Timing Issue 472
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500, 472, 425, 368 Discussion, Timing Issue 472 in Cadillac Engine Technical Discussion; Long time reader, first time writer. I was reading these forums before I ever bought a caddy. I finally bought ...
  1. #1
    Nrets is offline Cadillac Owners Member
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    Timing Issue 472

    Long time reader, first time writer. I was reading these forums before I ever bought a caddy. I finally bought a 1970 Coupe.
    I am a novice, mechanically, and will probably have a few people cringing when they hear how I caused my current dillema:
    My car was hesitating and running awful 2 nights ago. It stalled. I usually only stall when I'm leaning out. (I have run the thing out of gas). I got it to the station, put gas in and it was still running like crap. So I figured it was a timing issue. It was doing things similar to what it was doing when the timing was off before.
    I replaced the points fairly recently so I didn't think it was the points. In retrospect, it was running EXACTLY the way it ran before I changed the points...so I probably should have tried adjusting the points first.
    INSTEAD, under the assumption that it couldn't possibly be the points. I made a theory: The engine was whipped and is more whipped now from driving it for a year. It needed to have the timing advanced to run smoothly before the new points, at 7 and a half BTDC it would overheat and idle very rough, so I figured it was time to advance the timing again. It was already advanced as far as it would physically go. The vacuum advance was in the way, and someone had already bent it as far as it would bend against the AC compressor.
    I took the cap and rotor off witht he goal of taking the vacuum advance off so I could manually advance the timing more. The plate that the points sit on right above the vacuum advance base was originally very tight... and I couldn't get the screws off the advance because that plate gives very little clearance.. I forced them out by twisting them sideways under the plate. The plate is now very loose. wherin lies my question(s)
    Can the car run like this? Can I just tighten it back up somehow? Do I need to reset the timing? Did I break my distributor? Please, anyone who knows what I'm talking about, I'm in the dark and I want to get my Cad running again.

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    JTraik is offline Cadillac Owners Enthusiast
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    Re: Timing Issue 472

    You should have just negotiated the distributor out of the block and then put it back in, offset one tooth. Just be sure to mark everything before you take it out.

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    Nrets is offline Cadillac Owners Member
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    Re: Timing Issue 472

    Well, if I'm going to take the whole thing out...I figure I might as well convert to one of those MSD ignitions. Any recommendations about which one to get, and how to not mess up putting it in?

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    terrible one's Avatar
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    Re: Timing Issue 472

    Just to tell you, that will be expensive. MSD distributers don't stand alone, you have to run them through a box. $$$$

    Haha, at least that's what I thought about it. I'm broke though.

    If you go to Summit's site www.summitracing.com they offer the MSD Pro Billet distributor for the 472, then you can pick up a MSD 6A ignition box

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    Re: Timing Issue 472

    If you take the whole thing out just do a junkyard HEI. If you feel fancy (or if the old one's shot) pick up a new "hotter" coil. MSD units aren't worth it.

    I don't have experiance with a points distributor so I couldn't tell ya about that, sorry.

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    Re: Timing Issue 472

    If you're all the way against the vacuum advance and can't go any farther, there is more wrong than just having the timing off. I would suggest a new timing chain set, it sounds like the original is pretty worn, which is also throwing your cam timing off.
    The suggestion about a junkyard HEI is an excellent one. Shouldn't cost much and you just need one power wire (the one going to your existing coil should be sufficient).
    Points suck, HEI is MUCH better, and points just suck...

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    Re: Timing Issue 472

    That would be the breaker plate that is loose and will cause erratic timing cylinder to cylinder and a very rough running engine.

    For my money, I would install an HEI system. It drops right in and works great. There is a belt clearance issue around the cap, it is tight, but will usually work.

    I have done this in my '70 Fleetwood, and it's the best thing I did. I ran the base timing at 10 degrees, and hooked the vacuum advance directly to manifold vacuum. It greatly enhances low RPM part throttle response. Timing maxes out a 38 degrees at about 2800 rpm. The distributor came off a 1974 472, but you can use any HEI with the 4-pin module from 1974-80 from a 368, 425,472 or 500.

    You will also be bypassing that horrible transmission controlled spark if it is still there. This prevents spark advance in the 2 lower gears, making the engine seem sluggish.

    Mike

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    Re: Timing Issue 472

    Could be someone had the distributor out and it was installed a tooth retarded.
    Maybe they even re-routed the vacuum advance directly to manifold vacuum like the newer models did.
    The advice about HEI is good. Should not be hard to find and not too expensive. It will pay for itself in reduced crushed dinosaur liquid cost in no time.

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    Re: Timing Issue 472

    Quote Originally Posted by The Ape Man
    Maybe they even re-routed the vacuum advance directly to manifold vacuum like the newer models did.
    That is a good point - if the vacuum advance is hooked up and you set it to 7* advanced, your actual base timing will be retarded. You must always set timing with the vacuum advance disconnecgted and plugged (unless you are SURE there is no vaccum going to it at idle)
    Also, you say the vacuum advance is bent? That doesn't sound good, you shouldn't bend it. Is it possible that when they bent the piece that the metal cracked, opening a vacuum leak?
    Thinking of that, I'd check everything else out for a vacuum leak - leaks will make the car run like crap as well.

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    Nrets is offline Cadillac Owners Member
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    Re: Timing Issue 472

    Thanks for all the info.
    I think the advance is messed up. I did that thing where i blew through it and there was no resistance....like a straw. Someone had bent it up against the AC compressor. They pulled the vacuum hose off and stuck a broken fuse in it. What happens if I try to drive without the thing? Will it have no highend or something?
    I am going to tinker with it on Thursday. See if I can get it running at least. I will look for junk HEI's in my area tomorrow. If I find a good deal, maybe I'll be tearing the old points distributor out come Thursday. Perhaps a timing chain is in store, too. I can't afford to rebuild yet. So I'm wondering would I be asking for trouble replacing a stretched out chain in a motor that has probably been through the mill? I know in some engines, I would. But since Caddys are known for their heartiness, I'm thinking I can chance it. Any ideas? Maybe I should just stick in the HEI and keep it unnaturally advanced until I NEED to rebuild. Is that asking for a quagmire in the heads? Thanks, guys.

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    Re: Timing Issue 472

    Atleast replace that advance, and make sure the breaker plate is not flopping around in there. You will never get that thing to run decent if you don't.

    How many miles are on the engine? Timing chains are pretty hardy in these engines, but they do stretch. But, all too often, guys blame a timing chain for any and all engine problems. These are not the easiest engines to replace timing chains on either, so you'll want to be sure that is a problem.

    You can check the play in the chain quite easily. Turn the engine over in the direction of normal rotation by hand until the timing pointer on the crank pully is at TDC. Then turn it the other way until you feel resistance. This is the slack in the chain being taken up. Record how many degrees the crank turns on the timing gauge and you have the total timing chain slop. 10 degrees is not bad, but anything over that may be getting into a grey area. But, FYI, as soon as you put in a new chain and drive it 100 miles it will stretch out 3-5 degrees anyway.

    If you can find a good HEI distributor, grab it. They are very easy to check. Just put power to the + terminal and ground the housing. Give it a spin and you should hear the snapping as the spark jumps around in the cap. Also check the condition of the advance weights. They should be tight on the pins and swing out and return freely. Throw on a new cap, rotor and advance and you should be good to go.

    You will also need a new set of wires. The points wires will not work with the HEI cap. Also replace the spark plugs with R44XLS6's and gap them at 0.060"

    Mike

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    Nrets is offline Cadillac Owners Member
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    Re: Timing Issue 472

    I decided not to replace the timing chain at this time, thanks, guidematic. Anyway,,,current situation..The car hasn't ran at all since I loosened the breaker plate. It was running rougher than usual BEFORE I inadvertantly loosened the breaker plate. I figure to get it running, I just need to tighten everything down, gap the points and set the timing. I want to go the HEI route, though, and currently have a bid on an HEI on ebay which brings me to my current question. What would you guys pay for a used mid 70's Caddy HEI? How about new? I believe the one on ebay is used. It look very clean, though

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    Re: Timing Issue 472

    I'd pay $40 TOPS for an excellent used one, of course it depends on what kind of condition it is in. If it's worn out you will be dishing out some more cash for a rebuild or upgrade kit.

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    Re: Timing Issue 472

    You can buy reman units for under $200 if you shop around. They are complete and come with a warranty. Most have no core charge either these days.

    To rebuild a used HEI (I have done a few) can easily run this and more, plus the cost of the distributor, if you want to use all Delco parts. If the weights are worn, then you are fubared. None can be purchased except for those aftermarket units that may or may not work effectively with your intended spark curve. But, the internals of all HEI's are identiacl for all divisions, so maybe finding a junkyard Chevy unit with the correct and good weights may be a decent route.

    Mike

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    Re: Timing Issue 472

    Accel makes a replacement HEI distributer for the Cad 500 for $199

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