Removal and rebuilding of a Twincam

[1owner69Elan]

Thanks to Rohan for the very helpful and detailed tutorial. I picked up some useful tips along the way.

I would only note a few variations in my approach that might be useful to others:

1. I support the gearbox on a small, rolling transmission jack, with angle adjustment. Besides making it easy to roll into position and insert the gearbox in the tunnel, this allows me to fine adjust the height/angle while also being secure from falling off of a jack. Inexpensive from Harbor Freight.

2. I insert two long bolts in the gearbox mount loose, no nuts. This allows movement of the gearbox vertically, some horizontal, but not axially. This helps while adjusting the angle of the gearbox to mate with the block. The two gear box mount bolts are later secured after the engine is bolted in.

3. I use a tilting bar to precisely get the angle for the engine to mate to the gearbox. I have found when the proper angle is found, the engine and gearbox input shaft slide together by gravity without need for much rocking. I am always concerned about damaging the somewhat fragile pilot needle bearing (less of an issue with a oilite bushing) by rocking/pulling/pushing the two units together.

4. In fitting the TTR big bore race exhaust, I keep the engine on the crane (hoist) with no motor mounts installed. I feed the manifold (headers) up from the bottom of the car, no need to remove the heater valve. With no motor mounts installed I can also push the engine to the right to allow for more clearance.

5. I use the existing (not cut down) exhaust studs, installed in the head, along with k-nuts to secure the manifold . I don't relish screwing studs or bolts into the aluminum head on a repeated basis. I am sure with judicious care it doesn't have to be a problem but I don't even want to expose myself to the possibility of damaging the head threads.

6. I use a 1/4" ratchet socket and claw as "661" has noted to secure the k-nuts. Using the claw can be a bit tedious for some of the nuts. But, then again working on the TC requires patience in any case.

7. After the manifold is secured I then install the motor mounts on both sides (including the ground strap). Some of the motor mount bolts are easier to reach from below. Then remove the hoist.

As noted in other posts regarding installation of the Voigt 5-speed, I ended up removing and installing the engine more than six times in a short period of time (pilot bearing failure, annular slave cylinder leaks). This repeated remove/install process by luck happened to coincide with this thread so Rohan's information was very timely. In the end, the process became quite smooth. I can remove and reinstall the engine, as one person, in the span of a couple of hours. Of course that doesn't include all the ancillaries (carbs, radiator, hoses, starter, etc.)

[rgh0]

Fortunately I don't need to pull engines or transmissions out that frequently

One day I will get myself a transmission jack and a tilting bar for the engine hoist but to date I have survived with blocks of wood and ratchet straps !.

If I did not have the Maxjax hoist I probably would have already got the transmission jack but the hoist enables me to align the chassis height with the transmission easily without it.

Glad my posts have been useful, they will also be a reference for me as I tend to forget things every time I remove and rebuild an engine as you will see from some of my comments

Hopefully just one more day to refit all the other engine bits. A public holiday tomorrow so I should be able to get it finished.

cheers
Rohan

[rgh0]

Almost there!...

Thank you for all the detail in this post Rohan, I've really been enjoying it. Just about to replace my cylinder head & take a look at what's in the bottom end, so this should prove useful.

Hi Phil
Yes almost done with this engine.. hopefully it starts OK in the next few days. I sure dont want to have to pull it out again any time soon One of the pleasures of doing an engine rebuild on the internet is that if you screw up every one knows !

My spare 13:1 comp race engine is next on the list for a rebuild as since the regulation changes I cant use Avgas anymore and I don't want to pay A$4 per litre for unleaded high Octane race fuel. I need to pull the pistons out and machine the intruder down to get around 11:1. It also needs a bearing replacement after quite a few years of racing, I checked then mains and big ends when i first pulled it out and they all show signs of wear. The engine has been sitting for the last 3 years and time I got to its rebuild. Also have the gearbox I removed to rebuild as my spare so "no rest for the wicked"

cheers
Rohan

[Elanman68]

Just adding my thanks to you Rohan for your step by step photo essay on this and your gearbox. I'm about to pull my engine to replace the clutch release bearing, first time its been out in over 30 years so this is a great reference, thank you. Have a few other jobs to do whilst its out but not planning on a full rebuild (yet).

[rgh0]

Time to install all the engine ancillaries. I work from the back and bottom to the front and top as this makes access for installation easiest.

Starter first. I use a a pre-engage starter made by Bosch in Australia and used in 1970's Ford Escorts and Mazda 626 here. Its a 3 bolt design but the spigot ring and two bolts line up with the Lotus bell housing perfectly. Bosch also supplied the 9 tooth pinon that meshes with the Lotus ring gear. I cut half the third bolt lug off to clear the chassis on the right as i have pushed the engine about 5 mm to the right to get clearance needed for the TTR race headers on the left.

Top bolt for the starter needs a long extension and flexible joint for the socket. But easier with the carbs not on !

Fitted the oil cooler and sandwich plate and hoses and the filter and then pumped 2 litres of oil into the galleries to minimise time to build pressure when starting the engine.

Hooked up the clutch piping and refilled the system. Pushed the clutch pedal to start bleeding and the pedal stuck down . Remembered I had bought a pressure bleeder for use on the families modern cars and discovered the "European" adapter fitted the Girling clutch master cylinder - the European standard does not appear to have changed in 50 years. 10 PSI on the pressure bleeder with the slave bleed valve closed and the master cylinder piston popped back. Saved me having to pull the master cylinder and made bleeding the clutch simple ... as no need to pump to get the air out.

Fitted the heater hoses and then fitted the alternator bracket and the alternator. With the 3 inch small diameter crank pulley to not over speed the alternator and water pump at 8500 rpm I need a shorter V - belt. 11mm wide "A" profile which is standard but 785mm length.

Next the carbs bolted into place. Easy to do without the radiator

Called it a night with the dizzy to still be installed and the radiator and exhaust to be fitted. Plus need to finish filling the engine and gearbox to the correct levels with oil Not far from starting now !!!

cheers
Rohan

[2cams70]

Interested in what the purpose is of the hose clamp around the oil filter.

[Andy8421]

Time to install all the engine ancillaries. I work from the back and bottom to the front and top as this makes access for installation easiest.

Starter first. I use a a pre-engage starter made by Bosch in Australia and used in 1970's Ford Escorts and Mazda 626 here. Its a 3 bolt design but the spigot ring and two bolts line up with the Lotus bell housing perfectly. Bosch also supplied the 9 tooth pinon that meshes with the Lotus ring gear. I cut half the third bolt lug off to clear the chassis on the right as i have pushed the engine about 5 mm to the right to get clearance needed for the TTR race headers on the left.

Rohan

Rohan,

This has been a great thread, one I will refer to when I rebuild my engine next. Thank you for all the effort taken to post it.

One question, that starter looks like it weighs about the same as the rest of the engine. Have you considered a gear reduction starter in its place?

[rgh0]

Interested in what the purpose is of the hose clamp around the oil filter.

Good pickup. I must admit I deliberately did not mention it to see if anyone would ask

Spin on oil filters have been known to come loose due to the vibration in the nose of a Twincam at 8500 rpm. I position the clamp on the filter body so it stops it unscrewing as the screw adjuster section will not fit through the gap between the filter body and sump effectively locking the filter on.

cheers
Rohan

[rgh0]

One question, that starter looks like it weighs about the same as the rest of the engine. Have you considered a gear reduction starter in its place?

It actually weighs a bit less than the original Lucas bendix starters but certainly more than some of the modern gear reduction pre-engage starters.

I have stuck with these starters as they are very robust and and have proved to be reliable while some of the modern adaptions suffer from not fully engaging the flywheel ring gear correctly or the adapter bolts coming loose. Also under my competition production sports regulations, I am required to run at the original production weight of 700kg with allowed bits removed ( such as spare tyro and tools), which I do, so no real advantage going to a lighter starter as it is low down and relatively central mass. I have removed the original starter solenoid from the firewall at least

cheers
Rohan

[2cams70]

Spin on oil filters have been known to come loose due to the vibration in the nose of a Twincam at 8500 rpm. I position the clamp on the filter body so it stops it unscrewing as the screw adjuster section will not fit through the gap between the filter body and sump effectively locking the filter on.

Sounds like there may be a resonant frequency problem happening with those HP/HV oil pumps at racing engine RPMs - i.e the natural vibration frequency of the oil pump assembly is matching the vibration induced by the engine at certain engine RPM's to destructive additive effect. This is causing pump bodies to crack, blanking plugs to fall out and oil filters to come loose, etc. Probably eliminating the gasket has helped but not solved the problem completely.

Can probably be further improved by either increasing the stiffness of the oil pump body or decreasing the weight of the oil pump assembly in order to change it's natural frequency of vibration to something higher and outside the range of vibration induced by the engine.

Increasing the stiffness is probably a bit more involved but on the weight reduction side you could possibly consider:

1. Using a lighter weight HP only pump instead of the existing HP/HV one.
2. Using a light weight alloy end plate on the HP/HV pump
3. Using a current Ford specification short oil filter instead of the standard size Ryco Z62 one. Burtons sell them and you can probably get them off the shelf from a Ford dealer too as they also fit a number of modern vehicles. Reducing the filter size and hence the weight of oil contained within will reduce the weight of the pump assembly considerably. There's quite a bit of weight there with the filter, the oil contained within, the oil cooler adapter and the attached oil cooler hoses.

[rgh0]

Spin on oil filters have been known to come loose due to the vibration in the nose of a Twincam at 8500 rpm. I position the clamp on the filter body so it stops it unscrewing as the screw adjuster section will not fit through the gap between the filter body and sump effectively locking the filter on.

Sounds like there may be a resonant frequency problem happening with those HP/HV oil pumps at racing engine RPMs - i.e the natural vibration frequency of the oil pump assembly is matching the vibration induced by the engine at certain engine RPM's to destructive additive effect. This is causing pump bodies to crack, blanking plugs to fall out and oil filters to come loose, etc. Probably eliminating the gasket has helped but not solved the problem completely.

Can probably be further improved by either increasing the stiffness of the oil pump body or decreasing the weight of the oil pump assembly in order to change it's natural frequency of vibration to something higher and outside the range of vibration induced by the engine.

Increasing the stiffness is probably a bit more involved but on the weight reduction side you could possibly consider:

1. Using a lighter weight HP only pump instead of the existing HP/HV one.
2. Using a light weight alloy end plate on the HP/HV pump
3. Using a current Ford specification short oil filter instead of the standard size Ryco Z62 one. Burtons sell them and you can probably get them off the shelf from a Ford dealer too as they also fit a number of modern vehicles. Reducing the filter size and hence the weight of oil contained within will reduce the weight of the pump assembly considerably. There's quite a bit of weight there with the filter, the oil contained within, the oil cooler adapter and the attached oil cooler hoses.

Yes I agree there is a resonance problem and a stiffer mount has partially solved it. Reducing the mass of the pump / filter / sandwich plate would help move the resonance higher. All you're suggestions are valid and I should pursue, changing to a smaller filter is easy and I should try that first. Do Ryco list the smaller filter ?

cheers
Rohan

[2cams70]

Yes I agree there is a resonance problem and a stiffer mount has partially solved it. Reducing the mass of the pump / filter / sandwich plate would help move the resonance higher. All you're suggestions are valid and I should pursue, changing to a smaller filter is easy and I should try that first. Do Ryco list the smaller filter ?

I'm not sure of the Ryco equivalent but here's the link to the Burton catalogue. I bought one of these for my engine. As you can see the same filter fits a lot of current cars including those using the Zetec engine. You should be able to look up one of the more modern cars Burtons list it as fitting and use that car model to cross reference the Ryco equivalent.

http://www.burtonpower.com/ford-oil-filter-x-flow-cvh-lotus-twin-cam-bda-efl500.html

[alan.barker]

I think an Austin Mini one fits
Alan

[joe7]

Try a Fram PH3614. Compact and nice bright orange! Been using them for over 20 years.

[promotor]

Mahle OC21 is one of the shortest filters I've seen - you might want to check them out while looking into other filters.