Holley Sniper 2 barrel conversion (1 Viewer)

[Fj moneypit]

What would make the iac go from 4 at idle to a 1 at idle later on thru my drive? Thought once set it would hold somewhere around there.

 

[wngrog]

I’m not sure what you mean by 10* at flywheel and 15* at idle. The only time the timing should change from idle is around 2300 rpm when the advance kicks in.

I would try to mess with that a bit. Bump idle to 750 and then cap the vacuum and set the timing at 11* once the vehicle has stabilized at your new idle.

I’m pretty happy with this on mine

 

[samc2447]

I’m not sure what you mean by 10* at flywheel and 15* at idle. The only time the timing should change from idle is around 2300 rpm when the advance kicks in.

I think he means on the Sniper display in the cab it shows 15*.

 

[wngrog]

Sniper display for timing. 100% IGNORE. It means nothing unless the Sniper is controlling the timing

 

[wngrog]

What would make the iac go from 4 at idle to a 1 at idle later on thru my drive? Thought once set it would hold somewhere around there.

Your setting is at the lowest setting of the IAC window. Try setting it 7-8

 

[Fj moneypit]

I think he means on the Sniper display in the cab it shows 15*.

Yes this.

I’m not sure what you mean by 10* at flywheel and 15* at idle. The only time the timing should change from idle is around 2300 rpm when the advance kicks in.

I would try to mess with that a bit. Bump idle to 750 and then cap the vacuum and set the timing at 11* once the vehicle has stabilized at your new idle.

I’m pretty happy with this on mine

I’ll adjust the idle to 750. Why cap the vacuum? For no advance? Will setting timing to 11* increase the idle? Not sure exactly what the reasoning. I do think a high idle though will help a bit.

 

[wngrog]

When you adjust the timing it will increase the idle until the computer adjusts itself. Some people thinks the IAC does that. It does not.

Adjusting the timing with the vacuum plugged
Off is the most
Accurate way.

You want to adjust idle in setup menu.
Then adjust IAC per Holly instructons on the last page.
Then check timing with vacuum capped off.

The computer with these proper inputs will get you to 750 rpm

 

[thecrazygreek]

When you set base timing you cap the vacuum to ensure an accurate reading with no advance / retard.

As far as I know, the FSM recommendation for ignition timing for all 2F (1F??) engines is 7 deg before TDC. Timing mark (the small ball) should be under the pointer when using a timing light on #1 cylinder with distributor vacuum disconnected and at engine running at recommended idle speed.

However, @wngrog advice is solid as a bit more advance seems to work well with the Sniper setup. But Setting base timing is a critical step in making sure your Sniper performs well.

And as already mentioned, and can't be stressed enough, ignore the timing info on the sniper display. It threw me off for a while when I first started using the system.

 

[Fj moneypit]

When you adjust the timing it will increase the idle until the computer adjusts itself. Some people thinks the IAC does that. It does not.

Adjusting the timing with the vacuum plugged
Off is the most
Accurate way.

You want to adjust idle in setup menu.
Then adjust IAC per Holly instructons on the last page.
Then check timing with vacuum capped off.

The computer with these proper inputs will get you to 750 rpm

When you set base timing you cap the vacuum to ensure an accurate reading with no advance / retard.

As far as I know, the FSM recommendation for ignition timing for all 2F (1F??) engines is 7 deg before TDC. Timing mark (the small ball) should be under the pointer when using a timing light on #1 cylinder with distributor vacuum disconnected and at engine running at recommended idle speed.

However, @wngrog advice is solid as a bit more advance seems to work well with the Sniper setup. But Setting base timing is a critical step in making sure your Sniper performs well.

And as already mentioned, and can't be stressed enough, ignore the timing info on the sniper display. It threw me off for a while when I first started using the system.

Thanks guys. I’ll make the adjusts and see how it goes. My timing is at 10* because I’m running pertronix that po put on instead of points. I think that was the timing suggested. Anyhow I’ll play with it a bit more and see how she does.

 

[1911]

As far as I know, the FSM recommendation for ignition timing for all 2F (1F??) engines is 7 deg before TDC. Timing mark (the small ball) should be under the pointer when using a timing light on #1 cylinder with distributor vacuum disconnected and at engine running at recommended idle speed.

However, @wngrog advice is solid as a bit more advance seems to work well with the Sniper setup. But Setting base timing is a critical step in making sure your Sniper performs well.

The FSM spec for base timing is 7 degrees BTDC, but this is a conservative setting that allowed operation all over the world, including at seal level (or below), using sh!itty third-world gas, and etc. The farther above sea level you are, the more advance you need. De-smogged engines can use more advance. Short story, you can usually get a better tune out of most engines operating in most environments by setting your timing dynamically, that is by moving the distributor while the engine is running to get the best throttle response. Then, test it under load (going up a hill for example) and make sure it doesn't knock or ping (pre-detonate). The best amount of base timing advance for any given engine/environment is the most advance it will take without knocking or pinging under load. Sometimes it takes a bit of trial and error to get the perfect base timing.

As another data point, my 40 with a de-smogged 2F, a dizzy recurved by Jim C., and a stock Aisin carb running at home at +/- 1,000' elevation runs best at 10-11 degrees base timing.

 

[Dizzy]

The F, F.5, and 2F are the kings of low-end torque. Stock gears in low range with a clutch pedal, up a hill, no problem. That said, why 750? The 650 rpm FSM spec. seems fast enough already?

Before I got a good tach, I earballed the 2F at less than 575 rpm, it didn't seem to complain.

Not having a Sniper installed, and pardon my lack of familiarity, can it effectively run the 2F at siginficantly lower than idle rpms, under load, with no throttle depressed? To me, I would want it to hold an idle slower than the Aisan's and its active dependence on manifold vacuum. But I get the sense that the Sniper's performance, or instructions, are engineered around the bootleg industry instead of tackling terrain in 4-low.

 

[FJ60Cam]

The F, F.5, and 2F are the kings of low-end torque. Stock gears in low range with a clutch pedal, up a hill, no problem. That said, why 750? The 650 rpm FSM spec. seems fast enough already?

Before I got a good tach, I earballed the 2F at less than 575 rpm, it didn't seem to complain.

Not having a Sniper installed, and pardon my lack of familiarity, can it effectively run the 2F at siginficantly lower than idle rpms, under load, with no throttle depressed? To me, I would want it to hold an idle slower than the Aisan's and its active dependence on manifold vacuum. But I get the sense that the Sniper's performance, or instructions, are engineered around the bootleg industry instead of tackling terrain in 4-low.

It will go lower. The limit to to pulling under load at idle would depend on the load and how much air the IAC can supply. The throttle butterflies are cable operated, so at some point you may have to assist if the required amount of air & fuel dictated it.

I've not tested the lower bounds, but set a recent one at 600 and it did just fine. I ended up bumping it up a little which seemed to help with off-idle throttle blips, which no doubt would have smoothed out anyway as it learned. 650 seemed to be the sweet spot for out of the box, not-yet-learned off-idle drivability.

 

[FJ60Cam]

While this doesn't necessarily matter much for 2Fs, I was talking to an experienced hot rod shop that uses quite a bit of Holley product (I've found that performance shops in general seem to be fans), and he said that modern GM LS computers can deviate as much as 25% from the factory fuel programming, while the Holley systems can deviate 200%. This was the Holley system designed to run an LS, but the Sniper uses the same wide-band O2 and computing system.

I imagine earlier GM TBIs and Toyota EFI systems were much less than the 25% deviation.

Crawling under load at idle should be no issue with the Sniper. If geared low, it should be downright badass.

 

[Fj moneypit]

While this doesn't necessarily matter much for 2Fs, I was talking to an experienced hot rod shop that uses quite a bit of Holley product (I've found that performance shops in general seem to be fans), and he said that modern GM LS computers can deviate as much as 25% from the factory fuel programming, while the Holley systems can deviate 200%. This was the Holley system designed to run an LS, but the Sniper uses the same wide-band O2 and computing system.

I imagine earlier GM TBIs and Toyota EFI systems were much less than the 25% deviation.

Crawling under load at idle should be no issue with the Sniper. If geared low, it should be downright badass.

I was going to say the same thing. Efi is not a new invention in the off road industry nor with fj40s. Many have run old gm tbi on these cars with better results than carbs depending on terrain, altitude, incline. Seeing I have an fzj80 for the rough stuff, the fj40 will be my mild offroad vehicle and daily use, so efi seems like a good match for what I’ll be doing.

 

[wngrog]

My advice to raise the idle was for the guy with the truck stalling on him at stop signs.

I think his is an IAC posotion issue but it won’t hurt at all to have a bit more idle while he’s sorting his tune. That can be easily swapped back lower.

I happen to be in my Pig today. I think the computer is set at 690 rpm. See how it and the IAC dance.

 

[wngrog]

Here is a look at my screen rolling down the interstate at 75 mph using between 25 and 45% throttle depending on the grade.
Nice and smooth for a 2F pushing 6000# of Pork

 

[Fj moneypit]

More cruising. Used a gps speedo because mine is off a a tad

 

[wngrog]

More cruising. Used a gps speedo because mine is off a a tad

You make any adjustments? 73 at 3000 rpm. Sweet.

 

[Fj moneypit]

You make any adjustments? 73 at 3000 rpm. Sweet.

Adjusted the idle to 700. I still have a few issues. Still wants to stall every now and again when rolling to a stop. Also the iac was running perfect (4) at idle all throughout my ride until the end when it went to 1 and stayed there. I still get a tps of 1 which is a sticking throttle I think. I’ll go in and redo timing and recalibrate efi to what you talked about. Otherwise it’s pretty some cruising and throttle much more responsive than the carb.

 

[wngrog]

The TPS at one is not a big deal. Butterfly is closed.