Cast Iron Intake Torque?

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eekvonzipper

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I have the Early 273 2bbl with the 5/16" bolts...
Doing Intake Gaskets today, What's the finishing torque?
Thanks to all!
 
What year is an "early" 273 ? 1966 "FSM" for a 273 says 35 Ft Lbs. for factory intake to cylinder head, size 3/8" 16. Do you have a FSM ? Free downloads.
 
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35 is WAY incorrect. If you try to go 35 with a 5/16 bolt you'll be snapping them off left and right. Torque spec on those is 17-19 LB FT.
 
35 is WAY incorrect. If you try to go 35 with a 5/16 bolt you'll be snapping them off left and right. Torque spec on those is 17-19 LB FT.
I tq with a wrench, by feel.

However... In regards to the 5/16 statement...
What size are early sbc rod bolts and what is their torque value?
Food for thought.
 

I tq with a wrench, by feel.

However... In regards to the 5/16 statement...
What size are early sbc rod bolts and what is their torque value?
Food for thought.

And what grade bolt are 5/16 rod bolts VS 5/16 intake bolts? More food to munch on.
 
And what grade bolt are 5/16 rod bolts VS 5/16 intake bolts? More food to munch on.

Much them redheads I posted, When is the last time you snapped an authentic factory intake bolt?
I bet they are the SAME ase grade 8 engine bolt. Just a point that the old bolts we still reuse 50 plus years later are pretty tough, and that a 5/16 can handle 35 ft lbs given the right grade...which by looking at the rods I have here from a 56 motor..look the same, not dark moly.bone stock.
 
Much them redheads I posted, When is the last time you snapped an authentic factory intake bolt?
I bet they are the SAME ase grade 8 engine bolt. Just a point that the old bolts we still reuse 50 plus years later are pretty tough, and that a 5/16 can handle 35 ft lbs given the right grade...which by looking at the rods I have here from a 56 motor..look the same, not dark moly.bone stock.

How many of those same 5/16 bolts have people snapped trying to torque them to 35 on rocker shafts? A lot. Besides, the rod bolts are fine thread. That's comparing apples and oranges, since fine thread will take more torque anyway.
 
The 1969 FSM for 273 calls for 35 ft-lbs on the 3/8-16 intake manifold bolts. All 5/16-18 bolts are listed as 10 ft-lbs, 15 ft-lbs, 200 in-lbs or 210 in-lbs.
 
How many of those same 5/16 bolts have people snapped trying to torque them to 35 on rocker shafts? A lot. Besides, the rod bolts are fine thread. That's comparing apples and oranges, since fine thread will take more torque anyway.
How many dont on the exhaust, slant 6 as well...?

I dont think they are the same as a rocker bolt grade. Cause thinking on your point..its strange to get away with more on the exhaust, intake and I have...but the rocker shaft bolt snap off. I do those by feel as well, but I'd assume it's about 18lbs
 
The 1969 FSM for 273 calls for 35 ft-lbs on the 3/8-16 intake manifold bolts. All 5/16-18 bolts are listed as 10 ft-lbs, 15 ft-lbs, 200 in-lbs or 210 in-lbs.
Yes, correct. Im just "sound boarding" with Rob about diff Instances is all.
Beer talk. Circle of chairs at the end of the day...porch jamber
 
How many of those same 5/16 bolts have people snapped trying to torque them to 35 on rocker shafts? A lot. Besides, the rod bolts are fine thread. That's comparing apples and oranges, since fine thread will take more torque anyway.
Sad to say I watched as my dad told my son to torque the small block rocker shaft bolts to 35 ft-lbs.

When the first one broke on my son my dad threw a wrench across the shop and said to my son, "Now you f##ked it up!"

Dad and I had a little talk as I worked the broken threads out and we got new bolts and torqued them to 18 ft-lbs.
 
Well I looked it up on this. Was torgue specs for la motors. Probably is wrong for 5/16 tho now that you guys bring it up.

Screenshot_20200503-183259.png
 
Sad to say I watched as my dad told my son to torque the small block rocker shaft bolts to 35 ft-lbs.

When the first one broke on my son my dad threw a wrench across the shop and said to my son, "Now you f##ked it up!"

Dad and I had a little talk as I worked the broken threads out and we got new bolts and torqued them to 18 ft-lbs.
How many dont on the exhaust, slant 6 as well...?

I dont think they are the same as a rocker bolt grade. Cause thinking on your point..its strange to get away with more on the exhaust, intake and I have...but the rocker shaft bolt snap off. I do those by feel as well, but I'd assume it's about 18lbs

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What year is an "early" 273 ? 1966 "FSM" for a 273 says 35 Ft Lbs. for factory intake to cylinder head, size 3/8" 16. Do you have a FSM ? Free downloads.
Not sure what "FSM" (Factory Service Manual?) is but it's a '65 barracuda with the smaller bolts.
 
I would be more concerned about stripping the threads in the heads than snapping the bolt.
A good snug with an open ended wrench several times around is what I do.
 
Every 5/16-18 bolt in the 65 FSM is 15 ft/lbs (or 10) and the 65 FSM also covers the 66 model and they call out the intake as the 66's 3/8-16@270 in/lb, but still only 22 ft/lbs. in 66 + they went to 3/8-16@ 35 ft/lbs .
 
That is exactly why the poster should give Complete info on their car and should have the appropriate FSM for their car anyway. We all agree that the FSM says 35 ft lbs for a 3/8" x 16 bolt. But people have a tendency to jump in with different opinions and don't get or ask for more specific info from the poster on the year of his engine. I never believed in the "calibrated wrist" theory. The key to anything we want to do correctly is Consistency. A good calibrated torque wrench ,be it a beam or click type on a properly prepared fastener. That should be the starting point. You can't teach experience, you have to learn it.
 
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