you decide to go with? The Corvette one has been discontinued,

and the aftermarket one I found was close to 1000 bucks!

Tom

The exhaust manifolds on my LT1 exit at the rear, shouldn't be too much of a problem.

The A/C relocate kit costs $289.00. Go to http://www.bowersrodshop.com/home.htm.

[IndyJimW]

Here are the photos of the new exhaust. I did have to wrap the pipes near the passenger floor pan, it was starting to melt the undercoating. I still need to finish running the exhaust out the back.

Jim

[SBCA96]

The A/C relocate kit costs $289.00. Go to http://www.bowersrodshop.com/home.htm.

Nice find on that A/C relocating setup! THANK YOU! I might have to order one of those

up once I get complaints from the wife its too hot in the car. I need to shoot them an

email and find out if the lower delete pulley is the same as the GM one, I mean I know

its one they made, but I already bought the GM one!!

Nice exhaust, looks like you might have a leaking front main seal, or the back of the

intake manifold. Sure is nice to order -off the shelf- items!

Tom

[IndyJimW]

Nice exhaust, looks like you might have a leaking front main seal, or the back of the

intake manifold. Sure is nice to order -off the shelf- items!

Tom

Front trans seal started leaking, soon as we have some free time in the shop I'm going to replace the front and rear seals, bushings and install a B&M shift kit. Nothing on this car is just - off the shelf. The exhaust was supposed to exit out the rear, but because of the differences behind the rear axle I had to cut and exit behind the wheel opening. Soon as the exhaust bender gets here I'll finish the job.

[SBCA96]

Front trans seal started leaking, soon as we have some free time in the shop I'm going to replace the front and rear seals, bushings and install a B&M shift kit.

Until you get a chance .. throw in a can of "TransX" ... you will be amazed. Did that

on our 78 Camaro to drive it home 150 miles. Before TransX it leaked like crazy &

would only rev and not move, after TransX, leaks are gone, and 2 years later is still

moves ... with a little "warming up" first. Not bad for a "bad" transmission!

Tom