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BamaWagoneer 10-26-2018 12:46 PM

Holley EFI W/ Holley Hyperspark Distributor?
Hello everyone, long time lurker first time poster.

I have an 88 GW and love it so far (only 6 months in) but I'm in no shape or form a mechanic so a bit intimidating posting here among the experts so please forgive my ignorance on probably simple things. I've read through many of the posts here and have tried to put as many of the pieces together but still have questions.

After spending a life time of blissful ignorance enjoying fuel injection, trying to shift my reality to life with a carb is driving me nuts. I want to turn the key and the sucker crank :-) So I'm looking to add fuel injection with the Holley Sniper 2300 plus the fuel system kit:

What are the benefits of also upgrading the distributor along with adding the Sniper EFI? I've read the distributor threads and asking which one to use is going to give me a ton of answers that will confuse me more so to be more specific would using the Holley distributor be worth the price since it seems made to be compatible with the EFI?

In a nutshell, I want to convert to fuel injection:

1) So I can turn the key and it cranks
2) better/smoother idle and acceleration
3) not concerned so much with improved MPG or HP but if it happens all the better.

What if anything would upgrading the distributor add to this and what are the pitfalls? (I've read about the possibility of problems with the new distributor gear not fitting properly for example)

Would adding fuel injection and NOT upgrading the distributor result in other issues?


Bill USN-1 11-20-2018 04:54 PM

This is a good question.
My answer is that every EFI system should be just like the factory does them.
Complete fuel and timing control from the computer.
The drivability is dramatically increased by having timing control vs fuel only.
You can use a dixie cup to properly add fuel but timing needs to be right.

Now the bigger question, if I read your post correctly....
I added up all the parts you listed/required to purchase this complete system with timing control and it adds up to $1600.

My "complete" fuel and timing control system that uses all factory, over the counter parts, no after market mail order parts, for servicability on the road, retails for $1399.95 and $35sh.
i also provide a discount for all fellow Vets and first responders.

So the big question is, why pay more for less?

PBG928 06-24-2019 03:51 PM

I just did the Holley 2300 with Hyperspark and Robbmc powersurge fuel system. If you want to modify fuel lines and intake at tank you do not need the
Robbmc. Once dialed in it runs like a dream. Vacuum leaks really affected performance so check all of them. Holley Tech support is open 8-5 M-F and till 1pm on Sat. They are very helpful and knowledgeable. Sniper has ability to generate data logs you can email them to look at. I am a hobbyist with pretty good car skills with 4 Gws sitting in the driveway. Sometimes it is cheaper to buy the more expensive parts that are easy to install and cut down on a mechanics time installing it.I did the Howell system and if you live in Calif it is your only choice. Kind of antiquated when you compare it to Holley. the hyper spark is an easy install if you watch the Holley video :

Make sure when you go to TDC that the number one piston is on the compression stroke before installing the Distributor. Hyperspark controls timing after install. Clean setup. Not knocking anyone else I can only comment on the 2 systems I have used.
I am like you I want it to run smoothly especially if the wife is in the car. Good Luck on whatever you choose.

acct21 06-24-2019 07:09 PM

I did the Sniper 2300 and the RobbMc Powersurge as well. I have been running it as my dd since August. I want to convert over to the Hyperspark, but so far it starts and runs so well that I keep putting it off.

When I first back out of the driveway in the AM, if I rev it up too much and then hit the brakes, it will stall out. I bet that better timing control would eliminate this. Once it's warmed up after a few minutes, it won't stall under the same conditions.

So I may well be shortchanging myself on better performance or fuel economy, but it is a new car compared to how it was before EFI.

PBG928 06-25-2019 07:08 AM

I don't think your stalling is due to timing control. This is my second sniper system after the initial Howell efi. Howell had a DUI distributor, first sniper has an MSD with no box, and third had a DUI that I pulled out thinking it was causing miss in engine. Mechanic thought exhaust gas was getting in coolant. Tested that not the problem. Installed hyperspark and still had the miss, rough idle, stalling when coming to a stop or idle dropping to 400 when set at 700. Spoke to Holley and guy looked at my IAC numbers that should be between 2-12% in neutral or park. He was convinced it was a vacuum leak. I checked all the usual suspects and they were tight or plugged. I then noticed the lines at rear of engine. On drivers side you have a set running into the firewall to operate your 4wd with with small multicolored lines. I tested those with a vacuum pump and they held vacuum. I then looked at the two lines on the passenger side that go down behind engine and connect to 3 steel tubes. Tested these with pump and they do not hold vacuum. One runs to top of gas tank and the other goes to rear top of transfer case, Third I haven't traced all the way back yet.. There are vacuum lines on drivers side of tranny that operate 4wd shifter that come from multicolored lines going in and out of firewall. I temporarily pulled these from the port on manifold and plugged them all. It is a mess because charcoal canister requires a lot of connections.(I removed it previously). After that car runs better that any new car, smooth idle, no stalling when coming to a stop or shuddering. I think this has been the problem on my three cars all along. Will run down vacuum leaks in rear but I do not believe I need all those lines. For now runs like a new car. In hindsight DUI distributor was probably ok and will use it on another one of my cars. Holley hyperspark is truly plug and play. Good luck.

acct21 06-26-2019 07:07 PM

The three lines that go up to the back of the engine aren't vacuum lines. Two of them run to the vent/rollover valves on the top of the fuel tank. The third is the transfer case vent line.

It's a good thing they don't hold vacuum, because that would suggest the vents are clogged!

I've certainly not done a perfect job under the hood, but I've replaced every inch of vacuum tubing, capped every single unused port, and deleted all of the coolant temp switches/linear valves/etc. I have an absolute minimum of vacuum control on the rig right now.

When I suddenly reverse and hit the brakes, I can watch the RPMs fall and then try to catch before the stall. I just don't think the timing curve is right at the moment it is trying to back off all of the advance I just gave it with the throttle. I could probably prove it with a data log -- but did I mention that I'm also catastrophically lazy when it comes to little things like this?

Again, it cold starts instantly, and idles like it never did before. Once it has warmed up a few minutes I can't tell it from my 2015 Tahoe -- it starts, idles, accelerates, stops, re-starts just like a new car.

babywag 06-27-2019 01:11 PM


Originally Posted by acct21
The three lines that go up to the back of the engine aren't vacuum lines. Two of them run to the vent/rollover valves on the top of the fuel tank. The third is the transfer case vent line.

On 727/NP229 equipped there are 2 vacuum lines on driver side for transfer case shift motor.

No efi vehicle should stall I'd look @ IAC adjustment.

acct21 06-27-2019 03:34 PM


Originally Posted by babywag
On 727/NP229 equipped there are 2 vacuum lines on driver side for transfer case shift motor.

Yep -- 5 lines total. The two shift motor lines (yellow and green) as well as the cluster I was referring to -- mounted up near the top of the bell housing behind the engine. Those are all vent lines.

IAC is dead on at 6% warm. I haven't played with it to see if I can improve the first 2 minutes of run time.

BamaWagoneer 08-09-2019 04:26 PM

PBG928, did you use the distributor gear that came on the hyperspark or did you remove it and use the old/original one?

I want to make this upgrade but I've read so many horror stories of the new gear not matching properly and grinding things up.

Currently running the fuel injection and love it.

acct21 08-14-2019 04:20 PM

I know you didn't ask me, but I can answer you: take the gear off your distributor and install it in place of the gear on the Hyperspark. That way you are still running a matched set. Run the gear on the Hyperspark at your own risk. It may go 500 miles without issue, or it may go 5,000, or it may go 5. You'll almost certainly have problems.

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