Mercruiser outdrive parts *Alpha 1 lower unit *Repairs

Boatparts.ca ( Click here for home page )

V8 Mercruiser exhaust manifolds 5.0-5.7L

5.0, 5.7 liter and 260 engine manifold assembly with
gaskets for GM motors

  • Manufactured by GLM Marine with a 3 year warranty
  • Increased water cooling area over manifold OEM model
  • GLM Marine fully tuned design guides exhaust gases directly to riser without turbulence and back pressure that increases the engine performance up to 10%.
  • In addition the 40% more water cooling area will decrease the entire manifold body temperature significantly.
  • Port or Starboard Fits MCM / MIE GM V-8 (305, 350 & 377 cid) engines Years 1983 to 2002

51230 Mercruiser exhaust riser OEM 860246Q11

51230 Mercruiser exhaust riser OEM 860246Q11

P/N 51230 Exhaust manifold assembly - OEM 860246A10. Can be used with 3 inch or 4 inch riser.

$190.95 US

$251.95 CDN

Included
P/N 51230 Cast iron assembly / 860246A10
P/N 31100 Gasket / 27-33395
P/N 30240 Riser gasket / 27-863724

Manifold and riser gasket sets

Photo

Description / OEM #

Price
(USD)

Price
(Canadian)

31100-30240 Gasket set

31100-30240 Gasket set

P/N 31100-30240 Gasket set. 1 manifold gasket and 1 riser gasket.

$9.95

$12.95

30240 Gasket 27-860233

30240 Gasket 27-860233

P/N 30240 Gasket (2 units) OEM 27-860233

   
31100 Exhaust Manifold Gasket

31100 Exhaust Manifold Gasket

P/N 31100 Exhaust Manifold Gaskets (2 units)

   
39310 Ford 302-351 5.0-5.8 liter

39310 Ford 302-351 5.0-5.8 liter

P/N 39310 OEM 27-54566A1

   
P/N 39280 GM 305-350 CID 5.0-5.7 liter 198-270 hp.

P/N 39280 GM 305-350 CID 5.0-5.7 liter 198-270 hp.

P/N 39280 OEM 27-33395A2

Fits log style manifold GM 305/350 CID.
5.0 liter and 5.7 liter with 198 to 270 HP

   
39880 GM 305-350 center riser manifold 200-320 hp.

39880 GM 305-350 center riser manifold 200-320 hp.

P/N 39880

GM 305-350 engine with center riser manifold with 200 to 320 hp.

   
39890 GM 454-502 CID 7.4-8.2 liter

39890 GM 454-502 CID 7.4-8.2 liter

P/N 39890 GM 454-502 CID 7.4 and 8.2 liter
Fits center riser Merc manifolds

   
39880 GM 305-350 center riser manifold 200-320 hp.

39880 GM 305-350 center riser manifold 200 and 320 hp.

P/N 39880

GM 305 / 350 CIB with center riser manifold 200 and 320 hp.

   

7 Degree and 15 degree V8 / V6 risers

Photo

Description / OEM #

Price
(USD)

Price
(Canadian)

51110 Elbow

51110 Elbow

Can be used with above manifold assembly

P/N 51110 3 inch 15 degree elbow assembly with studs and gasket. OEM 98504A3
Model, CID, Year and Serial number for small block GM engines

185 229 V6 1985-1986
6330183-6919655 (4bbl)

185 262 V6 1985-1986
0A331455-0B527954 (2bbl)
205 262 V6 1985-1986
S/N 0A331455-0B527954

200 305 V8 1985-1987
S/N 6899058-0B525981

228 305 V8 1983-1995
S/N 6218462-0F600999

230 305 V8 1985-1987
S/N 6899269-0B525981

898 305 V8 1983-1984
S/N 6218462-68990571

260 350 V8 1983-1987
S/N 6218462-0B773304

260 350 V8 1981-1987
S/N 5907058-0F024999

$147.95

$194.95

51140 GLM 4 inch 7 degree elbow 807988A2
51140 GLM 4 inch
7 degree elbow
51140 OEM 807988A2
51140 OEM 807988A2
Riser 4 inch
Riser 4 inch

Can be used with above manifold assembly

P/N 51140
Replacement 4 inch 7 degree elbow assembly without spacer. Includes mounting hardware and gasket. 807988A2

Year and serial number for six cylinder and small block V8 GM engines

185 229 V6 1985-1986
6330183-6919655 (4bbl)

185 262 V6 1985-1986
0A331455-0B527954 (2bbl)
205 262 V6 1985-1986
S/N 0A331455-0B527954

200 305 V8 1985-1987
S/N 6899058-0B525981

228 305 V8 1983-1995
S/N 6218462-0F600999

230 305 V8 1985-1987
S/N 6899269-0B525981

898 305 V8 1983-1984
S/N 6218462-68990571

260 350 V8 1983-1987
S/N 6218462-0B773304

260 350 V8 1981-1987
S/N 5907058-0F024999

Riser 4"
7 degree
# 51140
$143.95

Riser 4"
7 degree
# 51140
$189.95

Manifold riser kits

Photo

Description / OEM #

Price
(USD)

Price
(Canadian)

50310 MCM MIE V8 risers 3 inch kit

50310 MCM MIE V8 risers 3 inch kit

P/N 50310 3 inch riser kit OEM 93320A13

MOM V6 & TBI engines w/ 2-piece exhaust manifolds 0EM 614999 & below
MCM / MIE V8 305, 350, 377, 454 & 502 CID engines with cast iron elbows 0EM 299999 and below
MOM V8 305 and 350 CID carburetor engines 0EM 300000 to 599999
MIE and Ski carburetor engines 0EM 300000 to 316999

   
50320 2001-2002 MOM 3 inch riser kit

50320 2001-2002 MOM 3 inch riser kit

P/N 50320 with 3 inch riser kit

2001-2002 MOM 4.31- MPI OEM 300000-614999
2001-2002 MOM V8 305, 350 and 377 CID MPI engine OEM 300000-599999
2001-2002 MIE and ski V8 with 350 and 377 CID MPI engines OEM 300000-31 6999 fits the above engines with cast iron elbows.

   
50610 Risers kit 6 inch

50610 Risers kit 6 inch

P/N 50610 6 inch riser kit OEM 93322Al2

MOM V6 and TBI engines w/ 2-piece exhaust manifolds OEM 614999 & below
MOM / MIE / Ski V8 305, 350, 377, 454 and 502 CID engines with cast iron elbows OEM 299999 & below
MOM V8 305, 350 CID carb. engines OEM 300000-599999 MIE and Ski carb. engines OEM 300000-316999

   
50620 6 inch riser kit

50620 6 inch riser kit

P/N 50620

6 Inch riser kit OEM 93322A10
2001-2002 MOM 4.3 liter OEM 300000-314999
2001-2002 MOM V8 305, 350 and 377 CID MPI engine OEM 300000-599999
2001-2002 MIE and Ski V8 (350 and 377 CID MPI engines OEM 300000-316999

   
50350 Dry joint 3 inch kit

50350 Dry joint 3 inch kit

P/N 50350
3 Inch riser kit for dry joint replacements

V6 and V8 small block dry joint replacement manifold and elbow years 2004 and up

   
50600 Spacer 6 inch cast iron

50600 Spacer 6 inch cast iron

P/N 50600 Spacer 6 inch cast iron

   
50300 Spacer 3 inch cast iron

50300 Spacer 3 inch cast iron

P/N 50300 Spacer 3 inch cast iron

   

Customers also purchased:

Photo

Description / OEM #

Price
(USD)

Price
(Canadian)

58232 GLM manifold kit

58232 GLM

P/N 58232 Mercruiser complete V8 manifolds and 4" risers. Set comes with hardware and gaskets. For port and starboard.

$599.95

$791.95

89120 Upper hose OEM 32-44348T

89120 Upper hose OEM 32-44348T

P/N 89120 Upper bellow OEM 32-44348T 4 inch center mounted riser to 4 inch elbow for (P/N 51140 shown below).

$34.95

$45.95

12120 Water pump

12120 Water pump

P/N 12120 Outdrive water pump impeller kit with housing. Compatible with MR/Alpha One models 1984 - 1990, serial numbers 6854393-OD469858.

$35.95

$46.95

GLM Marine separating V8 exhaust gas pulses

GLM Marine separating V8 exhaust gas pulses

GLM Marine aftermarket V8 exhaust manifolds

 

Separating Exhaust Gas Pulses

All V8 engines have a firing order that fires two cylinders within 90 degrees of each other on the same bank of cylinders. With a firing order of 1-8-4-3-6-5-7-2, we have #8 and #4 firing on the starboard side of the engine within 90 degrees of crankshaft rotation. On the port side, we have #5 and #7 firing within 90 degrees of crankshaft rotation of each other. Of course, this also means that the exhaust gases for these cylinders immediately discharge into the exhaust manifold one after the other.

At this point, when the two cylinders fill the manifold in immediate succession, the exhaust manifold becomes overwhelmed with exhaust gases, creating excessive back pressure. In fact, excessive back-pressure from an overwhelmed exhaust system will not only keep spent gases from leaving the cylinder head exhaust port, but in certain ports, exhaust gases from adjacent cylinders may find their way back in.

The solution is to isolate each exhaust gas pulse for as long as possible in the exhaust manifold. There are aftermarket manifold manufacturers that go to great lengths to isolate each exhaust pulse the full length of the manifold, and there are some that barely address the problem at all. Choosing a high performance manifold that isolates each runner is the key to building horsepower with the exhaust system.

 

If properly designed, it can achieve this by two ways: Separating Exhaust Gas Pulses and Lowering Back Pressure.

Because the starboard side of the engine fires #4 and #8 in succession, there is a cylinder (#6) separating the two. Dividing this manifold into two different sections by grouping #2 and #4 in the front half of the manifold and #6 and #8 into the back half of the manifold works relatively well in isolating the #4 and #8 cylinders. On the port side of the engine we have a problem: The #5 and #7 cylinders that fire in succession are next to each other.

Dividing the port manifold into a front half and a back half groups cylinders #1 and #3 together (which is okay), but groups #5 and #7 together (which is definitely not okay). This is exactly what we are trying to prevent! The correct way to build the port side manifold is to isolate the exhaust gases from cylinders #5 and #7 all the way to the manifold exit.

Lowering Back Pressure

Lowering back pressure in the exhaust manifold is a combination of isolating the exhaust pulses as discussed in the previous section, and simply making the exhaust system larger. Some techniques for lowering back pressure include: large passages in the exhaust manifolds, a large exit hole out of the manifold, a large exhaust pipe and large radius curves in the pipe wherever the exhaust gases have to change direction.

All V8 engines have a firing order

That fires two cylinders within 90 degrees of each other on the same bank of cylinders. With a firing order of 1-8-4-3-6-5-7-2 we have #8 and #4 firing on the starboard side of the engine within 90 degrees of crankshaft rotation of each other. Of course, this also means that the exhaust gases for these cylinders immediately discharges into the exhaust manifold one after the other.

It is at this point, when the two cylinders fill the manifold in immediate succession, that the exhaust manifold becomes overwhelmed with exhaust gases, creating excessive back pressure.

In fact, these two cylinders on each bank firing in succession, not only create excessive back pressure in the manifold, but all the way down the exhaust pipe. Excessive back pressure from an overwhelmed exhaust system will not only keep spent gases from leaving the cylinder head exhaust port, but in certain ports, exhaust gases from adjacent cylinders may find their way back in.

The solution is to isolate each exhaust gas pulse as much as possible for as long as possible in the exhaust manifold. There are aftermarket manifold manufacturers that go to great lengths to isolate each exhaust pulse the full length of the manifold and there are some that barely address the problem at all.

Divided Exhaust Manifolds

Because the starboard side of the engine fires cylinders 4 & 8 in succession, there is a cylinder (#6) separating the two. Dividing this manifold into two different sections by grouping cylinder #2 and #4 in the front half of the manifold, and #6 and #8 into the back half of the manifold with a divider, works relatively well in isolating cylinders #4 and #8. On the port side of the engine, we have a problem.

The cylinders that fire in succession, 5&7, are next to each other. Dividing the port manifold into a front half and back half groups cylinder 1 &3 together (which is okay) but also groups cylinder 5&7 together (definitely not okay). This is exactly what we are trying to prevent. The correct way to build the port side manifold is to isolate the exhaust gases from cylinders 5&7 all the way to the manifold exit. This can not be done with a simple divider in the middle of the manifold.

Lowering Back Pressure

Lowering back pressure in the exhaust manifold is a combination of isolating the exhaust pulses as discussed in the previous paragraph one. Simply making the exhaust system larger. Large passages in the exhaust manifolds, a large exit hole out of the manifold, a large exhaust pipe and large radius curves in the pipe wherever the exhaust gases have to change direction are the secrets to lowering back pressure.

For manufacturing information, please contact GLM Marine for exhaust manifolds