Building a 408
IF PERFECTION RUNS THROUGH YOUR VEINS AND YOU NEVER MAKE A MISTAKE THEN READ NO FURTHER……..
If you are still reading then I’ll assume that your like me and make mistakes more than we’d like to admit. The hardest hurdle to overcome for me was assumptions and total trust. So watch for the two deadly words all through this story. Assume and Trust. After all if you don’t trust someone or something that’s just wrong right? Wrong!!! I have built so many engines that I have long lost count does this make me a better engine builder than someone who has done half as many? Absolutely not! Experience is good but give me someone who crosses all the T’s and dots all the I’s they assume nothing and trust cautiously I’ll take that over an attitude of I’ve built 100’s of engines, hands down.
This story is about building the all impressive street/strip 408 351W based engine, but I’d also like to hyper focus on a couple of important issues when building an engine. Since I have already brought up the issue of trust lets go there first. If you buy used engine from someone be it a friend or junkyard do you trust the engine is good ………. Noooo! You take it to a machine shop and have it deep cleaned, measured, and check for cracks once it passes that test then you can trust your purchase. After all if we are building a good street/strip 408 then all will be using is the block and some hardware off of our original engine. We have to know we have a good block. For our build we purchased a used tired engine out of a 1994 F150 Pick-up with a 351W engine. This engine gives us the factory roller block which makes for a very nice beginning for our build up. We took it to our machine shop and had it hot tanked and bored .030 over for our stroker kit. The machine shop checked the block for cracks, and tolerances, all was well. A good machine shop will want your new pistons in order to properly hone the block to the required piston to cylinder wall clearance. In our case the piston manufacturer would like us to have .004 of clearance. I am fortunate I have a great machine shop I use and have a great deal of respect for his ability. So when I get my freshly prepped block I trust its all 100% correct. NOT!!!! No Sir I check behind him, I have my own measuring tools, dial indicator, micrometers, dial bore gauge. Does that hurt his feelings no, if I didn’t check behind him he would call me a fool. Again do not assume anything check it yourself, twice is good.
Ok lets start the building process I retrieved the block from the machine shop placed it on the engine stand and did the following:
1/ Careful visual inspection of the block : looking for cracks, burrs, make sure cam bearings are centered, flaws, broken bolts.
2/ Grab the correct taps and chase all bolt holes : especially the head bolt holes. Cleaning all of these thread holes guarantees an accurate torque reading. Using compressed air blow out all holes after tapping. If you do not have an air compressor go to a computer store and buy a can of air used to clean computers with.
3/ Pre-assembly: Because we are building a stroker motor we have to pre-assemble our rotating assembly to check for clearance since we have a longer stroke some rotating parts may come in contact with the block. If your not comfortable with this you can request your machine shop to do this for you. In our case there was no big obvious collision with the block, there was one slight tick in one place but in several places it was very close. So we took out our die grinder and increased our clearance on eight cylinders and one place at the oil pump area of the block. During pre-assembly it is not necessary to install your rings or torque the bolts. Make sure you lube your bearings and cylinders as you will need to rotate the assy. to mark your clearance spots.
4/ Now clean the block I know you assumed the machine shop did that. Well lets just pretend they did. How about the drive home from the machine shop you know the one where the block was in the back of your truck and you were driving home at 8...um 55 miles an hour I’m sure no dust or debris came anywhere close to your block. Also I’m sure that during the tapping of the bolt holes no debris was dislodged, not to mention the grinding that was done to the block for additional clearances. I use soap and water and rinse very well. Do not do this if the engine is going to sit up any period of time unfinished. It will rust. Wait till you know you are going to complete the engine at least a complete short block with oil pan. Once you have completed the cleaning dry off the block with compressed air or a towel. Go ahead and wipe some oil on your cylinder walls. This will prevent flash rust from the wash. I wash the crank, pistons, and rods. You can buy a paint gun cleaning kit from automotive paint store and use the little round brush to run through your crank oiling holes.
Organizing and more pre-assembly inspection Personally I have a big work table and I like to tape a large piece of paper (I use paper that’s used for painting a car) and tape it to the top of my table. This gives me a nice clean uncontaminated surface. Lay out all of you parts for the assembly. Rod bearings, mains, rings, main caps and bolts, rod nuts or bolts, lifters, pushrods, pistons, rockers etc… While everything is laid out make sure everything is there. I have been shorted a bearing, ring, and a lifter before so do not assume its all there. Now check all the components for, correctness, and condition. Remember this stuff has been through a few hands before it got to you, manufacturers, shippers maybe two or three times, and distributors
Things happen! If your crank is std or turned .010 verify you have the correct bearings. In most cases your rings are pre-gapped so file fitting is not required however a human or automated machine packaged this stuff, so are we going to trust or assume its correct? That’s right no!! hey your catching on to this! Take one of those rings and slide it into the cylinder and make sure its correct. Just because the label says it’s correct doesn’t mean it is until you say so. Look at your bearings the size is noted on the bearing read it and confirm its what you need. Examine you pistons look for evidence of possibly being dropped, or scratched. Concerning installing rings on your pistons, my personal opinion is to leave the rings in the box and as its divided into three sections. I pull out of one section at a time and keep installing on each piston until that section is empty. Then start with the next section and empty it. That way there is no danger of mixing rings up.
Now on the fun part we got a full rotating assy. From eagle which has forged pistons, h-beam rods, main and rod bearings, ring set and crank unbalanced. You can order balanced assemblies however you must be careful some kits are not balanced to what I feel is almost perfection. Some use the average weight or single reference method using one piston and rod assy. weight as a reference. I am fortunate to have a machine shop locally who has one of those computerized high dollar rigs that allows him to get it to NASCAR specs. Its easy to identify the quick balancing method as your rods and pistons will not show signs of material removal to reduce weight to make each component weigh the same. A good balancer will weigh each piston and find the lightest and remove material from the other pistons to match the weight of the lightest. You will see evidence of that procedure on the inside of the piston at the top usually. He will do the same with all the rods my guy weighs each end of the rod. You will see evidence of material removal on your rods at the top and bottom of an assembled rod. The balancer will also want your flywheel and harmonic balancer to complete the task.
We assembled our 408 with our balanced assembly checking all of our tolerances I use micrometers and a dial bore gauge but the do it yourselfer can by plastigauge at the local parts house. Remember to ask the people you buy your rotating assy. from what piston to cylinder wall clearance they require. It is very critical to get this right. Average in my experience is .004
Because of all of our pre-checks and measuring our rotating assy. Went together like cake. We called our friends at Erson cams and told them of our project I explained that I had a severe dislike for tires and I want to destroy them. We did not want a top end motor so they obliged me with a cam that they say will require a neck brace. Oh Yea!
Ok people one more thing I have to get on my soap box about and probably the most neglected part of a good engine build that I see. Degreeing a cam, alright now don’t skip this part hear me out. Look, if every cam manufacturer on the planet says you need to degree our cam then …..duh… we need to degree the cam. Hello its free horsepower people, you paid for the cam make it work for you. Beg, borrow, or buy what you need to complete this process its worth every penny. Click on the internet and type in how to degree a cam hundreds of topics will come up explaining the procedure find the one that you understand the best and do it!! Please!!!
We installed the erson cam and completed the degreeing process using a multi keyway on our timing set in addition this particular timing set uses a thrust bearing to reduce friction very nice upgrade. We started our degreeing procedure on std alignment and after a few adjustment attempts ended up at 4 degrees retard to meet the specs suggested by Erson.
After our cam was degreed in we installed our Edlebrock Victor Jr heads, roller rockers, hardened push rods, and roller rockers. Toped off with Ford Racing Valve covers, Trick flow intake, 42lb injectors, and 70 mm throttle body.
347 Stroker in a 65
We put fire in the wire to this bad boy 347 Stroker!! Nothin better than hearing a new build come to life!!