The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 07-12-2018, 12:29 PM   #101
Ekliptix
Registered User
 
Ekliptix's Avatar
 
Join Date: Aug 2013
Location: Calgary, Alberta
Posts: 673
Re: Install thread- Holley EFI Sniper on '72 402 big block

Weird, I'm not sure what the second port is used for on yours.

Last night I installed my first starter. Got it lined up and done. Was a tight fit and lesson in patience trying to do it all on jack stands.

Fired up first try. https://youtu.be/J5CxfMAJR5U

To do:
1) check for vacuum leaks.
2) determine why distributor is unreliable to deliver spark to each plug. Potentially replace distributor or at least, distributor cap.
3) figure out why brakes are so weak. This has been an issue since the 350-->402 swap. It may be the vacuum is too low, or another reasons.
4) install converter lock up wire + switch to 700R4. The vacuum line does not seem to engage the lock up, currently.
__________________
1972 Cheyenne Super SWB PS, PB, Tach, A/C, Tilt.
Drivetrain: Built 402BB, TCI Streetfighter 700R4, 2,500 stall, Eaton posi, 3.73. Suspension/Chassis: ECE 4.5/6.5 drop, CPP nitrogen shocks, CPP front and rear sway bar, CPP cross members. Exhaust: 3" exhaust with x-pipe, Spintech 3000 mufflers, Hooker ceramic coated headers. Best 1/4 mile time: TBD.
Ekliptix is offline   Reply With Quote
Old 07-12-2018, 05:06 PM   #102
driller35
Senior Member
 
driller35's Avatar
 
Join Date: Aug 2009
Location: Calgary,AB
Posts: 323
Re: Install thread- Holley EFI Sniper on '72 402 big block

Well good to hear you got back up and running , yes I would think with your lower vacuum, is giving your braking issues , is it possible for dizzy to be out one cog? if it dropped right into place after you changed out intake then I would think not

The ports believed by one fellow board member is one for gage the other for temp light as different gage packages used either side for sensor ,7 hole gage package drivers side , 3 hole gage package idiot light passenger side
__________________
72 Chev Cheyenne Super SB 4x4 350,4spd,buckets, tilt,tach,am-fm,extreme tow hooks,Canadian Model Production 1 of 52 SOLD

70 Chev CST, 350 auto, PS, PB, AC, tach
driller35 is offline   Reply With Quote
Old 07-12-2018, 09:03 PM   #103
Steeveedee
Who Changed This?
 
Steeveedee's Avatar
 
Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,019
Re: Install thread- Holley EFI Sniper on '72 402 big block

Check your rotor to see if it has a burn through. This is common with the HEI. If you have a badly worn plug or high resistance wire, the spark has to go somewhere. It can actually burn a hole through the rotor. Put a couple of drops of gas in the well below the center electrode and look for a wet spot, if the hole isn't obvious. The scorching of the plastic of the rotor can also make ready paths to other spark plug terminals in the distributor cap. It is possible that there is carbon tracking in the cap, from a worn button. You may not be able to see them with a black cap, but they would show up well on a red or brown cap. To be honest, the truck didn't sound that bad. One thing I did notice was a bog when you blipped the throttle. I see in this thread that there is provision from Holley for progressive linkage. I would use it, personally.

As for "weak" brakes, do you mean a hard pedal? If so, that's going to be a vacuum leak, I'll bet.
__________________
~Steven

'70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper

Simi Valley, CA
Steeveedee is offline   Reply With Quote
Old 07-12-2018, 10:50 PM   #104
Boog
laying low
 
Boog's Avatar
 
Join Date: Mar 2001
Location: Searcy, Ark. USA
Posts: 12,889
Re: Install thread- Holley EFI Sniper on '72 402 big block

I think he said it only has 6" of vacuum. That's not enough for power brakes. Either that is a real radical cam or there is a leak. It could even be the power brake booster leaking. I once had a spring in a booster break and the broken end of the spring wore a hole in the diaphragm which began to leak. It finally got bad enough I could hear the leak when I leaned up near the booster. The truck also idled like it had a large cam in it too but it was bone stock.
__________________
Boog
69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver
primer is finer
91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said.

I stand for the flag and kneel at the cross
Boog is offline   Reply With Quote
Old 07-13-2018, 12:43 PM   #105
driller35
Senior Member
 
driller35's Avatar
 
Join Date: Aug 2009
Location: Calgary,AB
Posts: 323
Re: Install thread- Holley EFI Sniper on '72 402 big block

Ekliptix, I have one of these progressive linkage parts Holley part number 20-54, if you want to try your more than welcome to, the sniper tuner allows for it thru my reading but Holley doesn't recommend at this time using it , some say it works others say it doesn't
__________________
72 Chev Cheyenne Super SB 4x4 350,4spd,buckets, tilt,tach,am-fm,extreme tow hooks,Canadian Model Production 1 of 52 SOLD

70 Chev CST, 350 auto, PS, PB, AC, tach
driller35 is offline   Reply With Quote
Old 07-13-2018, 04:04 PM   #106
Steeveedee
Who Changed This?
 
Steeveedee's Avatar
 
Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,019
Re: Install thread- Holley EFI Sniper on '72 402 big block

Quote:
Originally Posted by Boog View Post
I think he said it only has 6" of vacuum. That's not enough for power brakes. Either that is a real radical cam or there is a leak. It could even be the power brake booster leaking. I once had a spring in a booster break and the broken end of the spring wore a hole in the diaphragm which began to leak. It finally got bad enough I could hear the leak when I leaned up near the booster. The truck also idled like it had a large cam in it too but it was bone stock.
I get that he has low vacuum now, but was curious what it was like before the FI went on. I don't think that the FI is at fault for the weak brakes, if it was that way before.
__________________
~Steven

'70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper

Simi Valley, CA
Steeveedee is offline   Reply With Quote
Old 07-16-2018, 10:41 AM   #107
Ekliptix
Registered User
 
Ekliptix's Avatar
 
Join Date: Aug 2013
Location: Calgary, Alberta
Posts: 673
Re: Install thread- Holley EFI Sniper on '72 402 big block

I spent some time with the distributor yesterday. I'm back at square 1. Won't start.

Trouble shooting:
1) inspected the cap and rotor. Looks fine. (pics below).
2) turned the dist 1 tooth (clockwise), as suggested by some ppl as I had the cap way advanced to get the truck to run. Result: Won't start.
2) took my spare distributor, installed the spare dist cap on the current base. Result: Won't start.
3) installed the spare dist base + spare dist cap. Result: Won't start.
4) returned to the previous tooth position (counterclockwise) with the spare dist + spare cap. Result: Won't start.

Then I gave up for the day. I still suspect something is up with the spark. I had the timing light setup while trying to turn the engine over and it'd only flash some revolutions, not all.

I also checked a few vacuum things. I used my lungs to provide some vacuum. To the vacuum gauge, I was able to see ~9inches using my lungs. That was my baseline to compare with how much vacuum I could yield with other lines.
- The brake vacuum line, I could get ~4inches until it felt like a valve opened. Blowing (applying pressure), brake vacuum line was 100% sealed and would not take any air going in.
- The dist advance line took ~5inches of vacuum until it sounded like a diagram engaged.




Ekliptix is offline   Reply With Quote
Old 07-16-2018, 10:46 AM   #108
davepl
Registered User
 
davepl's Avatar
 
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
Re: Install thread- Holley EFI Sniper on '72 402 big block

Sorry to jump in near the end without reading all 100 posts first, but I wanted to throw out one thing:

The Holley EFI will not work well at all on a manifold with a split plenum (where it's divided right up to the carb). You have to open up that separator if you have one.

Any chance you have a split plenum like that? Because an intake like this will NOT work well at all:

__________________
1970 GMC Sierra Grande Custom Camper - Built, not Bought
1969 Pontiac 2+2 427/390 4-speed Coupe
1969 Pontiac 2+2 427/390 4-speed Convertible
davepl is offline   Reply With Quote
Old 07-16-2018, 11:01 AM   #109
Ekliptix
Registered User
 
Ekliptix's Avatar
 
Join Date: Aug 2013
Location: Calgary, Alberta
Posts: 673
Re: Install thread- Holley EFI Sniper on '72 402 big block

Mine has an open gap between the left and right, so there's no risk of that.
__________________
1972 Cheyenne Super SWB PS, PB, Tach, A/C, Tilt.
Drivetrain: Built 402BB, TCI Streetfighter 700R4, 2,500 stall, Eaton posi, 3.73. Suspension/Chassis: ECE 4.5/6.5 drop, CPP nitrogen shocks, CPP front and rear sway bar, CPP cross members. Exhaust: 3" exhaust with x-pipe, Spintech 3000 mufflers, Hooker ceramic coated headers. Best 1/4 mile time: TBD.
Ekliptix is offline   Reply With Quote
Old 07-16-2018, 11:15 AM   #110
54Caddy
GM Addicted
 
54Caddy's Avatar
 
Join Date: Jan 2009
Location: Visalia, Ca
Posts: 2,291
Re: Install thread- Holley EFI Sniper on '72 402 big block

If your wiring isn’t good go the tach signal the EFI will never fire off. Also check connections on battery. Ask me how I know hahaha. On the Nova I did last Sniper install on it would randomly shut off or not start. Battery connections from efi directly to battery from efi had high resistance just in the terminals. Very strange. Replaced them all problems went away.
__________________
..Mac’s Garage..
73 GMC, 54 Caddy, 2010 Silverado, 68 C10 RIP DAd

My 73 GMC Truck Build Pic
2010 Silverado 4/6 on 24s

IG:MacsGarage
54Caddy is offline   Reply With Quote
Old 09-03-2018, 03:18 PM   #111
Ekliptix
Registered User
 
Ekliptix's Avatar
 
Join Date: Aug 2013
Location: Calgary, Alberta
Posts: 673
Re: Install thread- Holley EFI Sniper on '72 402 big block

Great news. I managed to get the gentleman over who did the 350-->402 engine swap in my truck. We did the same timing check of #1 cylinder TDC, check the rotor direction, etc. The distributor appeared 1 tooth out so we pulled the distributor and rotated it 1 tooth. It started up. He adjusted the timing to 14 degrees advanced on the balancer. Done. It took 20 minutes. I'd tried this all before, alone, but I'll notch the 1-tooth-off on the distributor gear due to my inexperience.

I drove the truck for the first time in ~8 months, now with the EFI working. I made a drive to a classic drive in burger joint in town. I can't say how happy I am having this thing back on the road and with the EFI working as it should, after fixing my error with the timing.

It's definitely making more power, it idles 'too good' can barely hear the cam now. I did have to adjust the throttle cable/kickdown bracket to allow for 100% WOT from the floor peddle. It is really sensitive to throttle at low RPM so I may have to buy that part people have mentioned to solve this.

Next: drive 3 hrs to the drag strip and do some passes with drag radials. If I can dip into the 13's I will have met my 1/4 mi goal.

Maiden voyage with EFI. So happy.


A little wood prep for winter after I got home.

__________________
1972 Cheyenne Super SWB PS, PB, Tach, A/C, Tilt.
Drivetrain: Built 402BB, TCI Streetfighter 700R4, 2,500 stall, Eaton posi, 3.73. Suspension/Chassis: ECE 4.5/6.5 drop, CPP nitrogen shocks, CPP front and rear sway bar, CPP cross members. Exhaust: 3" exhaust with x-pipe, Spintech 3000 mufflers, Hooker ceramic coated headers. Best 1/4 mile time: TBD.
Ekliptix is offline   Reply With Quote
Old 09-03-2018, 04:50 PM   #112
Aus69c20
Registered User
 
Aus69c20's Avatar
 
Join Date: Jun 2015
Location: Melbourne, Australia
Posts: 231
Re: Install thread- Holley EFI Sniper on '72 402 big block

Good to hear you’ve got your issues sorted now.
Though it has for others, the progressive throttle didn’t work well for me. I just made up a small extension for the throttle and that helped the over sensitivity.
__________________
John

69 c20, 396, th400, dana60, ps, ac
Aus69c20 is offline   Reply With Quote
Old 09-03-2018, 05:25 PM   #113
mkmc69
Senior Member
 
mkmc69's Avatar
 
Join Date: Jan 2009
Location: Logansport,In
Posts: 544
Re: Install thread- Holley EFI Sniper on '72 402 big block

That's great, that you got the bugs worked out. What cam are you running, if you don't mind me asking?
mkmc69 is offline   Reply With Quote
Old 09-03-2018, 06:51 PM   #114
nlped
Senior Member
 
nlped's Avatar
 
Join Date: Jul 2009
Location: Hayden, Al.
Posts: 4,147
Re: Install thread- Holley EFI Sniper on '72 402 big block

Glad you got it worked out. How do you like the 3.73’s with the bbc & 700r4? How does it feel at highway speeds? I’m doing something similar & need to decide 3.42 or 3.73.
__________________
Carter

1968 Chevy SWB Fleet... Walt


1963-1/2 Ford Falcon Futura...Martha
nlped is offline   Reply With Quote
Old 09-03-2018, 09:42 PM   #115
Ekliptix
Registered User
 
Ekliptix's Avatar
 
Join Date: Aug 2013
Location: Calgary, Alberta
Posts: 673
Re: Install thread- Holley EFI Sniper on '72 402 big block

Quote:
Originally Posted by mkmc69 View Post
That's great, that you got the bugs worked out. What cam are you running, if you don't mind me asking?
Here it is



Quote:
Originally Posted by nlped View Post
Glad you got it worked out. How do you like the 3.73’s with the bbc & 700r4? How does it feel at highway speeds? I’m doing something similar & need to decide 3.42 or 3.73.
I'm seeing 2500rpm at 60mph. But, the converter is not locking up via vacuum. I plan to wire a ground to the manual lock up via a button in the cab. That may drop the RPM a little.
__________________
1972 Cheyenne Super SWB PS, PB, Tach, A/C, Tilt.
Drivetrain: Built 402BB, TCI Streetfighter 700R4, 2,500 stall, Eaton posi, 3.73. Suspension/Chassis: ECE 4.5/6.5 drop, CPP nitrogen shocks, CPP front and rear sway bar, CPP cross members. Exhaust: 3" exhaust with x-pipe, Spintech 3000 mufflers, Hooker ceramic coated headers. Best 1/4 mile time: TBD.
Ekliptix is offline   Reply With Quote
Old 09-03-2018, 10:36 PM   #116
driller35
Senior Member
 
driller35's Avatar
 
Join Date: Aug 2009
Location: Calgary,AB
Posts: 323
Re: Install thread- Holley EFI Sniper on '72 402 big block

Good to hear you got sorted and running good , great shot at Peters Drivein
__________________
72 Chev Cheyenne Super SB 4x4 350,4spd,buckets, tilt,tach,am-fm,extreme tow hooks,Canadian Model Production 1 of 52 SOLD

70 Chev CST, 350 auto, PS, PB, AC, tach
driller35 is offline   Reply With Quote
Old 09-03-2018, 11:09 PM   #117
CUDA8U
Registered User
 
CUDA8U's Avatar
 
Join Date: Apr 2018
Location: EDMONTON
Posts: 260
Re: Install thread- Holley EFI Sniper on '72 402 big block

what are you running for exhaust?
CUDA8U is offline   Reply With Quote
Old 09-07-2018, 12:51 PM   #118
Ekliptix
Registered User
 
Ekliptix's Avatar
 
Join Date: Aug 2013
Location: Calgary, Alberta
Posts: 673
Re: Install thread- Holley EFI Sniper on '72 402 big block

Hooker headers, 3" dual exhaust, x pipe, Spintech mufflers. It's great at idle. A little 'glasspack' sounding under WOT. Not mellow at all. I may look into some magnaflows or something else, later.

All packed up and headed to the drag strip tonight.

Ekliptix is offline   Reply With Quote
Old 09-07-2018, 01:31 PM   #119
mkmc69
Senior Member
 
mkmc69's Avatar
 
Join Date: Jan 2009
Location: Logansport,In
Posts: 544
Re: Install thread- Holley EFI Sniper on '72 402 big block

That thing looks nice!!
mkmc69 is offline   Reply With Quote
Old 09-08-2018, 06:15 PM   #120
jmking9
Registered User
 
jmking9's Avatar
 
Join Date: Sep 2006
Location: Riverton KS
Posts: 832
Re: Install thread- Holley EFI Sniper on '72 402 big block

Well, what did it run?
__________________
1970 SWB Build
jmking9 is offline   Reply With Quote
Old 09-08-2018, 07:13 PM   #121
Ol Blue K20
Proprietor of Dale's Corner
 
Ol Blue K20's Avatar
 
Join Date: Nov 2012
Location: Vacaville , CA
Posts: 15,830
Re: Install thread- Holley EFI Sniper on '72 402 big block

I think it's a surpise......lol
__________________
"Some Days Chickens And Some Days Feathers"

Dale
XNGH ECV Sam Brannan 1004

R.I.P. 67ChevyRedneck
R.I.P. Grumpy Old Man
Ol Blue K20 is offline   Reply With Quote
Old 09-10-2018, 08:58 AM   #122
Ekliptix
Registered User
 
Ekliptix's Avatar
 
Join Date: Aug 2013
Location: Calgary, Alberta
Posts: 673
Re: Install thread- Holley EFI Sniper on '72 402 big block

A sluggish 14.5 at 90mph. Something needs some adjusting.

If I left it in Drive, it'd do 14.7 at 88, shifting really early around 4000rpm. I tried tightening the TV cable to the 700R4. It didn't seem to make a difference.
Manually shifting from 1-2-3, I was able to make it shift around 5500rpm which netted the 14.5 at 90mph.

Traction was not an issue. I left as hard as I could which was at the 2,400rpm the converter would let me. 2.0 60' every time.

Possible reasons:
- engine is not making the claimed 430hp so some adjustments need to be made.
- trans is robbing the power somehow.

A fellow at the track said his friend has a TCI 700R4 and they had to change the 'module' to a corvette module and it solve the low rpm shift points. I'll look into it.

In case y'all think I need a 'driver mod', I've been drag racing for 20 years and am used to cutting 1.7# 60' times with manual transmission cars trapping 125mph.
__________________
1972 Cheyenne Super SWB PS, PB, Tach, A/C, Tilt.
Drivetrain: Built 402BB, TCI Streetfighter 700R4, 2,500 stall, Eaton posi, 3.73. Suspension/Chassis: ECE 4.5/6.5 drop, CPP nitrogen shocks, CPP front and rear sway bar, CPP cross members. Exhaust: 3" exhaust with x-pipe, Spintech 3000 mufflers, Hooker ceramic coated headers. Best 1/4 mile time: TBD.
Ekliptix is offline   Reply With Quote
Old 09-10-2018, 09:17 AM   #123
driller35
Senior Member
 
driller35's Avatar
 
Join Date: Aug 2009
Location: Calgary,AB
Posts: 323
Re: Install thread- Holley EFI Sniper on '72 402 big block

Dyno should help you in that area, how did the sniper feel compared to your old carb setup, better response all around or is it still learning
__________________
72 Chev Cheyenne Super SB 4x4 350,4spd,buckets, tilt,tach,am-fm,extreme tow hooks,Canadian Model Production 1 of 52 SOLD

70 Chev CST, 350 auto, PS, PB, AC, tach
driller35 is offline   Reply With Quote
Old 09-17-2018, 11:21 AM   #124
mkmc69
Senior Member
 
mkmc69's Avatar
 
Join Date: Jan 2009
Location: Logansport,In
Posts: 544
Re: Install thread- Holley EFI Sniper on '72 402 big block

Does installing the Holly system solve the fume issue from having the tank in the cab? Was it an issue for you before the install? Are you glad you left the tank in the cab, or would you recommend moving it to the rear? Thanks for any feedback you can provide.
mkmc69 is offline   Reply With Quote
Old 09-17-2018, 12:29 PM   #125
Ekliptix
Registered User
 
Ekliptix's Avatar
 
Join Date: Aug 2013
Location: Calgary, Alberta
Posts: 673
Re: Install thread- Holley EFI Sniper on '72 402 big block

I didn't have any fume issues with the in-cab tank while using a carb. There is still no fume issue now with the EFI. So far (500miles driving) I have had no issues using the in-cab tank with the EFI system. When I turn the key on and hear the pump prime, I can hear a little fuel coming from the return line into the tank, but it doesn't bother me and I can't hear it when the truck is running.
Ekliptix is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 08:18 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com