Sniper X Cleveland X Timings

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Alexei

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Dear Colleagues,
I’ve just had installed a complete sniper EFI kit, with their distributor and spark module.
Their screen allows me to set the initial timing, the timing at WOT and max cruising Timing. Currently: 13,5 - 35 - 33 respectively.
My 72 351C engine has a moderate cam, iron heads, air gap intake.
The trans is a Ford AOD.
The problem is that sometimes when in a low gear, a hill appears, and I have to press gas, the engine has lots of precombustion clicks! I have to kickdown to avoid it, even in a little inclination.
Any ideas on how to set the 3 settings?
Thanks!
 

Sheriff41

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What axle ratio are you running? If you're running a 2.75:1 you may be lugging your engine with the AOD in high gear. Also, did you readjust your AOD's TV cable when you installed the EFI? Your trans may be remaining in high gear (not kicking down) too long and causing the engine to lug.
 
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machphil

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Questions: Was this a 4 bbl engine with 4 bbl heads, and did you use the open chamber heads? Are you running 87 or 93 octane? What is your current compression ratio? Can you read the A/F ratio during those times of pinging? There should be compensation for enrichment under load.
 

Alexei

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Hi!
It’s a 2bbl engine with 2bbl heads, now with the 4bbl sniper:
The fuel is 87 octane
The compression is 9,3:1
The a/f ratio is 13:1
 
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I have never worked with a sniper system, but there has to be a way to adjust the timing curve more than just idle, cruise and WOT. The timing should start at 13 and go to 35 progressively based on RPM. What is happening is that it is advancing too fast from 13 to 35(maybe 33 as that is your cruise?). There has to be a way to set how fast or how slow you get that advance in. You may be getting to 33 or 35 by 1500 or 2000 RPM and that is just too fast for the compression and fuel you have under heavy loads and low RPM. Check on the timing menu, there has to be a way to slow the rate of advance. You should be able to say you want the advance to start at lets say 1000 RPM and end at 3000 RPM or 3500 RPM or where ever you need to end it at so that you do not have pinging.
 
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I would reduce the WOT advance until the pre-ignition stops. Reducing the WOT advance will also change the curve at part throttle. You may have to reduce the cruise advance a couple of degrees, too, although for economy you want it as high as possible. 33° to 36° seems reasonable to me for cruise advance.

I would also check the throttle position sensor readings to make sure it is functioning properly.
 

Alexei

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What axle ratio are you running? If you're running a 2.75:1 you may be lugging your engine with the AOD in high gear. Also, did you readjust your AOD's TV cable when you installed the EFI? Your trans may be remaining in high gear (not kicking down) too long and causing the engine to lug.
It’s a 2,80 rear ratio
 
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I have been reading up on Holley efi.

I think you can connect a laptop to even the base level sniper and have access to the full timing table.

you just have to get the app from Holley’s download site.
 
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Sherrif41 hit on a good point, axle ratio. With the AOD and 25.6" diameter tires your final ratio is about 1.88:1, which is pretty tall, especially even with a moderate cam, and your engine is running at less than 1,500 RPM at 60 mph. It's no wonder you have to kick down to a lower gear. Your engine will be a lot happier with a 3.73:1 axle ratio, which will give you a final ratio of 2.61:1, and good performance and economy. The camshaft has to be matched to your cruising speed, so your engine doesn't struggle when trying to accelerate.

If you stay with your axle ratio you might want to consider a camshaft designed for low RPM torque, and low RPM cruising.
 

Alexei

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Coudl you suggest a gear kit for this new axle ratio?
 

Alexei

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Yes it’s a 9 inch. The ratio was changed to 3,25 and also the speedometer gear.
After a little AOD tuning the car is running fine. Thanks for the help!
 
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