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1992 Ford Bronco XLT 5.8
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Discussion Starter · #1 ·
I am having a 351 rebuilt and getting the bronco back this Thursday. I am moving to Texas from Arizona and wondering if I can drive it. I was planning on taking it easy <65 and below 4k rpm and stopping to change oil after 500 miles. I spoke to my dad about it and he told me I have to break it in slowly with city driving not a long trip. I read a bunch of discussions here but they were old and wondering if opinions have changed. Is my dad right or he just being too cautious? My trip is 750 miles.
 

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The Tennessee Warden
96 XL, built 357W, E4OD, BW1356, 4.56 gears
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4,730 Posts
If you do the proper break in procedure using zinc/phosphorus break in oil you should be ok, but take it easy and don’t hold the same speed/rpm for extended periods of time. If it were me though, I wouldn’t drive it that far immediately after break in.
 

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Ford Hoarder
78 & 92
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Due to flat tappet you will want to follow that cam breakin typically 20 min at 2k+ rpm. Next to no idle time.
If you get threw that id change the oil and drive it a little local make sure it's good and Drive it. Try to very the rpm while driving it.

The trip part would not bug me so much for breakin, just new install issues that usually show up that maybe anoying to fix on the road. The break in test at work for us is usually at the rated power of the engine until the blowby evens out (just an example) or rather seating the rings.
 
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Eric
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Once you've primed the engine, by hand, and verified oil is reaching the rocker arms then you should follow typical cam break-in procedure. After that, allow the engine to reach operating temp, shut it down, change the oil and filter, and take it out for a test drive with varying RPM. Allow the engine to heat-cycle several times (warm to operating temp, cool down, repeat). Verify no leaks anywhere from the heat-cycling and take her out for the haul. Not necessarily advice to follow, but we used to hammer our builds pretty hard, right out-of-the-gate, to get the rings to seat quickly. Also, if something's gonna break catastrophically, it'll usually happen within the first few miles and is usually a result from faulty parts, or poor assembly. We used quality parts and had a decent background in engine building. Best thing you can do: ask the machine shop how they would recommend you break the motor in. They aren't going to tell you something that will result in a warranty return because it will cost them money to fix the problem.

When you get a brand new vehicle from the dealership, with a brand new engine from the factory, they don't take it out for a 30 mile drive around the city to "break it in" before they hand you the keys. But, above all else, your dad has your best interest in mind. He would not give you advice that he felt would compromise your well-being.
 

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Registered
1992 Ford Bronco XLT 5.8
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Discussion Starter · #7 ·
@MS88Bronc thanks for the response. I'm not sure what the engine shop will use but I'll definitely discuss what additives they used and their procedures. I am starting to come to terms with either I'll ship it or come back and get it a couple months down the line.

@CrazyBRONCOguy wouldn't the engine shop go through the cam break in? When I spoke to the guy he said they will drive it then put it on a lift and check for any leaks or other issues. He knows about my trip and said they want to be sure it's safe. I definitely do not want to be on the side of road on a sunny AZ day.

@silver70 I'll have to ask the engine shop if they went through the steps you mentioned. You're right, I'm sure my dad is just being cautious for my own good. He told me to just drive with my wife and kids and enjoy the ride. He also said not to worry, he'll break in the bronco for me and let me know when it's ready. Maybe that's the real reason 😀 he wants me to leave it.

Now that I've had more time to think clearly and not pissed off at the shop with being 3 days late on delivery, I'm leaning towards leaving it in AZ and having my dad pick it up for me. On a personal note, I would love him to experience how bad ass these trucks are again He had a 81 bronco and 93 f150 back in the day and is the reason I got into broncos. As he got older I guess his priorities changed but I want him to tap into that bronco guy side a little bit from 28 years ago.

Thanks for all your responses, I appreciate them.
 

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I would not assume the shop is going to do anything... If they are gonna drive it, I would hope they would know the correct cam break in procedure. Though not knowing anything about the shop, it is very possible they haven't dealt with a flat tappet non roller engine in a long time.
I would personally call and ask them what their break in procedure is, and see if they say anything about the cam, and bring it up as needed.
 
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95 EB 5.8
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If I had subbed out the build to a shop, personally, I wouldnt take it on a road trip of that long, that quickly. If I had done the rebuild myself, it would imply I could fix things, if needed on the road. Just my .02
 

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Addicted to Junk
85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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I had my 300 rebuilt by a reputable local builder. Put it in the bronco 2 weeks before leaving for Moab. After cam break-in, I changed the oil. Put 250 miles on it before embarking on the 900 mile-all highway at 3000 rpms- trip from eastern KS. Denver is about 500 miles away so I changed the oil in an autozone parking lot there. That was with 750 miles on the engine. Continued my journey to Moab, wheeled for a few days and made it back to KS with about 2200 miles on the engine. No problems at all.
 

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Premium Member
93 XLT 347, GT40 Heads, Bassani headers/exhaust, E4OD
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Now that I've had more time to think clearly and not pissed off at the shop with being 3 days late on delivery,
Ha! 3 days? You should read my build thread… engine builder was a month late and by day 7 at the installers @dash_cam had nick named it Project Blue Balls!
 
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Addicted to Junk
85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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Ha! 3 days? You should read my build thread… engine builder was a month late and by day 7 at the installers @dash_cam had nick named it Project Blue Balls!
Lol
My 300 was at the builder for 11 months... One man shop that was really busy. Plus part of that was waiting on parts.
 
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1992 Ford Bronco XLT 5.8
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Discussion Starter · #13 ·
That's a long time to wait. I figured since I gave him a date I needed it by and he agreed, he would meet it. Maybe next time I'll do reman or even used to make this process quicker.
 

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93 XLT 347, GT40 Heads, Bassani headers/exhaust, E4OD
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That's a long time to wait. I figured since I gave him a date I needed it by and he agreed, he would meet it. Maybe next time I'll do reman or even used to make this process quicker.
My rule of thumb? Take what ever date you are given, double it, then multiply it by 3 and finally add a day for safety...

My installer told me 2-3 days - a day to pull the old engine, a day to install the new engine and maybe another 1/2 day to get everything hooked up an running. 16-20 hours - and my final bill was spot on. What they didn't tell me was this was a side gig and they would only work on it for a couple hours a day between other jobs.

Fair warning, it's worth others asking in the future to avoid being surprised or disappointed. Don't get me wrong, they still work on my truck, I'm just certain to ask "when do you want me to drop it off" and "when will it be ready to pickup."
 

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Discussion Starter · #15 ·
Update: I got a call today that my bronco is ready to go. I asked about break in procedure and he said there is really no break in procedure for cam or engine except to change oil after 500 miles and don't tow for 1500 miles. He said engines are built differently than before back in the day. They provide 3 or 5 year unlimited mile warranty, can't remember which. My dad is going to pick it up for me and I'm thinking of having him follow the cam break in you guys mentioned and what about driving methods? Should he follow under 4k rpm and variable speeds, no long term constant speed.
 

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Cam break needs to happen, litteraly at start up on a flat tappet engine. If you went roller it's not a big deal to do.
If they don't do it, not worth having dad do it either. It's just gonna have to be ok as it is of you drive it home, or if they don't do it.
They don't build em like they used to is correct. However, take the efi away and your engine is remarkably close to 68 351w (yes deck height changes and stuff) So yours is built like they used to if it is still a flat tappet.

That said it has a warranty and they told you not to worry, so that is what I would do. Not sure if Ford broke in cams when new or just didn't worry about it either.
 

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1992 Ford Bronco XLT 5.8
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Discussion Starter · #17 ·
Cam break needs to happen, litteraly at start up on a flat tappet engine. If you went roller it's not a big deal to do.
If they don't do it, not worth having dad do it either. It's just gonna have to be ok as it is of you drive it home, or if they don't do it.
They don't build em like they used to is correct. However, take the efi away and your engine is remarkably close to 68 351w (yes deck height changes and stuff) So yours is built like they used to if it is still a flat tappet.

That said it has a warranty and they told you not to worry, so that is what I would do. Not sure if Ford broke in cams when new or just didn't worry about it either.
Thanks, I'll just do what they say and if anything goes wrong I'll take it back. I'm going back to Phoenix to pick up Aug 21 so this will be a long 30 days.
 
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