I recently purchased a good running 78 bronco with a mainly stock 400 in it. Im now finishing up a 429 swap from a 68 thunderbird. My problem that I have is a bad ground of some sort? or I have some wires not hooked up correctly? My issue is that my distributor has no spark at all when I crank the motor. So I pulled the dizzy out and when I did it was arcing to the block. The sparks lead me to think this is a ground issue? If I put a test light on the distributor when pulled out of the motor I have power to it, then as soon as it touches the block, it arcs and then nothing... I have the motor grounded to the battery the battery to the body and the body is also grounded to the motor. From what I remembered I have everything wired exactly how it was with the running 400. Any ideas on how to troubleshoot this? I have a spare dizzy, coil and module, and have swapped all of them and my problem has stayed the same. So I'm now open to all ideas, I'm sure its something simple that I'm over looking but I'm stumped!

 

Are you running the Duraspark II ignition from the Bronco (as I recall, the distributor from a 400 can be used in a 429 but don't quote me on this)?

I did a 429 swap into my 1971 LTD that came with a 400 (1st year for the 400). But it was a same-year swap so the engine harnesses were plug-n-play! I quickly upgraded to a stock Duraspark II setup off of a late-70s Ford which is an excellent ignition system. I've got a Standard Ignition Manual in my bookshelf here that covers the basics of the system that I can refer to if that is what you are running.

 

yes the 400 and 429 distributors are interchangeable. So if your not, use the dist from the 400,

 

Is there any grounds to the chassis?

 

Yes it's the dizzy from the 400. And I have a ground to the chassis

 

OK, so tell us more about this sparking that happened from the distributor to the block when you were removing the distributor - did you have the ignition turned on at the time?

 

Yes when key is on it sparks. Im in the garage right now and just checke all grounds again and every thing is good... If u need more details let me know, wiring isn't my strong point.

 

Apparently the FAQ for this site is out of date, as it says that I can attach a file to this post but darned if I know how to do it.

I have created a .pdf file of the relevant pages out of this service booklet:

Amazon.com: Electronic Ignition Service Manual: Inc Standard Motor Products: Books

I don't think that the .jpg file size limitation has enough resolution to capture the fine details on this manual (very small numbers on the wiring diagram). Sorry I'm getting into this here, but it would be much easier to post this data instead of typing out four pages of troubleshooting instructions.

 

5004, I sent you a PM - reply to it with your email and I'll send you the pdf so you can get your truck fixed. I am not a paying member here so I can't post a file to the site.