Bad Timing Cover Bolts...

[Rosco]

I recently replaced my timing chain and when I went to install the timing cover I realized my bolts all seemed too long- I'd had everything pulled apart for about a year before re-installing the cover again. Some of the bolt ends did look a little rough...

I was scrambling with the gasket sealer setting up on me trying to re-install the cover. All the bolts were bottoming out 1/2"-3/4" before they hit anything! I started looking around in a panic and ended up throwing larger nuts and a couple of oversized box wrenches over the bolts to get them to seal against the cover and allow the gasket sealer to set up. Junk show. Albeit sort of artistic looking. Right now the wrenches are out and other spacers are in.

I'm now thinking about a new bolt set- never knew (but suspected) that they have these readily available. Sure enough. I'd like to get a ss set which I assume will last longer.

Question is, What should I do about the bolt holes? I'm wondering if I should get a tap for the holes that the bolts didn't tighten all the way in? Don't have a clue. I've read on the internet that you should apply oil before installing some bolts. Is this a consideration for the timing cover bolts? None of them have lock-washers.

Also, how critical is it to use the specified torque values at every bolt location?

I have an old 1/2" Craftsman torque wrench but don't believe in it any more and rarely use it these days. I recently busted it out though to torque on the camshaft bolt for the new timing chain. The spec is 35 ft.lb. With my Craftsman torque wrench it felt like it clicked with the force that my 4 year old could apply with her pinky finger.

I'm not doing any internal engine work- just bolt-on parts. So w/out throwing down for a new expensive torque wrench I usually just tighten everything until it feels good. Am I blowing it?

 

[CBODY67]

The "35" torque is the same as with spark plugs in a cast iron cyl head. When I tried that with my new Craftsman torque wrench, years ago, I found out that it was "just contact", then about 1/4 turn past that. Which on gasketed spark plugs, compresses the gasket. On tapered seat plugs, less turns. That was also on a torque wrench that started at about "50", then backed-back from "50" a bit.

On the front cover, that's not a critical torque area for bolts, to me. Key thing is to not over-tighten and warp the housing so it won't seal too well.

For bolt specs, you might find something in the Mopar Performance Parts Manual. Seems like Chrysler used to sell those bolts in sets of chromed timing cover bolts, but you can at least find the bolt specs. Be sure to use flat washers under the bolt heads or a flanged-head bolt.

Just some thoughts,
CBODY67

 

[mikedrini]

I recently replaced my timing chain and when I went to install the timing cover I realized my bolts all seemed too long- I'd had everything pulled apart for about a year before re-installing the cover again. Some of the bolt ends did look a little rough...

I was scrambling with the gasket sealer setting up on me trying to re-install the cover. All the bolts were bottoming out 1/2"-3/4" before they hit anything! I started looking around in a panic and ended up throwing larger nuts and a couple of oversized box wrenches over the bolts to get them to seal against the cover and allow the gasket sealer to set up. Junk show. Albeit sort of artistic looking. Right now the wrenches are out and other spacers are in.

I'm now thinking about a new bolt set- never knew (but suspected) that they have these readily available. Sure enough. I'd like to get a ss set which I assume will last longer.

Question is, What should I do about the bolt holes? I'm wondering if I should get a tap for the holes that the bolts didn't tighten all the way in? Don't have a clue. I've read on the internet that you should apply oil before installing some bolts. Is this a consideration for the timing cover bolts? None of them have lock-washers.

Also, how critical is it to use the specified torque values at every bolt location?

I have an old 1/2" Craftsman torque wrench but don't believe in it any more and rarely use it these days. I recently busted it out though to torque on the camshaft bolt for the new timing chain. The spec is 35 ft.lb. With my Craftsman torque wrench it felt like it clicked with the force that my 4 year old could apply with her pinky finger.

I'm not doing any internal engine work- just bolt-on parts. So w/out throwing down for a new expensive torque wrench I usually just tighten everything until it feels good. Am I blowing it?

Not sure what engine you have, but for my 440, the timing cover bolts are two different sizes. Just want to be sure you have the correct bolts for the correct engine AND be sure you have cleaned the holes out.

 

[Rosco]

Yes, 35 ft.lb. was hard to walk away from w/ what the Craftsman said was 35. Especially considering the mayhem that would ensue if that thing were to back off. but I did put my 3/8 ratchet on it to see if it were indeed tight and it was. It just didn't take much at all w/ the long, giant Craftsman 1/2" wrench.

I've found a nice looking set of timing cover bolts. Stainless steel and comes with t-stat housing bolts, distributor bolt and others. Mainly, I'm wondering why my existing bolts didn't go in all the way. I don't want to tap the holes out if I'll be permanently damaging the block- can those holes be tapped? OR, spray de-greaser or something (KR oil?) and air compressor?? Should I oil the new bolts before installing?

BTW I am working on an LA318, 1973 (in a '68 Fury)

 

[Big_John]

Your 1/2 torque wrench isn't designed to be accurate at that low range.

Depending on the type, most wrenches are spec'd to be accurate in the upper 80% of the scale. Even then, they aren't really good when they are at the low end of that scale. Trust me, I've calibrated zillions of them over the years.

1/4 socket wrench until it feels "right" and call it a day.

 

[Rosco]

Well, I did call it a day w/ the cam bolt- it's in there and I feel pretty good about it after checking w/ my 3/8" ratchet. You are right. My big torque wrench only goes down to 55. I kinda eyeballed what I thought would be 35. So steer clear of the Craftsman 1/2" wrench for the lower torque values.

My biggest concern is what to do with the timing cover bolt holes to enable the new bolts to go in all the way.. Should I consider tapping them out or are the holes tapered or something at the end and tapping would screw this up? There were six bolts that would not tighten in all the way. They have between ohhhh 1/2" or so to just over maybe 3/4" to go before they touch metal. They're living with oversized nut spacers at the moment.

I guess the other option is to just leave them...Maybe I'm getting carried away with the new bolt kit.

 

[CBODY67]

You can use a tap to clean the threads, if desired. Doing that will not damage anything, might even help things a bit?

If you really want to "feel" the torque, find a new beam-type torque wrench like was all there was in the earlier 1960s. They are less forgiving than the clickers are, especially on the angle of the pull.

Enjoy!
CBODY67

 

[Rosco]

OK, so they (Chrysler) didn't machine the block so that the end of the hole is tapered or anything? Just a straight, threaded hole?

I rarely use a torque wrench for anything- I have that Craftsman torque wrench that I bought years ago to tighten down a cylinder head on a Honda YEARS ago but usually just snug things up. When I was younger I liked to tighten bolts until they were loose again But now I realize that you can break some bolts by over-tightening.

I am more curious than anything about why some bolts have eg 35 ft.lbs. and others 90. I would think the size of the bolt would determine the torque spec.

 

[traintech55]

Well, which bolts are you talking about. Some of the bolts hold brackets in place, (Power steering on the drivers side, and alternator on the pass. side). Some go thru the water pump into the block thru to the water jacket, and some don't. A picture would be a great help. Also does your car have factory A/C?

 

[Rosco]

Well. I don't have a great photo to show all the bolts that wouldn't go in all the way but this is the best I can do- my Plymouth is stored a long ways from where I live...This is the best I can do- you can see the nut spacer on the one bolt there. There are at least three others that I had to throw spacer on for them to work.

The bolt kit I'm looking at lists all the bolts for the timing cover, crank pulley, t-stat housing, etc. and they offer custom sizes/lengths upon request: MOPAR ENGINE BOLTS KIT SMALL BLOCK 273 318 340 360 POLISHED ARP STAINLESS STEEL | eBay.

But, like I said, I'm most concerned with tapping out a hole that was maybe machined to a certain depth with a tapered end. Is this at all how it works? Not an engine rebuilder or machine shop guy so I don't really know how they machine holes in the block for all the timing cover bolts.

I just don't want to screw up the block if you need some kind of special tap. C-body67 mentioned that I would be fine to just tap it out. Just want to double check. No offense intended C-body67...I just didn't get 5 guys saying "yeah yeah, go for it, no problemo". If they are just literally straight, threaded holes then I won't worry about screwing anything up by tapping them clean with a regular tap. Maybe everyone else knows this and assumes it goes without mentioning.

BTW, no A/C.

Is there a general rule about torque values? ie diameter and length of bolt? OR is it more application based?

 

[CBODY67]

No offense taken. Just use your hand to use turn the tap in the hole. No real effort, as you're not cutting threads, just cleaning them. Be sure to use some spray penetrating oil (one place where WD-40, or similar, might work well?) to lubricate things and to wash out the gunk that might be there. Remember, you're not cutting threads, just cleaning them.

Torque values depend on many things. One is the torque rating of the bolt (as in "Grade numbers" as evidenced by the number of markings on the bolt head. 3 evenly spaced bars means "Grade 5", which is a normal bolt. Grade 8 (6 bars) is harder and better, when needed. Bolts with an Allen head on them are all Grade 8s, as I understand it.

In the world of bolts and torques, it seems that ONE of those are supposed to be the "sacrificial" softer item. Usually, that's the bolt that you want to break or strip-out rather than the threads of the harder material they go into.

Bolt torque is determined by what items are being clamped together. At the desired clamping force, the bolt threads will stretch minutely to ensure a good friction-lock, but sometimes needing a lock washer under the bolt to ensure long-term tightness/clamping forces are maintained. Intake manifolds need less torque than main caps, for example. With the bolt size also being in that mix. Larger bolt thread diameter means more clamping force, for example. You can see some of these things in the bolt torque specs listings in the FSM, for example.

Should the threads in a item become damaged from some action, you then drill-out the hole, cut threads in it for a larger diameter, and then install a "heli-coil" insert to allow the orig size of bolt to still work in that repaired hole. There are kits for such sold by the auto supply stores. In the case of the Cadillac Northstar (aluminum block) V-8s, which only were disassembled after about 150K miles, they would usually end up with stripped head bolt holes. A "Time Sert" would by installed to fix that hole. Similar to the Heli-Coil repair, I suspect. But in our cast iron blocks, heli-coils work.

In some cases, as in carb mountings in aluminum intake manifolds, I like to use the "black" hard studs from the auto supply store. After unintenionally breaking a softer/normal car stud by accident. Put the hard stud in and forget it. Which makes the nut holding things down the sacrificial part of that situation, NOT the stud (which then has to be drilled out and such!).

Some use hard studs in the place of head bolts or main bolts. Usually race engines which are only worked on while on an engine stand, rather than while still in the car. Using bolts would mean more wear and tear on the cyl block's threads as many times as those engines are pulled apart between races and such. This means the nuts on the studs become where the wear point is, rather than in the block itself.

Of course, small bolts only can stand small torques, by observation. PLUS, when applying torque, start at the center of the item being torqued and work diagonally (in the case of wheels) or in a circle (as in a cyl head or similar, center to end), in multiple steps of increasing increments in torque amounts, until you get to the desired amount. EVEN with a clicker torque wrench. Snug is the staring point, usually.

One later model item . . . torque-to-yield specs. Like getting to a stated torque value and then tightening the bolt another amount of degrees to finish the job. The bolts for these specs ARE a of special metal (usually more tensile strength and make a different sound when dropped) to tolerate such things. First time I heard of that, in the 1990s, I thought of the old "As tight as you can get it and then another 1/2 turn for good measure" dialogue. Allegedly, these bolts are single-use, needing new bolts after each time they are torqued.

Hope this might help,
CBODY67

 

[Rosco]

Man. That is some great info. Thanks for taking the time to explain torque values and application for me to better understand. And, good to be reminded that even a screwed up hole has a heli coil waiting somewhere to come in and make it all good. I've never used a heli-coil but have heard of them all my life. Maybe I'll be lucky and never get to use one
Thanks too for reiterating the point about the tap process. Easy does it. Rog. I'll post up how the tap process went when I get the chance to try it.

 

[Rosco]

Well. I don't have a great photo to show all the bolts that wouldn't go in all the way but this is the best I can do- my Plymouth is stored a long ways from where I live...This is the best I can do- you can see the nut spacer on the one bolt there. There are at least three others that I had to throw spacer on for them to work.

The bolt kit I'm looking at lists all the bolts for the timing cover, crank pulley, t-stat housing, etc. and they offer custom sizes/lengths upon request: MOPAR ENGINE BOLTS KIT SMALL BLOCK 273 318 340 360 POLISHED ARP STAINLESS STEEL | eBay.

But, like I said, I'm most concerned with tapping out a hole that was maybe machined to a certain depth with a tapered end. Is this at all how it works? Not an engine rebuilder or machine shop guy so I don't really know how they machine holes in the block for all the timing cover bolts.

I just don't want to screw up the block if you need some kind of special tap. C-body67 mentioned that I would be fine to just tap it out. Just want to double check. No offense intended C-body67...I just didn't get 5 guys saying "yeah yeah, go for it, no problemo". If they are just literally straight, threaded holes then I won't worry about screwing anything up by tapping them clean with a regular tap. Maybe everyone else knows this and assumes it goes without mentioning.

BTW, no A/C.

Is there a general rule about torque values? ie diameter and length of bolt? OR is it more application based?

View attachment 461291

Here's a better link for a fine ss bolt kit that fits 273 318 340 360 small blocks:
MOPAR SMALL BLOCK SB 273 318 340 360 STAINLESS STEEL ENGINE HEX BOLT KIT | Alloy Boltz
found the grade 8 arp type kit in a flurry and didn't check price. Ouch!
This one's 304 stainless and has bolts for more parts...and, a quarter of the price.

 

[Big_John]

A couple comments about Heli-Coils and "tapping" existing holes...

First, Heli-Coils, done correctly, will give you a stronger, better thread than what the original. Back in my Tool & Diemaker days, part of my deal was repairing stuff and making prototypes. Repairing small threads got to be common practice, so much I think I could do a lot of them in my sleep (and probably did). Building the prototype or two, I can tell you that just about any threaded mounting hole in aluminum that was going in a government owned plane was spec'd with a Heli-Coil to start with.

And "tapping" existing holes can get you into trouble if you aren't careful. If you are cleaning out a hole, go for something like this: https://smile.amazon.com/gp/product/B00DTEFSWY/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

It isn't a cutting tap and won't "dig in" (best way I can describe it) like a cutting tap will. It's made to remove the junk from the threads. Safer to use and should be in everyone's tool box. The dies do the same and are handy too.

 

[Rosco]

A couple comments about Heli-Coils and "tapping" existing holes...

First, Heli-Coils, done correctly, will give you a stronger, better thread than what the original. Back in my Tool & Diemaker days, part of my deal was repairing stuff and making prototypes. Repairing small threads got to be common practice, so much I think I could do a lot of them in my sleep (and probably did). Building the prototype or two, I can tell you that just about any threaded mounting hole in aluminum that was going in a government owned plane was spec'd with a Heli-Coil to start with.

And "tapping" existing holes can get you into trouble if you aren't careful. If you are cleaning out a hole, go for something like this: https://smile.amazon.com/gp/product/B00DTEFSWY/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

It isn't a cutting tap and won't "dig in" (best way I can describe it) like a cutting tap will. It's made to remove the junk from the threads. Safer to use and should be in everyone's tool box. The dies do the same and are handy too.

Thanks Big J!
these look fricking great. Exactly what I need. I will look into a set of these with a long shaft so I don't have to remove the waterpump/timing cover to get to the holes.
I had no idea these things existed.