Question on torque tightness for 346 engine.

Started by vicbrincat, January 14, 2010, 12:43:20 AM

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vicbrincat

Just getting the engine ready to install in my '48.

I found all the torque tightness spec in the shop manual except this one:

There are six small bolts that hold the "harmonic balancer".(.at least I believe  that's what they called it) to the main crank pulley.
I removed these parts  for cleaning and painting. Now re-installing them.
What should I torque them down to?


Thanks in advance.

Vic



The Tassie Devil(le)

What size and thread-pitch are these fastenings?

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Glen

Glen Houlton CLC #727 
CLCMRC benefactor #104

Mark Lowery

Glen,
This is a great reference, in particular because it addresses adjustments for types of plating etc.  The first consideration when using the chart is the SAE grade of the bolt.  Unfortunately, GM cars of the 30's did not use the hash marks on the heads to designate grade.  Now days, one would assume that an unmarked hex head cap screw would be grade 2.  Grade 2 fasteners are not to my knowledge supplied in the fine series thread.  Since the flathead V8 has both coarse and fine thread fasteners, this begs the question: What modern SAE grade were most of these bolts equivalent to?  No doubt this question has been asked before, but if someone knows the answer, perhaps this would be a good time to refresh our collective memories!

Mark Lowery, CLC #25216

vicbrincat

Okay thanks..will try the link you supplied.

Meanwhile...the bolt has 1/2" head, thread is 5/16 NC18 and the bolt is roughly 1.25" long.

Vic

76eldo

The wise-ass answer would be tighten it until it snaps, then back off a quarter turn.

Actually, I would use lock washers and just tighten it down really tight, like 85-to 100 ft lbs.  The other thing is is it indexed or  keyed in any way to ensure you get the timing mark in the right spot? 

Brian
Brian Rachlin
Huntingdon Valley, Pa
CLC # 22443
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

The Tassie Devil(le)

Quote from: 76eldo on January 14, 2010, 06:29:17 PM
The wise-ass answer would be tighten it until it snaps, then back off a quarter turn.

Actually, I would use lock washers and just tighten it down really tight, like 85-to 100 ft lbs.  The other thing is is it indexed or  keyed in any way to ensure you get the timing mark in the right spot? 

Brian
DANGER DANGER.

Try 25 Ft Lbs. for these bolts.   85 to 100 will definitely snap them right off, even if you could get them to that tension in the first place.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

76eldo

I think I was a bit high on that answer.  I was thinking 1/2 in thread, then I re-read the question.  It's 5/16...

Brian
Brian Rachlin
Huntingdon Valley, Pa
CLC # 22443
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

vicbrincat

It just dawned on me that I still have the shop manual for my 1958 Cadillac.

Yes... I know that the '58 had a much different engine and it is at least 2 generations appart from the 346....but it does have a balancer which is very similar in contstruction. And yes, the manual has a spec for it:

Pulley to balancer......size 5/16-18....min 15 ft. lbs...max 18 ft. lbs.

Given that the 346 balancer is a bit heavier in  contruction, I will settle on a reasonable 20 ft. lbs.


Thanks for all the input

Vic

The Tassie Devil(le)

I love Shop Manuals.

Bruce. >:D

PS.   Yes, 25 was a bit high, but I was rushing to get the figure down from 85 to 100.

'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

76eldo

Brian Rachlin
Huntingdon Valley, Pa
CLC # 22443
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

Whit Otis, 1188

The torque applied to a bolt has nothing to do with what the bolt is being used for and everything to do with the grade and size of the bolt, as mentioned above.  By the way,  if you apply any type of lubricant to the thread, say anti seize compound, then you will need a torque chart that shows the "dry" torque rate and the "lubricated" torque rate..... there is quite a difference.
Whit
Whit Otis -
1941 6219D Custom
1941 6219D
1940 7533F
1948 6069X
1985 Eldorado Biarritz
1999 Bentley Arnage
2019 XT5
Drawing of AP Sloan Custom by Terry Wenger

Glen

Yes, the chart in the link I posted above has a listing for dry and another one for oiled.  I am amazed at the difference between the torque values. 

Glen 
Glen Houlton CLC #727 
CLCMRC benefactor #104