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258 Rebuild 87 Eagle Wagon |
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jdarosa 
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Joined: Oct/31/2014 Location: Portland, OR Status: Offline Points: 264 |
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 Topic: 258 Rebuild 87 Eagle WagonPosted: Jun/06/2020 at 11:44am |
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I know there's lots of threads about this already, and I've read most of them and got some input. Here's my situation. (Sorry this is so long).
'87 Eagle wagon is my daily driver. I want a little more power out of the 258 but I don't need serious performance or off road mods, just to be able to cruise at 75 or so on the highway when I need to. I used to own a '67 Rogue, and I built a mild 258 for it. Headers, dual exhaust, intake, Isky 256 cam, Holley 390 carb, HEI ignition, and shift kit in the 904 and it really woke up. Very responsive, topped out about 90mph before too much vibration made me nervous. Not looking for that performance this time, but I know the 258 has more in it, and I'd rather have an Eagle with a brand new motor than buy a mid-2000s Outback or Honda Element.. I don't have a shop now, so my mechanic is doing the install. I want to keep with as unbolt/bolt-in as possible for him, so no major fabbing or mods to the body. I'm budgeting around $6000. TRANNY: I'm going to rebuild the A998 with a Stage 2 shift kit. Will post lock-up converter questions in the tranny section. CAM: Can I run an Isky 256-type cam with the stock exhaust in the 4.2L? Obviously a header would be great but clearing the diff and bracket is not something I want to deal with. I assume that limits my cam options... CARB: If I stay with the 4.2L and run a small cam, what carb would work best with stock exhaust? Is pulling emissions stuff necessary and/or beneficial (aka ditch the factory setup)? 4.0 HEAD: If I were to swap a 4.0 on a 258 short block, I'd run into the same exhaust situation as above, right? I've read that the 4.0 head is a great addition to the 258 block, but I'm not sure what fabrication would need to be done or new parts sourced. Obviously that would open up FI instead of carb, which is the point of the 4.0 head right? Any input would be great! Thanks everyone |
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1968 American 440 – 232/AT 4dr
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amcfool1
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Joined: Jun/18/2011 Location: roanoke va Status: Offline Points: 1075 |
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Posted: Jun/06/2020 at 12:50pm |
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hi, I just "restified" an 84 Eagle. You have lots of options. The cam will be fine with the stock exhaust, though I would ditch the old "Air Injection" catalytic converter, (if you still have it), and get a modern free flow cat. I replaced my whole exhaust due to age/rust, but it is still the stock configuration. I think I went with a 2" exhaust, stock manifold. There are really no cost effective options BUT the stock exhaust routing on an Eagle.
As for carbs, assuming you are not keeping the stock CEC system, a Motorcraft 2150 is a cheap upgrade. You will need a carb adapter, available from Offy or Summit. To run a 4bbl, you will need the Offy intake, good, but not cheap. On this car, I kept the stock carb/CEC setup. It was a challenge! As for the 4.0 head, I haven't done that, but I rebuilt my stock 258 head with SBC valves, 1.84 IN/1.5 EX, and positive seals. Nothing wrong with the stock 258 head for a daily driver. (Opinions may differ:) I also installed Harlan Sharp roller rockers, again, not really necessary for a DD. good luck, gz
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george z
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73Gremlin401
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Joined: Mar/02/2013 Location: Stmbt Sprgs CO Status: Offline Points: 946 |
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Posted: Jun/06/2020 at 1:26pm |
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A couple of things to consider based on what I've done in the past with 4.2s Since you have an 87, you should have a fairly 'clean' underhood environment - by then the manifold air injection was gone, and the feedback carbs were pretty well sorted out, so they do work really quite well. The stock cam is actually pretty decent - and responds well to a 2 degree cam timing bump - you can use a Chevrolet cam bushing on the timing gear. Throw a 4.0 Jeep timing chain and gear on it (it's a direct swap, and is more robust) and that will minimize cam walk. I personally also like the OEM motorcraft distributor, which is easy to upgrade with a cap/rotor update that ford used. Fresh valve springs and keepers are a must. The MC2100 carb swap which is popular has I think has 1 big flaw - and that being you can't re-use the stock air cleaner assembly, leaving you with some cheap aftermarket thing that doesn't flow well, and you lose the proper PCV breather, heat-riser tubing and cold-air snorkle. All those things really help with daily-driver like useability in all weather conditions, and I don't like giving them up. A properly rebuilt and clean BBD will work just fine, and if you do bump the stock timing, will flow well enough for it. Exhaust wise, not much to do there, but increasing slightly the OD of the pipes might help a little. it is what it is. Hope this helps.
Edited by 73Gremlin401 - Jun/06/2020 at 4:40pm |
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73 Gremlin 401/5-spd.
77 Matador Wagon 360/727. 81 Jeep J10 LWB 360/4-spd 83 Concord DL 4-dr 258/auto  |
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amcfool1
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Joined: Jun/18/2011 Location: roanoke va Status: Offline Points: 1075 |
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Posted: Jun/06/2020 at 2:58pm |
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Hi, I agree with Mr. 73Gremlin . Which is why I kept my 84 STOCK setup., with the exception of the CATALYTIC CONVERTER air injection. Parts are impossible to find, and with a modern cat, that system, which is more or less stand alone from the rest of the CEC system, is not really necessary. Yes, the MANIFOLD air injection was gone even by 84. I used a Cloyes True Roller timing chain, but have used the 4.0 chain on another motor. Works well. Even has a tensioner provision.
I ran a MC2150 for over 20 years on my first Eagle. Yes, you do give up the cold air snorkel/heat riser, but even cheap aftermarket air cleaners have a provision for the crankcase breather fitting hose. The PCV itself goes to the back of the carb. Not a problem really, unless you drive in northern Manitoba:) i went to a 2" stock style exhaust, just a little larger than factory. Having said all that, keeping it stock was still a challenge. The computer, believe it or not, is still available from ANY auto parts store (84+), if the one you have is bad, though only the CA version. About $200. It gets information from 8 sensors, six of which, believe it or not, are still available, if you search and cross reference hard enough. The two not available are the knock sensor, which almost never goes bad, and the AIR CLEANER temp sensor, which can be iffy, though you can buy the pigtail, go figure:) Also, the Stepper motor in the carb, is still available new, with a core return, from some place in CA, through ebay. Long story short. it took over a year of searching/fiddling/tuning/cussing:), but my 84 Eagle is running pretty much like new. thanks, gz
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george z
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Pdok
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Joined: Apr/03/2011 Location: Alabama Status: Offline Points: 1025 |
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Posted: Jun/06/2020 at 5:35pm |
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Agree with everything said. I ran a 258 with the stock head, and a Comp split pattern cam and the Weber 38 and also the MC2100. Used a mid-80s intake under the MC and a Clifford intake under the Weber.
Would NOT recommend Weber unless you love to tune carbs. Would definitely recommend the MC, as the easiest solution if you're swapping carbs. I did not have a viable stock carb, but I agree the BBD is a decent carb. If you cam up, then I guess it could limit you but you can certainly do that at a later date without affecting your choices now. I would cam up. I'd also gasket-match the intake and head, and probably call it good. I don't think there's any point in getting further into the ports. When I ran that combo with the new cam, it was very peppy. Very. 3.08 rear end, 904 with a Cheetah valve body. Still running the transmission and it's awesome, hard shifts, great downshifts. Only thing missing is an O/D. 4.0 head...well, that does open the door to FI. However, it is a bit of a project too. Don't forget you could do FI on the 258 head as a TBI if you really wanted it that bad. I'd skip FI on the 258 if you ever think you'll want to swap to the 4.0 head. Obviously you can also carb the 4.0 head. Frankly, MPFI is awesome, after the fairly monumental wiring and fuel pump project. But, the MC carb was also superb and dead simple to tune, so all things considered, I'd say just run a well-rebuilt and adusted 2 barrel carb and you'll be happy with that combo. If you want, while you've got the head off swapping cams, have it checked for flatness, maybe take a bit off to bring up compression even. Check the condition of rods, rockers, springs, valves, guides and seals. You can probably just put it back on, stock valvetrain with that Isky cam.
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76 Grem X 258/904,4.0 head/MPFI, Comp X250H cam, Hughes springs, Clifford header, serpentine swap.
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73Gremlin401
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Joined: Mar/02/2013 Location: Stmbt Sprgs CO Status: Offline Points: 946 |
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Posted: Jun/06/2020 at 6:27pm |
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pdok brings up an excellent point with going to FI on the 258 - the Holley Sniper BBD replacement is a really good one, and it is a direct bolt-in. Since you've given yourself a healthy budget for this project, that to me would be money very well spent, and keep the entire engine bay looking stock.
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73 Gremlin 401/5-spd.
77 Matador Wagon 360/727. 81 Jeep J10 LWB 360/4-spd 83 Concord DL 4-dr 258/auto |
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billd
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Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894 |
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Posted: Jun/06/2020 at 7:42pm |
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I'd stick with the stock carb or go the Sniper BBD system.
The motorcraft swap is somewhat over-rated on these engines. Normally people say "it really woke things up" because they had issues anyway. Sure, they are good and the venturi design is better, but it's not a "night and day" difference if your carb is correctly/properly rebuilt. You can work with the stock head and line ports up (port matching), etc. Most cams I've seen that you get these days for the 258 are split pattern - the cam I put in my 4.0 would work well in a 258 as well - the xtreme 4x4 cam. You'll want to true up the head anyway - might have a bit shaved off, but keep in mind you'll have to consider your geometry then. I had to use shims under my roller rocker pedestals to get the rockers to center and hit the valves the way I wanted. The 4.0 timing chain is a roller setup - it's a bolt-on, no mods, no worries, perfect for a 258. You shouldn't have any issue with cam walk no matter what you do - it's controlled with the lifters and cam grind unless you really wear things, these just don't have a problem. If you used roller lifters, that's different, but standard hydraulic lifters you won't see an issue. Nothing at all wrong with the Ford ignition system, or you could put in a Chevy HEI using a 1980s AMC V8 gear on it - just be sure to tweak the flats to ensure it sits into the oil pump right if you do that.   |
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jdarosa
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Joined: Oct/31/2014 Location: Portland, OR Status: Offline Points: 264 |
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Posted: Jun/07/2020 at 1:55pm |
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Thanks for the input everybody. Those cam options sound great, and I didn't even know about the Holly Sniper BBD setup. Glad to hear the 258 is streetable and reliable without the 4.0 head and upgrades.
Also had no idea about updated the cat. Like the sound of that change. Billd you've got a beautiful motor! |
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1968 American 440 – 232/AT 4dr
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jdarosa
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Joined: Oct/31/2014 Location: Portland, OR Status: Offline Points: 264 |
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Posted: Jun/07/2020 at 1:57pm |
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I've thought about a small 4bbl, but I think it might be overkill on the stock engine otherwise. The Holly Sniper sounds like a good bet.
What made you go with those SBC valves?
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1968 American 440 – 232/AT 4dr
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billd
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Posted: Jun/07/2020 at 6:03pm |
Newer cat technology - it's amazing. Even for my truck there's an aftermarket system that flows a lot better and the dyno sheets show quite a change for exhaust-only changes. I may go with that after-market exhaust for my pickup. Thanks - I've owned AMC 6s since the 1970s - I have had several, used to autocross with one and it would hold its own against quite a few other cars just on the street. I have 2 77 AMXs with the 258 - drove one all around Denver and the Rockys and it was reliable, quick, strong, trouble-free engine. I've had 258s in multiple Eagles, too - and that's pulling a 3300-3500 pound car, depending on wagon or SX4. |
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jdarosa wrote: