73 360 Ignition timing after Chain replacement

Hey all. I did some searching here, and found dozens of varying opinions and figures.....none of which directly answer my question.....so I am going to ask again for the often asked "what timing should I run"

Details.....Engine is a 360, casting from July 72....I believe original to a 73 tradesman body Motorhome. (installed now in 74 D300 flatbed, but that's beside the point).

I recently pulled this engine out of said 73 tradesman RV.......Had the heads done full new valves, guides, and seats. New Rod and Main bearings.

While it was apart, I also replaced the timing chain with Mopar Performance double roller. Assuming the rest of the engine was original (seemed very untouched on disassembly)......I figured stock cam, so I set the new timing gear set to the stock notches (as opposed to 4 deg. + or - options)......I am about 98% certain I lined up the marks correctly.

Now I've got the engine installed in my 74 D300 dually. It fired up okay.....but clearly Distributor timing was off a bit......I moved Disty around until it idled ok.....warmed it up and put the timing light on it.

Here's where it gets me wondering......The sticker on the valve cover, for 73 models.....specs the 360 to be timed at 2.5 BTDC with vac port plugged. I can't get it anywhere near that....stalls out around 10 BTDC runs best with timing set between approx 15 degrees BTDC.......will run all the way up to 25+ but bucks on startup that far advanced. I haven't actually driven it yet as the truck still needs some other stuff done first.....but engine seems to start and run well with timing around 15 BTDC where I left it.

I verified the TDC mark on the pulley is correct, both by comparison to another pulley, and with a wooden dowel feeling piston rise/fall through spark plug hole.

Should I be worried my Cam timing is off? (Chain installed tooth off?) Or time it to feel, listen for pinging under load and adjust accordingly? Perhaps it has an "RV" cam? I mean it was pulled from a 14" RV? I hate to pull the chain cover back off just to find I did indeed set the gears correct. Like I said I triple checked the install and am about 98% sure that the double roller, Mopar made chain is correct.

Should I be dead set on getting it timed to 2.5 BTDC? or does 15-18-20-ish BTDC sound reasonable? any risks to consider? Just trying to bounce around ideas and talk myself into or out of pulling the chain cover to verify Cam timing.

Thanks to all those more versed in LA engines than I am.

Engine timing is pretty straightforward. 2.5 degrees BTDC is not much. 15 degrees BTDC is much more in line with most of my builds like best. Too much timing BTDC and it'll buck as you already experienced. Take it for a ride and get on it, if the motor pings you may want to back off the timing a couple few degrees. 65'

Plymouth 65 said:

Engine timing is pretty straightforward. 2.5 degrees BTDC is not much. 15 degrees BTDC is much more in line with most of my builds like best. Too much timing BTDC and it'll buck as you already experienced. Take it for a ride and get on it, if the motor pings you may want to back off the timing a couple few degrees. 65'

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That's what I figured, but was concerned that it wouldn't even run at the "factory" setting. Made me question whether Cam timing was correct. I hadn't worked on a V8 since my old FE block ford 390, in the 90's.....lol.

guess I'll have to get it out on the road to find out how it runs.

If Cam timing was off a tooth or 2, what would be the resulting driveability issues? no power? terrible mileage?

Too much timing will give you precognition, and it'll ping. Too little ignition it'll idle like ****, backfire through the carb and run hot as a *****! I think where you're set, 15 degrees BTDC is just about right. 65'

Plymouth 65 said:

Too much timing will give you precognition, and it'll ping. Too little ignition it'll idle like ****, backfire through the carb and run hot as a *****! I think where you're set, 15 degrees BTDC is just about right. 65'

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Thanks. I tow 7000+ lb trailers with this truck......so I really need to have it work under load. Don't need it to be fast, just need all the torque to be there when I need it.

This 15+ inititial timing is for hotrods. You are not going to want that in a 1 ton. But what you describe sounds like the cam is way off. It sounds like you bought a multi key-way advance/ retard sprocket kit. It sounds to me like you got the cam off somehow. One easy mistake is to use the wrong timing mark on the lower sprocket with the wrong key. The other mistake someone made is they tried to put the keyway at top instead of the mark. I'd start with checking cam timing. You can estimate this "in the rig." Read the shop manual which you can download many of from MyMopar for free

If you can "guess" what the cam specs are, you can estimate the no1 valve events degrees. There are various ways of doing so at the balancer, even measuring with tape and coverting inches to degrees rotation

If the distributor advance is not stuck, and has a stockish torque / truck cam, that engine should run decent at low speeds somewhere 5is to 12ish BTDC depending.

Load on the engine/ truck weight, engine temp, fuel, etc can affect, and "it might ping" if too much

67Dart273 said:

This 15+ inititial timing is for hotrods. You are not going to want that in a 1 ton. But what you describe sounds like the cam is way off. It sounds like you bought a multi key-way advance/ retard sprocket kit. It sounds to me like you got the cam off somehow. One easy mistake is to use the wrong timing mark on the lower sprocket with the wrong key. The other mistake someone made is they tried to put the keyway at top instead of the mark. I'd start with checking cam timing. You can estimate this "in the rig." Read the shop manual which you can download many of from MyMopar for free

If you can "guess" what the cam specs are, you can estimate the no1 valve events degrees. There are various ways of doing so at the balancer, even measuring with tape and coverting inches to degrees rotation

If the distributor advance is not stuck, and has a stockish torque / truck cam, that engine should run decent at low speeds somewhere 5is to 12ish BTDC depending.

Load on the engine/ truck weight, engine temp, fuel, etc can affect, and "it might ping" if too much

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The chain and gear set did indeed have 3 settings. However, I'm sure I used the "stock" marks not the +4 or -4. I also definitely did not put the crank keyway at 12 o'clock. Crank dot at 12, Cam dot at 6, keyway was about 35-45 degrees clockwise of 12.......The one possibility is perhaps I eyeballed 1 tooth off of "lined up" but I really don't think so.

Thanks for the input though......I will have to pull the drivers side valve cover and watch the valve timing, to see if it's obviously off. Although I have no way of knowing what the Cam specs are but I suspect they are stock, or perhaps an "RV" cam has been put in at some point in the rigs history.

I'm slipping. Pun intended. IT IS ALSO possible that the balancer has slipped the outer ring and that the timing marks are incorrect. Also it seems to me that some motorhome/ van engines had the marks in a different place??? Maybe I'm dreaming


This is easy to check. Buy or make a piston stop

Disconnect battery for safety and remove no1 plug or even all plugs. Make sure piston is 'down a ways' and install the stop. Wrench the engine around carefully until it stops against the device. Make a temporary, accurate mark under the TDC marker onto the balancer

Now rotate the engine CCW and do the same thing. You will have two temporary marks some distance apart. The correct TDC is halfway between

I made this one in the early 70's and still have it

67Dart273 said:

I'm slipping. Pun intended. IT IS ALSO possible that the balancer has slipped the outer ring and that the timing marks are incorrect. This is easy to check. Buy or make a piston stop

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Like I said in my original post, I verified that using a dowel rod feeling piston movement through spark plug hole(poor mans piston stop) and comparing to another 360 balancer pulley and it matched up exactly.

You have an engine that is nearly 50 yrs old. Quite possible & likely cam has been replaced & the new one has more oomph. Which would explain the need for more timing at idle for best idle quality. If you did inadvertently install the cam 4* advanced or retarded, doesn't mean it is wrong for that engine. Could be, but only way to know for sure would be to put the engine on a dyno & test all three cam positions.

Bewy said:

You have an engine that is nearly 50 yrs old. Quite possible & likely cam has been replaced & the new one has more oomph. Which would explain the need for more timing at idle for best idle quality. If you did inadvertently install the cam 4* advanced or retarded, doesn't mean it is wrong for that engine. Could be, but only way to know for sure would be to put the engine on a dyno & test all three cam positions.

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Yeah, the RV it was in had only 48K miles on it, and hadn't been registered for the road since 2001. I really, really think the engine had never been out......but I guess the cam could have been replaced at some point, and that could have been done without removing the engine.....there were signs the water pump had been replaced but every other bolt seemed original with factory paint on it still......The cam could have been swapped for an RV Cam, by the company that did the RV conversion (Beaver coaches, Bend, Oregon) in 1974. You would think they would have marked new tune up info somewhere though.

You should have degreed the camshaft. End of story. Now you don't know where anything is.

RustyRatRod said:

You should have degreed the camshaft. End of story. Now you don't know where anything is.

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The gear set I used only had 3 settings. I am 100% Confident I used the stock keyway notch and corresponding markings.

When I took this engine apart it had a stock Chrysler plastic coated gear set on it, with no adjustments. So there was really no reason to assume the cam was meant to use with anything other than stock markings.

Gloyale said:

The gear set I used only had 3 settings. I am 100% Confident I used the stock keyway notch and corresponding markings.

When I took this engine apart it had a stock Chrysler plastic coated gear set on it, with no adjustments. So there was really no reason to assume the cam was meant to use with anything other than stock markings.

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You are making the assumption that the timing set is accurate. It doesn’t have to be, and certainly could be off. By a big margin.

As RRR pointed out above, you don’t have a CLUE where your cam is timed. It’s a wild assed guess at best.

I suggest you pull it back apart and VERIFY where the cam is. If you can’t degree a cam, find someone who can and have them teach you or do it for you.

Until you do that, anything you do or change is just shot in the dark.

If you just refuse to do the obvious, then pull the drivers side rocker cover and out the crank on TDC overlap number 1 and look at the valves. If they are both open the same, the cam straight up. If the intake is open more then the cam is advanced. If the exhaust is open more, the cam is retarded.

That’s better than a guess. The issue becomes how far advanced or retarded the cam may be. You need a degree wheel and dial indicator to verify what you have.

yellow rose said:

You are making the assumption that the timing set is accurate. It doesn’t have to be, and certainly could be off. By a big margin.

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Yes I am assuming that the Mopar Performance Gear set is accurate. Why wouldn't it be? You think factory mopor parts would not be accurate?

At any rate.....i drove the truck today, and it was excellent. I don't think it would have run as well as it does, if the Cam was a full tooth off, which is the only possible mistake I thought I might have made. I didn't just throw the chain on any old place....lol.....I know that I used the correct marks, and like I said in my initial post I'm nearly certain that the marks where lined up correct. The excellent drive-ability pretty much confirms that. As to the ignition timing, best guess is that the Cam is an RV cam, not the stock.....and setting initial timing at 15 is gonna be fine.

This is a work truck. I'm not trying to build a hotrod or drag engine. So long as it runs well with good power and throttle response, I don't see a need to tear the waterpump and cover off again.

Thanks to all for letting me bounce my thoughts off your knowledgable group, even though this isn't actually an "a body"

Gloyale said:

The gear set I used only had 3 settings. I am 100% Confident I used the stock keyway notch and corresponding markings.

When I took this engine apart it had a stock Chrysler plastic coated gear set on it, with no adjustments. So there was really no reason to assume the cam was meant to use with anything other than stock markings.

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Once again, you know absolutely ZERO about "where" the camshaft is installed. It was very likely not installed in the correct position from the factory. They hardly ever are.

Do a search on how to degree a cam and read up on it. It's pretty important to get right. So much so that I'll never do another again without it, even stone stock.

Gloyale said:

Yes I am assuming that the Mopar Performance Gear set is accurate. Why wouldn't it be? You think factory mopor parts would not be accurate?

At any rate.....i drove the truck today, and it was excellent. I don't think it would have run as well as it does, if the Cam was a full tooth off, which is the only possible mistake I thought I might have made. I didn't just throw the chain on any old place....lol.....I know that I used the correct marks, and like I said in my initial post I'm nearly certain that the marks where lined up correct. The excellent drive-ability pretty much confirms that. As to the ignition timing, best guess is that the Cam is an RV cam, not the stock.....and setting initial timing at 15 is gonna be fine.

This is a work truck. I'm not trying to build a hotrod or drag engine. So long as it runs well with good power and throttle response, I don't see a need to tear the waterpump and cover off again.

Thanks to all for letting me bounce my thoughts off your knowledgable group, even though this isn't actually an "a body"

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Very simply because of factory machining tolerances. Factories spit those timing sets out millions at a time. Lets try to make this easier for you to understand.

In order for your camshaft to be in the right place, here is what has to have happened. The keyways on the cam and crank gears have to be in the correct positions, both relative to the camshaft and the crank keys on your engine. There is little chance of that happening. Why?

Simply because we are measuring in DEGREES. That is an uber small measurement to be certain everything is correct. It's perfectly "normal" and "accepted" that factory keys in cranks and cams be machined incorrectly. Also the same is true for any timing chain set with the keyways in the cam and crank sprokets. Add all of that "unperfectness" together and you could be way off, even with factory parts. It's a simple fact of life and it's very RARE for everything to be "just right" when you simply install dot to dot, or "wherever" without a degree wheel.

What we're telling you is true and 100% factual. If you choose to be hard headed and stubborn and ignore our advice, then so be it. But remember one thing. You ASKED this question. We cannot help that the answer is not one that you don't want to hear or accept.

Gloyale said:

Yes I am assuming that the Mopar Performance Gear set is accurate.

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You are making assumptions. It won't run, yet you claim "everything is OK" Well there HAS to be a reason. You have been given good advice here. Don't look away from it.

1. Never assume ANYTHING. Don't assume the cam is in time, don't assume you read the marks correctly, and don't assume the cam drive set was marked correctly. CHECK IT

2.....Check your timing marks with a piston stop. That is THE only way to know they are correct

3....Check your distributor. Make sure the weights are free. When "I was just a boy" I had someone with a Chev/ other GM and the then popular "window" adjust dist. THE TOP HAT assembly consisting of the points cam, the advance, and the rotor mount had come loose from the shaft. Yeh. That took some thinking.

Gloyale said:

Yes I am assuming that the Mopar Performance Gear set is accurate. Why wouldn't it be? You think factory mopor parts would not be accurate?

At any rate.....i drove the truck today, and it was excellent. I don't think it would have run as well as it does, if the Cam was a full tooth off, which is the only possible mistake I thought I might have made. I didn't just throw the chain on any old place....lol.....I know that I used the correct marks, and like I said in my initial post I'm nearly certain that the marks where lined up correct. The excellent drive-ability pretty much confirms that. As to the ignition timing, best guess is that the Cam is an RV cam, not the stock.....and setting initial timing at 15 is gonna be fine.

This is a work truck. I'm not trying to build a hotrod or drag engine. So long as it runs well with good power and throttle response, I don't see a need to tear the waterpump and cover off again.

Thanks to all for letting me bounce my thoughts off your knowledgable group, even though this isn't actually an "a body"

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....and we're not talking about "a full tooth" here. We're talking about DEGREES which is much smaller than a full tooth and can make an incredible difference right or wrong. But hay, you're obviously happy and that's good. Even if you're off by ten degrees and I've seen it happen. But you'll never know. Good luck!

RustyRatRod said:

....and we're not talking about "a full tooth" here.

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well, I've got the timing set I've got. I'm not buying a different setup. I was worried I might have installed it a tooth off. I am now convinced I did not.

Thank again, I think I'm good now.

Gloyale said:

well, I've got the timing set I've got. I'm not buying a different setup. I was worried I might have installed it a tooth off. I am now convinced I did not.

Thank again, I think I'm good now.

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You don't have to buy a thing different. I'm sure it's not a tooth off if it's running. You don't get it and you never will so have fun with what you have! That's what it's all about anyway, no matter what anyone thinks.

RustyRatRod said:

You don't have to buy a thing different. I'm sure it's not a tooth off if it's running. You don't get it and you never will so have fun with what you have! That's what it's all about anyway, no matter what anyone thinks.

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I suppose the set I have could adjust +4 or -4 degrees If I wanted to reset it all. But since it's running well, I don't see the point in pulling off the cover....spending money on degree wheels and $40 on new seals to reset it. Plus, in my experience, you never get quite as good a seal when you replace the cover with Oil pan in place, as you do when you put cover on first, and then install the pan like I did with engine on the stand.

Your advice has given me quite a bit to research and ponder. I've got a buddy whose 318, '88 d-150 just crapped again.......might be a plastic tooth chain issue, so I will get a chance to mess around with Cam settings again soon.

Gloyale said:

I suppose the set I have could adjust +4 or -4 degrees If I wanted to reset it all. But since it's running well, I don't see the point in pulling off the cover....spending money on degree wheels and $40 on new seals to reset it. Plus, in my experience, you never get quite as good a seal when you replace the cover with Oil pan in place, as you do when you put cover on first, and then install the pan like I did with engine on the stand.

Your advice has given me quite a bit to research and ponder. I've got a buddy whose 318, '88 d-150 just crapped again.......might be a plastic tooth chain issue, so I will get a chance to mess around with Cam settings again soon.

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That's very correct. The "by the book" method requires oil pan removal to remove the timing cover, but very few people do that and again correct that resealing the timing cover is difficult with the pan in place....although it can be done, it's a prime place for a leak, for sure!

I'll put it to you this way. Between camshaft timing and ignition timing, you can tweek both and if they are out significantly, you can add 30 HP real quick. That's a huge difference foe essentially "free" work. It sounds like your is running good though. At least good enough for you and isn't that all that counts?

I say your chain is OK. set the initial to 15 or 20 (with can plugged) then shorten the slots to get 35 total (can still plugged) then work with the springs to stay under the pinging point at
WOT (max load/max throttle/hot day) then plug in the can. bottom line NO pinging at any point in time.

Gloyale said:

Should I be worried my Cam timing is off? (Chain installed tooth off?) Or time it to feel, listen for pinging under load and adjust accordingly?

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No, on the first and
yes on the second.
But
First put all-new fresh gas in the tank, and drive it, If it still has problems getting down to a TRUE 2.5*; AND if you installed the original Holley 2-bbl; get rid of that trouble maker. The low speed circuit in that carb is nearly impossible to get right, it will take you hours and days. The simplest is to just get rid of it.

Here's the deal;
I ran the Mopar 292/292/108 cam, in from 4* retarded to 8* advanced and it idled just fine at from 5* advanced to 18* advance in any of those cam-timed positions. And with a Holley 4-bbl , after the tune was in, it took throttle like a champion.
So what you say.
So I don't care where your cam-timing is. IMO, for your application, if it starts and runs at 15*, the cam-timing is close enough.
Why it won't idle at 5* is a whole nuther problem. And I agree with everyone who says to go out and get a piston stop and PROVE your TDC mark! A dowel in the whole means absolutely nothing no matter how careful you think you are being. At TDC your 360 has a window of crank rotation, of at least 5*, where the piston just about dwells, with almost no piston movement. That's problem #1. And saying it looks the same as another one laying on the bench, is just as vague and means nothing.That's problem #2.
Problem #3, is that you haven't said a word about your Power-Timing so I assume you don't know it. And this is almost critical to know, far more critical than your Idle Timing. Lets say your mechanical advance system is set up for 2.5* advance at idle. That means the factoryD for that engine would have been designed for it and would probably bring the PowerTiming to at least 32* at some unknown by me higher rpm, guessing 3600. That means the centrifugal would be about 30 Degrees. Now, if you set the Idle Timing to 15, and the D brings in another 30, that totals 45, which is enough to rattle all your piston skirts straight into the oilpan. That's problem #3.
Problem #4 is we don't know your elevation, nor at what temperature your engine was running when it stalled, These are key things to know.
So you gotta fix these problems before you do anything.

However this does not prevent you from doing some other diagnostics as to why it won't idle with short timing. And my guess is,either;
1) the carb is not fueling correctly, or
2) the engine is getting too much air from an unregulated source, or
3) the valves are not sealing.

I suggest you start by making sure all the vacuum accessories are properly hooked up and functioning correctly, including especially the PCV system,and the brake booster; and if everything is; then
do a LeakDown test
Why?
If the valves are not sealing, the vacuum will be low. To compensate for this; You will either increase the throttle opening, or increase the timing, or perhaps both. But in either case the throttle blades will not be in the right place as regards the transfer slots.
So if you try to run at say 5*, you will have to increase the throttle opening, but the engine will not get enough fuel, so you will likely max out the mixture screws in an attempt to keep her running, or you will end up with a high idle.
But, at 15* you can reduce the throttle opening, and the Idle-vacuum will be higher, so now the carb is working "better". But the fact is still, that the manifold vacuum is too low in the first place due to the valves not sealing.
Without doing a LD test, you can chase yurazz around for hours because you don't know that the vacuum is or what it should be.
A compression test could be done, but has to be interpreted by the numbers and the environment. Saying "good" means exactly nothing to me. Your "good" is gonna be different from my "good" which is gonna be different than somebody else's "good" . Furthermore, this test gas to be done properly, which means;
disable the coil, wire the throttle at WOT, ALL plugs out, and with a fully charged battery, crank it as many compression cycles as it takes to get two consecutive same/near-same readings. Whether it be 5 or 12 cycles, just crank it.
But these numbers do not, by themselves, prove your valves are sealing.
They just give a general view of the condition of your engine. See, you said you put in new bearings, but you never mentioned rings nor boring nor honing, or what the ring gaps were, so the compression numbers would be somewhat meaningless, especially not knowing your elevation; Oregon is not Kansas.