Howdy

First time posting questions here. New to TBI tuning in general. More of a tinker project than anything really. Trying to learn something new. Apologies ahead of time for being long winded.

I have all the required Moates autoprom goodies and TunerPro RT and ready to jump in there but I am having some issues getting reliable timing setup. I have burned a couple of chips just to see how the process works but other than changing the Injector size and engine displacement, not much programming at all. This is a fresh rebuild and seemed to run fine on the engine stand using a carb and MSD vacuum advance but now I have the TBI installed and have some strange timing stuff happening. I have not tried much programming at this time mainly because I want to start with a stable base line and the timing jumping around is not giving me the warm fuzzy at the moment. Not sure if what I am seeing is normal or not as I have never worked with computer controlled distributor before]

Here is the engine setup:

1967 350 2bolt main 2pc rear main. [It was handy]
10.6:1 compression static. I checked out the Dynamic compression calculators and the one I feel most comfortable with is telling me 9.8:1 Dynamic.
Eagle .040 over balance rotating assy with bushed rods, 12cc dished pistons [not forged] Plasma Molly rings. This is the $800 set not the spendy stuff but we are not getting crazy here. Just tinkering.
.050 Squish-on the money. Was hoping for .040 but w/e.
601 heads ported per Fast305 outline on TGO minus the chamber grinding. [1.84 intake 53cc chamber. Yes I cc'd the chambers. They are 53cc. Intake and heads are port matched. I did measure the relative intake runner dims per outline from Fast305 at the time but I did not record the numbers. Bowl blending the same. It was very close if not exact. Installed Stainless valves hand lapped, new springs from Howards, New Viton seals etc. Guides looked pretty good. No more than .002 side wiggle. Also smoothed the cooling passages best I could.
Rt44 short plugs
8mm wires suppressed
New Accel distributor [questioning the ign module currently] Pertronix external coil
Performer style square bore dual plane manifold made by Dart
1" open spacer with 1/4" square bore to TBI adapter
Rebuilt TBI myself. Removed ridges, new injectors supposedly 'flow matched' @71/lb.hr @ 15psi. Installed 18psi spring. All the vacuum ports were thoroughly cleaned also.
Shorty 1.5" headers, 2.5" Y-pipe, Heated 02 in the collector, 3" single to dual 2.5" out Thrush muffler
Elgin stainless roller rockers[1.5]
Shorter push rods to accommodate the block milling and thin .015 steel gasket. Ie. rollers appear to be centered and tracking correctly. Valve lash set @ just shy of 1/4 turn. 5W20 oil.
High volume oil pump. [Leftover from a previous lifetime. Second guessing the high volume pump now. PLENTY of oil pressure though ]
Oh. The Cam is a Lunati 60101 [Dual pattern .454int, .468exh, .213int @.050, .219exh @ .050] Also from a previous lifetime.
Computer is 16197427 with $0D, [4l60E next on the rebuild list.]
New radiator, engine temps staying under 180F
EGR turned off VIA EGR-on temp. CCP is still hooked-up and working according to the scanner.

I had some backfire through the exhaust and it is mostly gone since putting the baby-tune 1/8-ish turns on the valve lash. Mostly gone means the frequency has been reduced to several back fires per couple of seconds to one every 5-10 seconds at idle.
I set the base timing @ 10adv, set initial timing in program to same. Have done the same @0adv. No knock counts to speak of. 2 [counts at start-up]

When the brown wire is disconnected at idle, timing is stable minus the slight retard seen [at the balancer] when the exhaust backfires.
As I increase the RPM to 1500 or so, the timing jumps an additional 7adv and stays there regardless of increasing/decreasing RPM. It immediately drops back to the set point once back under 1500rpm.

With the brown wire plugged back in, I am seeing a lot of retard [10+ Ret] as the RPM increases.

In both cases, if the throttle is goosed, it can backfire through the TB and die or if treated with less aggression will stumble for a bit then take-off.

I am hoping you guys have a simple solution perhaps.

Currently, I feel like:
  • I may be in Limp mode??
  • High volume oil pump is causing me a headache by keeping the lifters pumped up. I did see an improvement adjusting the lifters and moving to a lighter weight oil.
  • The ignition module may be faulty. Shouldn't the timing stay stuck @ the set point when the brown wire is disconnected?
  • My valve lapping was not as awesome as I thought. I checked with alcohol at the time with good results. But then again, I may have inadvertently ingested some of the said alcohol at the time also......
  • Perhaps the retard is due to the bog and I need to adjust the Fuel AE vs TPS somehow.?


Outside of that, I have a question regarding tuning once I get there.

  • What are the major areas I need to be concerned with given my setup? Fuel obviously. What else?


Really appreciate your time. Hope all is well with the craziness out there these days.

Jeremy