FE Timing
 

Guys I need your suggestions on possible timing problems with my FE. It's a Unilite dist. with a Mallory Hyfire. Vac. line is installed. Idle speeds run fine, up to about 3000, 3200 rpms. Timing is set at 35* total at 3000 rpms. Above 3000 engine starts to brakeup. The engine even at low rpms doesn't have a lot of crispness to it. It seems to run hard. Warm starts are hard starts on the starter. Are there any adjustments you can suggest.

Your 35* total timing was set with the vacuum line disconnected, wasn't it.

Brad W.

Ignition timing is a very small piece of the entire puzzle. There could be valve timing problems, loss of spark, fuel mixture issues... etc, etc.. Don't overlook the whole picture while focusing on one potential problem.

vac. was disconnected. idles well, cold starts well, climbs to 3000 well after 3000 or so starts to pop in the exhaust. Engines new only 100 miles on it. built a a local guy that builts race motors for boats. If I can't get if right I'll take it back to him in the spring.

Is this at WOT?

Some things I would double check on the ignition side:

1. Double check firing order and plug wires for giggles.
2. Do you have a rev limiter? Any chance that it's set that low?
3. Moisture inside the distributor cap?

On the fuel side:

1. How do the plugs look? Are they fouled? Does it smoke?

When it pops do you feel it missing? Sometimes a pop in the exhaust is the result of a blown header gasket.

I used the Mallory centrifigal distribtor amd HyFire VI box It has the option of programing in the amount of ignition retard under 500 rpm (starting). I have initial set at 14°bftdc and have 10°plate in the distribitor = 20° totaling 34° bftdc. I have 10° retard so starting isn't a prpblem. I allso have the boxe's programable rev limiter set at 6,000 RPM for safety.

I bought the new Mallory HyFireVI and almost a year passed untill I could actually use it. When the Engine and all were done the engine idled just fine but after a few minutes of driving away from my home anything above an idle was terrible, I'd turn towards home hoping I'd make it, The engine would idle just fine but getting the car to move down the street was terrible, The car would idle just fine. I'd clean the fouled spark plugs and try it again. Mallory has a shorting plug (box bypass)I used the plug and the engine ran fine. I blamed the box. Just within Summit warranty period I returned the box with a note. The next Mallory HyFire VI box worked flawlessly.

I just checked the Summit catalog and they refer to it as a Mallory HyFire 6 control box. I swear it has a Roman numeral on the actual box. I have all Mallory FE centrifigual distributor photo triggerd ,mechanicl tach drive with small cap. Mallory active power supply filter. Mallory Pro Master coil. I started with an older HyFire 4 box with a seperate dial rev limiter that didn't work with the box and the lable on theold HyFier 4 box needed replacing. So that is why I bought a new Mallory HyFire 6 box and the active power filter.

So you have never had the engine "run well," correct? If you were deaf, would you be able to feel the engine running poorly above 3000?

thanks for the help guys. rev limit set at 6000, double checked firing order, I didn't know the hyfire box was programmable. I don't see anything on Mallory's site for programing. I also had the box a couple of years before I used it during the build. Car just got titled last fall and put away before we got all of the kinks out. So I'm starting with a new build at this point. Other than slow runs to 50 mph I haven't pushed it during break in.
And yes if I was deaf I can feel it missing We changed plugs, reset valves, checked compression, and changed carbs. I'm begining to think I have a bad box too. Anyway to check it? Thanks! I really appreciate the help!

One simple, non-invasive test is to put a pyrometer (you know, one of those little point and shoot infra-red thermometers that you buy at Home Depot for about $40) on each of the primaries about an inch or two away from the head. Do this after you have been running it and it has been mis-firing. See if there is any obvious temperature change with one or two of the exhaust primaries thus indicating that cylinder is not firing consistently with the others. That will at least tell you if the problem is symptomatic of all the cylinders or just one or two. But considering this is a brand new engine, I wouldn't do a whole heck of a lot of work to get it to run right.

Try a coil.
At ten bucks and two wires its a ten minute diagnosing tool.
I've had bad ones do some crazy things...

ditto on barry's point, and let me add tachometers that are bad can do this too. disconnect the tach and try the car

Once again, I have a Mallory HyFire VI. It has programable spark retard for starting, programable RPM limiter, another programable RPM limiter that could be activated by turning on a switch suppling 12V, for staging and such . The box could do all sorts of things to accomadate nitrous, supercharging, and souch that I'm not using. My unit ran for a couple of hours during breakin didn't see a problem. But load up the wife and head out. It would run just fine. About one to two miles out it would start missing and bucking and backfiring , anything above an idle. I'd turn the car back toward home thinking that it would completely die and I'd need to call for a tow home. To my surprise it would idle just fine, but getting the car to move from a stop and carry the car down the road it was terrible. The spark plugs would be all carbon fouled. This went on for weeks. finally I used the supplied shorting plug to eleminate the box and just use the distributor. It ran great. I replaced the box and didn't have that problem again. As I remember the box get full 12v and acts as a power supply to the distributor. The distributor without the box needs a resister to drop the voltage. I anticapated that and have a resister mounted and all it take is moving a 1/4 inch spade connecter to accomplish the swap. I can tell when I reach the rev limit and it seems to always surprise me. I seem to reach it so quickly.

Ok Here's where I'm at. We reset the timing to 12 deg. BTC. at 900 rpms. The part that seems strange to me is the closer I get to TDC the worse the engine runs. This motor will not run at all at TDC. It like it around 22deg BTC.at 900 rpms. Is it possible when they rebuilt it that they are one tooth off on the timing chain. All temps at the exhaust are in the 300 to 350 range at idle. I will also try the tach. Any ideas? Jack

Mike if you remember which wires you jumpered to bypass the box let me know and I'll try that too. Thanks! Jack

Did you ever check to see if you harmonic ballancer s timing mark are true and accurate? The outer ring has been known to slip. I would propose the piston stop bolt test, are you familar? The piston stop bolt is a tool. I bought mine on ebay. The out side is made to match your spark plug threads in you heads (you'll have to figure out which spark plug threads your heads have ) and has an inner bolt (usually brass) that screws in and out to whatever depth you need to meet and stop the #1 piston. I bought two. The first one I put away some where safe. I haven't found it yet. I gave up and bought another piston stop bolt. I know where that one is.

The instructions for using the bypass connector on the Hyfire VI can be found here (Page 11, Figure 20): http://www.malloryperformance.com/pdf/685_6851.pdf

No Not familar with piston stop bolt test

My Mallory set up has four wires in a weather pack plug Yellow, black, green, and red. This shorting plug has two wires red, and black. Red is looped outside connection one side to outside connection on the other side. The black wire is looped connecting the inner two connections. So that ends up being red to yellow and black to green

My Mallory is a hyfire 6AL. Looks like yours is a little different. I'll check my wire colors and see if they are the same as yours.

I think you have a carb problem. Either with the pump or you have to big of jets installed (may even be a a power valve).

Did you dyno the engine?