Roger King

In similar vein I fitted a wind breaker to my Frogeye. Unfortunately, when we get home she complains about the difficulty of getting out of such a low car.

Dikko, as the owner of an actual Sprite (Frogeye) with a dynamo, I can only say that I have never had any issues with charging. The difference is that I have a mechanical fuel pump and contact breakers, but I suspect that won't make too much difference. I assume you are not driving this "strange" car to events so my view is that you are unlikely to have problems, particularly if you fully the charge the battery before events. This does of course assume that what you have is functioning well at present. One thing I have heard of - but never had to verify for myself - is that because dynamo casings have little in the way of venting compared to an alternator, overheating problems can arise with a dynamator.

I believe the reason for the cam change was cost - no cam to pay for, no engine strip down labour required.

I successfully honed the leaking wheel cylinders from my Austin Healey around 40 years ago. I used a flexhone for the job and with a new set of seals they worked perfectly. As others have said it all depends on there being no pitting. Mind you, it worked for me, but I've no idea if it's recommended practice; I only build engines.

A Sprint should come in one of two specifications. Later ones came bog standard as supplied by Ford, but with 2 x 40DCOE carbs, and earlier ones, the same but with an A2 camshaft fitted.

Unless this is a race engine with an expected limited life, I'd rather see the CR nearer 11:1. However, without knowing more about the engine that can only be a guesstimate. Whatever, you must use the highest octane fuel you can get. Regarding the Accralites - unless they've changed since I last used a set they are really excellent and use one of the lowest friction and best sealing ring packs available, but I always had to enlarge the valve pocket diameters if I was going for something like 1.625" inlet valves and 1.375" exhaust valves. They were fine with standard valve sizes.

Yes, you should be able to rock them by hand. I don't know which pistons you have, and it's 20 years since I last built an engine, but many of the pistons available in my day (even forged ones) had valve pockets that would need opening out if you were using larger than standard valves. Generally, the forged pistons have deep enough valve pockets to cater for longer duration, higher lift cam profiles, but you should always check piston/valve clearance unless the engine is completely standard. On my build sheets I always noted that figure, not so much because I might need the information for future reference, but because it ensured I checked it. Do you know the compression ratio? I would generally expect it to be in the range 10:1 to 11.6:1 depending on the engine spec and use. The lower figure would be for a mild road engine on 40DCOEs and the latter for a full race engine. There can be exceptions, such as supercharged and turbocharged engines.

Are you certain of this? A cold engine will have a large (.030"ish) piston to bore clearance which means they can rock considerably and the piston deck height can be "adjusted" simply by pushing them from side to side. If it's for real, I would most certainly be having a discussion with the builder. It may run, but it ain't right. However, the mere fact that you have piston/valve contact suggests some serious competence issues. You may now have slightly bent valves, and even if not, I would insist on them being replaced in case one of them decides to part company with its head.

Assuming it is low speed running that you are having problems with, then a standard GT cam should sort the problem. A 32/36 should run just fine with that. And definitely do fit a vac advance if you go for that combo. It is the old fashioned, and rather cruder, equivalent of 3D mapped ignition and will improve both economy and part throttle performance quite considerably. Sadly though, it doesn't really work with DCOEs because they lead to a strongly pulsing vacuum signal in the hose which can send the dizzy into spasms.

To be honest, I don't have the jetting for this, but from my experience you are likely to have problems with this carb/cam combination, particularly at idle and light throttle. The problem is that the A2 is relatively long duration and doesn't draw much air at idle which requires the throttle butterfly to be open more than a standard cam would. Unfortunately, this positions the butterfly beyond the idle jet and progression holes so that fuelling is very poor at this point. Once you get enough throttle and revs to get onto the main jet it normally runs OK. I have to declare that I don't have a lot of experience of this so I could be wrong, but this was my diagnosis the one time we tried this combination. Eventually, we fitted a pair of 40DCOEs and the engine was as sweet as a nut.

This is a constant energy system which means that the coil is a special part with low resistance so that it can charge very quickly. I've never tried running a standard type coil with this system but I expect there will be issues.

Don't feel foolish - you are learning "on the job". 36mm is far too big for a Supersprint, and is indeed unusual to use in 40DCOEs, being more common in 45DCOEs. Oversize chokes do nothing to increase power, but will lose you a considerable amount of low to mid-range drivability. If you change the chokes you will always have to change the jetting, assuming it was initially correct. Basically, you select a choke size suited to the engine capacity and specification, then set up the jetting to suit. This can range from simply changing the main and air jets to also including the emulsion tubes, slow run jets, pump jets, etc. A competent rolling road operator is needed for this unless everything is to an exact known spec in which case you may be able just to change the jets to a setup known to suit the engine. So far as I know (out of the business now for twenty years), 33mm chokes are not available, so you may need to settle for 32mm or machine out some smaller ones. If you do this, make sure that whoever does it maintains the correct internal profile of the choke or you'll be worse off than if you stick with 32mm.

Yes, as AncientAndrewE says, they both go in and are both required for the carb to function. Part 22 is the choke (or venturi) and part 17 is the aux vent (auxiliary venturi). The choke's job is to accelerate the air as it passes through the carb and thus lower its pressure, and the aux vent does the same thing, but in a localised area to lower the pressure even more in order to suck fuel through main jet and into the air stream through the annular centre of this part. It is more usual to change the choke size than the aux vent. So check that you have one of each type of part in every barrel and that they are all the same size. The chokes have their internal diameter cast into them though you may need a torch and/or mirror to read it in situ. It will be somewhere between 30mm and 36mm for 40DCOEs and a little bigger for 45DCOEs. Now, I think there are two possibilities here. 1) You need to learn more about carbs (not meant as an insult, I was the same once). 2) Your carb guy doesn't know what he is doing (this may be grossly unfair without knowing more). Without knowing more about your engine spec and installation it is impossible to make further useful comment, but a Supersprint will run 32mm or 33mm chokes in standard form.

By all means use a plain nut and spring washer, but don't be surprised when something works loose and is ingested. Since the 1970s I have been using the following method. Use a medium strength Loctite to fit the stud to the carb so it won't vibrate loose, then fit the trumpet, the trumpet retaining tab, and attach with a nyloc. It may look "out of place", but it's not visible when the filters are on. Whatever the situation, it will look less "out of place" than a destroyed engine.

Sealed system every time. Both systems are pressurized, but the "open" version is meant to pull (alright, technically, atmospheric pressure is meant to push) expanded water back into the system. It just doesn't work properly, sucking in air instead, whereas a healthy sealed system never loses coolant, merely allowing it to expand into space within the system; i.e. in the header tank. You don't need a cap of any sort on the thermostat housing, provided you use a housing with no facility for a cap, and filling is carried out via the expansion tank. However, you MUST run a thermostat to prevent water rushing out of the top of the engine and straight up the hose to the header tank. The most common fault with an "open" system is for a driver to check their levels, go out and do a morning session of a track day, and then forget to check the water level for the afternoon. What will have happened is that a significant amount of coolant will have been expelled into the catch tank, but not been drawn back as the engine cools, resulting in lovely great air pockets forming in the cylinder head at exactly the point where cooling is most critical. The afternoon session should then be just enough to cause major damage. The difference in head gasket failure numbers and overheated exhaust valves between the systems has to be seen to be believed.