I would not run power off the alternator, you want a really clean voltage source for the ecu. I ran power and ground (from the intake stud) directly to the battery.

I also don't think that the manifold is likely to be your problem. I have run Fitech on my car for about 5 years now, and the first 3.5 were with a Performer RPM, with full divider, no spacer, and a lot more compression and cam than you have. I also compete my car, certainly drive it aggressively, and it worked/works very very well. This video is with the Performer RPM:

 

Thanks much for that. perhaps you are confirming that I indeed need more compression. perhaps I am missing something huge in the tuning.
would you care to share some of your settings?

 

GKull I am going to have to call you out on this one. Not all of us like humongous cams like you obviously do, or an ill mannered 1100 rpm idle. The OP said he rarely takes it over 5000 rpm.
And what I said was he has too much cam for that low of a compression. His DCR is very low somewhere around 7.2 -7.5. Basically it sucks. Almost as low as a stock 71 8:1 low compression L48 with the stock very mild cam. Probably the same DCR. I am sure both your motor and your friends 383 start with way more than 9.0:1 CR. I'll bet his cranking compression is 130 or lower. 13.5 vac at idle with that cam is pitiful. Again no compression. Until it revs up. A 230 something cam is normally a nice street cam, it's not "tiny", but it's not a "race" cam either, but it does need a little compression to work well. 9.0 is not really enough for it. I have driven cars like that, and fixed them. He said it ran the same way with a carb, so it is not the EFI. I knew a guy that put a cam that size in an 8.0 CR motor. It could barely get out of it's own way.

I am trying to help the OP. Are you? I get you have a lot of race background. But this is a street engine with a less than ideal combination. He has a long first gear and needs all the low end TQ he can get. And he is missing a lot. The question is why?

Doc what is your cranking compression? Is it as low as I think?

 

You know, l'll need to bring my compression tester home, keep it at work. and actually run a test. I have all the factory ignition covers. but it should be easy enough to do the front 4. it's Wednesday lunchtime here now. most likely can this evening. I'll post up results.

 

OK. Got home. unplugged my distributor and one by one removed plugs and ran a compression test on cylinders 1,3,2 and 4. All readings cold, approx 65 degrees Fahrenheit. at sea level. Approx 300 metres from the ocean.
#1- 170psi, #3- 172psi, #2- 169psi. and #4- 171psi.
Edlebrock heads, 64cc chambers, Flat top 4 relief hyperunetic pistons, Standard Fel-Pro head gasket.
I'm thinking that 170psi compression isn't real high.
but isn't terrible.
Engine starts at just a touch of the key. idles straight away. Start up and warm up fuel seems to be very good. drivability is excellent. I can go up a steep hill in 4th gear at 35 MPH and it runs perfectly, never could do that with a carburetor.
Car runs so good in every situation except step on it hard when starting out at 15 - 29 RPM.
Oh and side to side plugs looked fairly equal as far as color/jetting is concerned. 1 and 2 a tad lighter than 3 and 4.

 

In some cases an engine will not indicate high compression test results even with high compression pistons / cyl heads.
Why? The Intake Valve is a little slow at closing with an additional duration / lift cam. And at the cranking speed during a compression test, that's normal.

Reading back through 60 some posts, I never did see an answer to my question about the age of the timing chain. I must have missed that part.
Just for clarification, do you know the age / mileage of the timing chain?

 

Very tiny cam. Poster said 13.5 vacuum at idle. I couldn't find at what rpm. Poster said selected cam 3. I still say the fitech is not doing a correct A/F map. Need to run a 10 or 12 gauge multi strand copper wire to both battery posi and alternator along with a run to battery negative post and engine grounds. My 79 actually has a ground stud on the firewall. on the backside it goes to the fuse block ground and then to the battery. It has the braided bare strap to the bell housing for engine ground.

I would think that the poster would have put in a new timing chain with the cam

• Duration @ 0.006&quote: 268° / 280°
• Lobe Separation: 110°

• Duration @ 0.050&quote: 224° / 230°

I found this on the Fitech websot:

Choosing a cam selection:

Cam selection is based on vacuum load of the engine. Cam 1 is for 15Hg or above, Cam 2 is for 10Hg to 15hg, Cam 3 is 8Hg to 10Hg, Cam 4 is 8Hg to 6Hg. These are estimates and you may need to switch between them if the vacuum load is between two different cam settings to get the engine to run better for your application

Yesterday out driving because of the week long car shows I turned on to the freeway on ramp and put my BIG cammed 1100 rpm hot idle that has a bouncy maybe 10 ish vacuum in 5th gear OD going up the freeway on ramp. 5th gear at about 1500 -1600 rpm. I don't even like doing it. I stomped it to the floor and it took off. Slower at first and by the time I was ready to merge I was going faster than most traffic at the post 65 mph in town. When I reached 3000 rpm I was doing about 85 mph. Fitech can do this if it's tuned and the poster has a 4 speed manual I think.

 

Based on the cranking compression and the fact that it runs good pretty much everywhere else, I would have to agree with gkull. Seems your fitech is a bit out of tune at one point in the air/fuel curve.

 

In answer to the question about my timing chain. yes new with the cam, heads,pistons and all rod and main bearings.
Agree that I'm missing something in the tune.
I can drive it and watch AFR's. But with this bloody hard lock down can't even pull it out of the garage. Bloody Covid!
Anyway, right now just trying to gather information and learn.
these 2 settings below control fuel when you snap the throttle open.

These we don't have tuning Harley's. the first one , Gain, I read has to do with sensitivity. This I understand the least. So I haven't played with it much. perhaps someone out there can explain this better than the Fi Tech website.
the second setting, Max, controls how much fuel it throws in over the base map. this I have played with. still a better explanation of how these work together and with the Accel pump function could help me a great deal. Once again, Fi Tech has been little help.

 

I just got the 2.5 RH w/2,5 ex w/.X pipe. from Pypes
Very throaty
Going to dyno soon.
Hoping for 300 rwhp!

 

Thanks much for that. Not real clear on how that helps me with my tuning problem. But we are all real happy for you with your new exhaust.

 

How was the fit?

 

Doc the compression is actually pretty good, for a 9:1 CR, and not as low as I was expecting.

The center divider being milled out should alleviate a MAP sensor issue.

So AFR could well be the lead suspect. Can you do datalogging to record AFRS? Or read it while it is "bogging"?

The one comment you made that concerns me is: "making the timing come in at a lower rpm makes it run significantly worse"
I don't know what that means as far as an issue. But it seems to indicate a timing issue. Have you ever tried reducing the timing at WOT 2500 rpm even more than it is at now?

 

Your numbers are almost identical to mine @6300 ft DA with CR of 9.9 when I had my Dart SHP heads. all of mine were 170-173 psi.

That is @ 4000 ft altitude and 6300 DA so the lowish numbers would be due to air density.
Using the Jeepstrokers DCR calculator it gives me DCR @ altitude. If I put in my numbers then and compute it the DCR drops almost by 1.3. From 8.17 to 6.91.
My corrected PSI for altitude would have been about 203 to 206 psi. ( if I were at sea level on a standard day)
So given your PSI @ sea level I would estimate your CR to be about 8.5:1 to 9.0:1. depending on how hot it was when you did your test.

Obviously things like cam specs, cranking speed and accuracy of the gauge come into play, but assuming these things are at least similar in your test to mine the numbers can be compared to some degree.
I would consider 8.5 to 9.0 a bit low for a cam with 54* of overlap. it is a small cam compared to a race cam but you've got to look at the whole equation. And specifically the overlap and intake valve closing and CR of the engine.
My cam also has 54* of overlap and it was not a barn burner on even a moderately hot day. And did much better on cool days. Then there is the flow of the heads to consider and the exhaust which can make it better or worse depending on what you have.
In my experience when I went from 9.9 to 10.6 CR and better flowing heads (AFR'S) it made a huge difference in power and throttle response. So much so that I had to drill the float valve inlet larger just so the carb would not run out of fuel at the top of second gear.

So it sounds like at least part of the issue is likely your CR. And rest of the problem is the tuning of the fuel injection system. How the intake manifold plays into the FI I wouldn't know.

 

Thanks much for all the feed back. really appreciate it.
Yes I too believe I have more than one issue, And tuning is certainly one of them, but perhaps I have been having a few issues tuning because the combination isn't ideal.
about the timing, I have tried numerous timing combinations, I must have 30 or more springs, several sets of weights, I ran a thread on here awhile back about tuning my distributor, And I got some good help from this forum.
I had a real bad stumble between 2500 and 3000 with just moderate throttle when I had all the timing coming in earlier. I had it all in at 2,200. really didn't like that. 2500, 2800. stumble cleared and car now runs great,(other than when you floor it) with 18 degrees initial, 34 total all in at 3100. with 11 degrees of vacuum advance. all vacuum advance in by about 11 inches of vacuum. 13.5 inches of vacuum at 820 RPM. If I bump the idle up to about 880. which is where I have been running it lately, vacuum is right on 14.
wish I could take it out for a few readings. I have been reading alot. and a few things I would like to try. But this bloody Covid hard lock down is preventing that. Car is on club rego, limited use. so if I get caught doing "non essential travel " big fine. And with club rego, never allowed to take it to the grocery store. And a bright red C3 kinda stands out.
Still hoping someone out there has some information on these dTPS Settings.

 

So it sounds like you reduced 2000 rpm timing some (by coming in later) and the engine now ran great, at P.T.
Sounds to me it still wants less timing at WOT at 2000. It's worth a try anyway. Easy and cheap. Unless you already did.
The puzzling thing is your curve "sounds" great, on paper.

Same thing with the 13" vac, it sounds too low for that cam.

 

Honestly, I haven't done much tuning, I've experimented with the afr targets and timing a bit (I use timing control), but mostly I just set the iac counts and drove it. Actually... How much have you driven it? I find after major changes or resetting the tune it can do what you're say initially, but after running it for a while through those rev ranges it sorts itself out quite well.

 

I assume you're not getting any error codes? I would be inclined to try running a clean power and ground wire.

 

How much have I driven it? About 3 - 4 thousand miles.
Electrical issue. Not thinking it's likely, I'm pretty happy with the wiring on this car. and a 5 mm wire from the solenoid to the Alternator is overkill. power is tapped off between the solenoid and the Alternator along this 5mm thick wire. ECU is mounted up in the wiper tray. Not on the throttle body. This is made by Fi Tech, but sold under the Summit brand. Ground is to the intake manifold, nice extra heavy ground cable from block to frame as well. perhaps I could run a ground directly to the battery as I did with the fuel pump. But if it is electrical, why is this issue just below 3k RPM and only when full throttle.
I have been reading all over the net. Chevelle Forum has a lot of information, a couple others as well.
Seems some have no issues, like you. Others like myself, can't get this full throttle thing right. Back to, get my combination of parts right. clear all learning, Start over.

 

Side note. maybe worth mentioning. When I first put in the cam, I to thought the vacuum a bit low. So I went on the net and questioned this. the responses I got were basically, yup, that's what I'm running too. So didn't give it to much thought or worry till it came up on here.
Today I talked with the friend that recommended this head and cam combination a couple years ago. Keep in mind this was and is a budget combination. Anyway, he reports on his 78. same basic setup. flat top pistons. same heads and cam. he is getting the same vacuum. And he's so jacked off with his EFI that he's ready to go back to a carburetor. Funny, I started with one and threw in the towel and went EFI.
this cam, these heads, these small rams horn manifolds, all the same combo as mine. And tune it to run good one place. runs like shmit somewhere else.
Thoughts????