7.5l Big Block - Working Out The Kinks - Rephased Cam

LS1Nova

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Jun 19, 2015
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I've got a 1977 Lincoln Mark V with the good ole 460ci in it.

Problem is, it's not as good as it should be.

I'm not looking to light the tires up, I'm just looking for efficiency and decent response for my 2-ton tank.

The problem with the engine is called the "EeeePeeeAye". Early in the 70's, auto makers rushed to tweak the power out of their proven designs to constrict the emissions out of them. Less going in, less going out.

This led to Ford brilliantly retarding the cam timing gear by half a tooth. It made it harder for the engine to breathe, and worse, it was harder to exhale all of the hot gasses it burbles out which made the engine run hotter.

Here's what I've done.

I've freed up the exhaust with dual crossover pipes and MagnaFlows. The setup is very mellow and well mannered as far as sound but the gas really kicks out the back with some considerable force.

I have a brand new aluminized-steel gas tank installed.

Next:

I've already purchased my "straight up" timing gear that will reset to 0° offset, the proper original timing. This will be installed as I do the following.

Replace fuel pump and filter
Flush block coolant
Clean oil pan/replace gaskets
Replace valve cover gaskets
Clean and tune 4bbl Motorcraft 4350 carb (650cfm I think)
Replace and tension accessory belts
Flush radiator and leak test
Replace air filter with Wix-brand
Clean or replace distributor cap and rotor
Set ignition timing and recurve for new cam phasing

Any tips as far as this procedure is welcome! This is just a basic write up of the process so I can get some input!

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LS1Nova

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Pulled the carb off and found that a sort of freeze plug had blown off of it. Good thing it sat tucked in the intake manifold. This may account for the backfiring when you drop the throttle.

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So I've cleaned the valve covers and replaced the cork with rubber while the carb is out. I'm debating removing the AIR system entirely. Opinions?

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LS1Nova

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Jun 19, 2015
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Ok I'm keeping the AIR injection, but I'll need to replace the valves to end the popping in the exhaust. I find it only happens when the vacuum signal hoses are plugged in. Unplug them and no noise! So time to diagnose and fix that.

I only had the weekend to get this done, so everything was rushed. Very impressed with my first car carb. She fired right up and hasn't had issues since. A lot more response now that the accelerator pump lever is adjusted, as well as the float.

Next week I hope I have the guts to get the new chain in there. The more I look at it the more it looks like a tight fit. I may also replace the front main seal since oil is appearing around the balancer.

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Last edited:

7991LXnSHO

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Sep 1, 2010
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Sorry I am late to the party.
DO NOT remove the AIR system, it costs neither power and the weight savings is negligible on a big car.
The little cam timing change may make little difference. The stretched chain may make a bigger change and is a good idea. Maintenance is always a good idea. Check and play with the distributor total advance and curve. That may have been de tuned too.

When it comes down to it, head porting work or new heads may be what it takes to make you really smile. One of the car mags just did a dyno test on new Ford big block heads, and it was quite impressive. It made the gas sucker put out the power to justify the low MPG the 460 always seemed to get.
 

LS1Nova

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Boy was that chain STRETCHED! It was even starting to wear away one of the oil plates in the timing cover (one of the little shields that keeps oil from dropping onto the crank.).

Again, I'm doing each step with only a weekend at my disposal. Thankfully, July 4 gave me a full Saturday!

This weekend I've replaced the fuel pump, water pump, front main seal and the timing chain.

The cover is on, but needs to be torqued down. Then the pulleys and accessory brackets can go back on and that's it!

Thanks for the advice. It's a given that the heads are where most of the power is. Deck height would be the real hurdle. But none of that will be done to this car. It's merely a daily driver and I want the economy and claw hammer reliability to go with a great and smooth ride. The timing chain was to improve efficiency and make it run cooler. The exhaust is to open up as much restriction as I can without replacing the heads. I have the taller dif. as well, which should make a big difference.

You're correct about the timing. It could definitely be recurved. I plan to match it to the curve needed for my new cam.

I've started her up with the new chain just to see that it works and she's idling smooth. Back to getting things together.

Next week might be distributor. Then that leaves brakes and my somewhat leaky radiator.

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7991LXnSHO

Now I want a 10 year badge
Sep 1, 2010
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With the fiber teeth gear and loose chain, that was a disaster waiting to happen!
I can not tell for sure on skittle screen, but that is a 4bbl carb and square bore intake? If it gives you more trouble, I would replace it in ainute with a street vac. secondary Holley. You can make the secondaries open only when you really romp on it and mostly sip through the primaries. And they are easier to tune than most stock designs.

As far as the leaky radiator, re-core or replace are the best answers. Then I run a tube of silver powder stuff in my coolant just in case (for my heater vote too) in my classics. If you have to cheap out after spending all your funds on the rest, use Bars Leak. The industrial strength rat poo in it works the best. It also can slow heater core flow of you use enough extra.
 

LS1Nova

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Jun 19, 2015
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You called it on the carb. Motorcraft. It doesn't give me any trouble starting or stomping the throttle. The secondaries open only when you're practically wide open.

The core of the radiator looks ok on the outside. The leaks are on the sides. I may as well replace the whole thing since my water pump is new and I don't want more crap accumulating again. Also, what's an extra $100 :)

I'm glad I took the chain out too. I assumed it'd be ok for only having 103k miles =\
 

LS1Nova

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Phew, this thing really moves now that it's properly tuned. I have left nice 3' long one-wheel skids all over town.

I've started replacing the rubber brake components and greasing the bearings well. I took a wire brush to some parts and lubed the caliper anchor plate grooves.

Now I'm noticing though that it will die if left to idle for too long. Give it 5-minutes and it will step down a few RPM before finally puttering out. Any thoughts? The plugs are fine and when you hit the key once it dies it carries on perfectly.

Thanks!
 

7991LXnSHO

Now I want a 10 year badge
Sep 1, 2010
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I see new fuel pump and filter are on the list, as is rebuild the carb. I would check the fuel pressure at idle and higher RPMs. Then I would start chasing down idle circuit and float level issues.
 
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