Install thread- Holley EFI Sniper on '72 402 big block

[Ol Blue K20]

Interesting that progressive is an optional item.

[davepl]

Yes, it really should have been that way originally I think, or come with it. Having the throttle open ALL FOUR blades IMMEDIATELY as it does in stock form makes for a very sensitive throttle!

[72Cheyenne454]

Davepl,

Where did you buy the throttle extension and progressive linkage for the Sniper? Can you provide part numbers?

Thanks,
Miles

Originally Posted by davepl

Yes, it really should have been that way originally I think, or come with it. Having the throttle open ALL FOUR blades IMMEDIATELY as it does in stock form makes for a very sensitive throttle!

[driller35]

Try this link for the Progressive, https://www.efisystempro.com/sniper/...ve-linkage-kit,


I was gonna purchase the fixed, price 13.18 but after seeing shipping to Canada costs 43.10 I might as well get one made here at a gold jewelry shop hehe

[72Cheyenne454]

Originally Posted by driller35

also look up, Holley 20-54 Carburetor throttle secondary connecting rod , on Amazon

Thanks for the info!

Miles

[Ekliptix]

Managed to get the truck started up. Idled well. But, I went back the next day and it started but sounded rough and would die without maintaining 1,200 rpm. I assumed the timing was off from removing the distributor then putting it back during the intake replacement, so I borrowed a timing light and was shown how to use it. Next day, tried to start it to check timing. It would turn over (not start) but sounded unhealthy/struggling as it tried to fire up so I couldn't even check the timing. I don't want to try turning it over again until I find something out of whack.

In the 3 instances of starting it since replacing the intake have become worse, I'm a little stumped. To trouble shoot, I've triple checked the plug wires and distributor are all in the proper firing order (even thought the engine never would have idled properly in the first startup instance). Vacuum hoses all appear plugged in properly. Oil is good. Battery is topped up. I don't think it has anything to do with they Sniper, but I'll review the startup and trouble shooting guide. I'm still suspicious of timing, as it's one of the only things that could have changed during the intake swap. I've been watching youtube vids on how to install a new distributor, getting the #1 cylinder to TDC and pointing the rotor at the #1 cylinder. These topics all new to me, so I'm hopeful https://www.youtube.com/watch?v=FHX1yXVyIMg.

Any mechanically inclined members in SW Calgary/Bragg Creek want to stop by any share some experience, I'll be very happy. Until then, I'll trouble shoot and maybe eventually bring it into town for some mechanical help if I can't figure it out.

[driller35]

Being you got it to start and idle well after first initial start doesn't sound like you did anything wrong with distributor , I would check fuel pressure and supply first ,

[Ekliptix]

I ended up checking the dist from scratch anyway. Took the plug out of #1 cyl, tapped the engine over until I felt pressure come out of the plug hole, saw the balancer was near the 0 position, hand-rotated the crank a little to make it exactly at 0. Noticed the rotor was not near pointing at the #1 cylinder. Thought 'a ha, the problem'. Rotated the rotor to point at the #1 cylinder, put the dist cap back on, connected the plug wires, triple checked their order. Tried to start it. No start, not ever struggling. I tried rotating the distributor slightly, both ways. No good.

There was also a terrible noise when cranking which I found was the starter teeth too far from the flywheel. Tightening the started mount bolts solved that.

Back to the ignition. Wanted to check that there was an actual spark occurring. Confirmed 12v power to the distributor. Took spark plug #1 out and visually saw a spark when attempting to crank it over.

Other thing to check:
Is my rotor 180 degrees out? I've read I can feel pressure coming out of cyl #1 on both the compression and exhaust stroke. I my case, I recall feeling vacuum on my finger just before the pressure coming out. Online material suggests this would support TDC to be achieved for Cyl #1, and the rotor to be correctly pointed. I may double check.

Other things to check:
- double check 12v power is going everywhere it needs to.
- disconnect fuel line to the EFI unit, get a bucket, turn key on and see if fuel pump is delivering fuel up the hose to the EFI unit. I can hear the fuel pump working now.
- double check all vacuum hoses, all fuel source and return lines.

It's frustrating having it idling well before the crack in the intake formed.

[Mike C]

I would pull a valve cover and rotate the engine over. Watch for the intake valve to close and then get the #1 cylinder and the rotor lined up. Sorry you are having these problems.

[driller35]

Well that's sucks was hoping you would easily have it sorted, I would volunteer to give ya a hand but presently overseas until July , then want to start Sniper install on my 70 Chev, might get cold feet here though and just rebuild the carb as I need the ole girl for the summer, gotta be something simple I still believe as you had running before manifold and just after
Cheers Lloyd

[Ekliptix]

I agree it's something simple. I'm still a fan of this thing and believe it's just a user error issue I've caused. I'll figure it out.

Off topic: Where are you overseas? I was in Dubai, Oman and Kuwait last year. I'm off to China, Tokyo and Seoul in 2 month. All for work in O&G, like you, I assume.

[davepl]

I hate to be the guy who says "I dunno, mine works fine", but "I dunno, mine works fine!". So I'm sure there's something small and obvious with yours. Hang in there, you'll find it!

[driller35]

Sorry for the triple post not sure how that happened,

Currently in Thailand retired from the O & G , seismic drilling services , if things would turn around in the near future would un mothball the drills but with the current political crap going not likely,

I,ve got pretty much all the components waiting for my return ,Sniper Master Kit, going to use the progressive fixed linkage as well and want to drill a hole into the fuel sender unit and use bulkhead fitting there for the 3/8 return, also picked up a 72 sending unit with the pre installed just in case I bugger the original one up,

[Ekliptix]

When I turn the key to ON (not start) the pump primes for ~4 seconds and then is quiet. This is what the manual says is normal. When I'm cranking, I can't hear the pump among the other noises.

[driller35]

Yes that sounds normal then should be fully pressurized with fuel, you may have already but I would then next see if all the electrical connections are secure and make sure no wire has been pulled out or sitting loose in the connectors

[Ekliptix]

I just returned from 2 weeks in Asia (China, Japan, Korea). Japan was awesome.
Anyway, spent a couple hrs on the truck today. Got it running after confirming wiring was correct, 12v everywhere it was needed, then:
a) plugging all the vacuum hoses and ports. It wanted to turn over, but didn't start until I,
b) turned the dist cap as advanced as it would go.

Once running, it sounded normal, all 8 cylinders. If I dialed back the timing by turning the dist cap, it would back fire a little, so I left it as advanced as I could with the cap position.

I hooked up the timing light and it appears ~12 degrees ahead of 0. But the weird thing is the timing light was not flashing steady, the light seemed to skip some revolutions. This is making me wonder if spark is actually travelling to Cyl #1 on every revolution, or if there's an issue with the distributor. You can see this action in the video.

So, next steps are:
a) reconnect one vacuum line at a time and see if/which line is causing a leak.
b) remove the dist cap for inspection/replacement.

Overall, I'm happy it's running again even though there are a couple bugs to work out.
https://youtu.be/uSN6lzK4BdA

[ncpetersc]

Congrats getting it running.

Yeah that timing light is not looking right at all. Maybe try a different plug wire to see if the timing light is at least nice and steady in period. Otherwise could be the timing light I suppose.

Edit: Could be wrong but I think I hear the engine sound change with the erratic light. Could be time to look at the spark/ignition side.

btw, I am no expert, just offering an opinion and diagnostic idea.

[Ekliptix]

Originally Posted by ncpetersc

Congrats getting it running.

Yeah that timing light is not looking right at all. Maybe try a different plug wire to see if the timing light is at least nice and steady in period. Otherwise could be the timing light I suppose.

Edit: Could be wrong but I think I hear the engine sound change with the erratic light. Could be time to look at the spark/ignition side.

btw, I am no expert, just offering an opinion and diagnostic idea.

I will try that. I used the light on my blazer today and it worked normally, but I may be able to use it on the C10 to see which wires are pulsing normally vs intermittent flashing.

[Boog]

Just for a test hook the timing light inductive pickup to other plug wires and see how consistent the flashes are. The engine sounds pretty salty right now. Have you driven it at all since you got it running again?

[Ol Blue K20]

Sounds pretty mean but something is up with that light....I'm not sure but I think you need to back the distributor back a tooth.

[bill3rail]

Just a thought...
Bad Plug Wire causing the timing light to misfire?

[Ekliptix]

Originally Posted by Boog

Just for a test hook the timing light inductive pickup to other plug wires and see how consistent the flashes are. The engine sounds pretty salty right now. Have you driven it at all since you got it running again?

I will do that, with the other wires. It sounded pretty mean with the carb too. It's not stock. Video with the carb: https://youtu.be/72JuaDfsrds?t=48s

Originally Posted by Ol Blue K20

Sounds pretty mean but something is up with that light....I'm not sure but I think you need to back the distributor back a tooth.

You may be right about 1 tooth off.

Originally Posted by bill3rail

Just a thought...
Bad Plug Wire causing the timing light to misfire?

I thought that too and replaced the plug wires about 3 weeks ago.



I'm hopeful and will report back with progress.

[clay68c10]

I have used a timing light as a diag tool to find an ignition misfire, it works well. You probably have an ignition caused miss if the flash is erratic.

I love it when a simple fix cascades into something more involved. But... It should be something relatively simple, there’s not much in the ignition system.

[Ekliptix]

Small update: I've easily started the truck a few times and brought it up to operating temp. Using the timing light, I check each plug wire. Strangely, they all appear to be flashing normally at this moment in time. I'm still suspicious of the distributor. I have a spare dist from the original 350 engine, but the timing curve is different in it.

I reconnected each vacuum line, one at a time. The engine appeared to run/idle the same with all vacuum lines connected vs all plugged. The vacuum at idle is only 6 inches according to the factory gauge, very low. I plan to try blowing into each vacuum line when the engine is cold to see if I get any leakage.

I took a risk and drove the truck down my driveway and back, about 1 mile. Everything was fine. I tried stomping on the gas and it lit the tires up from a stop through 1st gear and 1/2 way through 2nd gear. So, it's making more power now vs with the carb. I have no idea if the timing is optimal, plus the throttle is only opening a max of 85% until I adjust the throttle cable. Still, I was happy and felt some gratification feeling the new power and responsiveness the holley Spiper is going to give me once things are 100%.

Oh, I tried restarting it and the starter is no longer aligned with the flex plate. I got under it and there are no shims applied yet the starter teeth are not close enough to engage the flexplate. I tried torquing up the starter mounting bolts, but it didn't help. I removed the started and saw some tooth damage, so I bought a new starter today ($140) with more adjustments on it. I'll install it tonight and resolve the starter issue. Ugh.

[driller35]

Good to hear you are getting it sorted and its back up and running , passed thru Toyko yesterday and nice and sunny , got a few things to do to mine before I even start sniper attempt, just checking for temp sensor options and both head ports are in use ,I know one for factory gage and just guessing because of factory AC its using the other port, more research needed