May I have advice on tuning #50's FE? [7/23/2016 dyno tune update from 2013]

[robroy]

Good morning!

I'd like to learn how to do basic tuning on #50's new FE. I apologize in advance for posting a thread with such a potentially wide scope for discussion, yet I think I need some wholistic advice.

After I put ~500 miles on the FE (it has ~250 miles now, and I rack them up slowly), I plan to hire a professional tuner to put it on a chassis dyno and optimize the carburetor and timing. But in the meanwhile, I have some symptoms that I'd like to address, if feasible.

Symptoms:

1. The truck feels a little sluggish when starting out from a stop. Given the gearing and FE configuration, I'd expect it to feel undeniably peppy.
2. There's a strong exhaust stink while the truck's idling. After going for a drive, the smell's all over my clothes.
3. Even with only ~250 miles on the FE, the tail-pipes already look black and sooty.
4. When I measured the timing at 3,500 RPM, it appeared to be jittering between about 30 and 34 degrees; it didn't look steady. Lower RPMs did look steady.
5. I hear what sounds like detonation under these conditions:
   1. I'm in high gear, which for my truck means 3.73:1 (rolling on 31" tires).
   2. The RPM is above around 2,000.
   3. I give it more than about 15-20% throttle.

For those of you who may not be familiar with #50 (my truck) and its FE, its FE's described here: 390FE (406ci) for #50, built by Tom Lucas at FE Specialties. Here's a list of the specifications that I'm guessing may be pertinent in this thread:

1. Compression Ratio: 9.7:1
2. Combustion Space: 95.43 cc
3. Intake and exhaust valve sizes: 2.090" and 1.650", respectively
4. Gasoline choice: high octane pump gas
5. Camshaft: Erson custom roller camshaft Camshaft spec sheet
6. Current distributor: MSD P/N 8594 "Pro-Billet," centrifugal advance only--no vacuum advance. This distributor was not chosen by Tom Lucas, but by the shop that build my first, doomed performance FE
7. Distributor configuration: two light blue springs (MSD curve spec. "D," blue bushing (21 degrees advance limit). This configuration was selected by Tom Lucas.
8. Ignition box: MSD 6AL

Here's a graph I made of the Dyno 2000 software performance estimate that I received from Tom Lucas:



Here's the timing curve that I measured the other day, using my MSD timing light:



Here's a photo of the blue centrifugal advance springs I'm running today: MSD_Advance_Springs.jpg.

Here's the PDF instruction sheet for MSD P/N 8464, which is their centrifugal advance kit (springs and bushings). It explains the meaning of the blue springs and blue bushing I'm using today: 121-8464.pdf

Here are excerpts from the instructions, with today's configuration indicated in each.





If it weren't for FORDification, my uneducated approach would be:

1. Retard the initial timing ~3 degrees, and see if that cures the detonation sound. If it doesn't, the detonation's cause may be something other than unduly advanced timing. If the detonation sound DOES go away, then I would...
2. Replace the current MSD distributor with a distributor that features vacuum advance, and tap vacuum directly from the manifold. Then, with the vacuum advance connection plugged, adjust the timing curve slightly more retarded than the today's curve, plug the vacuum advance back together, and road-test.

Today's Questions:

1. What's the detonation sound's probable cause?
2. What's the jittery 30-34 degree timing at 3,500 RPM's probable cause?
3. What's the rich, smelly exhaust's probable cause?
4. Does everybody agree that my application would be better served by a distributor that has vacuum advance?
5. If vacuum advance would be best for me, which distributor would you recommend? A Mallory? Which one?
6. Not considering vacuum advance, does my current advance curve look ideal for this application?

Thank you all so very much for your patient and thorough guidance!!!
Robroy

[Mancar1]

Hello Robroy
I would say your carb is set to rich. Maybe lean it out a little. May help with the detonation sound. Sounds like you are on the right trac with the timing thoughts. I do like the dist with vac advance. I am no top gun on these matters. What little I know came from the school of hard knocks.
By the way, your posts are always great. Such attention to detail, and always well worded. Thanks

[woods]

First, yes, you should run vac advance and run it off of manifold vacuum, not carb port.

With the vac unhooked, I would set you initial timing closer to 14, but limit it to around 31 (due to your head design).

Also, the carb. You may have the throttle plates turned too far open to reach the idle you want. This will uncover too much of the transfer port and make it run very rich. Running a vac advance and running a bit more initial timing will bring your idle up so you can close the throttle plates more to where they should be.

As far as a vacuum advance distributor...really, the duraspark distributor is pretty darn good. I dislike the duraspark box, but you can hook the distributor to an MSD box or even an HEI module and have very good results. Of course, you will need to recurve it, but no big deal there.

If you still have pinging after all this. You need to find out what your quench area is set at. If it's too large, it WILL cause all sorts of detonation.

The timing jumping around could be a lot of things, so I need you try something. When your are checking total advance and it's jumping around, try turning the rpm a little higher and see if it stops jumping and stays steady. This will tell me a lot.

[cdeal28078]

What size and make of a carb. Are you running. I also would run a vacuum advance dist. and I now like it on full manifold vacuum. Used to like ported until Woods changed my mind.
Does sound like it is too rish by the look of the tail pipes and the smell but runs like it is too lean. Timing advance can sure mess with you and I know little but what I have read here about quench but understand it is very important to get right. IF I ever get to where I can put some Dove heads on my 460 you can bet my quench will be as good as I can get it. I wonder what a woman would thing we are talking about if they read this?
Clint

[woods]

The same thing I hear when my gal starts talking about her garden. I recognize words like tomato and dirt, but the rest just sounds like Charlie Brown's teacher "wonk, wonk, wonk".

[FreakysFords]

Hidy!

As always, my opinion is just that, but I'll happily share.

A) (thought it seems you already realize this) ALWAYS try to send the truck to dyno tune with the components you plan to run long term.

B) Spend some time getting accustomed to reading plugs.
1) Read what you've got and document
2) Pop in some base NGKs, do a warm up and run. Read and document
3) If plugs still clear (likely not), pop back in. Otherwise another set. Now a decent load pull and read.
*) If at any point in these reads you find a lean condition, CORRECT first! (because of build, components and tune, you can be rich at idle and lean elsewhere, so a pull on clean plugs with engine already warm MAY become wise............ That's steps ahead though.
4) If you find a range issue that's noticeable on a plug read, FIX IT before the dyno. (normally altering advance and / or fuel delivery at rpm............. NORMALLY, because there's a good chance you're going to change that distributor on the go anyway).

If your headers are already bunged for O2 sensors, you may want to look into buying or borrowing an O2 gauge for your end of the tuning. Personally, I like them for performance builds anyway, just to see what's changing as time goes on. (NOT a must have though)

To be honest, the first thing I would do though is lose the distributor. Toss that thing for a Duraspark and keep the 6AL. Since you've got an engine by Tom, ask his suggestions on the springs and weights, THEN start the tune. (SINGLE vacuum / non emissions Duraspark dist.) The duraspark setup is perfect for many applications, but where it's only a distributor and pickup (as in your case with the 6AL), it's the only way I'd go. Now you can tune timing between the dist and the 6al to near perfection.

I am actually a fan of the Edlebrock carb for many applications, but not yours. For your setup, I'd sooner have a mildly tweaked 4100 (or summit's 4160) OR a good Holley vacuum secondary, manual choke (so you don't have to change your setup). I don't know where that sits in your financial plans as to when and if, but if it's likely to happen anyway, consider moving up the time frame to make life a little easier on you.

Then there's one thing you can always attempt when you think you may have a lean only condition (not timing related, or more carb than timing). Pretty simple since you have a manual choke. Warm her up, take off as consistently as you can under same conditions a few times to make a second nature habit of the launch and the feel. THEN pull out the choke a fraction (about 1/8" movement looking at the valves). To do this, I'd find this point and familiarize myself with how far out the choke rod is before the begin of the test at all.
If it seems to HELP things, you're lean!
If it hinders, you're likely running rich.
If no change, add a tiny bit more choke till you notice a change one way or the other.

That lil trick works well with non vacuum advance distributors. Works for vacuum advance as well, but adds a factor or two.

Anyway, sorry for another long winded response, but that's where I'd start. I wouldn't even bother testing anything until I swapped the Distributor........ if that gives you a handle on how opinionated I am on the subject.

[DuckRyder]

I surprised by the animosity toward the distributor, yeah, it would be nice if it had vacuum advance but I don't think the lack of it is causing your symptoms. The distributors pick up is very similar if not identical to a duraspark and it is a well constructed piece.

The list number and jetting of the carburettor would be helpful and you've already been given good advice related to uncovering the secondary transfer ports. do you recall how many turns out the idle mixture screws are? Float settings?

We need some more information here but my initial thoughts are this:

You say it pings under load around 2000 rpm and your map of the actual curve seems to indicate a slight peak at 2000 rpm, I would probably start by slowing the curve down one step at a time to see if it stopped pinging. (this has the advantage of costing nothing but time if you have the spring kit)

I would also talk to Tom, if it is in fact pinging, you want to stop it immediately.

[tmcalavy]

If his tailpipes are black and sooty, his plugs are too...no word on what manifold or carb you're running. You've dropped some serious coin on it, so why not pull the current dist and ignition and put a points dist in there...set timing to 6 or 10 degrees BTDC, depending on transmission, set dwell and curb idle to spec (550-650 rpm in Drive), and put a vac gauge on it to help you even out the carb rich/lean settings. No clue what the smell is that you're describing, but I would run it stock and see which configuration you like. No idea what altitude Salinas, CA, is at...but it can affect how you jet the carb...I think the rule with Holley is two jet sizes smaller per 2,000 ft. above sea level...setting the float correctly is important, too.

[Ranchero50]

Read this earlier and thought about it for a while. Robroy's inexperience is his best friend and worse enemy at times.

For Robroy, are you sure it's detonating or are you just hearing the exhaust ping inside the headers under a load. If I remember right you went with some pretty quiet mufflers on the truck, the videos are quiet.

If you feel it's detonation I would suggest retarding the base timing 4` and trying again. That engine with the timing you have listed should run fine at that low of a throttle input. I would not suspect detonation unless you were running around 18-20` initial.

Black soot out the exhaust is hard to say if you are just putting around the neighborhood. At idle I would suggest the eyeball test, go back and scoop and handfull of exhaust off the pipe like you would water from a stream and pull it up to your face. If it's very rich and your eyes want to water, close your idle screws 1/4 turn and take it for a drive.

Sometimes it's so hard to diagnose a problem over the internet...
Jamie

PS. oh yeah, MSD goes from multispark to single spark somewhere north or 3k so you may be seeing that transition

[Ranchero50]

Yep, if you can't stand next to it while running adjust the mixture before anything else. Idle mixture screws are on each side of the front metering plate. Warm it up until the choke opens (it is opening right (otherwise the choke may be a lot of your problem)). Once the choke is open adjust one screw in at a time until the engine stumbles, then open it back up 1/8 turn. Do each side.

It's really hard to say any one thing is wrong. If it's idling super rich that is probably contributing to your other problems and I'd try to take care of that first.

Jamie

[70_F100]

Robroy, I know you've had the engine idling quite a bit during its short life, so the first thing I would do is to change the spark plugs and give it a test drive. There's a chance that the plugs are somewhat carbon- or gas-fouled, especially given that the exhaust smells so rich.

One other option, one that hasn't been mentioned (and maybe you've tried it already) is to take the truck out and give the engine a chance to "breathe" like it's built to do. You may find that all of your problems are solved. That engine was never designed to be babied, so open it up a little and let it feel its oats!!!

Given that your timing curve so closely resembles the HP curve, I wouldn't do anything with the distributor just yet.

Just my

[DuckRyder]

Oh! an Italian tune up!

Alright a couple of more thoughts...

According to:

http://www.holley.com/data/Products/Tec ... -3rev1.pdf

That carb comes with 67/73 jets which seems about right. If Tom installed it I feel it is unlikely that the set up is very far off.

With modern gasoline tailpipe color isn't a good indication of mixture and plug reading may be difficult.

Another option is to pick up a 5 gallon can of racing fuel to see if this makes the ping go away.

I do wonder if you are hearing "header ring" vs ping - none of your descriptions make me think ping.

[woods]

I have something else I am just a little more than curious about. I have taken a look at your camshaft numbers, static compression ratio, etc.
Do you own a compression gauge? With the given specs, your cranking pressure should be about 155 psi (154 point something).

I would really like to see a cranking pressure reading if you have the tool.

[BobbyFord]

I like what Woods said about the idle and initial timing. 9.7:1 is just about the end of the scale for a pump gas street motor (depending on DCR). Although you may be hearing the headers as opposed to actual detonation. I wound up increasing my initial advance to get the desired neutral idle that I needed for a good in-gear idle. Having the plates too far open at idle will result in richening the mixture and also contribute to possible dieseling on shut off. I have a little more compression than you do but I suspect my cam gives me a lower DCR than your cam. I'm running 15-16* initial timing. Perhaps you could let Tom drive #50 or at least sit in the passenger side and let a more seasoned ear determine whether or not you are actually hearing detonation or headers. Take your truck to someone that has a tailpipe sniffer and get some base idle emissions numbers and that may give you a general idea of where your carb is. Also, as suggested, toss in a new set a plugs and take the truck out for a long drive with varying RPM ranges, then pull the plugs and let Tom or someone with an educated tuning eye to read your plugs.

[mrtleavitt]

AS far as your distributor goes, leave it. I run the same one and about a year ago I started debating on running a different one that had vacuum advance. After changing the springs and bushings around I think I got a bit more power out of it. Honestly, I would not throw that one out just to get a duraspark or something else that has vacuum advance. Mine runs great advanced at 38 degrees @ 3,000 rpm. I would bet a bunch of money that you'd see no difference from changing your distributor, I'd focus on the carb.