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  Topic Review (Newest First)
10-01-2019 10:44 AM
FearlessAZ I think they realized this in the description cause if you look at the XFlows on Holley's website, it is right in the short description now before clicking on a specific one. You are right though that it should be stated better rather than buried in tech specs.

The extension makes it way more linear instead of hard toe in. I was reading around the Sniper forum (SO MUCH KNOWLEDGE) and they said the difference is the Sniper throttle linkage is smaller than a standard carb like a normal Holley or Edelbrock. It basically lifts the throttle linkage up a bit. Probably geometry too. Mine was doing kinda similar to what you described except for the stalling part. I would be driving though the neighborhood or stopped at a light and would try to ease in to the throttle but that super stiffness. Made it so I was kind of reving at other cars or reving in front of houses with super minimal effort. With that little extension, it felt like normal again.

My coworker has the Sniper set up on him late 60s Mustang and early 80s Cutlass and he has the same issue with both. He tried this extension on the Cutlass as a test subject for us and said it solved this same issue. Think he already ordered the same part for his Mustang. These were all auto vehicles so I would hope this helps a manual as well.

Really wish Holley would note this somewhere in their instructions or mention the possible issue. Shouldn't have to dig around a forum for that. I mean, it is a Holley part after all.
10-01-2019 09:47 AM
68WASAGOODYEAR
Quote:
Originally Posted by FearlessAZ View Post
Under the Tech Specs for the Sniper, it states 800 CFM. The newer XFlow unit flows 900 CFM. The newer XFlow does start at like $1300 for just the TBI unit.

I know your build is completely different than mine. Can't imagine how much harder it is with the manual.

Did yours have the issue with a touchy toe in off idle? I installed that throttle lever extension and man, what a world of difference on the drivability. I debated that progressive linkage to help a bit with cruising but haven't had any issues yet.

Once I do heads, cam and rebuild on the 400, I will do a custom tune. I can't see myself doing that until a little farther down the road.
You are correct about the 800 cfm being shown in the tech specs. I just wish they advertised that a little more up front - they only really talk about it supporting 650 hp. My engine makes 585 hp, so I didn't give it a second thought. As it turns out, I only need 830 cfm for my engine (not 870 as previously shown), so I'm OK with just 800.

The car was almost undriveable with the 1:1 linkage and manual transmission. The gas pedal was very stiff. In first gear I'd be trying to ease into the throttle, but the pedal just wouldn't move. Since I was slowing down, the car would then start to buck like it was going to stall so I would give the pedal more pressure and then BAM the tires would break loose. Engaging the clutch was a nightmare too. The progressive linkage really helped and I might try the extension as well.
10-01-2019 09:34 AM
FearlessAZ Under the Tech Specs for the Sniper, it states 800 CFM. The newer XFlow unit flows 900 CFM. The newer XFlow does start at like $1300 for just the TBI unit.

I know your build is completely different than mine. Can't imagine how much harder it is with the manual.

Did yours have the issue with a touchy toe in off idle? I installed that throttle lever extension and man, what a world of difference on the drivability. I debated that progressive linkage to help a bit with cruising but haven't had any issues yet.

Once I do heads, cam and rebuild on the 400, I will do a custom tune. I can't see myself doing that until a little farther down the road.
09-30-2019 10:51 AM
68WASAGOODYEAR I *think* I might have gotten all the bugs out of the EFI. Here are some final thoughts for anyone looking to do this as an upgrade:

1) Create a username and join the Holley Sniper forum
2) If you have a manual transmission, switch to the progressive linkage and perform the associated changes in the handheld (see forum for how-to)
3) Do not buy the Sniper master install kit. Do yourself a favor and get a seperate in-tank electric fuel pump. EFISystemPro.com.
4) You need a properly vented fuel tank. The fuel return line was enough to close the rollover vent I installed in my tank, which pressurized the tank and caused all sorts of weird issues with the EFI.
5) You will need a throttle return bracket and spring
6) Install an Innovate Motorsports (P/N HBX-1) bung extender/heat sink. This will prolong the life of the O2 sensor and prevent erroneous readings.
7) Keep the Sniper cables away from your spark plug wires. The Sniper is very susceptible to electronic interference. I used MSD plug wires with the insulation that minimizes interference as well as wrapped the Sniper cables in EMI tape and clipped them as far away from the plug and coil wires as I could.
8) Plan on spending an additional $500 or so having the Sniper properly tuned. This requires a dyno, laptop with software, and of course the know - how. I'm sure there is a vanilla 350 SBC out there that is just fine with the stock tune, but my engine required a full custom tune with fuel mapping, etc.
9) The Sniper only supports up to 800 CFM!!! This is not advertised anywhere that I could find. I heard this posted on the forum. The product literature says it supports up to 650 hp. This is not a deal breaker for me even though my 496 needs 870 CFM. I'm not racing the car; I'm just giving up some hp. If you need more, you need to look into the Terminator 950 or new dual quad Sniper set up they just released, which I'm sure is an absolute nightmare to get set up properly and is way more expensive.

I don't mean to dissuade anyone looking to do this mod. I'm sure I'll be happy with it in the long run. Just wanted to put this out there. It might have changed my mind.
09-20-2019 06:35 PM
68WASAGOODYEAR I did install the progressive link on mine. It's more or less required with a manual transmission, otherwise the drivability suffers. You also have to change a setting in the handheld to enable this and also remap the acceleration enrichment vs. TPS in the Sniper software to get the full effect of this. I'm reinstalling the sniper now...

I'm still using a throttle rod, just updated with heim joints on either end.
09-20-2019 10:54 AM
lovebohn I have the other TB, but did install that linkage adapter on mine since it was super touchy at idle and with all the power it make start interesting. The new adapter did really help but it has the linkage rod hit the firewall now at the very end of the throttle travel. I"m taking a 1/4" max of WOT which isn't a big deal.

I might try a wire throttle compared to the linkage, anyone update theirs to a cable before?
09-20-2019 10:46 AM
FearlessAZ I finally got around to having my sniper unit installed on my 70. Been good so far. Only problem I have is that stiff toe in off idle. Not so bad at cruising speed. I did read through quite a few posts on the Holley forum that discuss this same problem as well as talking to a coworker who has this setup on his late 60s Mustang and early 80s cutlass.

Some of the posts talked about the linkage on the sniper being smaller than a typical carb. Holley has a bracket extender that is supposed to make that throttle more linear instead super stiff off idle. The coworker also mentioned that he put a different return spring so it isn't as stiff.

EDIT: Here is the link to the throttle lever extension
https://www.holley.com/products/fuel...BoCYvUQAvD_BwE


I only have about 50 miles on this new setup but haven't noticed anything out of the ordinary yet.
09-17-2019 08:48 PM
68WASAGOODYEAR I have posted it on the Sniper forum (same user name) and gotten some feedback, but nothing I hadn't already checked. I did hear back from Holley and they said they had been able to "recover" the ECU and that the unit had passed all their tests. They're shipping it back to me. So I'm back to square one in terms of troubleshooting the issue and preventing a recurrence.
09-17-2019 05:09 PM
lovebohn Have you posted the problem on the Holley forum? I had a few bugs on the first setup, but a quick forum post and working with the person I bought it from solved the problem now. Sure I could and will tweak it some more when I can do a dyno tune, but I have zero regrets on spending the time and money on the EFI setup. I might even go the dual quad Sniper install this winter on a SBC update.
09-13-2019 09:02 PM
68WASAGOODYEAR The rear axle is set up and good to go, which was the last big step. I have had nothing but problems with the EFI and have sent it back to Holley again for repair. At this point, I do not recommend it. It is definitely not a reliability upgrade over a carburetor. I've only driven the car outside my neighborhood a half dozen times, and it's left me stranded twice already, once requiring a tow home. I want to believe, but my confidence in the system is seriously rattled and I'm not sure I'll ever be able to drive the car without fearing its getting ready to shut down due to some electronic gizmo in the EFI randomly deciding it wants to ruin my day.

I'm giving it one more chance and then I'll be scrapping the damn thing and going with a carburetor. If it was self - tuning like they say, there wouldn't be a Holley forum full of guys who can't figure out how to get their cars running right.

Attached are some pics - it's done at this point with the exception of the fuel delivery. Lessons learned:

1) EFI sucks. Nothing but a headache.
2) I had nothing but problems with the PTFE thread sealer as well. It leaked everywhere I used it. Coolant and oil. Replaced it with Teflon tape and haven't had any problems.
3) Retorque all fasteners after the first few times you drive the car.
09-13-2019 11:54 AM
lovebohn How has everything turned out? Did you get your rough idle fixed? I have a similar setup with a 502 and terminator EFI.
08-22-2019 03:01 PM
68WASAGOODYEAR
Quote:
Originally Posted by justjohn View Post
I think the only difference between our power plants is fans. I have a Griffin radiator with their dual electric fans. With AC on, mine creeps up to 200 sitting in traffic.
I'm going to add an electric 3000 cfm Flex-a-Lite auxiliary pusher fan on the front of the radiator and use the ECU to activate it above 200 degrees. This should do the trick. I don't want to convert over entirely to efans as the mechanical fan does just fine at speed.
08-22-2019 01:04 PM
justjohn I think the only difference between our power plants is fans. I have a Griffin radiator with their dual electric fans. With AC on, mine creeps up to 200 sitting in traffic.
08-21-2019 05:04 PM
68WASAGOODYEAR Drove the car today and unfortunately ended up sitting in traffic, which I try to avoid at all costs.
The temp guage started to creep up and got to 225 before I was able to get moving. Once moving at a steady speed, it came down to 180 or so.

Do I need efans? Everything is brand new - water pump, the biggest, baddest cooling pack made by U.S. Radiator, mechanical fan, fresh coolant, etc. I'm not sure what else I could have done to avoid an overheating issue....

Thanks for any replies.
08-17-2019 08:48 PM
68WASAGOODYEAR Any idea why my starter would make a grinding sound when starting the car? Only does this intermittently. Same sound as when you try to start it when it's already running. Whenever it does this, I key off and start over and it is fine...Thanks for any replies.

She's in the shop now getting new tires, exhaust, and a re-gear. Pics to follow and lessons learned. What a long, strange trip is been...
08-12-2019 04:38 PM
68WASAGOODYEAR
Quote:
Originally Posted by justjohn View Post
Quote:
Originally Posted by 68WASAGOODYEAR View Post
Drove it today around my neighborhood. Still have a few kinks to work out. Here they are:

1) Idle quality is terrible. Sounds like a Harley and the entire car shakes. Going to have to call Holley tech support on Monday.

2) Throttle is very stiff and unforgiving. I put increasing pressure on the peddle to no effect and then suddenly - BAM. Tire chirps. Will mention this to Holley.

3) Something sounds like it is repeatedly smacking the underside of the car on the driver side with a hammer. It's especially bad in a left turn. No idea. Will have to take the wheel off and have a look.

4) Oil pressure is staying around 60 psi. Very little movement of the needle. Again, no idea. The fuel pressure guage also says 0 psi, which can't be right for obvious reasons. Electrical Gremlins. Fun.

Nothing disastrous. No leaks either, which I'm very happy about. Any thoughts on the above are appreciated. Pics to come.
This is a self-tuning system? Holley is probably going to tell you to drive it some more on the first call.
The rough idle is due in part to my O2 sensor placement: too close to the engine and needs to be further downstream. Will fix this at the exhaust shop. The stiff pedal is discussed here

https://forums.holley.com/showthread...I-WAAAY-Better

and there is a fix. I have ordered the linkage and will report back if it works. Apparently it's more or less required for manual transmissions.

The thumping sounds are an interference between the driveshaft and body. Crawling under there tonight...
08-12-2019 09:55 AM
justjohn
Quote:
Originally Posted by 68WASAGOODYEAR View Post
Drove it today around my neighborhood. Still have a few kinks to work out. Here they are:

1) Idle quality is terrible. Sounds like a Harley and the entire car shakes. Going to have to call Holley tech support on Monday.

2) Throttle is very stiff and unforgiving. I put increasing pressure on the peddle to no effect and then suddenly - BAM. Tire chirps. Will mention this to Holley.

3) Something sounds like it is repeatedly smacking the underside of the car on the driver side with a hammer. It's especially bad in a left turn. No idea. Will have to take the wheel off and have a look.

4) Oil pressure is staying around 60 psi. Very little movement of the needle. Again, no idea. The fuel pressure guage also says 0 psi, which can't be right for obvious reasons. Electrical Gremlins. Fun.

Nothing disastrous. No leaks either, which I'm very happy about. Any thoughts on the above are appreciated. Pics to come.
This is a self-tuning system? Holley is probably going to tell you to drive it some more on the first call.
08-10-2019 05:46 PM
68WASAGOODYEAR Drove it today around my neighborhood. Still have a few kinks to work out. Here they are:

1) Idle quality is terrible. Sounds like a Harley and the entire car shakes. Going to have to call Holley tech support on Monday.

2) Throttle is very stiff and unforgiving. I put increasing pressure on the peddle to no effect and then suddenly - BAM. Tire chirps. Will mention this to Holley.

3) Something sounds like it is repeatedly smacking the underside of the car on the driver side with a hammer. It's especially bad in a left turn. No idea. Will have to take the wheel off and have a look.

4) Oil pressure is staying around 60 psi. Very little movement of the needle. Again, no idea. The fuel pressure guage also says 0 psi, which can't be right for obvious reasons. Electrical Gremlins. Fun.

Nothing disastrous. No leaks either, which I'm very happy about. Any thoughts on the above are appreciated. Pics to come.
08-06-2019 02:30 PM
justjohn
Quote:
Originally Posted by 68WASAGOODYEAR View Post
Wired it up as shown in the video and had no problems. She's running now. Hopefully will have video soon.
Looking forward to seeing your impressions. This is a winter project for me.
08-06-2019 11:18 AM
68WASAGOODYEAR Wired it up as shown in the video and had no problems. She's running now. Hopefully will have video soon.
07-31-2019 03:02 PM
68WASAGOODYEAR Good grief. Watch 30 seconds of this video starting at 7:55. The Holley guy doing the install sees the SAME EXACT voltage drop I'm seeing during cranking and doesn't bat an eye. The car fires right up. 12V needed during cranking my ***. All this running around and overthinking the issue. Oh well. Hopefully this helps someone avoid all the nonsense.

https://youtu.be/1mIhs4xahBY
07-30-2019 12:52 PM
Big Dave Like I said earlier the original starter (direct drive permanent magnet starter) with the added windings found in a high torque starter will drop a 12 Volts battery down to 8 Volts. You are ahead of the game with a mini-gear drive starter that doesn't draw as much current.

Big Dave
07-30-2019 11:23 AM
68WASAGOODYEAR
Quote:
Originally Posted by justjohn View Post
Quote:
Originally Posted by Big Dave View Post
You can get 12 Volts while cranking you just need a bigger battery:

https://www.foreverpureplace.com/24-...24-85-25-b.htm

But in all seriousness there is a special 16 Volt battery that racers use to run EFI on a race car. Battery has dual circuitry so that it never gets below 12 volts. Does require a charger that plugs into 110V AC household circuit to keep it charged.

https://lifelinebatteries.com/produc...s/ll-161240tb/

Big Dave
Seems simple enough...

I still can't believe Holley requires a minimum 12v during cranking. One of our engineers provides tech service to them, I see if he can get a definitive answer.
I spoke with holley tech support on the phone yesterday evening about the voltage drop and the voltage requirements of the EFI. They said there will obviously be some voltage drop during cranking, but that the amount I'm seeing (approx. 12.5V down to around 10.5V during cranking) seems excessive and that I should be fine with 11.0V+ for the EFI during cranking.

They suggested checking all my grounds, so I'll start there I guess. I have been hyper-vigilant about grounds and I'm pretty confident in them; all new grounds and even the old ones I've run across were taken down to bare metal, a ring terminal with splice melt attached to the ground wire, bolted to the bare metal, and covered in liquid electrical tape to seal /insulate the ground. All new ground straps were added during the engine swap as well. These were missing before.

I don't think it's the starter either; it's a new Summit high-torque mini starter which shouldn't cause that big of a drop.

Thanks for all the replies. This is the last thing before I can fire it up so it is super - frustrating.
07-30-2019 09:09 AM
justjohn
Quote:
Originally Posted by Big Dave View Post
You can get 12 Volts while cranking you just need a bigger battery:

https://www.foreverpureplace.com/24-...24-85-25-b.htm

But in all seriousness there is a special 16 Volt battery that racers use to run EFI on a race car. Battery has dual circuitry so that it never gets below 12 volts. Does require a charger that plugs into 110V AC household circuit to keep it charged.

https://lifelinebatteries.com/produc...s/ll-161240tb/

Big Dave
Seems simple enough...

I still can't believe Holley requires a minimum 12v during cranking. One of our engineers provides tech service to them, I see if he can get a definitive answer.
07-29-2019 12:55 PM
Big Dave
Quote:
Originally Posted by justjohn View Post
I think getting a dedicated circuit should be no issue but you'll never get a solid 12v during crank. The system just isn't designed that way.
You can get 12 Volts while cranking you just need a bigger battery:

https://www.foreverpureplace.com/24-...24-85-25-b.htm

But in all seriousness there is a special 16 Volt battery that racers use to run EFI on a race car. Battery has dual circuitry so that it never gets below 12 volts. Does require a charger that plugs into 110V AC household circuit to keep it charged.

https://lifelinebatteries.com/produc...s/ll-161240tb/

Big Dave
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