This article is a quick and simple example of how AWT goes about a stock type engine rebuild, some call this blueprinting, but it is not. Blueprinting in the original sense of the word is to build an engine to the specific dimensions of the original designers ‘blueprints’ and not to deviate from anything. This is not necessarily the most efficient and many ‘blueprinted’ engines are the result of a builders testing to find out what deviations from stock tolerances, but using stock components, result in a small gain which all add up. However, the term is flung around by many engine builders who couldn’t recap the clearances or dimensions of the most basic components used in the engine they just built you.

All machining work and block prep on this engine was done previously and so this is just an assembly log.

Start with everything needed in the build laid out or within easy access as this helps streamline the build process and eliminate mistakes or missed components as you will have to run a checklist first for all items.

The first part of any build is the checking of bearing clearances as they are vital to engine longevity and efficiency. We do this using both the manual calculated method for empirical accuracy, and plastigauge to confirm. All measurements are recorded in our build log book for future reference and so we can enter them into our build log and calculation program for triple checking.

The first step calculating bearing clearances starts with the measuring of the bearing housing/saddles. Each mains cap must be torqued up to final figures for an accurate reading using our bore gauge. It is important to measure across the saddles width at 12-6, 8-2 and 4-10 axis to check for out of roundness and taper. A good tip when disassembling the engine used to rebuild, is to examine bearing wear patterns which are a great indicator for any problems with geometry alignment present before you even take your first measurement.  

Once you have the OD of the journals and the ID of the mains saddles, you can then use them to calculate the bearing thickness. Subtract the OD from the ID and this will leave you with the total thickness between journal and saddle. From this you have 2 options, if you already have bearings, subtract the thickness of each bearing half and this will leave you with your clearance if you run those bearings. If you do not have bearings, subtract the clearance you WANT to run from the ID-OD, then half the number to give you the bearing thickness you will need to run to attain your desired clearance.

You will want to do exactly the same procedure with the big ends to calculate bearing clearance. Only thing to note is that your rod caps are torqued up to final specs and that if you are running aftermarket bolts such as ARP, then you have the rod resized with the aftermarket bolts in place.

Whilst everything is out and in pieces, you will want to take your piston clearance measurements. Start with the piston OD and measure with a micrometer, at no point do verniers come into play when measuring critical clearances and components. You want to record the largest OD on the thrust axis, not the pin axis, and this is typically ½” to ¾” from the bottom of the skirt. All your pistons should be marked on the crown with a pencil engraver or light scribe to make identification easy, or if you can find a pen that stays on with all the cleaning agents used….let me know.

You will then need to measure your bores with your bore gauge. I usually set the bore gauge to the OD of the piston for the corresponding hole I a measuring. This allows me to see the straight clearance value that the piston will be running. Walk the gauge down the thrust axis to check for taper (which there should be none, but depending on your machinist, a tenth of a thou is acceptable) then walk it down the pin axis to check for out of roundness (OOR), again there should be none ideally. Record the bores dimensions for the thrust and pin axis at 3 points along the bore. 

To double check the bearing clearances plastigauge is used and is normally spot on. Place the crank in the mains with a light dusting of WD40 to prevent scuffing and sticking of the plastigauge.

A thin strip of plastigauge on each mains journal, install the mains caps and torque up to final specs, walk away, have a cup of tea or similar.

Remove the mains caps and use the plastigauge reference strip to gauge the clearance. In this case, 2 thou, bang on the money from the calculated clearances. Its good to note that Renault range of engines do not benefit from the nice tri-metal bearings from ACL, and certainly not their race series bearings, so we have to live with the OE bearings or AE (if you want) which are softer. Because of this, bearing clearances need to be spot on, you need to make sure you run the correct grade of oil and that oil temperatures are constant along with good oil supply and pressure.

Before you bolt all the mains up again, we need to set the thrust bearing clearance. Starting with an oversize bearing we, as always, rub the back down with a stone to flat the face which it sits upon. We then install it and check the thrust and see how much it needs to be adjusted.

Once we know the value we can half it and remove the same amount from both thrust bearings using a surface grinder. Then double check the flatness of the bearing by using a micrometer along its entire length to see that the thickness is even and there are no high points. Once you are happy you can install and recheck.

With the Mains and Thrust clearances set and logged, you can use assembly lube and install all the bearings, mains caps, thrust bearings and rear mains cap oil seals.

Next step is to repeat the previous stage but for the big end bearings. Procedure is exactly the same so I won’t go over it again.

Make sure to arrange your pistons/rods/caps/bolts and bearings in numerical order and labelled for easy identification.

Next record the free length and position of your rod bolts and keep them for reference at a later date if needed. Recording free length will allow you to check for stretch outside its ‘new’ free length, and only one thou is required to scrap the bolt.

To set the stretch gauge, simple use an appropriate length slip gauge.

Set your ring end gaps before installing them onto the pistons. Easiest way to do this is to use a piston to level the ring in the bore, simply line the deck face up with one of the ringlands. Use a feeler gauge to measure the gap and one of the many ring files on the market to adjust the gap, but I prefer the electric ring files for ease of use. Don’t forget to deburr the ends once filed with a whetstone, and after I use an Arkansas stone to polish the edges just that little bit more.

Ring gap will depend on ring material, thickness, bore diameter, fuel, compression ratio, aspiration method and several other running factors. 

To install the pistons, use a tapered ring compressor, I’ve said it many a time before, nothing comes close. I have a set of almost new Snap-On scissor style ring compressors and they just sit there collecting dust. 

Next install the rod caps with bearings, bolts and finger tighten, nip up each bolt so that the cap is seated correctly, then wind off again. Place the stretch gauge on a rod bolt, zero, then torque up to the correct stretch amount, which for these bolts is six and a half thou.

That will be your rotating assembly built and ready.

A few points to go over, and that is lubricate! Assembly grease and oil on everything, you can never use too little, especially if the engine will be standing around for a while. A liberal coating of wd40 on the inside of the block, on the crank, rods and bores to prevent corrosion and aid ring bedding.

Install your oil pump drive sprocket on the nose of the crank, then the chain, chain guide, front plate with front crank oil seal and your water pump.

Install Oil pump (this is a high flow, low cavitation modified unit) and windage tray, then bolt on the sump.

Your short motor is complete.

The cylinder head is a vitally important component in an engine such as this. When using a stock type short motor, relatively mild compression ratio and camshafts which have short duration, yet decent lift figures, it is crucial to have a cylinder head that will work as effectively as possible within these parameters.

The cylinder head used on this engine build is running stock valves and valve train assembly and concentration has been on generating flow with significant area ‘under the curve’. This will ensure that it will be flowing significantly more at all lift points, and generate higher bulk flow numbers across the entire lift curve which results in more torque and bhp at all rpm points.

Comparison against a stock port and you can see the areas reworked. Particular importance is the valve seat configuration and getting them to work with the stock valves. The stock head has single angle seats which work surprisingly well, and swapping to the incorrect multi angle seat will damage the flow curve.

Without giving too much away, you might note in some pics which areas receive attention and which don’t. The stock heads are CNC’d from the factory, either because they were actually trying to provide a well flowing head, or because they found it was cheaper to pump out extremely cheap castings and resolve the flow issue with a quick stint on the CNC machine. Once problem is that they remove material from some areas which they shouldn’t have, in other words they ported TOO much in some areas. Because of this it is extremely important to know what you are doing with this head and precisely what shape modifications result in substantial flow gains. The port itself is pretty limited to modification and it is the details that will see you pickup the CFM along with flow quality.

When building up the cylinder head I use valve stem seal pliers to install as well as removing seals for this particular head. A light dab of oil on the inside of the seal, twist as you install and they will slide on easily and without damage.

Install the valves with a quick lick of lube, springs and then retainers.

When I install the collets I simply use a small amount of grease on the inside so it will stick to the keeper groove in the valve, and a small dab on the outside so it will stick to the small screwdriver.

Use a good spring compressor, I prefer G clamp types, compress the spring, slide the collet into position in the groove and then slide the screwdriver off.

Next install the head gasket on the block, and the head onto the block. I like to place the head dowels in the head rather than the block as there is less chance of damaging the iron block than the alloy head with any minute amount of shuffling that can occur when placing the head on. Use new head bolts, oil them, and torque up the head. And don’t worry, the camshafts on the floor were the old stock items which were binned, we don’t store on the floor!

Install the roller radius path followers, pivots and camshafts with liberal amounts of assembly lube. A quick line of silicone gasket is all that is needed to prevent leaks, no need to go crazy as it’ll only end up inside your engine.

The F4R has the cam bearings cast into the cam cover, so it is essential that this is treated well and correctly. Obviously painting of covers for aesthetic reasons is popular in all engine building and is the preference of customers; however in this instance I would just like to make some pointers.

The cover on this engine is painted in crackle effect paint for a classic look, however because the bearings are built in, it is essential that you spot face the area under the bolt heads. This is because paint has a tendency to soften and move, especially crackle effect, when hot. This can lead to bolts loosing torque or possibly loosening off all together. This can lead to uneven cam wear and possible failure. No doubt a few other builders will be happy they read this.

The timing belt procedure on this engine is a bit fussy, nothing overly complex so long as you follow the procedures. I still reference the manual every time just to make sure nothing is forgotten. To lock the engine at TDC I simply use an 8mm punch through the TDC locking hole which pins the crank at exactly tdc thanks to an 8mm slot machined into the counterweight. You can double check TDC as the keyway on the crank nose will align itself between the front two cast ribs on the front plate.

At the rear of the engine install the camshaft timing and locking tool. The cam locking tool is used due to the front pulley arrangement and no keyways are used to locate pulleys. The camshaft is ground specifically to time up correct with the stock timing tool, and it is vitally important that the tool is installed correctly with the grooves in the end of the camshafts offset correctly.

Install the cam pulleys (do not tighten fully, allow them enough slack to rotate), cambelt, front pulley (do not tighten fully as well), idler pulleys, tensioner and finally pulley locking tool (again not done up to lock the pulleys).

None of the pulleys on this engine run keyways or woodruff keys and rely solely on friction fittings. It is therefore essential that ALL grease, grime and oil is removed before fitting. With all items installed rotate the cambelt and set the tension (the pulleys will rotate even though the crank and cams are locked), then lock up the pulleys using the pulley locking tool. Double check tension, then tighten all pulleys to specified torque figures. Remove all locking tools and rotate the engine slowly to confirm everything is correct.

Your F4R engine is now assembled and complete ready for ancillary fittings.