New exhaust manifold question.

[NavyScrambler]

Howdy all,

This is my introductory post as well as tech related. My several hours of searching every combination I can think of has not provided an answer.

I am replacing my AMC 258 i6 / 4.2l with a reman 258. I have the MOPAR MPI kit on a 258 head with what I understand is an intake manifold from 91-95 xj's. It appears the stock or stock model 258 exhaust manifold is on there currently. I would like to know if I can fit the early 2000's tj two-piece exhaust manifolds onto the 258 head. Or if that doesn't work, the one piece with the flexible baffle.

I need to get this swap done in one fell swoop and can't really afford the time delay of a non-fitting manifold.

Any experience in this matter would be greatly appreciated.

 

[Torxhead]

I have never hear of that swap and would be quite suprised if it did work. Replacing a used AMC 258 i6 / 4.2l exaust manifold can be a tough as they tend to warp and might require a little bending work.

 

[NavyScrambler]

I have never hear of that swap and would be quite suprised if it did work. Replacing a used 258 exaust manifold can be a tough as they tend to warp and might require a little bending work.

Either way, the exhaust manifold going on there will be new, whether it's a tj or AMC 258 i6 / 4.2l manifold. Just interested in the TJ model for obvious reasons.

 

[NavyScrambler]

Ah well, shoot. Turned over that one last rock and found my answer. Not sure if the other exhaust ports and bolts will line up, but cylinders 3 and 4 sharing a single port on the AMC 258 i6 / 4.2l head will ensure that the TJ exhaust manifold (which is set up for two separate ports) will not line or bolt up.

Anyway, love the site. It has already provided quite a few answers in my search to keep this 8 from oblivion!

 

[ThisGuyUKnow]

Navy, Since you have the MPI kit you may want to consider swapping on a 4.0 head. I say this for several reasons, first you seem to want to run a 4.0 exhaust which will bolt to the 4.0 head. Also the AMC 258 i6 / 4.2l has a doglegged runners and the 4.0 head has runners at a 45* angle, instead of squirting the fuel around a corner that MPI kit will be able to squirt it directly to where it needs to go. Would really squeeze some more performance out of your FI and let you run the exhaust you want.

 

[NavyScrambler]

Thanks, ThisGuy. I will definitely be eying a 4.0 head for it not far down the road. For now, back on the road is good enough

Also, so I don't have to start another thread:


Can anyone tell me what diameter, length, thread, and how many of each bolts I will need to bolt up the intake/exhaust? I would like to show up with them in hand instead of driving around hoping somebody has some. I have found this packing list but cannot figure out which are correct.

MANUAL Transmission
P5249610
MPI KIT
PACKING LIST

DESCRIPTION PART # QUA.

1) WIRING HARNESS P4532698 1
2) THERMOSTAT HOUSING 53006192 1
3) COOLANT SENSOR 33004281 1
4) INTAKE MANIFOLD 9400045* 1
5) FUEL INJECTOR CLIPS 04418257* 6
6) FUEL INJECTOR 53030343* 6
7) FUEL INJ LINE-INLET 52018416 1
8) FUEL INJ LINE-RETURN52018417 1
9) FUEL PRESSURE REG 53030001* 1
10) FUEL RAIL ASSEMBLY 53030435 1
11) THROTTLE CABLE 52079382 1
12) THROTTLE CABLE BRCKT 53007486* 1
13) COIL BRKT & FUEL PMP PLATE P4532710 1
14) IGNITION COIL 04797293 1
15) SPARKPLUG WIRE SET 83507178 1
16) OXYGEN SENSOR 56028301 1
17) CRANK SENSOR 56026884* 1
18) THROTTLE BODY ELBOW 53006289 1
19) THROTTLE BODY CLAMP 53008274 2
20) FUEL PUMP-ELECTRIC P4532709 1
21) FUEL FILTER 33000076 1
22) FUEL HOSE-18"X5/16" 9400047 1
23) FUEL PUMP CLAMP MNT 9400009 1
24) HOSE CLAMPS 5/16" 9400002 9
25) INTAKE HOSE-CAT 18" X 2-3/4" 9400008 1
26) AIR FILTER ADAPTER 9400007* 1
27) K&N AIR FILTER 9400003 1
28) CLAMP 2-3/4" WORM 9400013 2
29) ADAPTER HOLDDOWN CLAMP 9400006 1
30) INTAKE HOSE ADAPTER 9400005 1
31) VENT TUBE 1/2" X 3/8" X 90' 9400010 2
32) CRANK SENSOR BRACKET 9400004* 1
33) MAT SENSOR 33004280* 1
34) MAP SENSOR 33000153 1
35) FUEL CANNISTER 53030500 1
36) TIE WRAPS 4" 9400014 1
37) THERMOSTAT 4494469 1
38) DISTRIBUTOR 9400046 1
39) M6 X 14M CAP SCREW 9400052 7
40) VALVECOVER FITTING (GRAY) 5303G497 1
41) VALVECOVER FITTING (BLACK) 53030495 1
42) VACUUM TUBING 53030728 1
43) BRACKET-FUEL CANNISTER 53009759 1
44) VACUUM TUBE 53006226 1
45) VACUUM TUBE 53030473 1
46) VACUUM TUBE 53030474 1
47) ECM MANUAL TRANSMISSION P4532679 1
48) M5 X 30M CAP SCREW 9400011* 2
49) FUEL PRESS. REG. CLAMP 04418897* 1
50) INTAKE MANIFOLD GASKET J3242855 1
51) THROTTLE BODY 04856107 * 1
52) THROTTLE BODY GASKET 53007543 * 1
53) 3/16' VACUUM CAP 9400049 * 1
54) FUEL LINE CLIP 34202997 * 1
55) VACUUM PORT 53004523 * 1
56) SPEED SENSOR 56027015 * 1
57) MAP SENSOR BRACKET 56027080 1
58) 5/8"X7/8" SPEEDO ADAPT 9400012 * 1
59) 1/2" PCV HOSE 9400048 2
60) 1/2" PLASTIC HOSE SPLC 9400016 2
61) 3/16" TUBE X 1/4" NPT 9400018 * 1
62) #10 X 1/2" SHEET METAL SCREW 9400020 4
63) 1/4" TUBE X 1/4" NPT 9400019 * 2
64) M5 X 20MM CAP SCREW 9400021 * 1
65) 1/4" NC X 1-1/4" CAP SCREW 9400025 2
67) 1/4" NC X 1 l/2" CAP SCREW 9400022* 1
68) M6 X 20MM CAP SCREW 9400023 * 4
69) M8 X 20MM CAP SCREW 9400024 * 1
70) 5/16" X 1" CAP SCREW 9400030 * 1
71) M5 FLAT WASHERS 9400027 * 3
72) M6 FLAT WASHERS 9400028 * 11
73) 5/16" FENDER WASHER 9400029 * 1
74) 5/16"X1-1/4" CAP SCREW 9400030 * 1
75) M8 LOCK WASHER 9400031 * 1
76) M5 HEX NUTS 9400032 * 2
77) 1/4" NC NYLOC NUTS 9400034 * 2
78) 5/16" NC NYLOC NUTS 9400035 *
79) 3/16" VACUUM HOSE 9400036 * 1
80) 2.5" ADEL CLMP (FUEL FILTER) 9400037 1
81) 1/4" NC X 1" CAP SCREW 9400039 2
82) 3/16" FLAT WASHER 9400040 2
83) 1/4" FLAT WASHER 9400041 3
84) CONCAVE EXPANSION CUP 9400042 1
85) INSTALLATION INSTRUCTS 9400043 1
86) DIODE SPLICE 9400044 1
87) #10 X 2" SHEETMETAL SCREWS 9400015 3
88) VACUUM TUBE 53006237 1
89) UNDER HOOD EMISSION DECAL 9400050
90) 3/8" MOUNTING CLAMP 9400054