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Unread 04-20-2013, 10:13 AM   #1
CJput
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Prestolite replacement HELP

Guys,
I've read many threads on this site, and I know this has been discussed, but I need some help replacing my Presolite ignition. The more I read, the more I get confused. I can build Jeeps, weld frames, yada yada, but I'm no motor guy. My 1977 CJ7 has the 304 motor which I want to keep. Don't get me wrong, I've rebuilt engines, but electrical/ignition changes arent my thing.

I need a step-by-step guide to doing the job, including parts. This jeep is a driver, I'm restoring it to keep in good shape, not show. I'm not running the 1/4 mile but would like better performance etc. I know there are many choices, HEI, replacing parts etc. Someone tell me what the best way to go is on this job. MY Prestolite has left me stranded for the last time.
Thanks,
Put

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Unread 04-20-2013, 11:31 AM   #2
WindKnot
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I went the MSD route. There are others. For me it was simplicity and reliability. Others have successfully gone down the other roads and done well too.

If you go the MSD route, you need to replace the distributor. The 1978 is a direct swap with the reliability of a FORD distributor. Everything will fit and you won't have to worry about whether the gear will be too hard as with some cheap DUI knock offs. It literally drops right in. RockAuto has a distributor for about $50-$70 plus a core charge of about $30-$40. Summit Racing has an MSD 6A ignition box for about $180. (There is a Street Fire version for about $120) A wire adapter runs about $16. The instructions are easy to follow.

I'm sure someone well versed in the other options will chime in.

It's a matter of choice. Make one and I'm sure you'll get all kinds of help.
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Unread 04-20-2013, 05:11 PM   #3
Oxmarqt
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Go here ---> http://www.jeepforum.com/forum/f8/ig...jeeps-1302352/


Post #5 applies to you. I recommend printing it off the whole thing and then reading it on the computer. Make notes on the written copy. JeepHammer outs the part numbers you will need in Posts #3 & #4.

I went this route. Ford F150 dist, big cap and Chevy HEI module "hidden" in old module case. Used the coil I already had and the majority of the existing wiring. Works great for me. No issues.

Paul
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Unread 04-21-2013, 06:05 AM   #4
CJput
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I really like the looks of Post #3 better. My question with that becomes: which CDI Module do most of you use? If it's the MSD 6 (at around $380) then the total cost ( with distributor, cap adapter, cap, and wire adapters) starts to push it. If this system is that much better, and JeepHammer has a great list of why he likes CDI over HEI, then I will gather parts and go at it with a CDI system, especially if I could find a module that's a little less costly. Any thoughts?
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Unread 04-21-2013, 06:12 AM   #5
HALOjmpr
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I went with the MSD too and the TEAM Rush upgrade for my 258. I used the Street Fire he talked about earlier and it was a simple and easy install and I have since cleaned out all of the throttle control and factory ignition wiring from under the hood and it looks 100% better. I am in the middle of cleaning out all of the vacuum lines and adding a weber 32/36 now. I did not spend the extra money to buy a harness for my factory distributor connection because I never intend to go backwards to the factory ignition. The streetfire is for 8 cyl engines also, but is not quite as hot as the 6A. For the 258 that isn't a concern since it is still 3+ times hotter spark than the factory ignition. Both the streetfire and 6a have a dedicated tach line out also. Have fun whichever way you go .... either one is a significant upgrade.
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Unread 04-21-2013, 06:25 AM   #6
CJput
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I'm headed that way. I'm having trouble determining which dizzy i need. JeepHammer says to use the 79 Jeep/Motorcraft but everywhere I cross reference thye say it will not fit a 1977 304. Anyone have the part number for the distributor I need for a 77 V8 304?
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Unread 04-21-2013, 06:28 AM   #7
HALOjmpr
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The MSD 6A should be in stock at O'Reilly's for $179 and the Streetfire was $129 at mine. I got them to match a online price for $119 for the Streetfire. Or was that total cost for everything you were talking?

This is the only thing I found for your 77, evidently you have to use the Ford distributor only,?

http://forums.off-road.com/jeep-shor...e-article.html

Hope it helps!
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Unread 04-21-2013, 07:54 AM   #8
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They tell you the distributor won't fit because they don't know what you're up to. If you were keeping the original spark box, the distributor WOULD fit, but it wouldn't work. It should say "It's the wrong application".

It does fit because the engines are the same, but the way of sparking the plugs have changed. The bottom end of the distributors are identical with the same gears. It's only the tops that are different.
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Unread 04-21-2013, 10:01 AM   #9
brian613
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http://www.summitracing.com/parts/sum-850048


thats the one i put in my 77 cj5 with a 304.. i put the old gear on the new dizzy dropped it in hooked up 2 wires and started right up
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Unread 04-21-2013, 11:34 AM   #10
CJput
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OK, here's my parts list to do a CDI swap for the Prestolite:
1. Distributor (part # ? Need help here for the correct drop in)
2. MSD Street fire ignition (MSD 5520)
3.Cap adapter (from a 79 Ford F150 with 300CID I-6)
4. Cap Kit (MSD 8414)
5.Adapter plug (Jeep/Motorcraft dizzy to MSD CDI Module)
6.Wiring extension (MSD 8862)

What am I missing?
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Unread 04-21-2013, 12:59 PM   #11
86cj74.2L
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I think the only thing JH didn't like about the HEI was the advance weights right under the rotor.

Buying a HEI module and installing in your gutted prestolite spark box would be much cheaper.
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Unread 04-21-2013, 02:27 PM   #12
Dngrs1
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Plug wires. get the ones that go with the Ford I6 engine the cap came from. Also make sure the MSD comes with wires to hook it up with. I went with the Summit SUM-850610 in my J-10. Am running HEI in my CJ.
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Unread 04-21-2013, 06:39 PM   #13
CJput
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Great suggestion. The only thing I cant get a handle on is which Motorcraft Distibutor I need to order. Can anyone help me with that part?
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Unread 04-21-2013, 07:09 PM   #14
86cj74.2L
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As far as I know any V8 AMC distributor after 78 will work. Pick a Wagoneer with a 360.
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Unread 04-21-2013, 07:16 PM   #15
ASteve
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Dizzy part number:

http://www.summitracing.com/parts/aa...view/make/jeep

It's a rebuilt Motorcraft.

SC
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