Cliffs: New lifters and Deltec coil per ignition system are going on the LT1. Going to check the fuel injectors too.

After 3 years of neglecting the car, I decided to fix what was wrong. Turned out to be that there was alot wrong with the car. First off it was way rich after putting in a fuel pump. It showed 46 psi at idle and 42 after the throttle was blipped.

So I decided to ditch my mail order tune and went out to see STLLT1. First off the two banks were doing radically different things in addition to being pig rich. The mass air flow curve was showing plenty of peaks and valleys, showing that the car was missing as well. We leaned the car out 10% across the board and evened out what the two sides were doing.

He had a faint miss like mine, due to weak valve springs. Mine had been in there for 30,000 miles with a monster cam. They were past due. So I changed the valve springs to Comp Cams 918 beehives (which Comp Cams recommended). A valve spring height micrometer was put to each valve to insure the right number of shims on them. I also replaced the spark plug wires and spark plugs for good measure (MSD wires and NGK TR55 plugs).

110.32 MPH in 1972 DA. Low, but better. Cars with my heads trap anywhere from 113-117.

Went back to STLLT1 today and hooked up the wideband this time on the passenger side. Went for a WOT run and he felt a slight miss over 6000 rpm. The MAF curve was still showing peaks and valleys, but not as bad as before.

Wideband showed high 11.7-12.1 A/F at WOT, so we leaned the car out 8% more across the board, which brough the passenger side up to 12.6-12.7 A/F at WOT but it began missing really bad over 6100 rpm. Crusing A/F were around the 13's and 14's.

Confusing, we leaned it out and it started missing worse over 6100. It had plenty of fuel, good plugs and wires. My friend Tom did the valve springs in the car (I didn't want to **** it up), and he said when adjusting the rocker arms, a lifter on the #6 cylinder wasn't adjusting correctly. He would adjust it correct, flip the crank over to do the other cylinders, return to the #6 and a rocker would be loose.

We've got a suspect on that bank that could be producing false readings. So we flipped the wideband over to the driver side to see what was going on. 15.7-16.4 A/F while crusing. Yikes! Was this the "true" side of what was going on? We blipped WOT just to see where it was at, and the A/F came right back down to 13.1-13.2, right were we wanted it to be. This was getting bat **** crazy.

Our final conclusion was that both banks were doing crazy things, but different crazy things. Since one lifter was known bad, the rest of them might be suspect. New lifters are going to go in.

While things are apart, we're going to check the push rods to see if any are bent. Also the fuel injectors are going to be flowed and checked.

Also the Deltec is going to go on, the optispark could be a culprit, but it is less likely.

Any input is appreciated.

Performance: Comp Cams “306” 229/245 duration 112 lobe separation 510/540 lift (544/576 with 1.6 roller rockers), Lloyd Elliot “LE2” ported heads with 271.7 intake cfm & 190.5 exhaust cfm @ .600 lift and 205cc intake ports, Ferrea 2.00 intake & 1.56 exhaust valves, Crane Gold non-self aligning 1.6 roller rockers for 7/16th studs, Comp Cam 918 beehive springs, Hooker Super Competition long tube headers, 3” Flowtech Purple Hornies Header Mufflers, Precision Industries Vigilante 3200 stall torque converter with 2.5 STR, TransGo shift kit with 3 washers, B&M 24,000 GWV transmission cooler, 1LE aluminum driveshaft, Strange 3.73 gears for a 2 series carrier, K&N FIPK, Racetronix fuel pump and hotwire kit, Accel 30 pound fuel injectors, 52mm BBK throttle body, tuned by STLLT1, MSD over the valve cover spark plug wire kit, NGK TR-55 spark plugs, Performance Friction Z-rated brake pads, Power Slot brake rotors, ARP 7/16th rocker arm studs, GM guide plates, Hypertech 160 thermostat, LT4 knock module, Stage 8 locking header bolts, two 24” inch O2 extensions, 1LE intake elbow, removed AIR pump & EGR, first gear mod, throttle body by-pass mod.

 

What kind of lifters are you putting in?

Be careful installing that Delteq. If you are using the fine thread bolts they give you to hold down the coil packs to the ignition module, they strip easy. They sent out a "fix kit" where they give you larger coarser thread screws to hold them down.

The Delteq install for me was pretty straight-forward for the most part, minus the crossed-up wire in one harness where the +/- was crossed, and kept blowing my fuse.

Are you getting valve cover or radiator support kit? What kind of wires, premade?

 

Probably stock Comp Cam replacements. I'm only spinning 6500-6600 rpm, and the springs don't have a ton of pressure. Why upgrade to a Morel lifter and add weight to the valve train?

Thanks for the advice, a friend of mine who has one is going to help with the install. I'll probably go for the valve cover kit, just so I can keep the spark plug wires short and over the valve covers so they don't get too burnt up. He is still using the wires that came with the kit and they work fine. If mine don't work out, I can always get some MSD wires.

 

How old are your 02's? Is it possible that a bad set could be giving you & the PCM false data? It sounds like you are taking the right approach at this point for a high rpm miss. IMO a lack of fuel or bad ignition would cause that and you are covering both areas.

Hmmm, just realized the age of this thread.