How to Break-In and Tune Your Ford Small-Block – Rebuild Tips

When you are about to fire a new engine, there are important considerations you must be attentive to first. For the break-in period, it’s a good idea to use Castrol conventional SAE 30 oil – save the synthetic for after the engine is broken in. Although a good many of us never do this, you should prime the oiling system and be sure there’s oil pressure. This not only confirms oil pressure and flow, it pre-lubes the bearings for that initial fire-up. Oiling system primers fit into the distributor opening and onto the oil pump shaft. When you spin the oil pump (the drill needs to be running in reverse, or counterclockwise), oil should flow from the rocker arms and there should be a healthy reading at the oil pressure gauge.

---

This Tech Tip is From the Full Book, HOW TO REBUILD THE SMALL-BLOCK FORD. For a comprehensive guide on this entire subject you can visit this link:

LEARN MORE ABOUT THIS BOOK HERE

 

SHARE THIS ARTICLE: Please feel free to share this post on Facebook / Twitter / Google+ or any automotive Forums or blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https://www.diyford.com/how-to-break-in-and-tune-your-ford-small-block-rebuild-tips/

---

 
 

Since Jim Grubbs wanted to know the kind of power a stock small-block Ford makes, he wasn’t releasing the 289 to Jeff Fischbach until it was fired and had a couple of dyno pulls under its belt for Mustang Monthly magazine.

Jeff’s stock 289-4V engine is on the dyno and ready for action. Jim Grubbs’ talented staff has done a magnificent job on this engine. It is built for good low-end torque and solid reliability. We’re about to learn how much power it makes.

When you install the distributor, make sure you get the timing right. Put that timing mark on TDC (number-1 cylinder) and put the rotor on number 1. Installing small-block Ford distributors is a pain in the neck. It’s hard to get the distributor seated and timed properly. A good rule of thumb is to get the rotor as close to number 1 as possible, then handcrank the engine, which gets the distributor lined up with the oil pump shaft. Finally, back-crank the engine and see where the rotor is positioned.

Carburetor static tuning is pretty simple. Be it an Autolite or a Holley, the drill is the same. Idle mixture screws get seated, then backed out 1-1/2 turns. Idle speed tends to be hit and miss. It’s a good idea to back the idle speed screw off to where the throttle plates are closed, then milk the speed screw open (during cranking) until the engine fires.

 

Mustang Monthly magazine wanted to run stock exhaust manifolds on this engine for accurate horsepower and torque readings. Unfortunately, Jim Grubbs Motorsports didn’t have the necessary exhaust plumbing to run stock manifolds. As a result, Andy is bolting on a set of dyno headers for this one. The engine made 212 hp and 282 ft-lbs of torque.

Professional Mechanic Tip

Ignition timing is set two ways. At idle, timing should be dialed in around 12 degree BTDC. Total advance should be no higher than 36 degrees BTDC. During our dyno pull, Jim Grubbs was able to get the maximum amount of horsepower and torque at 34 degrees BTDC.

After you’ve broken in the cam, let the engine run at a fast idle (about 1,200 rpm) until the thermostat opens. Keep the radiator cap in place, but loosen it enough to allow air to escape without spraying you with coolant. Like we said earlier, fill the radiator only to the top of the tubes, but no further until the engine is hot and the coolant fully expands. It’s also important to remember coolant has a higher boiling point under pressure. Keep the radiator cap secured once all air has escaped from the water jackets. You may actually burp off all air by removing the heater hose at the intake manifold as the radiator is being filled. This allows most of the air to escape without having to wait for an open thermostat.

If you are running a flat-tappet camshaft like we are, the engine must run at 2,500 rpm for 20 to 30 minutes to work-harden the cam lobes and set the wear pattern on the lifters. When we fired our Jim Grubbs 289, it sat on the dyno and roared with authority for 20 minutes to properly wear in the cam lobes. You don’t have to do this with a roller camshaft.

 

Professional Mechanic Tip

Distributor installation is always challenging with the small-block Ford. The distributor seats just so far – then we hand-crank the engine backwards and wait for the distributor to seat. Then, we check the rotor indexing for proper position.

While you’re wearing in the camshaft, check the ignition timing and set it to approximately 12 degrees BTDC  at idle. Watch the exhaust headers/ manifolds for excessive heat (glowing), which can mean late timing or a lean fuel mixture. Both can permanently damage the engine. A lean mixture can mean jets that are too small. It can also mean the fuel line is too small for how much power the engine is making. What size is your Ford’s fuel line? Most of them are 5/16 inch, which is too small for a powerful V-8. We suggest the use of a 3/8-inch fuel line if horsepower rises above 300. When power rises above 400, you need a 7/16-inch fuel line.

 

Jim listens for unusual valvetrain noises during warm-up.

An empty engine bay is like the artist’s canvas – ready for our close attention. Before the 289 engine goes into this one, it’s going to get spruced up.

Gunk engine cleaner is the same great solvent we were using 35 years ago to debunk engine compartments. It still works very well on the gummiest of engine bays. We spray it on, let it soak in, and then hose it off. Lots of sanding, too!

 

 

Classic Krylon semi-flat black looks great on a classic Mustang engine compartment. This is the most perfect paint and color. It goes right on and dries quickly.

The Jim Grubbs 289 receives its Centerforce Dual-Friction clutch on the tailgate of a pick-up truck.

When the engine has both reached operating temperature and run long enough to break in the camshaft (flattappet only), it’s time to set total ignition timing. Rev the engine to 3,500 rpm and hold it there. Check the timing and determine how many degrees you have at the pointer. Total advance should be in at 3,500 rpm. Each and every engine is different based on what it has for a camshaft, cylinder heads, and induction. Our project 289 engine was all finished at 34 degrees BTDC at 3,500 rpm. Some engines can go as far as 41 degrees BTDC, but this is discouraged. You have to develop a feel for your engine in all of this tuning. With the engine at 3,500 rpm, slowly move the distributor toward advance until it begins to misfire. If everything is pretty typical, it will get smoother as you move total timing toward 36 degrees BTDC. When you creep past 36 degrees, it should begin to run rough. Bring the timing back a pinch to 34 to 36 degrees BTDC. That’s optimum timing.

 

Professional Mechanic Tip

Senders are something we never think about enough. Coolant temperature and oil pressure senders need to be fresh and accurate. Not knowing these vital signs can cost you plenty.

Important!

Before you spin the engine, what kind of camshaft are you running? Roller camshafts need steel distributor gears. Iron gears should only be used with flat-tappet camshafts.

Dialing in the vacuum advance is an art. You want the vacuum advance to work hand in hand with the mechanical advance. As the throttle is opened, the vacuum advance should deliver a soft spike advance in the timing, which segues into the mechanical advance as revs increase. The vacuum advance’s job is to give an initial spark advance spike when the throttle is opened. The trick is to adjust it to where it’s a smooth transition from vacuum to mechanical advance. The result is a smooth application of torque as RPM increases. If you get pinging (spark knock) coming off idle, you need to slow the rate of vacuum advance. If the engine tends to fall on its face, you need to quicken the rate of vacuum advance coming off idle.

 

We don’t give much thought to ignition wiring, but it can cause engine damage via crossfire and misfire. This is especially critical if you are running nitrous or a supercharger.

Once the engine has had a chance to get hot and be driven, it’s a good idea to examine the coolant for discoloring, check the oil (which should be dark or black to some degree from assembly lube and molybdenum cam grease), and check for leaks. The rear main seal area should be free of leakage. Closely inspect around the freeze plugs, intake manifold gaskets, valve-cover gaskets, and the front timing cover.

When you have 500 to 1,000 miles on the engine, change the oil and run Mobil 110W30 synthetic engine oil with a Wix or Motorcraft oil filter. After you have 1,000 miles on the engine, do another inspection. Pull the dipstick and look at the oil. It should be free of debris and be relatively clear. If it is milky and looks like turkey gravy, you have coolant in the oil. The cause of coolant leakage must be determined and corrected immediately. If it is a heavy gravy, like mud in consistency, the engine must be torn down and inspected. Too much coolant in the oil will damage the bearings and rings, rendering a new engine old in short order. When you remember how important that layer of oil between moving parts is to engine survival, having pure oil in the pan becomes paramount.

It’s also a good idea to do a spark plug reading. The plugs should have a nice tan glow – not black and sooty, and certainly not snow white. Black and sooty means a rich fuel mixture. Snow white means it’s running too lean. Snow white with dots of aluminum is cause for alarm – too lean with piston melt. Spark plugs that are oily means piston ring leakage or valveguides that are in trouble. Rarely will you see oil on all eight spark plugs unless there was a gross error in assembly across eight bores.

While you are under the hood, listen to the engine at idle. Do any noises stand out? Any knocking or clicking? Do these noises happen cold or hot? Use a longhandled screwdriver to listen for noise and location. A steady clicking may be nothing more than the need for valvelash adjustment. But, check the source of the noise immediately. Remove the valve covers and watch the valvetrain at idle. Ascertain the source of the clicking.

If there is a knock, especially down low in the engine, this is a reason to be more concerned about assembly issues, clearances, and the like. If there is a knock in rhythm with the crankshaft, remove spark plug wires one at a time and listen closely. If the knock goes away on a particular bore, the problem is serious and mandates a teardown. If a knock is in rhythm with combustion pulses and vanishes when you remove a spark plug wire, the same logic applies. You will have to knock the engine down and determine the cause.

Written by George Reid and Republished with Permission of CarTech Inc