WHAT'S LIMITING MY POWER?!?!

Possible but that would NOT cause fuel to be spit out of the carb.

Just remember, that those carbs were jetted just fine from the factory and worked well. Granted ethanol fuel doesn't have the specific energy that pain fuel has so a little up-jetting is ok. That said, even a full step up won't cause it to GO SLOWER! It may idle like crap and run rich but it will go just fine. You would be hard pressed to go so rich on the jetting that you could smell unburnt fuel enough to burn your eyes. It is easy to get the timing off (Just switch two plug wires) enough to have lots of the stuff.

Just hook up a pressure gauge, my vacuum gauge is old enough to have a pressure side. BUT if you are going to the trouble to disconnect the line, make sure you check pressure AND flow!

 

It seems like you're close to running down many of the ignition-related concerns. I might like to try & clear it out 100% so I can say I'm done. Of course, first, I'd check with the PPI supplier to see if they were able to verify if the engine pulled to high RPM.

Ignition: the issues you'd noted, plus I don't recall information about the condition of your spark plug extenders?? A visual inspection could be performed to look for arcing. Did you check them for arcing by pulling the dust boots and revving the engine in the dark? Or you could try wrapping them with insulating material or just flat our replacing them.

I still want to verify that timing at 5000 RPM via the markings on the flywheel... Did he claim to do that or just idle timing? What timing is it programmed for at 5000?

 

I'm NOT running extenders. The electromotive came with new wires and the adapters that go down the hole.

I STILL cannot find - either in the manual, or on direct observation - where there is a jumper between DFUs that may have been reversed.

I have checked and checked and checked again, and the plug wires are on the correct DFU terminals. Also pulled off the ECU cover last night to verify the dip switch settings, and they, too, are correct for an 8cyl/4cyl tach setup, as per Electromotive's instructions.

Even if my mechanic accidentally threw the switch I cannot locate that would trip the secondary rev limiter, the manual says that the secondary limiter would just bring in the otherwise-dialed-in limit under certain conditions. My limit was at 10,500 when delivered from the shop, and I reduced to 7,500. At any rate, unless I have a defective unit, it's never been set at 5,500.

My settings advance settings currently are idle: 10, 3000: +24, 8000: -2. I got split answers from fchat and specialists between 8 degrees initial advance and 12, so I split the difference. Tell me if you think I should've done different.

 

Per those settings your total advance is 32* the 2v hemi head is not that efficient to run such low timing advance. 10~14* at idle is OK, by 3k rpm you can go out to 30~34* and by 8k rpm you can add +10 ~ +14 more. Total advance in default mode for the 2V is 36* at 5k rpm to redline, under normal operation it can get to 45*.

 

For a quick comparosin, I pulled up a dyno sim for a carb'd 308 engine. Adjusting the ignition curve down to match your settings the engines is down 62hp at 6k rpm.

 

Wait, ADD more timing advance at 8000? Everyone here, including Nick, has said retard the timing 2 degrees at 8000. What am I missing?

 

I'm also fine tuning my timing for the XDI system after a rebuild of my engine. I just contacted Nick who distributes the XDI system as a complete kit, and he suggested setting the knobs at 12-14 (initial), 28-30 (3000K) and -2 (8000K) which would make 40-44 at the higher RPMs and 38-42 at the top RPMS. Remember that you have to add (or subtract) each knob as you go along. I'm concerned about being able to hear the "pinging" of early detonation as the timing advances, however.

These numbers were higher that my previous conversion with him when my engine was new. Although we did discuss advancing the timing as the engine was breaking in. He mentioned that by 2000K to 2500K the timing should be about 33.

 

The std 2V has really low CR. going out to 42* total advance is OK. Nick's recommendations will get one in the ballpark, but it really is up to the owner to dial that in. Many factors at play with ignition timing on each engine, as many of the 2V's are anywhere from carb'd with P6 cams to bog std injected models with dished pistons and 7.5:1 dynamic CR.

Joe, by your numbers the range would 38~42* total.

 

Uhh, okay then. My advance has been dead wrong throughout this whole thread exercise

I'll still take that over a major carb rebuild or bad valves any day. Will reset and report back tonight.

JB

 

So let's say I start with 13*. Would I then add 25-27 MORE on the 3000 dial, and even MORE on the 8000 dial, or would I add in a larger number on the 3000 dial and then dial back the 8000 knob a few degrees.

I guess, still getting to the same overall number, I'm wondering if we just keep adding advance through the whole range, or a bunch through the upper range and dial it back some at 8000.

I can't imagine the PO installed P6 cams, so let's assume it's a stock US 2v carb engine.

In other words, not that I'll hold anyone to it, but what formula (ACTUAL DIAL NUMBERS) would you suggest for a fresh start here? Will try any good jumping off point. Thanks.

 

1st knob = 12
2nd knob = 18
3rd knob = 8

Start there, that gives this layout, intial 12, 3k at 30 and ramps up to 38 at 8k. You can add more to the 3rd knob as you see fit but I wouldn't go beyond 12 which I don't think you can anyways.

Or you could go with:
1st knob = 14
2nd knob = 18
3rd knob = 10

that's 14* to 32* to 42* total.

Just keep in mind that you add or subtract the numbers from each knob setting to figure out the total timing at that point.

 

SMG2-You are correct on that these numbers are enough to get it tuned, but then the owner needs to fine tune it based on the particular engine. I've read that the 2 valve motors like more advance and that the Weber carbs like more initial advance due to way the fuel circuits are constructed.

Justin, I hope it is as simple as turning a knob and gaining the lost RPMs and power, but I would not count on it. I've rebuilt my carbs and had my initial timing at 8 and it still would rev freely and felt strong. I've increased it to 10 now that my engine is broken in and the next step will be 12. Its definitely a process.

 

Walking to the garage with keys in hand now. Fingers crossed...

 

Didn't help

Carb still spitting. Makes a sound thats a cross befween a tiny pebble hitting a windshield and when you first take the air inflator hose off a tire, at regular intervals. Like a short, shrill "pffft." I THINK it's just the one carb.

 

Here's a new one, though. It actually didn't want to stay on idling. Since taking delivery, I've had to keep my foot on the gas for a minute or so after startup, but today, it just wanted to lose revs and crap out, AND I got an alternator light as it did. Could it be an alternator problem or is this common in stalling?

I asked my ignition installer if he ran power direct from the battery/alternator instead of stock wiring loom. He said he used the loom for "some parts," but doesn't like to wire an ignition off the alternator, and instead found a terminal on the starter motor. He's one of electromotive's top installers, but does this sound problematic to anyone?

 

Can you disconnect the new ignition and hook up the distributors (Or is it just one ?) That will quickly determine if it's your new ignition system?

 

Hmm, interesting. Sounds like a weekend project, but possible.

 

Strictly speaking, since the hot main terminal on the batt is connected via the large + cable directly to the starter, if he used that starter terminal, he is essentially doing exactly the same thing as running a direct to the battery. And since there is a terminal there which is easy to utilize as opposed to adding connection at the battery terminal, it probably made for a neater/cleaner installation...or at least it SHOULD have...

 

You know, it just occurred to me that I think the original impetus for getting this system was that the PPI noted something was "off" about the distributors. The old system was badly misfiring. That OR - with the benefit of hindsight - cam timing is off, causing any properly-working ignition to be misfiring?

 

When the power-limiting happens does anything funny happen on the tachometer?

Reason I ask is if the tach is dropping out this would indicate the ignition box is losing crank sensor pulses at higher RPM which might be caused by the sensor gap being incorrect. Just a thought.

 

I need to fire it back up and check, but I don't THINK so. It displays the revs accurately; the damn thing just won't go past 5k-5500.

 

Does it actually stop revving at 5-5500 or just continue to rev slowly past that? IOW, does the engine just "shut off" at the specified RPM and then "stutter" at that RPM level as the RPM drops back down/increases/shuts off/increases? If it does that, it would indicate that there is a rev limiter involved. I know you mentioned it was set for 10.5k or something like that but if the symptoms fit, I would sure recheck that. It's interesting that if the rev limiter was set to 10+ as you mentioned, that the shut-off is at about 1/2 that... I'd take a hard look at the way everything is set on that ignition. Though I guess that's some "DUH' kind of advice that you have already looked at.

 

Re: wiring to starter terminal

Sounds good to me.

It's a "best practice" to wire to the battery vs directly to the alternator as the alternator output can have electrical noise on it which the battery smoothes out. Using the big wire Enzo installed from the battery to the starter is plenty reasonable.

 

You probably checked all the fuel filters, i replaced mine after it wouldnt rev past 5k, now it pulls to 8k no problem.

 

Fuel filter is next. Snagged a couple OEM bosch filters cheap off eBay, only to find out the carb cars need some other weird filter that I couldn't find anywhere. Just ordered from Superformance two days ago, waiting for arrival.

BTW, someone here mentioned their SECONDARY fuel filter being clogged. Where's the secondary?

Mark - It doesn't sputter or crap out when it hits that 5-5500 rev range. It just tops out with seemingly nothing left to give.