Holley Sniper EFI on my Nailhead

[BetsytheRiv]

I'm truly inspired Dave!  I had already been looking at the Sniper for my 65 - 401 but hadn't 100% committed.  My carb was replaced with an Edelbrock by my Uncle a couple years ago and despite many attempts by "experts" to dial it in it would always revert back to running rich every couple of weeks which sucks when she is my daily driver.  After seeing your post, I went hog wild with the Holley holiday sale and should have the Sniper EFI, Distributor and Ignition arriving in the next week or two.

 

The bracket I ordered was the GM Throttle adapter which I'm hoping will work without me breaking out the welder. (This is different from the one you originally listed as ordering):  https://www.holley.com/products/fuel_systems/carburetor_components/brackets_and_linkage/parts/1952

 

I'm curious why you went with the 4BBL (550-510) instead of the Quadrajet (550-867)?  First glance it may be the 650hp (yours) vs 500hp (Quadrajet) but I'm really curious if there was any other motivation since mine isn't installed yet.  

 

I was really teetering on getting the in-tank fuel pump but didn't want to get too deep into messing with the fuel system when I wasn't 100% sure on the Holley parts being compatible and/or the best fit for my 65.  She is my daily driver and I don't want to get into something I haven't completely researched and risk her being down.  

 

I drive like an old lady (at 39 y/o) in Southern California so I'm not too concerned about more power.  Most of the time I'm on city streets or in traffic on the freeways.  Kids will pull up at a light and rev their engine like they want to race and I just roll my eyes.  Clearly they don't know how much premium fuel is these days!  I remember back when I was 16 y/o leaving a car show in the 57 Thunderbird I restored and some teenage boys wanted me to light up the tires.  My dad still laughs to this day at me hanging out the window shrieking "Do you know much these wide white wall tires cost?!?!  Impressing you is not worth the wear on my tires!"  If I want to race I take my car to the track.  It's far too dangerous around here to fully enjoy the power our cars have on the city streets.  I know I can handle driving the higher power but the idiots running around here driving far too fast diddling around with the phones they're not supposed to be using while driving will put me in the grave and my poor Riv in the junkyard.  My Riv has made it 3 generations in my family and I'll do whatever it takes to keep her safe in this crazy city we live in.

 

Really appreciate the help & Happy New Year!!

[J3Studio]

This is a very cool thread.

Edited January 1, 2020 by J3Studio (see edit history)

[steelman]

7 hours ago, BetsytheRiv said:

I'm truly inspired Dave!  I had already been looking at the Sniper for my 65 - 401 but hadn't 100% committed.  My carb was replaced with an Edelbrock by my Uncle a couple years ago and despite many attempts by "experts" to dial it in it would always revert back to running rich every couple of weeks which sucks when she is my daily driver.  After seeing your post, I went hog wild with the Holley holiday sale and should have the Sniper EFI, Distributor and Ignition arriving in the next week or two.

 

The bracket I ordered was the GM Throttle adapter which I'm hoping will work without me breaking out the welder. (This is different from the one you originally listed as ordering):  https://www.holley.com/products/fuel_systems/carburetor_components/brackets_and_linkage/parts/1952

 

I'm curious why you went with the 4BBL (550-510) instead of the Quadrajet (550-867)?  First glance it may be the 650hp (yours) vs 500hp (Quadrajet) but I'm really curious if there was any other motivation since mine isn't installed yet.  

 

I was really teetering on getting the in-tank fuel pump but didn't want to get too deep into messing with the fuel system when I wasn't 100% sure on the Holley parts being compatible and/or the best fit for my 65.  She is my daily driver and I don't want to get into something I haven't completely researched and risk her being down.  

 

I drive like an old lady (at 39 y/o) in Southern California so I'm not too concerned about more power.  Most of the time I'm on city streets or in traffic on the freeways.  Kids will pull up at a light and rev their engine like they want to race and I just roll my eyes.  Clearly they don't know how much premium fuel is these days!  I remember back when I was 16 y/o leaving a car show in the 57 Thunderbird I restored and some teenage boys wanted me to light up the tires.  My dad still laughs to this day at me hanging out the window shrieking "Do you know much these wide white wall tires cost?!?!  Impressing you is not worth the wear on my tires!"  If I want to race I take my car to the track.  It's far too dangerous around here to fully enjoy the power our cars have on the city streets.  I know I can handle driving the higher power but the idiots running around here driving far too fast diddling around with the phones they're not supposed to be using while driving will put me in the grave and my poor Riv in the junkyard.  My Riv has made it 3 generations in my family and I'll do whatever it takes to keep her safe in this crazy city we live in.

 

Really appreciate the help & Happy New Year!!

If you ordered the Quadra jet injection, you will have to send it back as it will not fit. Your stock intake takes the 4BBL Dave bought. Base mounting flange is different. Your manifold has a pattern for a Carter AFB, not a Quadra jet.

[RockinRiviDad]

On 5/16/2019 at 1:29 AM, jeepsterdk said:

Hi

 

Looks great! What intake manifold do you have?

oops…kind of late…never saw this…sorry

Running unmodified stock manifold. I should do the “doc mod” to it but I haven’t. 

[RockinRiviDad]

10 hours ago, BetsytheRiv said:

I'm truly inspired Dave!  Sniper EFI, Distributor and Ignition arriving in the next week or two.

 

The bracket I ordered was the GM Throttle adapter which I'm hoping will work without me breaking out the welder

 

I'm curious why you went with the 4BBL (550-510) instead of the Quadrajet (550-867)?  First glance it may be the 650hp (yours) vs 500hp (Quadrajet)

 

I was really teetering on getting the in-tank fuel pump

 

3 generations in my family and I'll do whatever it takes to keep her safe in this crazy city we live in.

Happy New Year to u too brother & congrats on your purchase. I didn’t get the distributor yet. I probably shoulda asked Santa for that this year haha. But my Riv is running so nice now & I wanted more muscle car sound so I asked for headers instead 😬. 

 

The bracket u ordered is not gonna work if u are trying to keep the Kick Down block switch functional. There’s lots of info on Facebook on how to use a Nitrous Switch in place of the KD block if u are hard pressed to use that bracket u ordered and/or if u can’t get your KD block switch to work. 
 

Steelman is correct. The Q-jet has the spread bore base. Our stock intake manifolds are NOT spread bore. Also, the 4BBL 550-510 Throttle body I got is 800cfm not 650. My last carb that gave me troubles like yours was 600cfm. Our Nailheads LOVE cfms. I totally felt a difference in performance when I went from 600 to 800cfm’s 🕺🏻🏋🏽‍♂️
 

U don’t “need” the in-tank fuel delivery system. It’s just more efficient, quieter & will lasts longer than the external pump that comes in the kit. 
 

U should start your own thread on your Sniper install. I’m sure u will find better/other ways to skin this cat. Guys will appreciate the write-up. Don’t forget pix to prove it all. U know what they say “if no pix…it didn’t happen” 🤣

[BetsytheRiv]

11 hours ago, steelman said:

If you ordered the Quadra jet injection, you will have to send it back as it will not fit. Your stock intake takes the 4BBL Dave bought. Base mounting flange is different. Your manifold has a pattern for a Carter AFB, not a Quadra jet.

It’s a stock manifold.  I’ll contact them today and get it exchanged.  Thank you so much!

[BetsytheRiv]

7 hours ago, RockinRiviDad said:

Happy New Year to u too brother & congrats on your purchase. I didn’t get the distributor yet. I probably shoulda asked Santa for that this year haha. But my Riv is running so nice now & I wanted more muscle car sound so I asked for headers instead 😬. 

 

The bracket u ordered is not gonna work if u are trying to keep the Kick Down block switch functional. There’s lots of info on Facebook on how to use a Nitrous Switch in place of the KD block if u are hard pressed to use that bracket u ordered and/or if u can’t get your KD block switch to work. 
 

Steelman is correct. The Q-jet has the spread bore base. Our stock intake manifolds are NOT spread bore. Also, the 4BBL 550-510 Throttle body I got is 800cfm not 650. My last carb that gave me troubles like yours was 600cfm. Our Nailheads LOVE cfms. I totally felt a difference in performance when I went from 600 to 800cfm’s 🕺🏻🏋🏽‍♂️
 

U don’t “need” the in-tank fuel delivery system. It’s just more efficient, quieter & will lasts longer than the external pump that comes in the kit. 
 

U should start your own thread on your Sniper install. I’m sure u will find better/other ways to skin this cat. Guys will appreciate the write-up. Don’t forget pix to prove it all. U know what they say “if no pix…it didn’t happen” 🤣

I’m going to have to research more on the bracket.  I like the KD as it is now so I’ll have to get creative.  I’ll start the New thread.  Trust me there will be plenty of pix - nobody believed I could change oil, flush the radiator, change a battery, install a radio or any of the other things I’ve had to do to get my riv running steadily without pix to prove it...  the joys of being a girl.  😎

[RockinRiviDad]

35 minutes ago, BetsytheRiv said:

change oil, flush the radiator, change a battery, install a radio or any of the other things I’ve had to do to get my riv running steadily without pix to prove it...  the joys of being a girl.  😎

I work with a guy who knows/does very little “hands on” type stuff. Weird to me cuz we are “blue collared workers”. All the stuff u listed above are basics that most of us “guys” do while sleepwalking 😆. I read your list & only heard blah blah blah until I got to the part where u said your a GIRL 👍🏽…I’m impressed…congrats…u have my coworker BEAT 🏆 haha. I can barely get my wife in the garage to hold a part for me while I wrench it tight. She did help for 10 minutes during my header install…only cuz I was cursing so loud & she tried to get me to quiet down 🤣. 
 

I’m not very active in this forum anymore. But I started my build here 8 years ago & would like to finish my build here. I could be wrong but I don’t think we’ve had a girl on here in those 8 years. U might be a first 
 

Welcome to the forum from SoCal. I think u said your in SoCal too. U are more than welcome to come cruise with us anytime. Doing a brunch cruise this Sunday. Come on out. At 46 y/o I drive like an old lady too…kinda…ok…not really 🤣

 

[RivNut]

I have a 66 Q-jet spread bore manifold for my 64 as well as the stock square bore manifold.  Is there the same advantage for running the Q-jet Sniper set over the square bolt Sniper? Not quite there yet, but curious.

 

Ed

[RockinRiviDad]

16 minutes ago, RivNut said:

Is there the same advantage for running the Q-jet Sniper set over the square bolt Sniper? Not quite there yet, but curious.

My guess would be no.

The Q-jet Sniper is only 715cfm’s.

The square bore Sniper is 800cfm’s. 
The more cfm’s the better

[EmTee]

On 1/2/2020 at 3:44 PM, RockinRiviDad said:

The Q-jet Sniper is only 715cfm’s.

The square bore Sniper is 800cfm’s.

 

Hmmm, that's odd, given the Q-Jet carb was bigger than the Carter (due to the massive secondaries).  I'm guessing that maybe the Q-Jet Sniper has smaller primary air valves to match the manifold, but same smaller secondaries as the square bore version? 

[carbking]

I would be interested in learning how rated CFM for efi compares to rated CFM for carburetors.

 

After 60 years of playing with carburetors, the best explanation for carburetor CFM that I have seen was written by Mark Twain!

 

Jon

Edited January 4, 2020 by carbking (see edit history)

[RivNut]

1 hour ago, carbking said:

After 60 years of playing with carburetors, the best explanation for carburetor CFM that I have seen was written by Mark Twain!

 

Jon

And that is......?

[carbking]

49 minutes ago, RivNut said:

And that is......?

 

"Figures don't lie, but liars figure".

 

Quotation attributed to Mark Twain.

 

CFM

 

And to take the comment about liars even further, one company making carburetors wanted a 600 CFM for comparison with a competing brand. When engineering informed sales that since the company historically had not made a 600, new components (throttle shafts, throttle plates, venturii, etc.) would all have to be designed and machined, sales said "no problem, just take a 625 add a new id number, and sell it as a 600!

 

Jon.

Edited January 4, 2020 by carbking (see edit history)

[J3Studio]

1 hour ago, carbking said:

And to take the comment about liars even further, one company making carburetors wanted a 600 CFM for comparison with a competing brand. When engineering informed sales that since the company historically had not made a 600, new components (throttle shafts, throttle plates, venturii, etc.) would all have to be designed and machined, sales said "no problem, just take a 625 add a new id number, and sell it as a 600!

 

Yep … companies know that almost nobody has the tools or the inclination to actually measure things.

Edited January 4, 2020 by J3Studio (see edit history)

[RockinRiviDad]

In hopes to help keep others from making the same mistakes I am making, I edited my original post. Again, I was so focused on getting my throttle linkage hooked up & simply too excited to be making progress that I forgot to recheck my TPS (throttle position sensor) after fab’ing a bracket to incorporate my kickdown. My kickdown switch was limiting throttle travel to 76% @ WOT. A few days work but finally got it to 92%…I am good with that…92% gives me enough power to smoke my meats!! 🤣

[hollon]

On 5/6/2019 at 11:53 AM, RockinRiviDad said:

Update:

Another detail that I learned about my Sniper EFI TB (throttle body) is that the primaries & secondaries do not work like they do on a standard carb. My TB opens all four butterflies/barrels at the same time. They call this 1:1 linkage. Not sure if all TB fuel injected systems are the same. But I found this next topic very interesting. 

 

There is tons of info online about what is called a progressive linkage for the Sniper. Aftermarket companies sell this easy to install linkage which allows secondaries to open at about 40% (varies on some cars) of acceleration. There are a few steps to follow in order to reconfigure the software & tell the ECU what is going on & what to do. That is where my head starts to spin, my vision gets blurry & limbs go numb haha. TMI haha. I’m not that smart haha. Some guys make it sound easy & some make it sound complicated. It seems that the guys who know what they are doing are using a laptop computer to reconfigure the ECU 🤷🏻‍♂️

 

Bottom line:

Some guys LOVE the progressive linkage & claim that Holley should sell the TB’s with this setup. I agree. 

 

Most guys had issues with the setup causing their cars to run like poop. So they went back to the 1:1 linkage & reconfigured the ECU to original settings. 

 

All this to say Holley actually does NOT recommend this modification haha. So if something goes wrong it’s on the user/installer. Although, the Holley Sniper apparently has a progressive linkage option in the setup/startup menu 🤷🏻‍♂️. 

 

My car runs great with the 1:1 linkage. The only linkage issue I had was with the angle in which the throttle pedal pulled the TB linkage. I bet some guys who want to switch to the progressive linkage only want it to fix the same problem I had. But that may not be the answer. Anyway, I thought I would post this update for those interested in going with an EFI system. 

 

 

RockinRiviDad, you are truly ROCKIN!  This is the answer I have been searching for.  I just had a Holley Sniper installed on my '64 Rivi with a 425.  Right off the bat, the gas pedal was trash.  It barely moved and was all or nothing when I got it back.  In the interest of not paying someone else to tinker with it, I took it home and have been trying various modifications over the last week.  The first problem, as you pointed out, was that there was no travel in the pedal.  Even with the throttle arm threaded all the way in, I had to put deeper bends into the stock arm to shorten it.  Once there was more play, I tried various spring setups to increase tension as the accelerator was pushed.  This helped tremendously and allowed me to control the acceleration at slow speeds.  But it still goes WOT when trying to accelerate quickly.  I similarly concurred that it was the location of the throttle arm attachment on the Sniper linkage.  It should attach at a point allowing for linear movement of the linkage.  But the stock attachment point on the linkage is slightly lower than horizontal in the range of motion causing it to jump once it reaches horizontal.  This bracket setup appears to correct that and I'm planning to fabricate one next week.  

 

My one question is:  Why did you modify it by welding in the tab that moves the throttle arm attachment point closer to the Sniper?  It looks like the stock bracket would work just fine as is and the throttle arm has tons of side to side play in it.  Was there a clearance issue or a conflict with the kickdown setup?

 

Your posts and additional feedback are greatly appreciated!

[BulldogDriver]

My Sniper install is as clean as could be done with a 4L60E transmission that needs a TPS remotely mounted, and a cable for the Rostra cruise control. The bracket for the cables had to be widen by 1/2” due to our Nailheads using the inner mount holes. 
 

Ray

[RockinRiviDad]

On 10/9/2020 at 1:11 PM, hollon said:

 

 

RockinRiviDad, you are truly ROCKIN!  This is the answer I have been searching for.  I just had a Holley Sniper installed on my '64 Rivi with a 425. 

 

My one question is:  Why did you modify it by welding in the tab that moves the throttle arm attachment point closer to the Sniper?  It looks like the stock bracket would work just fine as is and the throttle arm has tons of side to side play in it.  Was there a clearance issue or a conflict with the kickdown setup?

 

Your posts and additional feedback are greatly appreciated!

 

Your funny...I’m glad this helped. Congrats on your Sniper install 

 

I decided to make my throttle mounting point on the bracket a little closer to the sniper due to my aftermarket air cleaner. It used to hit my hood when hood was closed. I found a low profile air cleaner base which allowed my air cleaner to sit lower. A lower air cleaner base meant I didn’t have much room to change the geometry of my throttle linkage by simply raising it up, I also had to go inward. That & a little persuasion with my ball peen hammer on the air cleaner base & wah-lah...it worked

 

Somewhere in this thread I added another idea for someone to try. That was to simply cut off the the mounting hole tab, rotate it 180 degrees & weld it. I think that would have eliminated the need for u to shorten your linkage with extra bends.

 

I’m glad u posted your details. The guys who follow our lead will make less & less mistakes. DON’T forget to keep checking your TPS (throttle position sensor). 

 

Keep us posted on the bracket u fab up. Maybe u will create something better than mine

[RockinRiviDad]

On 10/9/2020 at 4:13 PM, BulldogDriver said:

My Sniper install is as clean as could be done with a 4L60E transmission that needs a TPS remotely mounted, and a cable for the Rostra cruise control. The bracket for the cables had to be widen by 1/2” due to our Nailheads using the inner mount holes. 

 

Congrats, I agree. Looks like very clean work. Looks like a high dollar build done right (unlike my shoddy a$$ DIY work 😀). 

 

It also looks brand new, as in “not driven” yet. Have u had a chance to drive it? I am interested to hear how your setup performed. It doesn't look like the throttle geometry was addressed. Your throttle linkage looks parallel to valve covers. We had to raise ours up some so that it would pull Sniper linkage from slightly higher. U might find u have the same issues as we did. 

 

Keep us posted 

[BulldogDriver]

Price of parts for Sniper EFI is the same for everyone unless you have friends in high places. All work has been done at home myself with common tools and a lot of elbow grease. Only things I’ve farmed out are the transmission, rebuild of steering box, booster, master cylinder resleeved, and welding. Would have done the engine myself but didn’t  feel comfortable with machine shops in my area so it went to a trusted builder I’ve know for 40 years. All of their work is done in house. 
 

I hadn’t addressed the throttle rod height when the photo was taken. Here is my solution for short throw on the Sniper. This bracket will give an additional 3/4” distance on the linkage which is the most I could get using a lowered air cleaner base. Can be made with a file, drill, and hacksaw. If you want a pattern email me your address and and I’ll get a template to you. It also gives you a way to attach the cruise control cable if you go aftermarket. Everything is close but nothing touches. 
 

Ray

[RockinRiviDad]

On 10/13/2020 at 1:52 PM, BulldogDriver said:

Price of parts for Sniper EFI is the same for everyone unless you have friends in high places.
 

This bracket will give an additional 3/4” distance on the linkage.
 

a way to attach the cruise control cable if you go aftermarket.

I do happen to have a friend in high places. 
 

Nice bracket. So have u had a chance drive it & test your creation?

 

Cruise control? Hmmm…now there’s an idea. I never thought of that. I will look into that 

[Bill Stoneberg]

1 hour ago, RockinRiviDad said:

I do happen to have a friend in high places. 
 

Nice bracket. So have u had a chance drive it & test your creation?

 

Cruise control? Hmmm…now there’s an idea. I never thought of that. I will look into that 

Look at Dakota Digital Cruise Control.  I have it on my 1960 Electra and it works great.  Other friends have it on their 55 Buick’s or on his 64 Riviera (also with Sniper EFI).

[BulldogDriver]

Haven’t driven it yet, still working on drive shaft setup. Hoping to run it sometime next week. I don’t see anything major being a problem with my setup. Engine has been run in, others have done 700R4/4L60E trans conversions, AC and Cruise Control are pretty much a plug and play thing these days. Biggest concern is EMI issues with the Sniper EFI. I’ve done some shielding of the wire harness as a precaution but my placement of the coil and closeness of the wiring harness to the distributor might dictate more shielding.

 

I believe that Rostra is Dakota Digital’s cruise control. With everything that I’ve done to this car, new cruise control was a given. I hid the control panel in the ashtray and left the original cruise switch in place so the interior still looks original. 
 

Ray

[RockinRiviDad]

Very exciting. Good luck.
 

I see that u installed what looks like the Holley Hyperspark too. U will probably have RFI/EMI issues. I did. Tech support had me wrap my dizzy in tin foil & it worked. That was just to isolate/troubleshoot where is was coming from. They said my air cleaner was acting as an antenna between the Sniper ECU, Hyperspark & Holley coil (old style coil, mounted in stock location). So they had me add a ground wire to the base of my air. Problem solved. Weird. I’m learning a lot. 

[telriv]

ALSO the metal stud that holds down the air cleaner acts as an antenna & applify's the signal. Use a plastic stud

[RappinRickRivi]

Hello everyone, I know this thread is a few years old but thought I’d try to reach out for some guidance. I am installing a Aces Killshot on my 401 nailhead (65 Riviera) and am unsure if I need to connect the hard lines for choke on this Efi setup or if I need to plug the exhaust manifold hole and lower tube access points? Any help would be much appreciated!!

[EmTee]

What do the instructions say?  It's hard to imagine that an EFI throttle body would require the old carburetor choke heat tube...  From where does the EFI get its engine temperature reading?

[RappinRickRivi]

Well I’m certain it is not going to run on vacuum, my main concern is whether I need to plug the holes or not due to performance issues or hazards? The manifolds are in good working order so the inner tubes have no leak issue that I’m aware of.

[RappinRickRivi]

I’m sorry the temp reading will come from the intake manifold where it collects data sent to the computer module.

[EmTee]

There's no vacuum and shouldn't be any exhaust in that choke heat tube.  You should be able to simply remove it.

[Bloo]

Although, it might just be a tube carrying clean air through the exhaust gases in the exhaust manifold (to warm the clean air) rather than a proper choke stove. If it *is* just a piece of steel tubing traveling through the hot exhaust gases, then removing it might leave 2 holes into the exhaust in the manifold you would need to plug. They wouldn't be vacuum. They would be exhaust leaks.

 

As @EmTee already mentioned, there's no vacuum. The tiny bit of vacuum it originally had was supplied from the carburetor end to help move clean hot air up the tube.

[RappinRickRivi]

Thank you guys, this information is very helpful. I think my best bet would be to plug them in a way that would allow me to revert back in case I ever wanted to return it back to stock in the future. I really appreciate it!

[NTX5467]

Curious, what makes the Aces item a better option to the Holley Sniper item?  Just curious.

 

One thing which always bugged me about the 4bbl TBI EFI units was their 1000cfm potential airflow on an engine whose prior carb was more like 650cfm.  If all of those big throttle plates open in unison, seemed like it would cause a huge bog at lower rpms, like a QJet whose secondary spring tension was zilch.  Is that a valid presumption?

 

Thanks,,

NTX5467

[RivNut]

There is a tube within the exhaust manifold that has the air passing through it heated for the choke. NO exhaust gasses go into the tube, therefore there is no exhaust gas leak when the steel tube from the manifold to the carb is removed. 25 years ago I put an electric choke on the AFB on my 63 and never experienced an exhaust leak. 25 years ago, this 63 Riviera was just another used car that was my daily driver. Drove it that way until 175K miles of use brought a bunch of problems to a head all at once.  It’s sitting in a garage awaiting some TLC. 

Edited July 28, 2023 by RivNut (see edit history)