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 02-21-2011, 10:18 PM   #1
ricks71pu
Registered User
 
ricks71pu's Avatar
 
Join Date: Feb 2010
Location: salem oregon
Posts: 225
HEI * spark plug question

ok, here i go. i have a 1971 GMC 3500 (Longhorn?) with a transplanted 1975 454. It does have an HEI. Problem is, one head is an older 396 head. Each head has a different spark plug length! i am going to put NGK V-power plugs in, but will need to get 4 plugs with 1/2" threads and 4 plugs with 3/4" threads.by this i mean thread length. this does not bother me (too much). My question is, should i gap the 396 head with 3/4" length tread plugs @ .35, or @ .60? remember i have an HEI dizzy, and was told with this dizzy to gap plugs at .60. or should i gap at .35?
ricks71pu is offline   Reply With Quote
Old 02-21-2011, 11:45 PM   #2
Wrenchbender Ret
Registered User
 
Join Date: Oct 2005
Location: Overland Park, Ks.
Posts: 5,206
Re: HEI * spark plug question

.045 on all of them.
Wrenchbender Ret is offline   Reply With Quote
Old 02-22-2011, 02:51 AM   #3
ItsRandy
Registered User
 
ItsRandy's Avatar
 
Join Date: Nov 2010
Location: Grand Terrace, Ca.
Posts: 1,607
Re: HEI * spark plug question

You should put on a matched set of heads...just saying.
Posted via Mobile Device
ItsRandy is offline   Reply With Quote
Old 02-22-2011, 12:48 PM   #4
ricks71pu
Registered User
 
ricks71pu's Avatar
 
Join Date: Feb 2010
Location: salem oregon
Posts: 225
Re: HEI * spark plug question

yeah, matching heads is the right way. but were on motor when i bought truck. PO always used long reach plugs in both heads, and i did not notice difference till a day or so ago, when i went to change plugs.
ricks71pu is offline   Reply With Quote
Old 02-22-2011, 05:44 PM   #5
MARKDTN
Registered User
 
Join Date: Jan 2011
Location: Chattanooga, TN
Posts: 2,144
Re: HEI * spark plug question

Quote:
Originally Posted by ItsRandy View Post
You should put on a matched set of heads...just saying.
Posted via Mobile Device
X2

It would bug me to death to have them mismatched.
__________________
'83 K20-TPI
'73 C10
'79 C10-ex-diesel(SOLD)
'07 Tahoe(Son driving)
'14 Suburban-DD
'71 C10-current project
MARKDTN is offline   Reply With Quote
Reply

Bookmarks


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 01:10 PM.


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