Update:

So, I haven't touched much of anything since my last post. Just been driving it, and getting a feel for it.

On the downside, the chirping noise from the rocker arms has returned. The oil grooved rocker arm ***** kept it away for a good week to a week and a half, but it's sloooowly crept back in. At first, I thought I was imagining things, but every day it's been getting a tiny bit louder. It's still nothing like it was before, but it's there. No one else notices it, so I'm probably just sensitive to it, but I still know it shouldn't be there, so it bugs me. But, at least I know what it is, and that it's nothing to be overly concerned about.


Other than that, I'm at about 480 miles on the engine. Up to this point, I haven't gone much past 3000 RPMs or over half throttle. Some spirited driving, but nothing crazy.

The engine's smoothed out a lot and is driving really nice.


But, I've been getting a little antsy to really feel some performance!
So, on Friday, while driving on the interstate back from a movie, and seeing as it was my birthday, I decided to floor it. Holy cow. This rich, deep, melodious roar sang from the engine bay and the front end just about lifted as the Bronco rocketed from about 40 up to 80mph like it was nothing. It sounded and felt amazing!

Yesterday, my brother and I took it off road on some trails near his house, and I put the pedal to the floor. The rear tires broke and threw dirt and it just pulled and pulled. There's some serious power under the hood. I'm excited to start playing.


In retrospect, if I could change one thing, I think I would have picked a cam with the power band slightly lower in the RPM range. This cam really builds it's power between 2000 and 5000 RPMs, but doesn't have a lot in the way of throttle snap off idle. Especially with my big 3.00 rear end and 32" tires. In 1st gear (not granny), 2000 RPMs is almost 20mph. I'd have sacrificed some of my new found top end for a little more low end. But... that's a minor thing and I'm just thinking aloud.

Either way, wow, now that I can actually play around and see what it's got, this thing's a beast.

 

Hoorah!! Excellent to feel the power!

At this point I know you just want to drive it, but I would consider advancing the cam. What t.gears did you use? I'd run your specs by pmuller9, the cam guru on the other forum. I'll bet a few degrees advance on that cam would pick up the off the line zing.

Iirc, isn't that an Erson cam? Don't they recommend 4* advance on all their ford 300 cams (all three of them)?

That brings up a good question regarding the t.gear advance key that Mr. Gasket used to make. I wonder if it is still available since Mr.G is gone.

 

Sucks about the chirping. It might be time to start saving for some roller rockers.

Glad to hear you can finally start having some fun with it!

I don't think the cam is your problem. I think your cam is too small. I think you need to swap gears! The 3.00 gears in a 4x4 is no good! I don't like the 3.50 gears in my 4x4! I want some 4.10/4.11 gears!!

 

Is there some kind of standard ratio rockers you could put in? I would think that would fix your chirping, and using the truck as a daily driver, I doubt you will ever tell any difference in power with the rpm band you use.

 

I thought he was running stock rocker arms.

 

I thought he was running a comp 260 cam.

 

Well, just got back from crossing the 500 mile mark.

Yeah, Erson recommends 4 degrees advance on it, which my machinist took into account when he degreed it. So it's degreed and installed according to their specs. And, IIRC, he used an advancing key on the timing gears, since my set only had 1 setting. You asked me a while back what timing gears I had, but I can't seem to find the post, or my info on them. I think they were Comp or something. I'd have to look in my notes. Either way, they only have 1 degree setting.

That's an interesting idea about advancing it some more, but right now I don't know if I want to go tearing back into it quite yet.

I'm running an Erson E270321.

Ford 6 Cyl 240-300 CID Hydraulic Cam & Lifter Kit- 220/220° @.050 .504/.504 lif | USA Performance Parts


And yes, I think I'll probably start saving up for some roller rockers. Chirping means friction, no matter how you look at it, so it can't be a good thing.

As for the gears, I know I'm pushing the 3.00 gear to their limit, especially with 32" tires. But, with the NP435, it keeps my highway RPMs down, and I do like to go on trips and cruise at 75 - 80mph. So, it's a give and take sorta thing. If I regeared, I'd probably go with 4.11s and a ZF5, but that's an expensive endeavor, and certainly no time soon...

Yes, I currently have the stock rocker arms on it.

 

Where the hell did I come up with a Comp 260? Your cam is pretty close to what I'm going to go with. But was leaning towards Crower on the cam (not the lifters ) . With that cam you should have a pretty good lope at idle.

If you want to give up a little top end for more bottom end maybe look into the Cloyes adjustable timing set down the road.

With spending all that cash on the build, I'd be a pretty PO'd if it was chirping. With that much lift are you sure the slots in the rocker arms are long enough? I know that can be an issue on the pedestal mount rockers. I don't know what the stock stud mount rockers can handle for max lift. Roller rockers aren't cheap but they should fix the friction problem.

The tall gears with the NP435 are a good low budget OD alternative but they are a compromise. You are giving up a whole lot of go in 2nd, 3rd and 4th gear. Even 3.50's would be a pretty good improvement without hurting the top speed.

It sounds like it's time to change the oil and start having some fun with it!

 

Oh, ok. I thought you had Chevy rockers on it.

 

It does have a bit of a lope at idle, which I really like. Nothing extreme, just nice and pretty. I'll get a recording of it here soon and throw it on here.

I've seen the adjustable timing set before, it might be an interesting idea. I'm curious how it would affect things.

Yes, the chirp gets on my nerves especially since it overshadows any of the other sounds at idle. I thought about the slots, but checked those closely and there is enough room. If those were the issue, I don't think the sound would have ever gone away. The fact that I was able to completely eliminate it, and then it slowly crept back in over about 100 - 200 miles says a lot. I'm thinking the wear pattern on the rocker arm ***** just isn't conducive to good lubrication. Time to start saving up for some roller rockers.

3.00s are definitely a compromise and an OD of sorts. 3.50s would put me right about 3000 RPMs at 80mph, whereas I'm at 2600 right now. I remember my '84 had 3.5s and that thing was a beast. I never drove it as fast due to the RPMs though.
If only I could find an NP520 five speed, I'd have it all.

 

Well, yesterday I took out the DSII and swapped the DUI ignition back in. I left the wires and spark plugs, and swapped just the ignition, since I wanted to isolate one thing at a time. Lo and behold, the issues I was having previously did not return. The popping, surging, bucking, etc. were non-existent. So, as far as I can tell, it's either a wire (highly doubtful) or one of the new spark plugs I bought was bad. I'm going to go with spark plug. So, I'll be returning those here soon.


The DSII has a completely stock curve to it. I've never modified it, so it's completely off the shelf. Stock coil, cap, rotor and some cheap wires. I just keep it in a box for emergencies and if I have to put it in, I just plug it into the ignition module which sits on the wheel well. Nothing fancy.

I set it at 12° advance and it felt quite rip-roaringly powerful above 2000 RPMs, but not so much below that. It's what I've been driving around for the last week or two after I pulled the DUI unit out after all the surging/bucking/backfiring issues.


The DUI was custom curved to my previous engine's specs. I asked them at the time when I had it built if it would need to be recurved when I rebuilt my engine, and they said it shouldn't need it unless I went over around 10:1 compression (mine's 9.1:1). They said to install it at 12° advance.


It drove well, but it just did not seem to have the oomph that the DSII had. It pulled nicely up to 4500 or so, but didn't have the deep tone I'd been enjoying the last few days.

I decided to do what was mentioned above and tune the DUI for maximum vacuum at idle (around 25° advance or so), and then hook it up to ported vacuum to keep it from pinging. I noticed that it performed over all better, and had MORE torque on the bottom end (more than the DSII) but still not the same top end, and still a little lack luster.

So, I'm thinking I'm having timing curve issues and may need to map out the curve of each unit and see how they differ.


Here's the timing curve that PerformanceDistributors put on the igntion:

Base Timing

12°

Mechanical Advance
(Base timing included)

500 - 12°
750 - 14°
1000 - 18°
1250 - 22°
1500 - 25°
1750 - 27°
2000 - 29°
2250 - 30°
2500 - 32°
2750+ - 34°

Vacuum Advance

< 8hg - 0°
9 - 1°
10 - 5°
11 - 7°
12 - 11°
13+ - 14°


Does anyone see any issues with this curve? I just don't get why the DUI would feel weaker/less aggressive. It's all in by 2750 RPMs, so at 3000 RPMs and above, they really should feel the same. On my stock engine, the DUI was a night and day improvement over the DSII.

 

With a 284 adv. duration cam I would expect it to sound more like my favorite 240/300 video on youtube.
The video's you posted with the rocker arm chirping sounded way smoother. But when you get a chance post another video! We like those just as much as pictures!!

The Cloyes timing set just has three choices. All it's going to do is move the power band around.


The rpms don't bother me much. My old 87 F250 had 3.73's with a 5.0L/NP435 combo. 70 mph was right around 2950 rpms. And I ran that up 90 mph a few times. The higher rpms will hurt the wallet by using more fuel. But the steeper gears sure make it more fun to drive!! Good luck with finding a NP520! I've never even seen a NP520 in person before. With the Bronco's short wheelbase your OD options are a lot fewer then mine. I've got a 4.10 geared rear diff I'm swapping into my van. I'm going to see how long I can live with the 4.10's and NP435. When I've had enough I'm going to either add the Advanced adapters Ranger OD box or Brownie/Spicer auxiliary transmission. But neither are cheap, so I'll be screaming my 300 for a while.

 

It isn't quite that lopey. But, then again, it sounds like he doesn't have a muffler, which (I think) adds to it. Or, if nothing else, makes it a lot more noticeable. You can't even hear the engine over the exhaust in that video, whereas mine's quite the opposite.

Yeah, I'm not holding out much hope for an NP520, but it's still on my dream list. I wish there were more OD options for the Bronco. If I did another transmission swap, it'd be to a ZF5, but I'd have to go to at least 4.11s to really get anything out of that. 3.50s wouldn't do much due to the ZF5's 2.94:1 starter gear (as opposed to my current 3.34:1). Eh, time'll tell.

So, I had an interesting chat with Clifford Performance today. I called to ask them what rocker arms they use on their builds, and told him about the chirp I was having.

He was adamant that either the valve stem length was wrong (there were two different valve lengths for the S.I. valves, can't remember which ones I got), or the bosses for the screw in studs were too high. I started to get a little frustrated with him since I couldn't get any details as to why that would cause the problem, but he said he knew exactly what was wrong and that it's one of those two things and that it was throwing the geometry all off. Not only that, but if I don't fix it, it's going to screw it up pretty badly.

That said, I simply cannot think of a reason why that would be the case.

The rocker arm sits in the middle of the stud. If I raised or lowered the boss, the stud may move up and down, but the rocker would stay in the same place since it's adjusted to where it needs to be. It'd just sit higher or lower on the stud.

If I had a different length valve stem (as long as the spring rate is correct), I'd simply need longer or shorter push rods to accommodate.

Am I missing something?

 

Yea the one in that video is a open header.

I like the NP435 way more then the ZF 5psd. The ZF is a good transmission. But I don't like the slave cylinder design, non removable bell housing and the aluminum case. The 435 is tough, easy to work on and best of all cheap! I can buy 5 or more NP435's for the price of one ZF.

Clifford is the last place I would ever call for advice! You already checked your geometry when you checking your push rod length, right?

 

I'm a huge fan of the NP-435, I just wish I could get more low end gearing for off the line acceleration without giving up my low highway RPMs. What can you do.

I mainly called Clifford to find out what rocker arms they use on their builds, but was confused by how extremely knowledgeable and adamant he sounded about this exact problem. I've never had a high opinion of them myself, but it's hard to ignore when someone sounds like they know of your exact problem and what the cause is, especially when they can rattle of the two different valve stem lengths from memory and ask which one I bought from S.I.
The reasoning just doesn't make any sense!

Yes, I checked the geometry by marking each valve stem with a felt marker, installing the rocker, and turning the engine over. Then, adjusting the push rod length until the wear mark was dead center. I have 3 different lengths of push rods because of it. Last time I popped the rockers off (after about 250 miles), each had a wear mark right smack dab in the middle of the valve stem, so I know my measurements are correct.