dumb question
Thread Starter
TGO Supporter
iTrader: (2)
Joined: Oct 2001
Posts: 926
Likes: 0
From: Englewood, CO
Car: 1990 Trans Am
Engine: Lb9
Transmission: factory T5
Axle/Gears: 3.08 limited slip
dumb question
how do you guys judge when your plugs are tight when you do a tuneup without a torque wrench, ive heard to hand tighten till they are against the head then an extra 1/4 turn. Thanx
Member
Joined: Jul 1999
Posts: 223
Likes: 0
From: Oklahoma City, USA
Car: 89 IROC
Engine: Yes
Transmission: That, too.
The general system I use to apply torque to a bolt when I'm not using a torque wrench depends on the size of the ratchet.
1/4 in ratchet: One grunt past snug.
3/8 in ratchet: Two grunts past snug.
1/2 in ratchet: Three grunts past snug.
1/4 in ratchet: One grunt past snug.
3/8 in ratchet: Two grunts past snug.
1/2 in ratchet: Three grunts past snug.
Supreme Member
Joined: Dec 2001
Posts: 1,158
Likes: 0
From: Greenville S.C.
Car: 87 Grand National
Engine: 3.8 SFI Turbo
Transmission: BRF 200R4
Depends on what kind of heads you have. Most of the time the rating for plugs is in inch pounds but I don't have the rating. Usually with iron heads just turn about 1/4 past seat. On Aluminum you need to be careful and not overtighten because the threads can be easily damaged.
Lots of variables.
Gasketed plugs get more turn, less torque. Tapered seat plugs get less turn, more torque.
The rules of thumb that I've seen recently are:
Gasketed spark plug - 1/2 turn past contact;
Tapered seat plug in iron heads - 1/8 turn past contact;
Tapered seat plug in aluminum heads - 1/16 turn past contact.
The old specification from the late-'60s and early '70s (when gasketed plugs started to disappear) SBC heads was 15 ft/lb on 14mm tapered seat plugs in iron heads (excecpt fo the SBC 400, which called for 25 ft/lb for some strange reason). Ford listed 15-20 ft/lb for their 18mm tapered seat plugs in iron, 10-15 ftt/lb for 14mm plugs. I don't have torque specs from those days for aluminum heads, since they didn't really exist in stock applications except for a few rare engines. Buick was specifying 20 ft/lb in their aluminum heads.
Hopefully, that should give you some guidelines.
Gasketed plugs get more turn, less torque. Tapered seat plugs get less turn, more torque.
The rules of thumb that I've seen recently are:
Gasketed spark plug - 1/2 turn past contact;
Tapered seat plug in iron heads - 1/8 turn past contact;
Tapered seat plug in aluminum heads - 1/16 turn past contact.
The old specification from the late-'60s and early '70s (when gasketed plugs started to disappear) SBC heads was 15 ft/lb on 14mm tapered seat plugs in iron heads (excecpt fo the SBC 400, which called for 25 ft/lb for some strange reason). Ford listed 15-20 ft/lb for their 18mm tapered seat plugs in iron, 10-15 ftt/lb for 14mm plugs. I don't have torque specs from those days for aluminum heads, since they didn't really exist in stock applications except for a few rare engines. Buick was specifying 20 ft/lb in their aluminum heads.
Hopefully, that should give you some guidelines.
Thread
Thread Starter
Forum
Replies
Last Post
NinjaNife
Tech / General Engine
27
Aug 23, 2015 11:49 AM








