A hole story

The following technical tip is reproduced by kind permission of Kit Car magazine as part of Gerrys' Tech Tips series. We shall be including one 289 relevant tip from Kit Car each issue. If you are impatient, back issues can be obtained at 25% discount by mentioning that you are a member of the 289 Register.
If you have a technical tip that would help other members, please consider forwarding a copy to Kit Car. You never know, you may get it published and acquire national notoriety!

A common problem is how to rectify incorrectly cut holes in GRP bodywork. It's the sort of thing that happens when mounting bumper brackets or tubes, such as roll-over bars - but it also applies to larger openings such as headlamp apertures. The front bumper mounting tubes on Cobra replicas are particularly difficult to fit correctly at the first attempt, mainly because of the body curvature at this point - the actual shape of the hole being oval rather than round. Because of the difficulty, the holes usually end up being much too large, or off-centre to the tubes. Correct shaped grommets are virtually unobtainable and various shaped discs of stainless steel are frequently used to hide the errors - not very successfully. In the case of roll-over bars, the holes are usually at eye level so any mistakes are painfully obvious. Again, a disc of steel or aluminium is often used - a bodge to cover a bodge. Here's how to make a repair that looks good.


Cut out a piece of washing-up liquid bottle or a piece of plastic of similar thickness - we use the plastic tubes in which welding rods are contained so that it fits neatly round the tube without overlapping. Give the plastic a couple of good coats of mould release wax, slide it over the tube through the hole in the bodywork and secure it to the tube with masking tape, rubber bands or tie wraps. Mix up some resin, hardener and choppies (If you want to know all about fibreglass techniques and materials see June 1997 Kit Car - back issues available from +44 - 1293 - 886998), and fill in the gaps between the bodywork and the tube (now covered with its plastic sleeve). If the hole is big, it may be necessary to first put some larger pieces of glassfibre mat at the back, or use tape to stop too much resin mix falling through. Either way, it is wise to mask any vital trim or parts that may get dripped upon. Fill the hole as near to the surface as you can and allow to cure.


When cured, remove the plastic sleeve and the bumper bar, or roll bar, or whatever, and sand the surface flush. Fill any small imperfections and when cured sand flush again if necessary. When the repair has been painted, you won't be able to see where you made the mistake. Everyone who sees the car will wonder how you managed to cut such perfectly neat holes with equal gaps all round your tubes. They're much too good to cover with great big ugly grommets or stainless steel washers. On final assembly, if you want a water tight seal, a thin smear of Sikaflex at the back will be all that is necessary.


Feather back the edges of the hole and remove the dust particles with a brush or vacuum cleaner. Brush the edges with a drop of acetone - nail varnish remover will do the job. Refit the tube in its correct position and tighten the fixing bolts.

Oil level

Over the past year it seems I have been forever filling up the oil in my Rover. Despite the fact that I have cured the sump leak and greatly reduced the engine's tendency to pump oil up the dizzie shaft I still seem to be stuffing oil into the engine at every opportunity. Now I suspect that the oil is actually being burned after dribbling down the valve stems so until I have the heads machined for unleaded in the winter I guess I'll have to live with it. In the meantime it has taken me several months to get to the point where I now know how much oil to put in! Daft isn't it?
In the hope that it might be of interest to some other poor sod I can now divulge my calculations as follows:

The distance between the High and Low marks on an SD1 dipstick is 70mm. It takes approximately 3 litres to fill from Low to High. According to my calculations that is a little over 4ml for every 1mm up the dipstick.

So, if you measure the difference between the current height of the oil and the top of the High mark in mms and multiply by 4.3 you will know exactly how much oil you need to fill-er-up. Mind you, you then need a measuring jug to accurately measure the oil. Perhaps there is one in the kitchen?

Rover SD1 cooling

One of the many faxes I received from Gerry on a Sunday morning contained this diagram of the cooling system for a Rover engined Hawk. Given that we are having a reasonably hot summer I thought it appropriate to include in this issue.

Build Experiences 1

Adrian Bowden

I stress that this contribution is not an attempt to upstage Gerry Hawkridge's excellent Technical Tips. It is really out of guilt and embarrassment that I sit before my PC keyboard. Ever since I started my build back in 1989 I have called upon the editor for help and advice. Now I feel that it is about time for me to put some knowledge back into the pot!

First of all I own up to being the "anonymous member" referred to in the second edition of the 289 Register with the creative approach to registration. The registration saga continues because I am waiting for the final V5 document from the DVLC. Certainly the local VRO does not think there will be any problems. So, the answer seems to be to change the details in your V5 gradually over a period of time first the chassis then the engine and perhaps then the colour. The final hurdle is to change the type/model from MGB GT to Hawk 289. I will keep you informed!

Stop Press: Adrian received his completed V5 recently describing the car as a Hawk 289 2-axle-rigid-body-convertible. He keeps his original number plate and feels himself pretty damned lucky. Not luck, Adrian, just a sneaky approach and good organisation. I'm not sure everyone would be so successful so I cannot recommend anyone else follows the same procedure. I think Adrian's local VRO staff are working to a different rule book than the rest of the country!

I have built a number of "kits" in the past starting with a Burlington Arrow, a sort of aluminium skinned ply wood box built on a Triumph Herald chassis. This was an amazing success and was sold to pay for an NG TF. The NG was a very pretty car and went together well. The next project was a Chesil Speedster. The final product looked good but lacked oomph with the standard Beetle engine. An Alfa Sud flat four was then installed with a radiator in the front spare wheel well. The local central heating plumber helped me with the cooling system and the end result was very effective.

That could have been the end of my "builds" had I not happened to read a Kit Car magazine with an article on the Hawk 289. The old stirring in the loins occurred again and the FINAL project was undertaken.

So far the Hawk has gone together beautifully, based on previous experiences, and any problems have been solved readily by GH and his team.

Anyway here are a couple of observations that might save other builders a bit of time and heartache:

THERMOSTAT HOUSINGS

David Pilbeam will vouch for the fact that I have thrown a great deal of time, money and energy into this topic. In fact I think I now have the most comprehensive collection of SD1 thermostat housings.

If a standard housing is used with the SD1 Rover engine the hose from the housing to the header tank runs too close to the vacum mechanism on the side of the distributor. There is also a high point in the top hose which could lead to overheating problems due to the restriction in the circulation of the coolant.
David has overcome the problem by having a new housing cast. An expensive remedy unless a number of builders could be persuaded to go down that path and justify a run of 10 or so.

The next solution was to purchase a modified housing from V8 Conversions in Kent. £25.00 including postage and I thought that I had found the remedy. Unfortunately, this housing was rather disappointing. The top hose was still at too high an angle and it fouled the vacuum mechanism on the side of the distributor. Also, the heater bypass hose was only an interference fit into the casting and held in place with epoxy glue. It did not inspire confidence and so back to the drawing board.

In order to experiment cheaply a second hand alloy housing was purchased from Parts for Rovers in Leyton. The top hose outlet was the sliced off at an oblique angle. The pipe was then rotated until the correct angle was obtained. This was marked with a permanent felt pen with two aligning marks. I then toured the local engineering works until I found one that took pity on me. I am, in fact, known quite well to most of them and some have been known to close their gates quickly when I arrive!

Eventually one took pity on me and agreed to weld the outlet pipe up for me. I expected to be asked to come back in two weeks or so. In fact they did it for me whist I waited and charged me a fiver. The complete job cost under a tenner. The final result is very good and the top hose is now clear of the distributor and is at the correct angle for the header tank.

As luck would have it this engineering company also specialises in pipe bending. I made up a cardboard pattern of the pipe route from the lower radiator hose up over the steering rack to just overhead the lower universal joint on the steering column. They were able to follow this pattern and make up a 38mm stainless pipe. I used a QH RH 1908 hose for the right angled bend from the stainless hose to the water pump and cut four inches off this rubber hose to join the stainless pipe to the bottom radiator outlet. I was going to have the stainless pipe with 35mm one end and 38mm the other end to accommodate the different diameter of the water pump and the lower pipe on the radiator. But I found that a 35mm hose could easily be made to fit over a 38mm pipe with plenty of Fairy Liquid and a few bruised knuckles. I had the stainless pipe made over length and cut it to size once it had been offered up. The intention was then to return the pipe for a knuckle to be formed at the end to prevent the pipe slipping off under pressure. However, the 35mm pipe forms such a tight fit that I am sure all that is required is the jubilee clip to make a watertight seal. If not I will get the knuckle formed at a later date.

At the moment I have used Vulco Flex hoses for the top hose, a VF203 from the header to the top of the radiator and a VF215 from the header to the thermostat housing. However, the stainless pipe in the lower hose looks so good that I might make a similar arrangement for the top hose.

I have a Pacet electric fan and sender. The sensor for the sender fits into the top hose with a dense foam rubber pad to protect the copper capillary pipe and form a seal. It fits well with the Vulco Flex 215 hose but only time will tell if it is an effective seal.

HEATER FITTINGS

Still on the theme of water works. If an open/closed tap is used in the hot side of the heater circuit then when the heater is off the cylinder head overheats. The heater can always be left on all the time but I did not consider this as a suitable solution. KL Automotive products manufacture a very neat 3-way hose (an E2107) which overcomes the problem because in the off position water still circulates through the manifold thus avoiding the overheating problems.

The next problem was routing the heater pipes and how to take them neatly through the bulkhead into the passenger compartments. Here I have welded a 2 inch circle of stainless in the middle of a four inch length of stainless heater pipe. All you have to do then is drill a hole for the pipe and insert the pipe from within the passenger compartment. The circle can then be drilled and bolted through the bulkhead, obviously with the bolt heads showing in the engine compartment. This gives a very neat passage through the bulkhead and means that the heater tap can be positioned more easily and once installed the heater is independent of the engine compartment allowing the heater to be removed without having to disconnect the pipes from the heater valve etc. All much more convenient and looks good in the engine compartment.

Provided the technology of my digital camera works I will include pictures of the modified thermostat housing and these heater pipe fittings. In fact the photos were very difficult to compose. Perhaps I should have taken them before painting the housing black and the detail would have been more obvious.

(Ed - I did try to get the pictures in but black isn't very good at showing contrasts - sorry Adrian)

The hose now runs around the distributor and is below the level of the header tank.

ENGINE COMPARTMENT

Apparently, once the V8 starts rumbling away the temperature inside the engine compartment goes up with a vengeance. Various methods have been used to keep the heat in the manifold and therefore reduce the temperature in the engine compartment and improve with the scavenging of the gasses out of the exhaust system.

My first attempt at wrapping thermal tape around the manifold was an astounding failure. I finished up with a bad case of basket weaving. However hard I tried I could not get that tape to stay in place around the manifold and those stainless steel clips were absolute torture. The next step was to throw away the bandage and go for a jacket. Once again an astounding failure, it was impossible to feed the jackets between the manifold branches.

Back to the drawing board.

I then paid more attention to the method used on aircraft to keep the engine compartment insulated from the passenger compartment. A sandwich of sheet ally and a layer of insulating fibre is used. Fixing the ally sheet to the bulkhead with a spacer in between further enhances this insulation. The resulting air gap improves the barrier and further reduces the heat transfer.

The surfaces inside the engine compartment on the 289 are largely flat with very few complex curves. Provided the job is undertaken with the body off and the bonnet removed it was easy to make up cardboard patterns and then cut the ally sheet to shape. The sheet complete with the insulating fire resistant fabric was then fixed in place with spacers and self-taping screws. The engine compartment now looks very business like and my feet should remain cool in the footwell!

Well, I hope that my ramblings might come in useful for other 289 builders. It certainly has been a very enjoyable experience and I will pass on any other tips that come to light.

I can be contacted on email mailto:abowden@swordfish11.freeserve.co.ukshould any of the above require any further clarification.

Build Experiences 2

Bob Lawrence, Texas, U.S.A.

My car (Hawk 289, Ford 289, MGB rear end) had its maiden voyage last Saturday. I am still fine tuning the engine and watching for bugs. I was surprised at how well the car handled and braked. My only complaint is that the back end seemed a little bouncy during the first little bit of travel. Small jolts don't seem to be dampened at all. I am blaming the lever arm shocks for now.

I don't intend to race the car and am trying to achieve a comfortable ride that is still competent at higher speeds. By the way, I found a web site with some very interesting MBG info and test results using various brands of brakes, springs, and other info and recommendations: http://www.289register.com/www.mgbmga.com

I was a little amused at all the ink in the newsletter regarding unleaded fuel. But then I remembered how worried we were over here 20 years ago. We were told that besides lead being dangerous it was not compatible with the catalytic converters that had become standard on all cars around 1979.

Many companies marketed to us worried car guys in the '70's by trying to sell us lead substitutes and so on. Unleaded turned out to be no big problem and today they can't give away lead substitutes. I have spoken to engine builders who have told me that they have never actually witnessed damage to an engine because of unleaded fuel. However, it is a common practice to install hardened exhaust seats when rebuilding an older engine which is all that is done for unleaded fuel. I have never heard of anything special for valve guides. We use the same old bronze guides. Most people with older cars just run the unleaded and don't give it a second thought. Engines don't seem to be wearing out any faster.

(Ed - This may be because in the past engines were larger and less highly tuned in the USA. As they became smaller and lighter they were built specifically for lead free gas. There are fewer old engines affected that now need conversion)

The biggest concern I think you have over there is declining octane ratings. In the U.S. every gas pump must display the octane rating and the method of calculation. All stations here sell three grades of gas (sorry, petrol) regular 87 mid grade or "Plus" 89 and premium 93 - 94 octane. This has kept our engines to 9 - 10:1 compression. Many Cobras I know of run 10.5:1 and get away with it (being light helps!).

Over here the problem of having to much compression for the available octane rating was a much bigger problem than switching to unleaded.


I do have a panhard rod and the car has no skip and is great around corners. I do not have anti tramp bars but there is no wheel hop when the tires spin. The bouncy stuff is at lower speeds on our concrete streets. You can push the back of the car down about ¾" before the dampers seem to do their job. Maybe my dampers have a problem. I did notice when I put the new valves and 20wt oil in, the lever had a little play up and down before they got harder to move. Based on what I read at mgbmga.com, the Spax tube shocks on a lighter setting may work better. The front suspension feels real good ('66 MGB GT springs and sway bar with 1/8th inch spring spacers).

I was pleased to see that I don't have any over heating problems. The car can sit and idle in the 90f degree Texas heat without a problem and does not heat up with harder driving. I am using Gerry's radiator with Flex a Lite fully shrouded dual 10" fans. The whole unit is one piece and fits the radiator perfectly.

Also hints for the members running ford 289/302 engines:

Fords love timing and need at least 38 degrees total advance. Most guys run a total advance of 38 to 42 degrees. Carb should be around 600 cfm with a cam in the .500 to .530 lift and 280-290 duration (216 to 228 @ .050 lift).

The 715 Le Mans carb on my car looks great and original, but is not ideal for a street driven car. At around town speeds my car had uneven mixture resulting in some cylinders that were too lean. I replaced the stock .68 jets with .72's and increased the .25 accelerator pump squirter with a .31. The car now runs very well but would probably run even better with a 600. I am thinking about putting the Le Mans bowls on a 600 Holley. If you are not familiar with this rare Holley/Shelby carb look at the picture of my engine on the web site. It was Holley's first attempt at center hung floats and was developed for Shelby because the cobras would starve for fuel on the long turns at Le Mans. This carb was also used on the '65 -'66 Shelby GT 350 Mustangs with the Cobra high rise intake. Incidentally the original Cobra high rise intake was make by Edelbrock back then, and is the same as the old Edelbrock F4B. Modern intakes that are comparable are the Edelbrock Performer RPM and the Wiend (spelling?) Stealth.


I was reviewing some older e-mail from you to see if I was responsive to all your requests. I remember that there were a few things that you thought the membership might be interested in but I did not want to go into detail until I had actually got the car running so that I could report if things worked. One thing you mentioned was the dual circuit brake system.

Because all my MG donor stuff came from the same wire wheeled '66 MGB GT car my four way brake union was for a single line system, which is how I originally plumbed the car. Friends who saw the car while I was building it never failed to look at the brake system and tell me I was crazy, and that I should convert to dual line for safety. It is important to note that single line systems were outlawed on new cars in the U.S. around 1968. Converting to dual line was very easy and only took a couple of hours.

The only parts needed were a dual circuit master cylinder and a 5 way proportioning valve from a later junked MGB, and a couple of new lines. The 5 way union has two lines going in and three coming out (one for each front brake and one for the rear). The union also has and electrical sender which is to warn of low pressure on either side. I did not hook a warning light to this switch since I already have plenty of lights on my dash, but the switch should not be removed. The MG line pressure brake light switch from the four way union can be used if you can find the proper tee to install in one of the lines going to the five way union. I just bought a new switch and tee kit for 3/16th line from a local hot rod shop. The switch looked like the MG unit and is very sensitive and turns on the brake lights with just slight pressure on the pedal. When I pulled the 5 way union from the junked MG I mapped out how it was plumbed so that I would not screw things up. I also found it useful to keep all of the brake line fittings/nuts from the MG because they have different threads than what came with the new sections of brake line. I also reused the three steel nuts that are at the end of the hard line where they connect to the flexible lines.

The only part of the brake system that had me worried was trying to reproduce the bell shape flare that MG used. I could not find a tool that was made for this type of flare. What I did was use my tool that makes double inverted flares. If you install the pipe in the holder a little higher than normal with the 3/16th button and give it just one full squeeze you can make a bell flare that is just right (with practice first).

The other thing that I would like to share is that my external clutch slave cylinder works great! I decided to do this when I realized that a potential leaky hydraulic throw-out bearing could only be fixed by removing the engine. The clutch slave is from a BMW 2002 and fits into an easily made bracket. The clutch slave is the same bore size as the MG clutch master and the cut down Ford push rod is adjustable for fine tuning. If this slave ever leaks it can be replaced in just minutes. If there is any interest from the Ford powered guys I can e-mail pictures to you. This is great way to go for cars under construction, but engine removal would be required for cars that are on the road since a standard throw-out bearing and clutch fork is required. Also the best Ford blocks for this are the earlier ones that have a threaded hole in the back of the block for a mechanical clutch linkage. This hole is one of three mounting points for the bracket. The other two are the motor mount bolt (rear into block) and the rear corner oil pan bolt.

If there are ever questions relating to the Ford stuff (such as various engines, bell housings, and Transmissions combos and compatibility) feel free to send my way. I am an ex-Ford drag racer and am familiar with anything that is Ford V8 related. Because of my drag racing background I am killer on the straight-aways and scared to death in the turns. My Cobra really seems to take the curves well and is inspiring confidence. I just want to make sure it is not over confidence.