351C where to start?

[351mach1]

Hello all! This is my first technical question post. I just purchased a 71 Mach 1 and need advice on troubleshooting steps and where to go from here.

Quick backstory: The car is an M code with Ram Air so I am assuming the ram air was aftermarket as the wiki says the factory ram air cars are Q code. The vehicle came with basically no history so lets assume we don't know anything about its past life. The only clue I have is that at some point the factory 4 speed was swapped for a C6. The P/O claimed that it was likely they rebuilt the engine when they did the swap based on how good the engine looks. It's also possible that they just threw a different engine in when they did the swap as I have not confirmed whether the engine block number matches the vin. It is definitely a 351C 4V and has a stock split bore intake manifold. I have an in depth mechanical background specializing in diesel truck repair but have never touched a carburetor; so while I may be ignorant to how to tune a carb, I do know how to turn a wrench.

Problem: Engine runs and revs ok but when in gear, it has no power, backfires, and has a big hesitation when you hit the accelerator. None of the interior gauges work and the wiring harness is pretty hacked up. P/O claimed that a month ago they borrowed a friend's edelbrock carb to put on there (to replace the Chinese copy that was currently on there) and that it ran just fine so it just needed a new carb. I installed a new Holley 600 CFM Street Warrior Carburetor and it runs exactly the same as with the chinese carb so it would appear that there is more to the story.

Goals: I want this to be a reliable weekend driver with a good bit of get up and go. From my brief research it seems that I could easily pull 400 HP/Torque from this engine with minimal upgrades. I don't have an unlimited budget and will be trying to save on costs as much as I can but am also willing to buy high quality parts if they will last the lifetime of the car.

So far: I purchased the Holley carb and have also purchased an Edelbrock performer #2665 intake manifold. I have not installed the intake yet. I plan to install the intake and replace the ignition system and perform a tune up at the same time.

Questions:
1. What ignition system to go with? I am seeing many different recommendations on several different forums. It appears that the Ram Air will limit my choices. I like the idea of the MSD plug and play options but everything I read would make it seem that they will not fit with the ram air. How much of a difference does the ram air make? If my car didn't come stock with the ram air, should I convert it back? What distributor is recommended with the ram air? It also looks like I need to choose a distributor that is compatible with the camshaft; due to the unknown history of the engine, how do I verify the camshaft?

2. Due to the unknow history, is there a way to check the timing chain and gears without pulling the front of the engine apart? Should I just plan on doing the timing chain regardless? If I have to dig in there, should I also just do the camshaft upgrade at the same time or save it for down the road?

3. What steps should I be taking here to get this engine running correctly? My current plan is to:
-Check compression to get an understanding of general engine health
-Install edelbrock intake manifold and Holley carb (any must know advice on the intake install?)
-Install upgraded ignition system (need suggestions on what to go with)
-reset ignition timing, perform tune up (plugs and wires) and see how she runs.
-Verify healthy timing chain

Other desired upgrades: I would like to upgrade the exhaust and camshaft. Suggestions?

I am currently away from the car on a work trip so wont really be able to verify anything until I get back to town. I plan to buy the shop manuals and the 351c rebuild manuals. I did snap these photos before I left. Thank you for any and all help/advice.

 

[giantpune]

For 1, I went with a pertronix 3 guts inside a stock style distributor.
1b - you need to make sure the gear on the bottom of your distributor is compatible with your cam. Typically, the difference is if you have a roller or flat tappet cam. The 351C only came with flat tappet. Somebody may have put a retro-fit roller cam and lifters in it. You can pop a valve cover, look down the holes in the block at the lifter valley to see the lifters. The retrofit rollers would need to have something for alignment like dog bones. Flat tappet ones do not. You can also try watching the upper tip of the push rod. Sometimes you can see it rotating on flat tappet motors. Once you know what style cam it is, you can make sure your distributor has the correct gear.

For 2, yes. The distributor is meshed with the cam. That means you can pull off the distributor cap and watch the rotor spin as the crank shaft moves. And that means you can rotate the crank 1 direction to take out the slack, then rotate it the other way and see how much it moves before the distributor rotor starts to move. That is the amount of slop in it from something like a stretched out timing chain.

Another thing you can do is remove the fuel pump and stick a boroscope in the hole. That will give you a view of the upper and lower timing gears and the chain.

3, Be mindful of your height. Many aftermarket intakes are taller than stock. That matters when you want to run ram air, which interfaces with the underside of the hood. The cheapest edelbrock, like the performer, is pretty close to stock and does good for street cars. Thats the one I'm running. And maybe its just me, but I have a terrible track record with intake manifolds if I use the torque specs in edelbrock's instructions. They seal up, then develop a vacuum leak after a few heat cycles. Edelbrock's instructions are good. I just use the normal factory torque specs, not the ones edelbrock suggests.


4, I'm a fan of long tube headers. And I like running RV style cams. They are designed for high torque and smooth idle and used in production vehicles for 100k+ miles. They have lots of torque down low where your car spends most of its time. As you go wilder in cam shaft, you give up torque down low to gain more peak horsepower up high. You also give up smooth idling, the wilder you go.

This is my 351C v2, running the edelbrock performer intake, pertronix guts in the distributor, flat top pistons, long tube headers, and RV cam. This combo is 400ftlb, 325HP and runs on 87 octane pump gas. You can shift that to 400HP, 350 ftlb with a wilder cam, and all the power will happen higher in the power band.

 

[Stanglover]

I didn't read all your post (yet), but the first thing I noticed was that the intake manifold is wrong for a 71...... unless someone put an aluminum Boss 351 intake on it!! You may have a 72 motor which would be a Q code. You need to check the block and date numbers located above the starter as well as the partial VIN stamped on the back left side block just under the head. It ought to match the car's VIN. You could also pull the valve covers and look at the date codes between the springs.
71 M code has very large intake ports and won't match the 72 intake
71 M code did have ram air but optional. Mine doesn't unfortunately. However it the motor is indeed a 72, the ram air could have been added.
Sorry but that's my unqualified thoughts so far.

 

[giantpune]

unless someone put an aluminum Boss 351 intake on it!!

All the nuts and bolts from the lowes fastener section make me doubt that.
Half the bolts we can see in the engine look like they came from the hardware store.

 

[Sheriff41]

I think your approach as listed in your #3 is sound. Don't overlook the simple stuff like fluids, belts, hoses (heating/cooling and vacuum), etc.

It's not uncommon for people to put the wrong style thermostat in 351Cs so you may want to check it while your working on the engine. https://flowkoolerwaterpumps.com/co...-balanced-sleeve-thermostat-with-bypass-plate

The symptoms you describe in your Problem paragraph may indicate retarded timing. Set your base timing to 16° and see if it helps.

Buy a set of ARP bolts for your intake manifold or source all your engine's external fasteners from AMK Products ( https://www.amkproducts.com/i-kits/...ar_=1971&model=Mustang&category=Engine - 351C ).

I run the same Edelbrock dual plane intake you bought and it works well with my ram air.

The 600 cfm Holley is a bit on the small side for a 351C 4V. It should run okay but you'll be giving up some performance.

@giantpune made a good recommendation of the Pertronix ignition. I prefer retrofitting a Ford Duraspark 1 ignition. If you use the regular point distributor cap you'll have no clearance issues with the ram air air cleaner. The procedure for the Duraspark would be straightforward for someone with your mechanical ability. It's described in the Ignition System Improvement section of https://pantera.infopop.cc/topic/sticky-3-351c-basics-and-performance-tuning .

If you decide to change the cam, talk with some of the custom cam providers, e.g., Brent Lykins https://lykinsmotorsports.com/ so you can match your cam with the other mods on your car. You want to build it as a system rather than just throwing parts together.

Ceramic coated Hooker Competition headers have performed well for me and have held up for over 20 years.

Keep us posted on your progress with your build!

 

[Steve McMahan]

Just a thought since your car has amnesia, it’s possible your symptoms point to a contamination fuel tank. I know you changed the carb, but did you trace back to the pump and the tank to verify clear fuel flow? Since the PO didn’t give you the straight story, what else did they fail to mention? Just to alleviate worry, I would check that out. Good luck.