Chronicles of a Community College Engine Rebuilding Class

[BDA]

Thanks Grumblebuns! Another interesting day at school! My experience with this sort of thing was to give a block, crank, rods, and pistons to a machine shop and let them do whatever they do and expect them to know what they're doing. It's nice to get more insight into all the things they look at and how they look at it. It's usually more involved than you think!

[surfguitar58]

Finally got around to reading this thread start to finish. Very informative! Your descriptions and photos fill in a lot of gaps in my knowledge that the Miles book assumes the reader already knows. What a shame the Covid-19 outbreak cut the class short. Still, hope to be following this through reassembly. Keep up the great work Joji! 
Tom

[Grumblebuns]

I believe there is only one more week of class before the state imposed stay at home order was imposed. Kind of jumping ahead in the story, just after the order was announced the instructor allowed me to retrieve my engine block from the engine lab at school. Not knowing how long crisis this was going to last, I wanted to bring the block in to a machine shop for block cleaning and perform a professional inspection to confirm my classroom measurements. So the story will continue, stay tuned.

Joji Tokumoto

[Grumblebuns]

                                                                             
                                                              Chronicles of a Community College Engine Rebuilding Class

Week 6

Unbeknownst to me at the time, I had no indication that the Stay at Home Order for the entire state would be issued by the Governor of California at the end of Week 6. I did not have a chance to discuss my measurements with my instructor and get his input before all formal in class lectures were cancelled.


Day 11- The lab day starts off with the instructor demonstrating a method for cleaning hard carbon deposits from the tops of pistons. His preferred method is to use a wire wheel on a bench grinder. He does stress that there are dangers to the body using this method. It takes great care and focus using this method but it is quick and effective. The technique is just to wire away the hard carbon crust but not get into the aluminum top of the piston. Also the wire wheel should never be used on the ring groove area. To clean the grooves, break an old compression ring in half and use the end to scrape off the gunk inside the grooves (Pic).

With all the measurements pointing to the block potentially needing a rebore, we magnaflux the head to confirm that rust in #2 cylinder was not caused by a cracked cylinder. The results are negative for cracks in all of the cylinder bores.With measurements and testing completed on the block we move on to measuring the pistons to determine piston to cylinder bore clearance.
The Wilkins book states that all production pistons are now C”’ type and give diameter according to original factory grading, from 1-4 in 0.0003” increments (3.2467-3.2470 to 3.2476-3.2479). I have no idea what grade my pistons are or their original diameters. Neither the service manual nor the Wilkins book specifies a gauge point to measure piston diameter. Falling back on the general rule of thumb, pistons were measured at the widest part of the piston, the skirt area  ½” up from the bottom.
My stock pistons are Hepolite “C” type with the following diameters, average of four readings:
   
Piston #1: 3.2462”
Piston #2: 3.2464”
Piston #3; 3.2462”
Piston #4: 3.2468”

The service manual states a piston to bore clearance spec of 0.0030”-0.0036” irrespective of piston grade. These are the piston to bore clearances of my engine using the widest measurement.

Cylinder #1: 3.2545” - 3.2462” = 0.0083”
Cylinder #2: 3.2560” - 3.2464” = 0.0096”
Cylinder #3: 3.2555” - 3.2462” = 0.0093”
Cylinder #4  3.2550” - 3.2468” = 0.0082”

I don’t have the experience to know if the clearances we measured are way out of spec or is within the normal expected wear range for an engine with this much miles but
looking at just the amount of cylinder taper measurements, it appears that a rebore of my engine block is needed. Even taking into account the inexperience of the measurement takers, the consistency of the readings should not be discounted. I’ll have the instructor look over the data sheet to confirm our conclusion.

Visually to my inexperienced eyes, all four pistons look pretty undamaged. There are no stuck rings,or any major scratch or scrape markings. There appears to be normal scuffing on both the major and minor thrust areas with most of the scuffing along the major thrust (inlet) side.

I was hoping for a budget rebuild with the possibility of reusing the original pistons and just do a re-ring and re-hone the bore but apparently is not to be.This ends Day 11. About the only measurement left on the bottom end is the crankshaft. This ends Day 11. About the only measurement left to do on the bottom end is the crankshaft.

Pic 1 - The instructor demonstrating the use of a wire wheel with a junk piston to clean carbon from the tops of pistons. There is always the danger of the wire wheel catching the edge of the piston and throwing across the room, thus ruining the piston. Great mental focus is required using this method.  Note that the connecting rod is kept installed to allow greater control of the piston. If my stock pistons were going to be reused, my plan was to use a chemical process to clean the carbon from the piston tops.

Pic 2 - Next four pictures show the condition of #1 piston. Again to my inexperienced eye, I see no signs of severe engine overheating or lack of lubrication as there are no deep scrapes or scratches, just smooth wear on the two thrust face areas. Picture 2 shows the rear view of the piston as it fits in the cylinder bore looking from the rear of the engine to the front.

Pic 3 - Picture 3 shows the front of the piston

Pic 4 - Picture 4 shows the left side, exhaust side or minor thrust side of the piston. The black dot indicates where the piston diameter was measured. Compare wear patterns to the right side

Picture 5 shows the right side, intake side or major thrust side of the piston. Most of the piston wear occurs on this side. On the top of the piston, the cutout for the intake valve is slightly larger than the exhaust cutout.

[BDA]

I can't say that my eye is really any less experienced than yours, but that piston looks good to me.

Again, being inexperienced, I would prefer to chuck the piston in a vice and then use a wire brush on a drill but the carbon via chemical means makes more sense to me.

[Grumblebuns]

                                                                                                     Chronicles of a Community College Engine Rebuilding Class

Week 6

Day 12 - The instructor started the morning lecture by discussing crankshafts. Inspection,  measurements and repair of the journals are covered during the classroom session. During the disassembly of the engine earlier in the semester, we did a quick cursory exam of the crank and there appeared to be no discoloration or deep scoring of the journals. There may have been some very light scratches or scoring on one or two of the main journals.I’ll have the instructor make an evaluation on the crank next week or so. The scratches are not deep enough to catch a fingernail and so I’m hoping a crank journal polish will be enough and not a crankshaft regrind..According to the instructor  crankshaft journal grinding is a very specialized skill that not too many auto machine shops have the equipment or machine operator to perform.

During the lab session, the instructor plans on doing a couple of demonstrations. If there is enough time after the demonstrations, my partner and I will try to get the crank journals measured. The lab session is all about connecting rods. The first demonstration is the proper way to torque the end caps to the connecting rod  without damaging or stressing the con rod beam using a dedicated fixture. Before the big end can be measured for roundness the end cap nuts have to set to the factory torque specs (Pic1).
The next demonstration is using the built in micrometer of the rod honing machine. The micrometer is set to the big end journal spec and the rod is set on the measuring pegs and rotated about 180 degrees in both directions.Note that the micrometer measures, within an accuracy of 0.0005”, any deviation from the preset nominal diameter of the big end journal, not the actual big end diameter of the con rod. Any deviation greater than 0.001” will require the big end to be resized which essentially grinds down the end cap a few thousands and the rod assembly re-torqued and manually honed in a connecting rod honing machine to achieve original diameter and maintain roundness to within specification (Pic 2).

With the end of the planned demonstrations, there is just enough time for my partner and I to measure the crankshaft journals. Each journal, both main and big end, are measured in four specific locations. We start at the front of the crank, normally where the crank pulley and keyway are located. Each main journal (5) and big end (4) are numbered sequentially from front to back for measuring purposes. For the mains the keyway is used as the reference point and designated as the 12:00 position. Each main journal is measured at the 12:00 and 6:00 o'clock position and the 3:00 and 9:00 o’clock which will determine roundness of the journal. To determine taper both the front of the journal and the rear of the journal are measured at the same four points.

The connecting rod journals are measured essentially the same way. The only difference is the location of the designated reference point. I believe we used the casting lines on the crank as the reference. These are the specifications per the workshop manual:

Main: 2.1255”/2.1260” (53.987mm/54.000mm)
Crankpin: 1.9370”/1.9375” (49.199mm/49.211mm)

These are our crankshaft journal measurement points.
Pt A = 12:00 & 6:00 position/front
Pt B = 12:00 & 6:00 position /rear
Pt C = 9:00 & 3:00 position /front
Pt D = 9:00 & 3:00 position/rear

#1 main journal - Pt A = 2.1259///Pt B = 2.1258///Pt C = 2.1256///Pt D = 2.1256
#2  main journal - Pt A = 2.1258///Pt B = 2.1259///Pt C = 2.1256///Pt D = 2.1256
#3  main journal - Pt A = 2.1256///Pt B = 2.1258///Pt C = 2.1258///Pt D = 2.1258
#4  main journal - Pt A = 2.1259///Pt B = 2.1259///Pt C = 2.1259///Pt D = 2.1258
#5  main journal - Pt A = 2.1257///Pt B = 2.1256///Pt C = 2.1257///Pt D = 2.1257

#1 crankpin journal - Pt A = 1.9370///Pt B = 1.9371///Pt C = 1.9371///Pt D = 1.9371
#2 crankpin journal - Pt A = 1.9370///Pt B = 1.9371///Pt C = 1.9370///Pt D = 1.9371
#3 crankpin journal - Pt A = 1.9369///Pt B = 1.9369///Pt C = 1.9370///Pt D = 1.9370
#4 crankpin journal - Pt A = 1.9369///Pt B = 1.9369///Pt C = 1.9370///Pt D = 1.9370

From the above reading for the mains, the journals are well within spec for roundness, taper and diameter. The crankpin readings are also within spec for roundness and taper but all of the journals appear to be on the low end of the spec. Journals 3 & 4 are slightly under the minimum specification. Re-measuring of the crankpin journals and consultation with the instructor will be required. This ends Day 12.

One day after Day 12, a stay at home order due to the Covid-19 outbreak  was issued for all of California and the Community College immediately announced the cessation of all classes for the next two weeks.Anticipating that this could turn into a longer break, I immediately email my instructor to see if I can pick up my engine block. He designates next Monday as the only day students can pick up their equipment if desired. If I had thought ahead, I should have picked up all of the disassembled bits but only ended up picking up just the block and piston/rod assemblies which I then dropped off at a local auto machine shop not far from the school.I asked them to clean the block with their pyrolytic oven, jet wash the oil galleries, and re-measure the cylinder bores to double check our measurements.They also recommend shot peening the block to relieve the metal of any residual stresses.. Since the block needed a re-bore, I agreed. While the block is out with the machine shop, I am on the lookout for a replacement jackshaft.

Pic 1 & 2 - The con rod fixture is secured in a vise with the rod big end clamped securely but not tight in order to torque the end cap to the rod. The rod needs to be at correct torque for the big end measurement checks.

Pic 3 - The instructor is demonstrating the measuring micrometer of the rod honing machine.

[BDA]

Another interesting post, Joji! I don't think it ever occurred to me that a journal might not be round or not cylindrical.

It's too bad your class was cut short!

[Grumblebuns]

A bummer to be sure. The instructor is floating around the idea of finishing up the semester during the summer break all depending on the Covid 19 situation of course. My next posting will bring the engine block status with the machine shop up to date from their inspection. If the stay at home order is extended through the summer, I'll contact the instructor to see if there can be an exception made to allow me to pick up the the remainder of the engine components. I also have my 365 transaxle I left at the school. I  was using their parts cleaner to clean up the casing and bell housing on the 365 which did a pretty good job of getting rid of 30+ years of dirt and oil crust.

The semester is essentially over; we took the final exam online a week ago. If worse comes to worse and the California university system is shut down for the rest of the year, I'll try to get my engine pieces and tranny back and install a spare TC motor I picked up a few months ago into 3923R and finish up its resurrection. I may decide to reassemble the motor on my own but I'll make that decision if and when I get to that point.

   

[BDA]

I sure hope you guys aren't locked down through the summer much less for the rest of the year!

[Grumblebuns]

                                                                                            Chronicles of a Community College Engine Rebuilding Class

Week 1, Covid-19 lockdown

When I dropped the engine block off at the machine shop the young kid at the counter immediately recognized the block as coming from a Lotus as they had just done an engine from a Lotus 7 not too long ago.Hmmm, I was thinking, this engine block may be good hands. I request that the shop  re-measure the cylinder bores to double check our measurements taken at the class and ask what methods they use or recommend to clean blocks. He recommends doing a pyrolytic oven clean followed by shot peening the block. I also request a jet clean to follow up the oven clean to clean out the oil galleries. I pay a small deposit and I’m on my way.

I should note that the community college does have a pyrolytic oven to clean blocks and equipment to bore blocks.A new facility was also built to house additional equipment  but again due to budget shortfalls,there was not enough funds to hook up power to the stored equipment. Any engine block cleaning that a student may need to have done will be up to the student to have done by a commercial shop. The school does have a couple of boring bars to bore out blocks and if needed I can use to over bore the Lotus block.  The school has a Rottler computerized honing machine to complete the re-bore with the final finish hone and brushing. The lack of funding comes into play once again with the honing machine not having the tooling to hone out blocks smaller than the 4” bores used in the Detroit V-8s. So again any rebore of small displacement engines will be at the students expense at a commercial machine shop

During this waiting period, I need to use the time to locate a replacement jack shaft. During the engine disassembly earlier in the semester, we noticed a major problem with the jackshaft. Some of the helical teeth on the jackshaft for the oil pump gear drive had been broken off  (Pic 1). It’s possible that some of the broken bits had traveled with the oil flow into the crankshaft and caused the light scoring on some of the journals. I found one of ebay for $175 which is a decent price seeing that a new one from Pegasus racing goes for around $400. I came close to hitting the “buy it now” button before I back out at the last second and decided to keep waiting for a cheaper one to show up. With my sometimes good luck,one did fall into my lap. I was visiting my machinist friend about making another run of high balance tube manifolds for me. He had recently retired from doing any machine work in his shop due to health reasons but a fellow machinist friend comes by on a part time basis to help out on work that occasionally comes in, like mine.Knowing that he had a lifetime of Lotus and FF parts collected over the years stashed in his shop, I asked him if he had any Kent engine jackshafts lying around. In the middle of our conversation, he suddenly asks me if I’m still interested in the Stromberg head I had asked about a few weeks back. At that time, we were in the engine disassembly period and I was looking ahead to the possibility that I may want to have a replacement head as back up in case there was an issue with my current head in the TCS. I made an initial offer which he thought was too low and that he told me that he would think about it. Apparently he had changed his mind in the intervening weeks.So I came out of that visit with a Stromberg head along with a usable Kent jackshaft, a set of Stromberg carbs and stock airbox out of an Elan.

Week 4, Covid19 lockdown.

I finally get a call back from the machine shop. They confirm the cylinder bore measurements taken by us during our lab session engine disassembly and recommend a 0.020” overbore for the block which I agreed with. I saw no need to go with a larger bore size thus leaving room for additional overbores when needed. I call Dave Bean Engineering and a couple of days later a package shows up at my front gate with a set of four 0.020” over forged JE Pistons/wrist pins/ring set along with a set of cam bearings for the jackshaft and new bushings for the connecting rod small end.. Seeing what is required with the installation of the jackshaft bearings, I elected to have the experience of the shop install the cam bearings for me.

This pretty much brings my story up to the present, just waiting for the machine shop to tell me that they are done with my engine block. The unknown is what the Community College will do for the upcoming semester. The instructor is talking of re-commencing and trying to complete the class during the Summer session but I suspect the class will be cancelled and graded as Incomplete. As California starts to slowly re-open its business’ and institutions, there should be an opportunity to retrieve my engine components and start my engine reassembly albeit on my own without an experienced mechanic to directly ask for help and guidance.

Pic 1
A jacked up jackshaft. .Damage probably occurred during one of the oil pump removal and reinstallation. Unsure or don’t remember how the damaged gear teeth affected oil pump operation. Will have to disassemble the oil pump to see if the internals can be cleaned up prior to reinstallation. If not a new oil pump will be ordered

Pic 2
The included Strombergs, also probably from an Elan ( bottom airbox is Europa). Notice that on the Elan the airbox inlet faces in the opposite direction from the Europa.This may be a good alternative for a cold air style induction system if taking air from the bottom of the fuel tank location since there is no modification to the Europa airbox required. Problem is that a stock Elan airbox will probably be hard to locate.
 
Pic 3
Replacement jackshaft. I’ll have the machine shop polish the journals

[BDA]

Nice write up, Joji! Hopefully you'll be able to continue your class soon. Keep us informed about future progress.

[Grumblebuns]

                                                                     
                                                                                        Chronicles of a Community College Engine Rebuilding Class


Week 20, Covid19 lockdown

I receive notification from the class instructor that the school administration has allowed limited resumption of the engine rebuilding class. On the first day back, the limited resumption timeline of the class was laid out. The class will meet for the next four days from 8am to 4pm. With parts that I will need to order and my cylinder head still not touched, there was no way that I could get my engine back together properly in the allotted time. My only choice was to request a withdrawal from the class and retake it next Spring. I spent the remainder of the morning collecting and cleaning my parts in the school’s parts washer. The final task was to load my cleaned parts into my Yukon and finally leave the campus.

Being left high and dry with the most important part of the rebuilding process yet to come, I’m scrambling to find space in two packed garages to begin the reassembly process on my own without technical assistance available. I’ll keep posting my progress in case my experience helps anyone else contemplating or needing an engine rebuild and the process involved.

[BDA]

That's too bad you were caught unawares! Are there other measurements you have to make before you can start building?

[Grumblebuns]

The next step in the rebuilding process would have been to check the crankshaft clearances. With the machine shop still in possession of my engine block and spare crank, I'm stuck. If the crank journals need to be ground, that will be an additional few more weeks. I believe one of the con rod big end journals was at the lower end of the spec on the crank held captive at the school. The status of the spare crankshaft that the machine shop is inspecting is still unknown. I'll drop off the original crank with the machine shop to get their opinion of its usability.



 

[Grumblebuns]

                                                                                                           Left to my own devices

Chapter 1, The cylinder head

With all of the engine components back in my possession, most importantly the head and crankshaft. I started looking for an engine builder to inspect and work on my cylinder head. Following the recommendation of a machinist friend, I contacted and dropped off my head with long time Lotus specialist, John Kouba.. He did an initial check of the head and found nothing obviously out of the ordinary. The head I brought up to John Kouba is not the original head on 3229R. This replacement head was installed back in the 80s when the original head was too badly overheated to remain in use. The head appears to have been previously skimmed but was still within specification for head thickness.
All the head needed was his standard head refurbishment procedure. This was good news as no extra money will be needed for additional repairs to the head unless something unexpected comes up during the disassembly process.

Around two weeks later I get an email from John stating that my head is finished and can be picked up. I made the two and a half hour drive up to John’s place and he went over the work that was done to the head. During the disassembly of the valve train components are examined as they were removed. The only item he found out of the ordinary was some minor pitting on the exhaust cam lobes. I exchanged it for one of his spares. Once the head is completely disassembled, his standard refurbishment procedure is to clean and degrease the head and oil galleries and blast the head with walnut shells to decarbonize the combustion chambers. Valve guides, valves, and buckets were replaced with new replacement parts as a matter of course with this engine builder.

With new buckets/cam followers installed and there is still the slightest discernible play between bucket and the cam follower bore, then new sleeves will have to be installed. This procedure is described in the Miles Wilkins book. Obviously this extra machine work increases the final cost of the head rebuild. If the valve seats are in good condition, they are re-cut for a fresh three angle valve job. Valve face to seat contact is checked and the valve is lapped in. Next, valve spring pressure and height is checked and shimmed as necessary to specification. New cam bearings are installed and if requested, which I did, valve clearances are set on the bench. The basic “valve job'' is complete.

I’ve scanned and attached the total cost that John Kouba charged me for the head work, rounded down to $1000 even for payment. My head work may or may not be typical and final costs will depend on the amount of additional machining work required to repair any issues. It’s possible that some costs can be reduced by the owner setting the valve clearances otherwise expect to pay your local engine guy some big bucks for a basic valve job. The extra $100 on the invoice was for the exhaust camshaft exchange and I had John inspect my spare Weber head at the same time. Additional items that will need to be ordered are eight exhaust studs, valve cover cork gasket and eight Seloc valve cover washers. I plan on reusing the original valve cover locknuts. The engine builder supplied the exhaust manifold brass lock nuts free of charge.

I added another invoice for the inspection and rework for a Weber head I've had for over 30 years for reference.