"Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover." - Mark Twain
It was a warm California June afternoon as the sun was descending upon the horizon. Clothes wreaking of unburned hydrocarbons, I slowly pulled into the garage after a nice drive and turned the key toward myself for the last time before the cars metamorphosis. As I shut the garage I thought, "No biggy, ill have this thing back together in a couple of weeks max." FAIL. It has been way too long since the time of feeling the chills from the acoustic exhaust note, but I am finally finished preparing the engine to handle the turbocharger. Why so long? As Murphy's law puts it, "Anything that can go wrong will go wrong."
Picking up from my last blog post, I took the home ported heads to the machine shop to be rebuilt because I do not have the necessary tools or skills to do so:
1. Using magnets to check for cracks. Cracks cause sealing problems.
2. Machining the valves and guides so that the proper clearances between the two are achieved in order to cool the valves properly so that they do not get burned and deteriorate. Typical clearances between the two vary from .001" to .004" depending on the application (Tight fit huh?!).
3. Installing hardened valve seats. Leaded fuel used in older cars back yonder lubricated the surface where the valves shut against the cylinder head, so cutting these seating surfaces out and inserting hardened ones is a good idea to maximize life with modern fuels.
4. Machining the main surface that faces the engine block. Not a single nick or scratch can be allowed, and it needs to be perfectly flat. More than .002" change in any 6" area or more than .004" change overall will require resurfacing.
5. Performing a 3, 4, or 5 angle cut on the heads and valves in order to create a semi-curved surface to improve airflow in and out of the combustion chambers. I got the 3 angle because it was the most practical.
6. Install new coolant passage plugs and valve seals.
Let's get to the wrenching shall we? The goal was to simply change the cylinder heads from small chamber 72 cc heads to large chamber 98 cc heads in order to drop the compression ratio from 10.3:1 to 8.11:1.
This required tearing the engine literally half way apart. The adventure started with jacking up the car and draining the cooling system and removing it. Following this was the intake system, belts, hoses, alternator, power steering pump, and finally the exhaust system. Removal of the exhaust system from the engine requires the engine mounts to be unbolted so that the engine can be tilted to one side to remove the exhaust header bolts.
Problem #1: As I raised the engine, the drivers side engine mount flapped down and showed its rubber guts. When engine mounts go bad they generally get a little torn or cracked, but witnessing a new one torn almost completely in half is a clear indicator that stock engine mounts are an inferior part to be used in automobile racing.
Once stripped down to a bare
short block, keeping it clean is a must. I packed a combination of assembly lubricant and
duck butter into the cylinders with coffee filters and shop towels to seal and catch any outside debris while the engine was apart. Following this was checking the engine deck surface for straightness across 5 different directions using feeler gauges and a precision straight edge. The same rules apply here as they do when checking the cylinder head.
*Short block - there are 4 stages of an engine build. The first stage is a bare block, which is self explanatory. The second is the short block, which is the bare block filled with all of the main rotating parts. Next is a long block, which is the short block with the addition of the cylinder heads and the assembled valve train. Next is the complete engine, which includes everything to seal off the motor like the intake manifold, headers, etc.
*Duck Butter - a slang term for "white lithium grease"
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| Checking for straightness |
Problem # 2: I received a phone call from the machine shop, so I stopped by. The valves could not be turned into Joan Rivers because they were too pitted and rusty. I couldn't argue, they were pretty bad. For replacements, i called up Ferrea Racing Components and upgraded to some racing ones. Made from
EV8 stainless
steel, these things can handle some serious abuse.
Problem #3: I received another phone call from the machine shop, so I stopped by again. These new valves which I had gotten via priority shipping were the wrong ones. A call to Ferrea confirmed that the guy had given me the wrong part number. They were just a hair too long, and the valve seat angle was incorrect. We decided to install them anyways and machine the seats because I was pressed on time. If done right I could reuse my old valve springs and all would be gravy.
Problem #4: I received an additional phone call from the machine shop, so I frustratingly stopped by one more time. All was not gravy. Our idea to custom fit the parts failed, and the valve spring installed height was incorrect now. The valves have grooves near the top which designate where the springs will be held down at by their retainers and locks. These grooves were still too tall to hold the springs down at the proper level. If not correct, the spring pressure will be reduced and the valves will float and become uncontrollable while the engine is running. The camshaft designates what springs to use, so i called Crower Camshafts and ordered some new dual coil racing springs made from a special tungsten alloy.
This picture of the old hardware below displays how how the spring would be installed on the valve. The cylinder head goes between the spring and the wide part of the valve. Spring pressure would push back against the disk shaped retainer. The two little locks fit in the grooves on the valve and will be wedged between the valve and the retainer by spring pressure in order to lock the assembly together. The location of this groove is essential to spring pressure.
The consistent problems at the machine shop provided much time to tinker with the car. I made haste and got to work on a few things which will be covered in the next post. Jumping ahead to the installation of the cylinder heads, I was happy to finally have them back. They even came in some nice heavy duty industrial grade plastic bags.
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| The blue dye is to help visualize the cutting of the valve contact surfaces during machining. It's so shiny!!! |
When engineering and researching, I was originally going to use
MLS head gaskets which required the head and engine deck surfaces to be almost mirror smooth. The
MLS head gaskets are perfect for my application, but this would require resurfacing the engine block if the block is not smooth enough. To do this would require a complete engine overhaul. Because of my concern with surface finish, I decided to justify my decision on a different head gasket by purchasing a machinists camparator gauge. It is simply a pallete of different
Ra surfaces that is held up against the surface that is being measured. Because there is more than can meet the eye, dragging a fingernail across the surfaces is the best way to ensure accuracy.
*MLS - (multi layered steel). Head gaskets need to distort and be pliable during movement with engine heat, especially under boost and racing conditions. Stock composite gaskets will tear and blow out in a short period if used in this environment. The best gasket to use would be a soft sheet copper gasket that wont blow out, but using them requires o-rings to be cut into the engine deck surface to help clamp down and hold them in place, a process that I was not willing to do. The next best choice is the MLS gasket because it has the strength, but does not require the o-rings.
*Ra (rougnness average) - It is the measurement of a materials surface. Opposite of sand paper, smaller numbers indicate a smoother surface, while larger number indicate a rougher surface. The measurement is a representation of an actual mathematical measurement called micro inches. One micro inch is considered a millionth of an inch (0.000001").
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| The camparator gauge, feeler gauge, and precision straight edge. Because humans make mistakes, I also double checked the straightness of the freshly machined heads. |
The engine deck came out to a 115 Ra, and the cylinder head to a 35 Ra. I wanted to order the head gaskets that I needed before working on the engine, and I had a feeling that the engine's deck surface had a higher Ra. I was correct. While researching head gaskets, I discovered the latest and greatest gasket to the automotive market. It is called the ICS Titan, produced by SCE Gaskets Incorporated. It combines the strength of a soft copper gasket with the easy of installation like a stock head gasket. A benchmark in automotive technology, these things are able to withstand at least 20 psi boost by using integral coolant seals with combustion chamber armor rings, and they require no special surface finish!
The wire insert is the fire ring/armor ring that goes around the combustion chamber. The gasket gets compressed between the engine deck and the cylinder head to lock the ring in place, while the integral coolant seals prevent engine coolant from leaking past the copper gasket. Photo courtesy SCE Gaskets Incorporated.
I was advised to spray them with a light coat of gasket sealer to help glue them down. The glue will help seal any surface imperfections between the gasket and surfaces. Spraying it is like shooting silly string. It comes out looking like red spider web and is so sticky that even a light misting on the ground made my shoes stick like super glue.
The next step was to clean the surface of the head from any residual rust or contaminants from the old gasket material. I used a flat sanding block with 600 grit wet sanding paper soaked in penetrating lubricant and sanded in a diagonal patter to eliminate cutting grooves on the engine deck. Something to always do when working with delicate engine parts is to clean the bolt holes out. Because I don't have a thread chaser set, I purchased a properly sized bolt at the hardware store and cut slots in it to catch all the crud when turning it in and out of the head bolt holes. This is essential for proper fastener torquing.
I evacuated the cylinders of their grease and coffee filters and oiled them up. I then used aerosol brake cleaner to remove all oil or dirt from the head and engine surfaces. The trick is to get it so clean that the health department wont look twice if it were to be used for prepping fresh sushi. Once I was finished, I cleaned it again, and after that I did it some more. Then I placed the gaskets on the engine and set the cylinder heads over them. Let me stress that the last phrase stated was not so easy. I'm not sure how much an assembled cylinder head weighs, but I would assume it's probably some where north of 60 lbs. Sweat dumping down my forehead, I had to literally crawl into the engine compartment and stand on the cars frame rails in order to set these things down straight without breaking my back or nicking the machined surfaces.
I then cleaned and re-used the ARP brand head bolts to assemble the heads to the block using lubricant. Anything that can break or stretch during racing usually does, so using bolts with a high
tensile strength is recommended.
*Tensile strength is the maximum stress used while pulling on the bolt without causing failure to the fastener, rated in pounds per square inch (psi). Classifying them in grades is a way of knowing how strong they are, so the higher the grade, the higher the tensile strength. Most automotive fasteners are grade 5, and the strongest are generally grade 8. The ARP bolts that I used are made from 8740 Chromoly with a black oxide finish. Rated at 190000psi tensile strength, they are much more superior than a typical grade 8 bolt rated at 120000psi. Rock n' Roll.
The bolts were torqued in proper steps and sequence to 95 ft/lbs using a torque wrench. This changes depending on the engine, but usually includes starting in the middle of the head and going in a circular pattern outwards. The goal is to clamp evenly so that the head does not become distorted. If any bolt holes protrude into the coolant passages of the block, gasket sealer on the threads will be required as well. My 1974 Pontiac block had all blind holes and thankfully did not require this.
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| An adjustable click-type torque wrench |
With the "heavy" work out of the way, it was now time for the intricate valve train to be installed. This was a challenge because of the new spring installed height as discussed above. What normally happens when the engine is running is the camshaft will rotate and displace the lifters in which ride on its lobes. These then push on pushrods that touch
rocker arms which finally push the valves open. The main problem is that the stock length pushrods would now be too short for correct valve train geometry, meaning that I would need longer ones to compensate for the taller valves. Racing cams have higher lift numbers which generate more stress on moving components because of the wider geometry angles created, especially with higher valvespring pressures. This requires hardened pushrods made from heat treated chromoly that resist flexing, but something to keep in mind is that at high engine speeds these pushrods will still tend to flex slightly. Hard metals are not very malleable, mandating the use of guide plates to keep the pushrods straight so that they don't fatigue into a catastrophic failure. I used ARP rocker arm studs with
Loctite to fasten down the guide plates and got straight to the measuring.
*Rocker arm - basically a lever that will turn the pushing direction of the cam lobes 180 degrees and push down on the valves that open up the cylinder head ports. Reducing weight and friction increases horsepower. Stock ones are made from stamped steel and create a lot of friction. The best of the best cost a fortune and are made from billet machined aluminum, including roller tips and needle bearing pivot fulcrums. Mine are the Magnum series from Comp Cams which are basic stamped steel with roller tips. They are also available in different rocker ratios. A 1.5 ratio means that the lift of the valve will be 1.5 times what the cams lift is. Going to a higher ratio will be the same as getting a cam with more lift, so the only reason to change ratios is if you picked the wrong cam.
*Loctite - A thread locking compound used on bolts. It is made from a fluid plastic that cures into a hardened plastic when exposed to air. Using this stuff prevents engine vibrations from loosening parts. There are different colors available which differentiate thier strengths and melting points.
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| Rocker Arm Studs |
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| Pushrod guide plates |
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| The guideplates and rocker arm studs installed |
Some engines use mechanical lifters which require adjusting for clearance as the engine wears over time. To eliminate this, manufacturers invented hydraulic lifters which are self adjusting. They use a piston and spring to work on the basic principal of
Pascals Law of hydraulics. They are pumped up to the proper clearance using engine oil pressure when the engine is running, so to measure pushrod length correctly they need to be pumped up. The problem is that the engine isn't running yet though. Confusing right?! The most innovative idea that I could come up with was to donate $4.50 to the local parts store for a hydraulic lifter for my engine and dissect it for experimental use to create a dummy lifter. I eyeballed the distance of the lifter piston travel at the bottom most position and compared it to its top most position. The correct piston depth when the engine is running should be at approximately the midway point. I simply used a combination of small nuts and washers under the piston to position it correctly in the lifter and had a proud smile on my face when finished:)
*Pascals Law - When force is applied to a liquid confined in a container or an enclosure, the pressure is transmitted equal and undiminished in every direction. In other words, liquids are not compressible.
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| The exploded view of the dissected lifter |
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Side view of rocker arm installation over the valve and pushrod.
Too short of pushrod allows the rocker arm to ride on the left side of the valve, too long on the right side of the valve |
Placing the dummy lifter into the lifter bore over the camshaft, I installed one of my old pushrods into it to verify that the pushrods were indeed to short. This was done by using a felt tip marker on the tip of the valve where the rocker arm pushes. Installing the rocker arm over the assembly with its pivot ball and lock nuts, I then turned the engine two complete revolutions so that the cam would make one complete revolution. Removing the rocker arm will show the witness mark on the tip of the valve where the ink was wiped off. The mark is supposed to be in the middle, but mine was on the inside edge. Leaving the geometry like this will result in increased valve wear on a good day, and broken parts on a bad day. I then used an adjustable pushrod length checker and lengthened it until I got the correct witness mark. Now that the correct length was found, using a precision digital vernier caliper tool to measure it determined that its new length was .120" longer than the stock pushrod length of 9.136"
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| Witness mark on inside of valve tip. It should be in the center |
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| The adjustable length pushrod checker and home made dummy lifter |
Finding the closest length that I needed, some pushrods were to be ordered, but only after inspecting some other parts first....
Problem # 5: The pivot balls allow the rocker arms to be held down on to the valves and pushrods while still allowing movement. Upon the discovery of a chunked pivot ball, god only knows where the missing portion is. My guess is that the engine has decided to domesticate the cookie monster which has probably established a small cabin in the corner of the oil pan constructed from various metal fragments.
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| Chipped pivot ball |
Once the new parts were in my possession I was finally ready to get everything installed. There are a few ways to adjust the valvetrain, but the simplest is going back to the basics of the 4 stroke engine discussed in the last blog post. Simply following the
firing order of the engine allows the valve adjustments to be made on both valves for each cylinder at once. This is due to the fact that the engine is on the compression stroke and the cam is not trying to open the intake or exhaust valve. Using a little math, consider that the crankshaft needs to rotate two complete revolutions (720 degrees) for a cylinder to complete a cycle. Dividing 720 degrees by the number of cylinders (8) provides 90 degrees, meaning that a cylinder fires every 90 degrees of crankshaft rotation. Starting with the first cylinder in the firing order at the top of its compression stroke, tighten down the
prevailing torque nuts over the rocker arm pivot balls until the lifters are half way into thier travel distance. This is usually 1/2 a turn to a full turn once all the clearance has been eliminated. Once both valves are done, rotate the engine 90 degrees and do the next cylinder in the firing order.
*Firing order - The order in which the sparks enter the cylinders of an engine as it is running. The cylinders are numbered in a certain order due to thier mechanics, but this varies by engine and manufacturer. The firing order for this engine is 18436572. If standing facing the front of the car and starting at the front of the engine, the old school Pontiac V8 has cylinders 1,3,5,and 7 on the drivers side, and 2,4,6,and 8 on the passenger side.
*Prevailing torque nuts - Some guys at autoparts stores will argue on what they are called, but this is the correct term. This will not be the last of my ranting about parts store employees. They are basically nuts designed to not loosen by use of a triangular deformation on one side. Once screwed down onto the bolt far enough, this deformation interferes with the threads and distorts to bind the two together. Because the triangular shape can be worn off once removed, prevailing torque nuts should never be reused.
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Lining the timing marks on the crank pulley to zero degrees
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| Using chalk to mark the crank pulley every 90 degrees once the timing marks are aligned |
Once finished installing and adjusting the rocker arms came the installation of the valley pan, also known as a pushrod cover.
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| The valley pan with a cork gasket and black gasket maker |
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| The installed rocker arms and valley pan |
Nearing the end of the engine build, the next step was to install the intake manifold.
Problem #6: The manifold fell right into place with its gaskets, but when torquing the two front bolts....well they just never torqued because the threads pulled out. Not having the bolts tight can lead to manifold warpage, vacuum leaks, coolant leaks, or any combination thereof. Who ever worked on the previous engine that had used these cylinder heads had weakened the bolt hole threads by taking the liberty of over tightening the bolts. Awesome.
Repairing stripped threads is actually kind of easy. It usually requires drilling out the stripped hole, and cutting new threads using a thread tap, then using bigger bolts. Heli coils are a special kind of thread repair that take it a level farther by allowing the use of the original size bolts. Using the proper size kit and corresponding drill bit size, the hole is tapped and a threaded spring insert is installed using Loctite compound with the included adapter. Bada bing, its repaired!!
With the manifold all zipped up, the vacuum hoses, fuel system, power steering pump, and all the pulleys went on without a fuss. The new heads have provisions for coolant temperature sensors between the exhaust ports, so I simply bolted in some tapered brass plugs to seal them off.
Problem #7: I had ordered the wrong spark plugs. I had a new set of NGK spark plugs to go with the build up just to discover that the new heads require tapered seat plugs instead of the gasket washer plugs as used previously. A call to NGK provided the part number of the same type of plug, only with a tapered seat instead. More on which plugs I chose when I cover the ignition system. A call to parts stores in the area yielded no results for the ones that I was looking for. I did find one store that carried NGK plugs, but the guy on the phone had no idea how to look them up in his inventory. Some people are not very tech savvy, and that is okay, but if you're working in parts store use some common sense. I even helped him break up the part number to increase the results on the computer. Still, nothing. Frustrated, I promptly drove down there and used his computer to do it myself. The ones that I needed were indeed in stock, so I had him show me where the plugs were located and I proceeded to grab them myself. Poor guy, I hope he gets an IPod for his next birthday.
Plugs installed, and plug wires attached, I painted the old school Mickey Thompson valve covers that I had gotten with the cylinder heads. Laying down a few coats of transparent high temperature engine paint, I let it dry then covered the top surfaces with automotive grade masking tape. Spraying down some gloss black engine paint covered the remaining areas, leaving a brilliant black and aluminum finish once the tape was removed.
After installing the headers for the exhaust system, I bolted on some new engine mounts from Butler Performance due to the old ones being broken from the increasing performance upgrades. Made from solid steel plate, these will never tear. Solid mounts will increase the noise vibration and harshness of the car because of the lack of dampening rubber that is on the stock mounts. The truth is that the car is so damn loud as it is, this was the last of my concerns.
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| Solid steel engine mount on the left, and the mushy stock rubber on the right |
Problem #8: Lowering the engine onto the mount locations of the frame was a complete nightmare. I could get one side to bolt in and the other would be off by a 1/2 inch or so. I thought of a couple things that would make this possible, a twisted frame being one of them. Farther inspection discovered that the countless hours spent when the car was painted could have been reduced. The C
pillar on the drivers side has a slight ripple, and there are cracks in the paint on the A and B pillars inside the door jambs, indicating severe body twist. I lowered the car off of the jack stands to see if the frame could settle a little, but this did not help. Elongating one of the bolt holes was the only thing that would work to make the engine mounts bolt up. I always did think the car sat a little funny!! Gotta love torque huh?
*Pillars- These are the main structural supports to the roof of any car. The A pillar is the section of the body between the cabin and the front windshield, the B at the mid section, and the C between the cabin and rear windshield.
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| A crack in the paint on the A pillar due to body flexing |
One of the things that I did to pass time while waiting for the cylinder heads was fitting the intercooler for the turbocharger. More details on it when I cover the cold side plumbing, but the point is that I installed it in front of the radiator which shifted some things. Putting the radiator and cooling fan assembly back into the car is usually pretty straight forward, but I was on a streak here, so I ran into another issue.
Problem #9: The fan shroud was now touching the engine pulleys due to the slight rearward movement of the radiator to make the intercooler fit. A constructed hybrid of junkyard parts from some modern Ford vehicles, it consists of a large plastic radiator cover with a giant electric fan bolted to it. The whole point of the system is to create a suction of air from the whole radiator so that it cools the engine efficiently. I had to adjust the depth of the installed fan closer to the front of the vehicle, but also trim some plastic off so that the fan support was not too close to the radiator that the shroud would be rendered useless.
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| Hate me or eat some cotton candy but yes, I have Ford parts on my Pontiac. |
With everything completely put back together, I filled the cooling system with a 50/50 mix of
antifreeze and water, and topped it off with some Redline Water Wetter.
*Antifreeze - You've heard of it before, but there is more to it. It is designed to not only keep the engine cool, but to not freeze and crack the engine block in snowy weather like water would. It also lubricates the water pump bearings and fights corrosion inside the coolant passages of the engine. Made from ethylene glycol, it is poisonous but smells and tastes sweet. For this reason alone, it should always be disposed of properly so that the local felines and K9s don't induce it from the gutter and pass away.
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| A modern cooling system additive that enhances the chemical properties of the coolant so that it dissipates heat better and reduces cooling system temperatures |
Upon initial cranking of the engine, it fired off a couple cylinders then failed to repeat itself after trying for a few attempts.
Problem #10: Gasoline had hustled its way outside of the carburetor and all over the intake manifold. Because the car had been sitting so long and the carburetor had not been used, its gaskets had dried up just slightly enough to allow gas to be sprayed everywhere when ever the fuel pump tried to create pressure. No fuel pressure means no running engine. After cleaning up the gas that was all over the intake manifold and tightening the bolts to the fuel bowls, fuel pressure was restored.
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| The final product: A low compression beast hungry for some boost. |
After a long and stressful process, the next turn of the key rewarded me with the loud shriek of the timing gears as the engine boasted to life and cackled fire through the new cylinder heads, baking on the fresh engine paint and filling the garage with fumes. A major benchmark in the progress of the turbo conversion, the cylinder head swap had finally come to a successful end. The first drive was a bit fussy, but after playing with the ignition timing I discovered that the car had not lost much power from the lower compression. At this point, I seriously can't wait to get the giggles from adding some turbo boost!
