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Old 07-12-2018, 12:29 PM   #101
Ekliptix
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Re: Install thread- Holley EFI Sniper on '72 402 big block

Weird, I'm not sure what the second port is used for on yours.

Last night I installed my first starter. Got it lined up and done. Was a tight fit and lesson in patience trying to do it all on jack stands.

Fired up first try. https://youtu.be/J5CxfMAJR5U

To do:
1) check for vacuum leaks.
2) determine why distributor is unreliable to deliver spark to each plug. Potentially replace distributor or at least, distributor cap.
3) figure out why brakes are so weak. This has been an issue since the 350-->402 swap. It may be the vacuum is too low, or another reasons.
4) install converter lock up wire + switch to 700R4. The vacuum line does not seem to engage the lock up, currently.
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Drivetrain: Built 402BB, TCI Streetfighter 700R4, 2,500 stall, Eaton posi, 3.73. Suspension/Chassis: ECE 4.5/6.5 drop, CPP nitrogen shocks, CPP front and rear sway bar, CPP cross members. Exhaust: 3" exhaust with x-pipe, Spintech 3000 mufflers, Hooker ceramic coated headers. Best 1/4 mile time: TBD.
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Old 07-12-2018, 05:06 PM   #102
driller35
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Re: Install thread- Holley EFI Sniper on '72 402 big block

Well good to hear you got back up and running , yes I would think with your lower vacuum, is giving your braking issues , is it possible for dizzy to be out one cog? if it dropped right into place after you changed out intake then I would think not

The ports believed by one fellow board member is one for gage the other for temp light as different gage packages used either side for sensor ,7 hole gage package drivers side , 3 hole gage package idiot light passenger side
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Old 07-12-2018, 09:03 PM   #103
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Re: Install thread- Holley EFI Sniper on '72 402 big block

Check your rotor to see if it has a burn through. This is common with the HEI. If you have a badly worn plug or high resistance wire, the spark has to go somewhere. It can actually burn a hole through the rotor. Put a couple of drops of gas in the well below the center electrode and look for a wet spot, if the hole isn't obvious. The scorching of the plastic of the rotor can also make ready paths to other spark plug terminals in the distributor cap. It is possible that there is carbon tracking in the cap, from a worn button. You may not be able to see them with a black cap, but they would show up well on a red or brown cap. To be honest, the truck didn't sound that bad. One thing I did notice was a bog when you blipped the throttle. I see in this thread that there is provision from Holley for progressive linkage. I would use it, personally.

As for "weak" brakes, do you mean a hard pedal? If so, that's going to be a vacuum leak, I'll bet.
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Old 07-12-2018, 10:50 PM   #104
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Re: Install thread- Holley EFI Sniper on '72 402 big block

I think he said it only has 6" of vacuum. That's not enough for power brakes. Either that is a real radical cam or there is a leak. It could even be the power brake booster leaking. I once had a spring in a booster break and the broken end of the spring wore a hole in the diaphragm which began to leak. It finally got bad enough I could hear the leak when I leaned up near the booster. The truck also idled like it had a large cam in it too but it was bone stock.
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Old 07-13-2018, 12:43 PM   #105
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Re: Install thread- Holley EFI Sniper on '72 402 big block

Ekliptix, I have one of these progressive linkage parts Holley part number 20-54, if you want to try your more than welcome to, the sniper tuner allows for it thru my reading but Holley doesn't recommend at this time using it , some say it works others say it doesn't
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Old 07-13-2018, 04:04 PM   #106
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Re: Install thread- Holley EFI Sniper on '72 402 big block

Quote:
Originally Posted by Boog View Post
I think he said it only has 6" of vacuum. That's not enough for power brakes. Either that is a real radical cam or there is a leak. It could even be the power brake booster leaking. I once had a spring in a booster break and the broken end of the spring wore a hole in the diaphragm which began to leak. It finally got bad enough I could hear the leak when I leaned up near the booster. The truck also idled like it had a large cam in it too but it was bone stock.
I get that he has low vacuum now, but was curious what it was like before the FI went on. I don't think that the FI is at fault for the weak brakes, if it was that way before.
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Old Yesterday, 10:41 AM   #107
Ekliptix
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Re: Install thread- Holley EFI Sniper on '72 402 big block

I spent some time with the distributor yesterday. I'm back at square 1. Won't start.

Trouble shooting:
1) inspected the cap and rotor. Looks fine. (pics below).
2) turned the dist 1 tooth (clockwise), as suggested by some ppl as I had the cap way advanced to get the truck to run. Result: Won't start.
2) took my spare distributor, installed the spare dist cap on the current base. Result: Won't start.
3) installed the spare dist base + spare dist cap. Result: Won't start.
4) returned to the previous tooth position (counterclockwise) with the spare dist + spare cap. Result: Won't start.

Then I gave up for the day. I still suspect something is up with the spark. I had the timing light setup while trying to turn the engine over and it'd only flash some revolutions, not all.

I also checked a few vacuum things. I used my lungs to provide some vacuum. To the vacuum gauge, I was able to see ~9inches using my lungs. That was my baseline to compare with how much vacuum I could yield with other lines.
- The brake vacuum line, I could get ~4inches until it felt like a valve opened. Blowing (applying pressure), brake vacuum line was 100% sealed and would not take any air going in.
- The dist advance line took ~5inches of vacuum until it sounded like a diagram engaged.




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Old Yesterday, 10:46 AM   #108
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Re: Install thread- Holley EFI Sniper on '72 402 big block

Sorry to jump in near the end without reading all 100 posts first, but I wanted to throw out one thing:

The Holley EFI will not work well at all on a manifold with a split plenum (where it's divided right up to the carb). You have to open up that separator if you have one.

Any chance you have a split plenum like that? Because an intake like this will NOT work well at all:

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Old Yesterday, 11:01 AM   #109
Ekliptix
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Re: Install thread- Holley EFI Sniper on '72 402 big block

Mine has an open gap between the left and right, so there's no risk of that.
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Drivetrain: Built 402BB, TCI Streetfighter 700R4, 2,500 stall, Eaton posi, 3.73. Suspension/Chassis: ECE 4.5/6.5 drop, CPP nitrogen shocks, CPP front and rear sway bar, CPP cross members. Exhaust: 3" exhaust with x-pipe, Spintech 3000 mufflers, Hooker ceramic coated headers. Best 1/4 mile time: TBD.
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Old Yesterday, 11:15 AM   #110
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Re: Install thread- Holley EFI Sniper on '72 402 big block

If your wiring isn’t good go the tach signal the EFI will never fire off. Also check connections on battery. Ask me how I know hahaha. On the Nova I did last Sniper install on it would randomly shut off or not start. Battery connections from efi directly to battery from efi had high resistance just in the terminals. Very strange. Replaced them all problems went away.
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