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
What size and thread-pitch are these fastenings?
Bruce. >:D
Try a generic torque setting chart such as this one: http://www.raskcycle.com/techtip/webdoc14.html
Glen
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
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
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
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
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
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
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.
Sorry... :o
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
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