1984 Bronco build thread

That Offy C and 390 is a great combo for the 300!
I gave one to a CT member from FTE (Josiah) with the Holley (black) cap.

So, was it you, or your machine shop that didn't scrub out the engine before assembly?
That's got to be frustrating, to lose a fresh engine.  😖

Hi Jim!

Unfortunately, that was the machine shop. I picked up a completed long block from them. The issues are better documented on ford six, but I had to go into that block before installing it to retime the cam ("yeah, we timed the cam, it was right at zero" - whatever that was supposed to mean) as well as resealing the oil pan gasket and a few other issues. I feel much better about the shop that did the work this time around but its hard not to be nervous after my first experience!

I still dont know what was causing my come and go loss of compression on Cyl 5. It is made especially odd by the fact that it made zero PSI, not just low pressure.

I really like my 390. My guess is that the primaries are actually flowing about the same amount of air or just slightly more than the factory 1 barrel leading to great throttle response at part/light throttle where most driving actually happens, but the secondaries are there when you want them. If someone made a smaller 4 barrel, or even some kind of vacuum actuated staged 2 barrel (think half of a 600 cfm 4 barrel) Id be mighty interested, but out of the commonly available options I like the 390 a lot. Assuming the vehicle stays carbureted I dont anticipate ever replacing the 390.

😳  Yeah, that's definitely their problem.

I don't know much about timing the geared cam in a 300.
I assume you can get offset keys, like my Ducati bevel's?

"Straight up" or zero with a 460 is when the crank and cam keyways are pointing directly at one another.

If you are thinking about a 2-Barrel consider a progressive Weber.
Some hate them and some love them. 🤷‍♂️
I remember when the Ducati 906 Paso came out with one. They worked really well.

Jim,
You hit the nail on the head! Offset keys are really the only option for adjusting 300 cam timing these days. I believe there were adjustable timing sets of some kind in the past but Ive never seen one.

Ive read a bit about the webers! That is an exciting concept to me, but I think I would rather it be vacuum actuated than mechanical. Then again, Ive never tried one. Thry might be dandy

Weber is huge. They owned all the Carter and Edelbrock patents for decades.
It's likely the YFA that came on your truck was made in their factory.....

Late to the party as I've been driving all day.  But those bearings look BAD!  That's a bummer!

But you are well on your way to having a great engine.  

StraightSix wrote

Last Summer I developed a miss at idle.
.....cylinder 5 made 0 psi. I started the truck up and drove it into the workshop where I discovered that unplugging the #5 plug wire with the engine running caused an immediate reduction in idle speed, quality and vacuum as well as causing the wide band O2 to show leaner - so cylinder 5 was indeed combusting and doing something. I repeated the compression check and found that cylinder 5 was still making 0 psi. From there I decided to pressurize cylinder 5 with both valves closed to see which side the air came out through - there was a small puff of air under the paper towel covering the carb inlet, then a clicking sound, and then the cylinder started to build pressure. A subsequent compression check showed 150 psi like the other cylinders.

.......from there I decided it was either a bent/sticky valve or a valve seat issue

I never did find the root cause of my miss at idle, the valves were straight and felt very good in the valve guides, no apparent seat issues.

If the valve went click when you did a leak down and made pressure after that, it wasn't a seat issue.
Tight, sticky, something...

Jim, I would have bet anything you were right before taking it all apart but I never found anything sticky. The valves felt perfect in the guides sliding and spinning. Like floating on a film of oil. You must be correct but I sure dont know what part is to blame.

Gary, the positive outlook is always appreciated, and for a chronic worrier like me, needed.

Lots of good progress on dressing the engine tonight. I got the water pump, thermostat housing, fuel pump, dip stick, ps brackets and intake/exhaust studs all installed. Now the intake is in a soapy bathtub full of hot water heat soaking, Im trying to get all of the fine chips from porting the inlet out. Thats probably where Ill leave it today!

I plan to take the transmission and transfer case down before flying the engine in, maybe Ill get that tomorrow! I also need to verify TDC against the balancer marks. I may be able to get all of that tomorrow which would leave me ready to fly the engine this weekend!  It might still take the better part of next week to finish dressing the engine in the engine bay (intake, exhaust, carb, PS, wires and such. Im feeling pretty good about getting it going in the next 10 days or so!

Can you just take the sticks and transmission mount off and slide the TC/gearbox assembly back out of the way on the crossmember?

I've done this quite a few times and it saves me having to fight it back up into place.
Of course I'm usually working without a lift or even a proper transmission jack so it might not be a big deal for you.

Jim,
Thats a great idea. I am working with a transmission jack, but your suggestion would still possibly be a time saver. Ill look at it when I get under there!

It's a real timesaver when you're doing a clutch on your back in the driveway.  👍

Hi guys! The block is in and the drivetrain is all put together. I did end up pulling it all down. The engine is about half dressed, I still need to do the intake, exhaust manifolds, carb/fuel system, ignition, and the alternator. Im hoping for a mid week start up! Pictures to follow!

Progress!  Hope you get it started up soon!

Big steps!

Congratulations .

StraightSix wrote

Jim, I would have bet anything you were right before taking it all apart but I never found anything sticky. The valves felt perfect in the guides sliding and spinning. Like floating on a film of oil. You must be correct but I sure dont know what part is to blame.

I was thinking about this while sitting here in the truck tonight.
I wonder if the 'sticky' wasn't a lifter in the bore rather than the valve in the guide?

I think you said everything seemed normal when you had the valve cover off, but this may be a plausible explanation for the #5 valve hanging open... 💡

Hi guys! Everything but the distributor is installed. Water, oil and gasoline are primed.

I still need to click the torque on the balancer bolt (140ftlbs), prime the oil pump, roll the engine to tdc on the power stroke, and install the dizzy.

Engine was assembled with high zinc grease, valve spring pressures are at spec for seat and pressure at lift. The thermostat has a hole in the top to burp air on startup. Ill draw fuel from a gas can on the ground to avoid fuel starving issues (bit me last time). We will check for fuel, oil and water leaks on startup as well as monitoring water level. We will run about 2000 rpm for about 20 minutes for cam break in.

Ill have a friend present so it will be much easier to monitor everything while one man works the throttle from the drivers seat and watches oil pressure, water temp, AFR, etc.

We are planning to start up on Thursday afternoon. Am I forgetting anything major?

Jim,
Your theory makes as much sense as anything else Ive come up with. I did check lifter bores with an inside mic and compare to lifter diameters as well as disassembling and inspecting the #5 lifters without finding anything that was obvious to me. Perhaps it was an issue that would only present itself in operating condition?

Congratulations!
I hope it goes well this time around.  🙏

Thermostat shouldn't be a problem with Ford's, the heater circuit is always open

Hi Guys. A lot has happened since my last post. We attempted to start the engine on 2/1 but never got it to fire. Initially, it attempted to start but never fired (we suspected ignition trouble). We replaced the DS2 box, checked spark plug wires, and even restabbed the distributor. Towards the end of the night as I was working the throttle manually looking down through the bores of the carb I noticed that the pump shot didn’t look too confidence inspiring. I pulled the fuel line apart between the carb and the mechanical fuel pump and wouldn’t you know, it was dry. We called it quits for the night and I ordered a new mechanical fuel pump in. on 2/2 we installed the new mechanical fuel pump and the engine fired almost right away. It had a loud ticking sound form under the valve cover that I assumed at the time was the rockers contacting the inside of the valve cover. I made a judgment call to finish the cam break in because we had had so much trouble getting the engine to start. During this time we also found that the new mechanical fuel pump had a pretty bad gasoline leak at the crimp.

 

The rest of the cam break in was pretty uneventful with the engine drinking about half a gallon of coolant and running fairly smoothly. Oil pressure at 2000rpm at first fire was 60psi and oil pressure at 23 minutes of run time and 2000 rpm was 48psi. At the 23 minute mark, we decided to call the cam broken in and attempted to set the base time. The timing was fairly retarded (timing light read 14 degrees of advance at 2500 rpm during cam break in meaning that my base timing was probably about 0 BTDC). As soon as I loosened the hold down bolt for the distributor the distributor rotated slightly in the “retard” direction because of the spring of the spark plug wires, and the engine died (it was idling at 500 and sounded pretty weak). We attempted to restart it but the starter wouldn’t readily turn the engine over. I turned the engine over by hand with a ratchet on the harmonic balancer bolt and satisfied myself that the engine was not locked up, infact is was spinning over more easily than I would have expected. I pulled off the valve cover and looked for signs of interference between the rocker arms and the valve cover and didn’t see anything. At that point we did an oil change and called it a night.

 

At this point, the three issues I needed to solve were – no start condition, probably battery/starter – tapping noise from valve train – fuel pump.

 

I spent a weekend trying to troubleshoot the starter so I could get the vehicle into the garage before tearing into the valve train. After blaming and replacing most everything but the starter (including the battery) I finally pulled the starter down and found that I couldn’t even get it to turn over on the bench with leads from a good battery connected directly, I think it may have had an internal short because it did draw current, but it didn’t spin. With a PGMR starter installed I have found that the engine now turns over readily. The new starter does sound different than what Im used to though. I used a starter for a 96’ F150 W/ 300-6.

 

At some point while I was trying to troubleshoot the no start condition my dad came over and helped my push it inside, so I had already begun troubleshooting valve train. I believe the noise is valve train because it always sounds like its coming from the head no matter where you listen form. It soulds sorta like lifter noise and sorta like an exhaust leak, it’s a ticking sound. It is synchronous with engine speed. I took off a few rockers and the wear was heavily biased towards the rocker side of the valve stem. The guys on ford 6 advised me that I needed 0.150” worth rocker shims to account for the longer chevy valves in my head. I ordered a variety of shims and found that the Diechem pattern on the valve stem was perfectly centered with 0.150” worth of shim. Unfortunately, with all of the shims I need new pushrods (ordered, delivering around Friday) and my valve cover will no longer fit. Ive laid out a pattern on a piece o 0.250” aluminum to cut a valve cover spacer. I believe the bad rocker geometry was the cause of my noise.

 

Finally, the fuel pump. I have installed an electric fuel pump. Its mounted on the passenger frame rail, it’s a Holley Mighty Mite rated for 4-7 PSI. after mechanically installing the new pump I started to ask myself how I was going to power it, what would the trigger for the fuel pump relay be, and where would I mount that relay? Well, I got to looking at and thinking on a lot of my previous electrical improvements, and it was a spaghetti mess of butt splices, relays all over under the dash, non automotive wire, and just a general lack of any coherent plan.

 

I went back to the old drawing board and came up with a new power distribution plan for the truck. There are now two 120A relays mounted on the fender under the starter solenoid. They are both triggered by Key in on/run signal from the ignition switch.  Each one feeds a 12 slot fuse box. One relay/fuse box for loads like fuel pumps, radios, air compressors, headlights and one relay/fuse box for more sensitive loads that may need cleaner power like the O2 meter, maybe an ECM down the line, trigger wires for additional relays, etc. I also installed two bus bars for grounds in the front fender by the battery, one bus bar for the high amp draw dirty loads and another for the potentially more sensitive loads. The volt meter, O2 meter, radio, and fuel pump have all been migrated to this new distribution set up. Now it will be quick and easy to add new loads to the truck with good circuit protection and no need to go digging under the dash looking for a good trigger and mounting location for another random relay.

 

I will likely install a bank of relays on the driver side fender at some point that will be triggered by switches in the cab (headlight upgrade, maybe an air compressor, and I may also migrate the fuel pump to this eventually so I can switch it off if need be without having to turn the truck off). This bank of relays will draw power from slots in the two new fuse panels and will receive voltage to their coils from rocker switches in the cab.

 

Also, since I do think I actually had a bad DS2 box at the start of this whole adventure on 2/1, Ive decided to get out of the DS2 game and have purchased an MSD 6AL. I will get the engine running on the DS2 spark boxes first and will probably preserve all of the original pigtails so I can still keep a DS2 box in the cab as a spare, but the MSD box will go into service soon. For those of you who are running an MSD ignition system, where did you mount the box? Im currently leaning towards mounting it on the driver side wheel well next to the factory DS2 location.

 

As it stands, I need to cut out and fit my valve cover spacer, get the new pushrods in, land a few more wires under the dash, put the dash back together, and hypothetically it will then be road worth. If all goes well it may start up again on Saturday morning.

 

Thanks for reading!

Wow!  That's a lot to digest.  But it is also a LOT of work!

Glad you got the engine started.  That can be a very stressful time, but you got it done.  And noises and issues are frequently part of that.

But what caused the engine to drink half a gallon of coolant?  That sounds like a problem and I missed the solution.

And yes, a PMGR starter has a very different sound than the earlier starters.  Almost like the old Chrysler starters.  And the engine spins faster as well, so everything sounds different.

Your power distribution plan sounds a bit familiar.  And good.  Much better reliability, brighter headlights, etc.  And much easier expansion.

But your expansion ideas sound familiar as well.  An air compressor?  Switches on the dash?  O2 meter?  ECM?  Yep, yep, yep, and yeppers!

As for where to put the MSD box, I've not done that but why not right where Ford put the DS-II box?

And please show us drawings and/or pics of the valve cover spacer.  That's cool.

Good luck!  

Move all the leads one post to the left

I've always had good luck with Carter pumps.

(bailed when I saw Gary had replied)