Howdy folks.....having some issues getting my freshly built 2F to idle properly, and some ignition timing issues.
Here are my engine specs.
'76 2F Bored +1mm, and head milled to get around 8.5:1 CR
Head modified for SBC valves and springs
Delta Cams KC859 (262 duration) cam (valve lash set at .008 / .012, per phone conversation with Delta)
De-smogged 1978 carb, rebuilt by Jim C.
1979 Toyota electronic dual advance distributor / ignitor (plumbed into ported vacuum fitting on carb).
New OEM Toyota plug wires, cap, and rotor button
Stock 2F intake
3FE cast iron "2 into 1" manifolds
Engine is freshly rebuilt, and only has about an hour of run time on it.
Compression = 150PSI +/- 3 on all 6 cylinders (rings aren't fully broken in just yet).
Have measured valve lift on all cylinders to confirm no flattened cam lobes.
Have checked for vacuum leaks 4 different times, using multiple methods.....none found.
Have confirmed proper float level, and that it doesn't go too high/low during running.
Temporarily using a 30GPH electric "click clack" fuel pump (showing 3.5 PSI at carburetor)
I'm running into two problems.
1. Anything less than 16-18 deg timing at 650-ish RPM, and the engine runs like crap (sounds like dead mis-fire), and will barely stay idling. It smooths out some around 18 deg., and I took it for a drive to check 4th gear WOT @20 MPH....didn't get any pinging. Haven't checked total mechanical and vacuum advance yet. That was one of the things I'm planning to do this weekend.
2. With the "hotter" cam, I'm pulling about 15-18 in HG at 650-750 RPM. At light throttle, just off idle, there is some surging, and if I blip the throttle there is a slight stumble before it revs. Cupping my hand over the air horn a bit improves the idle quality, which indicates lean idle circuit. I tried richening up the idle mixture screw, but it didn't have any affect. Jim C. and I chatted on the phone, and he thinks the lower vacuum signal is pulling less fuel at idle, so he sent me a couple of extra idle jets to try out. Haven't installed them yet....also on the list for this weekend.
With all that being said, I have a few questions for the Mud brain trust....
- Anyone ever have issues with the KC859/262 cam, specifically reduced vacuum at idle, and/or reduced idle quality?
- I know the 2F's like a bit more timing than stock, but is 18 deg BTDC way off in left field?
- Any idea why the misfire / crappy idle is so extreme at closer to stock timing?
- Finally.....and here's the most important question. My 40 isn't road legal yet, so is there anyone in the Raleigh area who would be willing to take a drive down to Fuquay-Varina and give me some assistance getting this critter dialed in? I can offer cold beer and free pizza!
Hopefully I've given enough information for someone to have some ideas......
Thanks in advance....
Here are my engine specs.
'76 2F Bored +1mm, and head milled to get around 8.5:1 CR
Head modified for SBC valves and springs
Delta Cams KC859 (262 duration) cam (valve lash set at .008 / .012, per phone conversation with Delta)
De-smogged 1978 carb, rebuilt by Jim C.
1979 Toyota electronic dual advance distributor / ignitor (plumbed into ported vacuum fitting on carb).
New OEM Toyota plug wires, cap, and rotor button
Stock 2F intake
3FE cast iron "2 into 1" manifolds
Engine is freshly rebuilt, and only has about an hour of run time on it.
Compression = 150PSI +/- 3 on all 6 cylinders (rings aren't fully broken in just yet).
Have measured valve lift on all cylinders to confirm no flattened cam lobes.
Have checked for vacuum leaks 4 different times, using multiple methods.....none found.
Have confirmed proper float level, and that it doesn't go too high/low during running.
Temporarily using a 30GPH electric "click clack" fuel pump (showing 3.5 PSI at carburetor)
I'm running into two problems.
1. Anything less than 16-18 deg timing at 650-ish RPM, and the engine runs like crap (sounds like dead mis-fire), and will barely stay idling. It smooths out some around 18 deg., and I took it for a drive to check 4th gear WOT @20 MPH....didn't get any pinging. Haven't checked total mechanical and vacuum advance yet. That was one of the things I'm planning to do this weekend.
2. With the "hotter" cam, I'm pulling about 15-18 in HG at 650-750 RPM. At light throttle, just off idle, there is some surging, and if I blip the throttle there is a slight stumble before it revs. Cupping my hand over the air horn a bit improves the idle quality, which indicates lean idle circuit. I tried richening up the idle mixture screw, but it didn't have any affect. Jim C. and I chatted on the phone, and he thinks the lower vacuum signal is pulling less fuel at idle, so he sent me a couple of extra idle jets to try out. Haven't installed them yet....also on the list for this weekend.
With all that being said, I have a few questions for the Mud brain trust....
- Anyone ever have issues with the KC859/262 cam, specifically reduced vacuum at idle, and/or reduced idle quality?
- I know the 2F's like a bit more timing than stock, but is 18 deg BTDC way off in left field?
- Any idea why the misfire / crappy idle is so extreme at closer to stock timing?
- Finally.....and here's the most important question. My 40 isn't road legal yet, so is there anyone in the Raleigh area who would be willing to take a drive down to Fuquay-Varina and give me some assistance getting this critter dialed in? I can offer cold beer and free pizza!
Hopefully I've given enough information for someone to have some ideas......
Thanks in advance....
