I have a running 1970 ford 302 that I pulled the rod bolts on to check condition. I torqued them to 24 foot pounds which is what 5/16 rod bolts call for. Dumb question is I dont know if I have 5/16 or 3/8th rod bolts which are supposed to be torqued to 45 foot pounds . It runs fine has good oil preasure, 45 at hot idle and probably wont see 1000 miles a year. What problems will I have if I torqued them too loose ? Thanks.
I torqued it to the specs for 5/16 rod bolts, didnt pay att to socket size, then I realized there were two different torque specs.
Depending on the size and location of the oil drain hole you may be able to see one. Big spread between settings, don't think I'd take a chance not knowing. As Beanscoot said, might just be the hipos with 3/8.
To answer the rest of your question. If they are not tight enough there is a very good chance of it just plain coming apart at R.P.M. "NOT good" ! To tight and you can distort the rod shape and take out the Bearing. When working with bearing spec.s in as little as 1/2 thousands there is little room for kind of close torque settings. Another thing, Mechanics know that Torque Wrenches need to be caliberated often to make sure what it's telling you is actually what it's doing. It's not a guessing game and kind of close don't get it. The Wizzard
If your engine is very well balenced you will probably not have a problem. Vibrations are the killer for any fastener.,
Rod bolts too loose = rod cap in oil pan. If you already got the motor in the bar you are asking this question too late.
The manufacturer's torque spec for a main or big end bearing is what they had the bolts tightened to when they finish machined the bearing bores. So that's the torque setting at which those bores will be perfectly round, significant over or under tightening of the bolts will result in the bearing bore being slightly out of shape, and your bearing clearance being inconsistent around the crank journal. Can't see that the bolts are especially likely to come undone at 24 ft lb though if they have the usual fine thread.
A good reason to rely on a bolt stretch gauge along with a calibrated torque wrench, they verify one another.
What wolfcreek steve just said !! “ it should be ok” Would drive me nuts every time I got behind the wheel. It ****s to yank the engine again, can you may be loosen the mounts raise the engine and sneak the pan out or down enough to get to the bolts? It would end up being an expensive fix if something decided to come lose. And just knowing .... maybe.... eh.... ahhh...... every time you jump on the go peddle would not make for fun driving.
If you tightened to 24 ft lbs . It will run till the cows come home . There isn’t much chance that you have 3/8 rod blots . 99% of SBF engines are 5/16 and 24 ft lbs is plenty good Sent from my iPhone using H.A.M.B.
Thats what Im hoping , doesn't look like anything has been done to the bottom end, has cast pistons, 289 heads on 302, big cam with screw in studs , no port-polish. It had a knock-rattle at 2500 rpm. when I put it back togather the knock was gone but then I noticed the 2 different torque specs.
If you are losing sleep at night over it then drop the pan and check. If not, drive like you stole it.
If I stole something I would try to drive very carefully, keeping within speed limits, using turn signals, complete stop at signs, etc etc in order not to draw attention to myself and risk getting pulled over.
Its a engine swap into a ot car, big engine small car, have to pull engine to pull pan. Might just have to take my chances.
Isn't therapy great. You sat on the couch just 2 day's ago and proceeded to tell us about a problem you already knew how to find the answer to and correct if need be. Did you really think we could have made the rod bolts tighten themselves?
An endoscope/borescope probe should fit through your sump plug hole; then you could get to see the rod bolts without pulling the sump. If you post the images on here, plenty of people should be able to identify whether you have 5/16" or 3/8" bolts on your rods. Cheapanese endoscopes are available on eBay for not much money.
If this motor is going in a bar all bets are off! Not a bad idea though, I'd frequent any bar that had a running engine. Speaking of beer, years ago a beer guzzling friend rebuilt a 455 Olds and called me up to watch the beast fire up in his Cutl***. Sounded great, we cracked open a couple of Buds while it idled there, then he reached over and gave the carb a goose. Kaboom! Crawled under and there was a rod cap poked through the pan. A few minuted later found a rod nut still on the bench.
I often wondered about these on early SBC's. Did they really stop the nut from coming loose or did it serve as a secondary look as it was installed to be sure "the" rod nut was there?
Just dis***embling and re***embling cured the knock, or did you replace knock-causing components? If the bolts you are replacing are ROD bolts, then you're missing an important step. If it's oil pan bolts or motor mount bolts you're OK.
Never found cause of knock, went away when I put it back together. Used the same nuts on the rod bolts, just pulled them apart to check bearings.
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