View Full Version : Mark IV - cracked exhaust manifold
05-07-2010, 04:32 PM
The good news is that's it's not pre-ignition knock.
The bad news is that the tapping or clicking sound on accelleration has been determined to be the fault of the right hand side exhaust manifold which has a crack.
Although we're discussing my 460 Mark IV I'm leaving this thread here in the technical area as it could well apply to our Mark IIs
This is a common problem on all 430/462 and 460" engines. That is why I had them re-manufactured with better material and offer a lifetime warranty. View our website for a photo.
05-07-2010, 04:34 PM
Very common problem. I believe strengthened aftermarket manifolds are available.
When I recently redid my 460 I followed some advice about removing the bolts. I was advised to use an impact rather than a breaker bar. However, that may pose a problem if the engine's still in the car.
05-07-2010, 06:55 PM
Glad you found the problem. ....
on your car there is an adjustment on the vaccum advance element. Uing an allen wench ..remove the vacuum advance hose and insert the allen wench in the fitting. Using your timing light you can adjust the internal spring tension limit your advance. there was a TSB on that as well...
05-08-2010, 02:13 PM
Continental59... thanks for the tip. I'll keep it in mind for the future. I intend to re-place the timing set in the Mark IV to one pre-1972 -- also intend to switch out the distributor to a recurved one for a match with the timing set, and lastly go with a new carb. The immediate need is replacing (Jack got the order) the cracked exhaust manifold which now has me tempted to put on a dual exhaust on the passenger side ( right now I have a single muffler and resonator). Additionally I still have an "intermittent" high speed shake which seems to be coming from the right front wheel -- so I'm going to change out some steering components which appear to have ancient bushings, such as the pitman arm, idler arm, etc.
05-08-2010, 02:20 PM
Lincolnland seems to have the best price so far on suspension parts. They have a fairly complete kit for my '68 for $312.
I put a dual exhaust on my '77 TC. I don't believe it was available for the Mark or the TC. I had a local fab shop bend and fit the pipes to the car. I was going to go stainless, but decided against it. Be sure to drill drain holes in the mufflers and resonators or they will fill up with water. I like the way the system sounds and I like the downturn chrome tips barely visible.
That goes for Mark IIs, too.
05-13-2010, 07:25 PM
On my 1976 Mark IV. I installed the factory specified Holley that replaced the Motorcraft 4bbl. That was a factory recall. Using a half inch pipe plug just under the carb you can opt for the EGR delete.
I machined a half inch aluminum spacer and mounted it under the carb to dissipate the heat...
I set the timing to 12 Degrees. Adjusted the total advance via the set screw. There are other tricks for that distributor ...so it really does not need replacing.
The timing gear and chain was replaced with a double roller chain set. I also installed a new performance camshaft with the associated parts.
The dual exhaust made the difference. Going from 6 (cats resonators and mufflers) to 2 mufflers
I used two "test" tubes eliminating the cats.
Two performance flow through mufflers with a cross over pipe
eliminating the two end mufflers.
The addition of chrome walrus tips from a 78 trans am with the exhaust coming out the side just after the rear wheel well opening just sets it off...
I can tell you a new modern carburetor and a slick flow through dual exhaust will really wake up that engine.
Of course my favorite part is the looks you get with the low decibel tone at the traffic light.
05-13-2010, 09:10 PM
Tomorrow I should receive the new exhaust manifold from Jack and I'll get it installed. Right now I have a single exhaust w/ a stock muffler and large resonator on the end. No cat. Probably going to make a basic dual system with another stock muffler and crossover w/o resonators. After I hear what that sounds like I might have to add resonators if it's too loud. I'd like that nice low sound, but too loud is only good on a motorcycle.
05-13-2010, 09:13 PM
I have mufflers and resonators on my '77 TC. It does sound sweet. I kept the cats.
05-26-2010, 06:53 PM
I visited my Mark IV at the mechanics (an ex-Ford mechanic who has been running his own Meinke shop for the last 15 years near my house). All the front end steering stuff has been replaced and alighned. Hopefully that will eliminate the small occasional shakes. The new right side exhaust manifold from Jack has been installed. Unfortunately a bolt broke while attempting its removal and that required welding on a bolt head etc. and I'm told took an hour to get off. Certainly glad I didn't try it myself. They're finishing up adding a dual exhaust on the right side with an "H' section, muffler, small resonators and stainless steel oval tips. I'm very anxious to see and hear the result. Planning on picking the car up Friday night nad spending the week end cruising.
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