In this months Tech article we’ll be looking at Chevy Classic exhaustsystems. In part 1 we’ll identify and then in part II we’ll install. First let’s lookat how to identify and restore correct exhaust manifolds for 1955-1957 V8s.One of the main problems that 1957 owners encounter with exhaustmanifolds is the rusting away of the inner tube in the right-side manifold. Thisinner tube forms a “heat chamber” for the heat choke tube. This article willexplain how to replace this inner tube on the 1957 manifold as well as how torestore any exhaust manifold. In the chart at the bottom of part 1 are listed the casting numbers for ’55-

‘57 exhaust manifolds and the part numbers for the heat risers found on theright-side manifolds. (Note: the 1957 F.I. engine did not have a heat riser; buta “spacer” was substituted so that the same exhaust pipe could be used.) In Photo #1 a pair of 1955/1956 2 BC and 4 BC exhaust manifolds are

pictured. The right-side 1955/1956 exhaust manifold has a plate which formsa “heat chamber” for the heat choke tube P/N 54-36 (Photo #2). Photo #3 shows the right-side 1957 exhaust manifold, casting 3733976.

What is somewhat interesting about this manifold is that the same castingnumber manifold was used on the right side of all 1957 V8s, the F.I. enginesas well as the others. The fuel injection engines did not use a heat choketube, thus the manifold was not drilled for the tube. In photo #8 the right-side exhaust manifold for 1957s with carburetors is shown.

1. Before starting to restore a pair of exhaust manifolds, check the castingnumbers to make sure you have the correct manifolds. (This will not beimportant if you do not need original exhaust manifolds).

2. Carefully check the manifolds for cracks. Look around the ports and thestuds for cracks which could make them unusable. (Cracks around the studscan sometimes be repaired).

3. The 1957 exhaust manifold that we restored for this article had the heatchoke tube hole welded shut (Photo #4). By carefully grinding this area, wewere able to determine where the hole was located. We drilled out the holeout by using a 19/64" bit and drill (Photo #5).

4. Many of the inner tubes rust away in the middle, leaving the remains of thetube in the upper and lower part of the exhaust manifold. The inner tube isflared at the bottom, so the lower piece must be driven down and out of theexhaust manifold. (Try using a flat-nosed punch to drive the inner tube out ofthe exhaust manifold).

5. The size of the upper hole is 19/16" and the size of the lower hole is21/64". You can use a drill and bit to clean out these holes to the proper size.

6. Check the exhaust manifold studs, do not replace any studs unless youhave to. Many exhaust manifolds have been broken by people trying toreplace studs. The studs on the right-side exhaust manifolds are longer thanthose on the left side because the heat riser is on the right side.

1955-57 EXHAUST MANIFOLD IDENTIFICATION &RESTORATION & 1960-64 ALUMINIZED DUAL TURBOEXHAUST INSTALL

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‘55-’56 Heat Riser Tube Access Plate, P/N 54-36

10 December 2012 ChevyClassics

by Randy Irwin

#5

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7. If you must replace a stud, work slowly and carefully. Use a solvent, suchas Liquid Wrench. Allow the solvent to soak into the manifold. You can tryheating the exhaust manifold with a propane torch— not too much heat!Once you “break” the stud loose, work the stud back-and-forth. Slowly backthe stud out of the manifold.

8. Use a 3/8-16 tap to clean out the threads in the exhaust manifold. Workslowly and use cutting oil. You can break the manifold by running the tapinto the manifold without stopping and backing up.

9. Bead blast or sandblast the exhaust manifolds.

10. If you are restoring a pair of 1957 exhaust manifolds, install a new innerheat choke tube into the right-side manifold. You can order this tube as P/N18-94 (Photo #6).

11. The new stainless steel inner heat choke tube is installed by sliding thetube through the lower hole in the manifold and then up into the upper holein the manifold. The tube should be flush at the bottom (Photo #7) andshould be flush at the top (Photo #8) when properly installed. Use ahammer to drive the tube into position. If the tube does not have a tight fit,use a tapered punch to flare the lower end of the tube.

12. To coat the manifold, we suggest using Eastwood’s High Temperature“Stainless Steel Coating.” This is an excellent product that we have used forseveral years. Add just a little thinner to make it sprayable, crank up the airpressure to about 60 psi, and apply one good thick coat.

13. Install new studs where required (Photo #9). We use stainless steelstuds with brass nuts P/N 18-178. At this point you should have a pair ofnicely restored exhaust manifolds which are ready to bolt onto the engine.(Photos #1, #2, and #3).

Year Engine Carburetor Exhaust Manifold Number Heat Riser Casting Number of Studs Part Number

1955 265 2 BC & 4 BC 3704791 (L) 2 3721509 3704792 (R)

1956 265 2 BC & 4 BC 3704791 (L) 2 3725981 3704792 (R)

Early 265 2 x4 BC 3725563 (L) 2 3725981 1956 3725563 (R) Later 265 2 x 4 BC 3731557 † (L) 3 3731396 1956 3731558 † (R) Early 265 2 BC 3733975 (L) 3 3734204 1957 3733976 § (R) 1957 283 2 BC & 4 BC 3733975 (L) 3 3734204

3733976 § (R) 1957 283 2 x 4 BC 3733975 (L) 3 3734203

3733976 § (R) 1957 283 F.I. 3733975 (L) 3 3737631*

37339761 � (R)

† . . . Casting number in the middle of “ram’s” horn. § . . . Drilled for heat choke tube. H . . . Is not drilled. No hear choke tube. *. . . This is a spacer only.

ChevyClassics December 2012 11

We’ll now be installing an Aluminized 2” Dual Turbo Exhaust System on a1964 Late Great Chevy with headers.

Photo #1A & #1B: We removed all of the old exhaust system. Next, thestock exhaust manifolds must be removed. The manifolds are held to thecylinder heads with six bolts. The driver’s side manifold also has a boss onthe front, where the alternator mounts. This will have to be replaced. Theheaders do not have a provision for the alternator bracket.

PART II

1955-57 Fuel Related Items: Member price

563105 Alternator Bracket, Small Block $90.24 ea524300 58-74 Small Block Headers 256.49 set524216 60-64 Aluminized 2” Dual Turbo Exhaust

Free Flowing Turbo Mufflers, No Hangers 442.69 set

Tools Needed: 7/16 wrench1/2 wrench3/8 ratchet

7/16 socket1/2 socket9/16 socket

Time Frame: 5 Hours

#524216

#524300#B

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Part # 524216 Aluminized Turbo System is a bolt-on system to be usedwith headers. This full exhaust system (P/N 524216 with Turbo mufflers, seephoto A) will bolt in place of the stock system, and bolt up to headers. Thissystem features Flowmaster mufflers. The pipes are 2" aluminized pipe andare mandrel bent for a full custom look. Photo B shows the headers we willbe installing P/N 524300. They are equipped with 15/8" primary tubes anda 3" collector (sold separately from the exhaust system). We will beinstalling this system on a 1964 convertible.

Photo #2: The header set comes complete with a left and right header,gaskets, street reducers/collectors, and bolts. The header is held to thecylinder head with six 3/8" x 3/4" header bolts, and uses a gasket betweenthe header and cylinder head. Carefully install each header and tighten thebolts to the cylinder head.

Photo #3: To remount the alternator we are going to use a bracket P/N563105. This will keep the alternator in about the same position. Thisbracket bolts to the upper water pump bolt, and uses two of the headerbolt holes.

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Photo #4: The headers exit just behind the lower a-arm and under theframe.

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12 December 2012 ChevyClassics

Photo #5: Bolt the street reducer/collector to the header flange with thethree 5/16" x 1" bolts supplied with the kit, making sure the gasket isinstalled between the header and street reducer/collector.

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Photo #8: The 2" tail pipe attaches to the rear of the muffler right wherethe stock tailpipe once was. It is held to the muffler with the 2" clamp for themuffler hanger. There is a tail pipe hanger right over the rear end that holdsthe pipe to the frame.

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Photo #9: The tail pipe exits from the body right where the stock tailpipe was. It is held in place with the rear tail pipe hanger. For installation,tailpipes are oriented (left and right are different from each other) with theoutlet facing down and to the outer corners). With the turbo system it canbe bolted on in place of the stock system, without having to do anymodifications to the exhaust system hangers. Make any adjustmentsnecessary for proper system fit by loosening clamps and rotatingpipes/mufflers as needed. This installation is very clean, addsperformance and sounds great.

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Photo #6: Now the exhaust pipes can be installed. This is the pipe that willconnect the muffler to the header on each side. This is the short 90° pipeand is the same for left and right sides.

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Photo #7: The muffler is held to the exhaust pipe with a 2" clamp, and isheld in place with the stock muffler hanger. All mufflers, including stock,turbo and Flowmasters will be oriented with the center inlet to the front andoffset outlet to the rear and inside toward the frame. With this system, thestock brackets and hangers are used.

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ChevyClassics December 2012 13

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On the 3rd Day of Christmas...