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1978 Mercury Grand Marquis timing chain

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Jul 1, 2014, 4:30 PM

Post #1 of 3 (2737 views)
1978 Mercury Grand Marquis timing chain Sign In

Hello. I have a 1978 Mercury Grand Marquis with a 460 V8. The car has 130K miles on it. A gentlemen at the auto parts store who seemed to know alot about late 70's Fords and Lincolns suggested that at 130K miles I should get a new timing chain. He based this on listening to the engine and the high mileage. He thinks I should do this ASAP or I could damage the engine. The engine seems fine to me, but I'm not a mechanic. The only problems I can tell is that it needs an accelator pump repair for the carb (I was told this by a local carb mech), and it idles a little high when its warmed up. It takes a while to start when cold, but this could probably be the accelator pump. Does getting a new timing chain seem like a necessary precautionary step to take with the car? Any advice would be greatly appreciated. Thanks!!!

(This post was edited by 78merc on Jul 1, 2014, 4:41 PM)

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nickwarner profile image

Jul 1, 2014, 7:25 PM

Post #2 of 3 (2722 views)
Re: 1978 Mercury Grand Marquis timing chain Sign In

These chains spend their whole life bathing in engine oil to keep them lubed. Your engine is not one that is revved to high RPM nor does it have a high-lift cam requiring stiff valvesprings. That chain is just fine most likely, and not worth just changing for the sake of changing it. You have met yet another parts store "expert."

Doing a 460 timing set on your car is a pretty easy task, but unnecessary to do just because of mileage. I've seen them in good shape still with twice the mileage. I'm glad you came here to ask before wasting your time and money doing that.

As far as your cold start goes, see if the choke is closing properly when you are at a cold start. This should have an electric choke and may not be working right. Last owner may have possibly set the idle adjustment higher to help compensate for that, but that would need to be looked at.

I'm not a carb guy, but we have some old-school guys here that will probably be dropping off their two cents on this and they have experience working on your type of setup.

Nice to see someone keeping one of these on the road. I used to have a 78 LTD with a 351W. Still miss that big boat. I was the only one of my friends that could parallel park it.

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jul 1, 2014, 8:28 PM

Post #3 of 3 (2718 views)
Re: 1978 Mercury Grand Marquis timing chain Sign In

Again - Chains are not common on these unless it used a nylon cam gear and still there. Just maybe you can see it thru where the fuel pump mounts with that removed otherwise you wouldn't know till there and just do a new one.

Carb pump? If OE might be external, four screws and don't lose a spring inside there and done with it. That was common. Ask me via PM might have a new one on hand!


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