FJ40 Holley Carburetor Questions for 1977 2F Successful Setup Needed (1 Viewer)

[Adog]

1977 fj40 with headers, Holley 4412-3 carb. Valves are set correctly. Dizzy is vacuum advance,new from city racer. Carb is clean, new kit installed with #35 nozzle and 4.5 power valve.
Engine starts great, idles great, accelerates ok until you make it pull and it falls off, hesitating unless you really mash the gas, then runs smoothly at a steady state.
Questions
1. What are timing recommendations ? Mine is set to where bb is at bottom of window, about 13-15 btdc. Then hook vacuum line to manifold vacuum and it advances out of site at idle. Should I hook vacuum advance to ported vacuum on carb?
2.What pump nozzle are you running? Carb is clean, float set properly and vacuum holds steady at 18 inches after idle mixture adjustment. Pump nozzle was a #28 and I changed it to a #35. Did not seem to help.
3. What power valve are you running? Mine is a 4.5 and I have ordered a 8.5.

I am not wheeling this unit, I just want it to run smoothly.

All recommendations will be appreciated.
Thanks

 

[Downey]

When Downey Off Road Mfg. first started in 1970 we sold Holley 500's (4412's) until we finally figured out that a Holley 350 was a perfect match for the 6 cylinder ,with no modifications needed at all. With the 500's we had to jet down 3 sizes, and power valve down 1/2 size (but can't remember back to 1970 "49 years ago" what size power valve was stock in the 500's). Then we had to advance the timing to 10-12 degrees advanced (and not use a retard smog dizzy at all). Even if you do opt to keep the 500, check out my ebay #254041028091, particularly the 3 drawings.

 

[DougAustinTx]

Downey is the expert on these, but I have been running a Holley 350cfm (2300 series Holley) for about 7 years and it works great. I use the Downey 2bbl adapter with a modified original FJ40 air cleaner. I made my own cable linkage to the throttle. Welded on a bell crank from a Toyota throttle body to prevent cable breakage. I disconnected the exhaust manifold from the intake ( and added a block-off plate) to reduce heat buildup on the carb.

 

[DougAustinTx]

Just wanted to make sure you understand how the Holley power valves work. They don't put out any extra fuel until the vacuum drops BELOW the preset value of the valve. For instance, the vacuum level has to drop below 4.5 inches of vacuum before the 4.5 valve will open to allow more fuel. If you jump to an 8.5 power valve, you will get more fuel when the vacuum drops to 8.5 or below during hard acceleration. I find used 2300 series carbs (350 cfm) on Craigslist for about $100 and rebuild them.

 

[65swb45]

You never mentioned what your manifold vacuum is at idle. Because ALL carburetors are passive fuel management, they are 100% dependent on adequate manifold vacuum to run properly.

 

[Adog]

You never mentioned what your manifold vacuum is at idle. Because ALL carburetors are passive fuel management, they are 100% dependent on adequate manifold vacuum to run properly.

Idle manifold vacuum is 18 inches steady.

 

[Adog]

We have liftoff. Installed 8.5 power valve and that was the final piece to the puzzle. She purrs like a kitten and has gobbs of power. For the record, #61 jets, #35 nozzle and 8.5 power valve. Timing set with bb at bottom of window(vacuum disconnected) and then hooked to manifold vacuum. Will fine tune tomorrow as I want to check point dwell again, set idle at 650.
Thanks for everyone’s help and ideas.