Holley Sniper 2300

[mcmyket]

Hello,

I have a 64 GMC with a 305 v6 that I've recently purchased and was considering a Holley Sniper 2300 fuel injection setup for it. I see there was a thread in 2020 talking about it, but I don't see where anyone has completed an installation. Has this setup or any other fuel injection system worked for anyone yet.

Thanks!

Mike

[Gwhizzard]

the only thing that doesn't help and might throw it off is the intake being it does not really distribute fuel equally. but have seen post on the 67-72 forum that showed a 61 suburban with 88 gm tbi unit on it. so id say go for it and see what happens lol ive looked into it as well. but haven't pulled trigger et on anything due to other projects inline first.

[Prowbar]

the only thing that doesn't help and might throw it off is the intake being it does not really distribute fuel equally.

How do you know it doesn't distribute the air-fuel mixture properly?

@Mike: I for one, don't know anyone that has one of these V6's on (Holley) EFI, except for the Chevy TBI system. I'd be very interested though if you decide to try!
But I believe that port injection is superior to these TBI units though.

[James]

How do you know it doesn't distribute the air-fuel mixture properly?

@Mike: I for one, don't know anyone that has one of these V6's on (Holley) EFI, except for the Chevy TBI system. I'd be very interested though if you decide to try!
But I believe that port injection is superior to these TBI units though.

I have flow tested the intake manifold and found with the stock two barrel carburetor the flow is about equal. With the Holley two barrel the center runner flow is very low. This is why the magnum intake has no divider between runner 1-3 and 4-6. If you look at the top of the manifold you will see the center runner makes a 90° turn, air don't like to make sharp turn so it restrict the air flow.

In my opinion, port injection is superior but with these engines a TBI would be better base on the intake limitation.

[Gwhizzard]

Prowbar.. I personally have not flow tested or tried to improve the intake yet... but i have read alot of the 4 barrel carb mods and the one thing they do is soften the turns up inside of the intake to make it smoother transition. There are a few on 67-72 and jalopy journal of people modding these intakes. if they are still out there.

[James]

Prowbar.. I personally have not flow tested or tried to improve the intake yet... but i have read alot of the 4 barrel carb mods and the one thing they do is soften the turns up inside of the intake to make it smoother transition. There are a few on 67-72 and jalopy journal of people modding these intakes. if they are still out there.

This is what I had done to my intake ports and the carb flange on the intake manifold:

On the carb flange picture, I was almost done, just wanted to show how much metal was removed.

On the ports, I left a small section of the runner divider to hold the gasket in place and so I would be able to install any small port heads without issue. Did not make the port any larger, just remove the divider.

This manifold now flow very well with the Holley 2 barrels.

It took a lot of work and patient to get it there. Engine run better too. Want to pull harder.

[Prowbar]

Looks excellent. Regarding the Holley conversion, this is something that one needs to pay attention to.

Quite surprised the intake does distribute the flow equally. However, with the sonic pulses that might be different. The only way to test that would be to make a spacer plate that mounts between the cylinder head and exhaust manifold and has 3 O2 sensors, connected to each runner, to measure the A/F ratio of each cylinder.

Another point regarding the A/F ratio of each cyl. would be the PCV valves tapping into runners 3 and 5 but not in runner 1. This should affect the A/F of 3 and 5 to some degree. Especially with a worn engine.

A centralized PCV would be better I think.

[Gwhizzard]

Nice setup. I like what you did with it..

[James]

Another point regarding the A/F ratio of each cyl. would be the PCV valves tapping into runners 3 and 5 but not in runner 1. This should affect the A/F of 3 and 5 to some degree. Especially with a worn engine.

A centralized PCV would be better I think.

The PCV valves will lean out cylinder 1-3 and 4-6. It also effect the flow through the runners, base on my flow bench numbers. Blocking the passage between the ports will change the flow rate. When I get done with modifying my spare heads, it will not have the internal PCV valves only an external one.

[Prowbar]

You're correct regarding the ports. I'm still thinking about the PCV system conversion. On my IMPCO propane mixer air cleaner, I have a way to attach a PCV hose. Now to tap into the engine. Either convert the filter canister on the back of the block or use one of the valve covers. I don't like drilling holes in original parts, possibly a custom oil fill cap with a PCV hose fitting in the center.

What are your thoughts?

[James]

You're correct regarding the ports. I'm still thinking about the PCV system conversion. On my IMPCO propane mixer air cleaner, I have a way to attach a PCV hose. Now to tap into the engine. Either convert the filter canister on the back of the block or use one of the valve covers. I don't like drilling holes in original parts, possibly a custom oil fill cap with a PCV hose fitting in the center.

What are your thoughts?

I'm thinking something like this:
https://www.summitracing.com/parts/sdk-c8az-6766-b

I don't know it this one will work. I would need to research this. It also seems to me that the later model V6 had this type of cap (or something similar) or maybe it was the Chevy that had it, I don't remember. Maybe someone else in the group know something about this.

[Prowbar]

I'm thinking something like this:
https://www.summitracing.com/parts/sdk-c8az-6766-b

I don't know it this one will work. I would need to research this. It also seems to me that the later model V6 had this type of cap (or something similar) or maybe it was the Chevy that had it, I don't remember. Maybe someone else in the group know something about this.

Looks like a nice cap, although not cheap. Wonder if these have a built-in PCV 'regulator' with a ball that controls the stream of gasses. The question section does have some measurements regarding fitment.

[Gwhizzard]

I didn't know these had an internal PCV setup. I guess you learn something new everyday. I am just now getting into these old engines and I'm starting to love them and trying to learn more about them. So im watching more then knowing on these engines lol

[anomalyjustin]

Hello,

I have a 64 GMC with a 305 v6 that I've recently purchased and was considering a Holley Sniper 2300 fuel injection setup for it. I see there was a thread in 2020 talking about it, but I don't see where anyone has completed an installation. Has this setup or any other fuel injection system worked for anyone yet.

Thanks!

Mike

I'm running the 4bbl 4150 Sniper on my 60 GMC with the 305. I converted it over about 4-5 years ago and never looked back. Once you get the learn procedure completed and do a few tuning tweaks, it works great. Definitely invest the progressive linkage add on though. The throttle is really touchy without it.

[sclor]

Regarding pcv valve, I switched mine over to Ford setup used in the seventies. Don't remember exact application, but it shouldn't be too hard to find. Ford used them on their v8's. I was uncomfortable with middle cylinders running leaner under the original GMC factory system.

Hope that helps.
Regards
Steve
New Orleans

[Gwhizzard]

I'm running the 4bbl 4150 Sniper on my 60 GMC with the 305. I converted it over about 4-5 years ago and never looked back. Once you get the learn procedure completed and do a few tuning tweaks, it works great. Definitely invest the progressive linkage add on though. The throttle is really touchy without it.

Nice... Do you have pictures of the setup on the engine??

[Prowbar]

Regarding pcv valve, I switched mine over to Ford setup used in the seventies. Don't remember exact application, but it shouldn't be too hard to find. Ford used them on their v8's. I was uncomfortable with middle cylinders running leaner under the original GMC factory system.

Hope that helps.
Regards
Steve
New Orleans

I like your solution. Tried the external PCV setup before but didn't succeed. Going to try it with a PCV valve on intake vacuum. I assume that is what you connected the hose to?

[James]

I like your solution. Tried the external PCV setup before but didn't succeed. Going to try it with a PCV valve on intake vacuum. I assume that is what you connected the hose to?

Yes, the hose connect to intake manifold vacuum.