bevans6

to measure compression ratio: Measure the volume of the combustion chamber in the head. Do this using a burette and a fill plate with a small hole in it to seal the chamber and drip the liquid from the burette through the hole until the chamber is full. Measure the volume of the piston dome or dish. With a dish (or with flat top pistons that are set down the bore at TDC) use the same method as measuring the volume of the combustion chamber. With a dome piston, set the piston down the bore to an exact measurement from where it is at TDC so that the top of the dome is below the block, measure the volume, subtract the volume of the bore times the distance the piston is down the bore, and that's the volume of the dome. Calculate the total combustion chamber volume by adding the numbers that you got from your measurements. Remember that the volume of the dome is a negative number. Calculate the total swept volume of the cylinder. That's the bore times the stroke. Calculate the compression ratio. That's the cylinder volume plus the combustion chamber volume divided by the combustion chamber volume. You're done! A compression check on an engine with a lot of cam will be pretty useless as far as estimating what the actual compression ratio is. The late closing of the intake valve makes the compression check number very low. Brian

I think that for a street engine in a stock configuration, the Maxsil would be an excellent choice. One thing is that they are supplied with a slightly oversize pin, according to their website, which simply means getting the rods resized by the machine shop and having them fit the pins to the rod small end, which can be easily done but adds cost. The JE forged pistons I used did have stock size pins. http://www.bmwpiston.com/specifications.html Brian

Singh's grooves in the squish area are very different from the MM ridges in the chamber wall area. The only way to tell if this works is back - to-back dyno testing, which MM no doubt did do. As with many similar modifications, it may work by masking another problem which might well be fixable with "normal" means - just not as easily as wacking in some grooves! Brian

I wouldn't guess. You can find TDC to within 2 degrees or so by using the "screwdriver in the spark plug hole" method. Those marks are pretty big and at a glance about 10 degrees apart - so I would just find TDC, look and see which one lines up. The diameter of the pulley is so small that the mark will be quite inaccurate in use anyway. You really need to find TDC and mark the flywheel. I'm assuming all you need is TDC and you use a decent dial timing light. Brian

I happen to be in the camp that thinks that a well set up Bosch blue coil and points system is completely adequate with dual Webers up to a quite high state of tune. I run 11:1 compression, dual 45 DCOE's, open header exhaust, 316 cam, and the stock points in a Tii distributor with a non-RPM limiting rotor as the only modification, and a Bosch Blue coil. I run it to 7200 rpm and I have zero issues. I also don't run it below 4000 rpm and I'm happy if it idles at anywhere between 1,000 and 1,500 rpm (it doesn't have much flywheel). The key is a well balanced engine specification. You normally add dual Webers because you've added "stuff", maybe a cam and headers, that creates a need for more airflow. Enough compression for the cam is pretty much the most important thing. If you try to run a 304 cam with 9:1 compression, the dynamic compression ratio will be so low at low RPM that you may well experience misfires - not truly "ignition" problems, BUT an MSD will make the thing burn and correct the problem. So, adding a more serious ignition system can add to the specification of some engines and make combinations that are a little marginal work better. But don't overlook the inherent quality of the stock pieces - they are really very good! Brian

I would be very careful of media-blasting pistons, it's all too easy to ruin the fit of the pin bores and the ring lands. If you do this, tape off all but the piston tops...I use solvent and rags to clean the pistons, or a 3M pad. Deglazing refers to the bore surface in the block. If there is ANY ridge at the top, you really should be boring and fitting new pistons. If there is no ridge, you need to create the new cross-hatch finish in the bore surface for the new rings to seat to. That's deglazing. Honing is when you use a Sunnen type hone that removes a small amount of material and creates a truly round and taper-free bore (in the hands of someone who knows how to use it). There are manual hone heads but most shops use an automatic machine. These are NOT the $12.95 three stone things sold in cheap autoparts stores, they are good for light deglazing only... Brian

If you are disassembling a head that's been together for a long time, the shafts will almost always be hard to get out. Tapping on a drift with a soft faced hammer is almost the ideal situation. I use an aluminium drift, and it always needs to have the ends cleaned up during the process as they mushroom out a bit. In an ideal world, new shafts will slide right in. Any head that's been though 20 years of heat cycles will take a little persuading to get new shafts in, but a real problem is indeed a sign of a warped head. Just because the face is flat now doesn't mean it wasn't a little warped in the past, and cleaned up. the fit on the rocker shaft bores is such that .001" of twist will impact the rocker shaft fit. Brian

how did you actually measure the clearance? The only way I know involves a dial bore gauge to measure the bore for out of round and taper, and a micrometer to measure the piston skirts. If you measured with the piston in the bore as it sounds, I wonder how you did that. Cast pistons usually run fairly tight clearances. It's often possible to install forged pistons, which use looser clearances, by just honing to clean up the bores. It's also really very possible to just re-ring and deglaze and re-use the existing pistons. You need to check to see that the skirts are not collapsing by comparing to new piston specs, and you need to check the ring lands to see that they have not opened up too far. That's what I call an engine "refresh" instead of a "rebuild". Cast iron Moly rings are good to use for re-ringing. A ball type hone will give a good finish, but won't straighten the bores at all. Brian

It's about making do with what you have as tools. When we tune racing engines, we do it on an engine dyno, we usually don't pull the plugs once, and we change the ignition timing total advance and the jets in the carb to get to where we want to be. We can easily repeat pulls to back up any changes we make. Street cars are different. You need to be a whole lot more concerned with part throttle and low rpm driveability. On a race engine you really don't operate it below maximum advance rpm, so you ignore the advance curve. On a street car, the advance curve is critical. I'm a big fan of vacuum advance distributors for street cars, since the engine is happier with a lot of advance at low throttle if you can take it away again at high throttle load conditions. But people like to put in the mechanical advance distributors and make them work. I would try things like this: advance the timing about 5 degrees from normal, see what it does to idle stability(you'll need to adjust the carb to get it right) and to low throttle, low rpm driveability transitioning from idle to pulling away from a stop. if it helps, you need to reduce the total advance in the distributor so you can get the greater advance off idle, and still have the same total advance at higher rpm. Then do the same thing at mid throttle, mid rpm (2500 - 3000). if more advance wakes it up a bit, then you need to use lighter springs that bring the advance in sooner. If it doesn't want the advance, but seems to ping a bit, heavier springs will delay the advance. In either case, maximum advance at full throttle, high rpm will be the same based on maximum power developed. It's an iterative process. You try a little more advance, you try a little less advance, and at the end of the day you have a map of the modifications you want to make and you can recurve the distributor. The things you can change are simple - you can change the total amount of advance, typically in a range between 15 and 30 degrees, and you can change the speed at which the advance starts and stops with the springs.. Hope this helps a bit. Brian

If you have a castellated nut where the hole is really out of alignment at both the low end of the torque spec and the high end of the torque spec, then either substitute another nut, or shorten the nut a little bit. If you have a lathe handy (how do people without lathes and milling machines work on cars I often wonder) then face off a few thou. Alternative is spend a few minutes dressing the nut on some sandpaper on a flat surface. It takes very little to get the hole in line. I do this every time I build up a Hewland gearbox for the first time. There are two castle nuts that you have to undo every time you change gears. Do this once, and for ever more all you have to do is line up the holes and wala - correct torque! Brian

If all you want to do is get on the road again, then when you get the head off you'll know. If the bores are worn there will be a marked ridge at the top of the bore where the rings stop. If you have that, you probably need to bore and use new pistons. If you don' then you can deglaze with a ball hone, new rings on the old pistons and on your way. With some cars you can drop the pan and do that in the car...I wouldn't personally, but it's been done. Things you can change while you're in there are bearings, chains, gaskets, seals, etc. Just because it's best to do a proper rebuild doesn't mean that a simple ring job won't get you another 40K miles... Brian

Same as Lee, if the car is driven in weather I use antiseize on the threads. If the fitting is a hard line, I try to get a little on the outside of the line where it goes through the fitting. Brian

This MSD system is a complete 4 cylinder distributorless ignition with programmable advance, triggers, the whole nine yards. You need to work out the crank wheel and add coils. I wish someone would try it and tell me how it performs! http://www.msdignition.com/ignition_14_6214.htm Brian

I use Pauter rods and I think they are pretty good, but for your application I would also recommend Carrillo's. Get the ones with SPS-CARR rod bolts, as far as I am concerned the best rod bolts available. Brian

When you talk about single vs double springs, remember that single springs can and should mean PERFOMANCE oriented single springs, not stock springs. That's been pointed out already but bears repeating. Many serious race engines are now using single springs with a beehive shape, the variable diameter does the same job that the inner spring on a dual setup does - remove harmonics. The inner spring is NOT there for rate, it's just there to change the tendency of the single spring to react to a harmonic frequency. You can use stock valve caps with double springs, you do need to cut them to fit the inner spring. I do that, but then again I'm a pretty decent racing machinist. If you don't happen to own a lathe and know how to use it, it would be cheaper and better to buy the right caps to match your springs. Concur with the advice to cut the existing valve guides to suit the smaller (and far better) valve seals. Again, I would do this myself, and I would make the tool to do it, but any competent machinist can do this for you. As far as valve float is concerned, the cam has an awful lot to do with it as well as the springs. Stock cams can often float the valves at a lower RPM than a performance cam with the same valves and springs, simply because the performance cam has greater lift than the stock cam so the spring is more compressed and there is greater control over the valve. As far as street driven vs race is concerned, there is a great difference between driving around town and occasionally getting up to 7000 rpm, and never getting below 6,000 rpm and spending most of the time between 7000 peaking at 7800. If you got 50 hours or 5,000 miles out of your street engine before you needed to do a total rebuild, you'd be very unhappy...if I get 50 hours out of a race engine, I'm very happy! Cheers, Brian

M10 engines, when they were used in things like Elva's, Chevron's and my NTM MK4, were usually mounted at 18 degrees. The main reason was the oiling drain from the head needed some angle, and the stock angle was too great - it made it hard to fit the engine in with a decent exhaust system. Dry sump systems usually like an angle, it makes the pickup point in the sump easier to engineer. Newer cars, like the F2 and F1 cars that used the M13 engine based on the M10 block mounted it upright for aerodynamice reasons - they wanted room for tunnels on the side of the block, and to facilitate the packaging of intake and exhaust. Brian

After having a rocker lock come loose at VIR this weekend, resulting in a broken rocker and a cylinder head with a hole punched in the cam valley, I need another cylinder head. I run the 121 type head, so if anyone has one and will help me out, please let me know. All I need is the bare head casting. I will do my porting, install the valves, etc. If it has been crack tested and so on, so much the better! Thanks, Brian

make sure it can be converted to gas later. The thing about cheap welders is the quality and control of the arc is poor, the drive mechanism is poor, the gun is poor - you get the picture, and it's probably what you expected to hear. Flux core wire is actually prefered if welding outside or in a drafty area. You will be able to get started, learn a bit, and decided if you want to move on up later. I started with a 70 amp welder, and did a lot of cars with it. I now have a Lincoln 175 Mig, a Lincoln 185 Tig, a Miller resistance welder, and of course oxy-acetelyne for cutting and brazing. Brian

Hopefully this advice is NOT needed: Slow in, Fast out, late apex everything... Good advice for beginning racers and for learning a new track! have fun and good luck! Brian

bad MC or MC pushrod too long by just a little. This is classic MC not returning fully. Brian

I agree that a helicoil for the spark plug is a repair, not an upgrade. I like to use anti-seize compound on the spark plug threads - sparingly! - and have never seized one. But I have seen them seized on high-mileage engines that have not been maintained. Probably the best thing to do is change the plugs every so often - that will keep any corrosion at bay. I do have a head on the shelf where there were helicoils in two of the spark plug holes. When I took the plugs out, one was seized to the helicoil and it came out with the plug. The other was just bad - the plug wouldn't thread in any more. I used the solid plug repair inserts to repair the bad helicoil repair... Brian

Also remember that FFords weigh about 925 lbs, have 115 hp, and not a lot of tire. Not very similar to a 2002... Brian

When you increase the gap, it takes more voltage to form the spark and you do get a hotter, larger spark. If you have a poor mixture at idle, you may well find that a larger gap helps things. You need to have a coil capable of supporting the higher voltage required, and the higher voltage may cause problems with things like distributor caps, rotors, pulg wires. It's possible for a coil to support the higher voltage requirement at low rpms and fail to at higher rpms when its saturation time is lower - so don't overdo it! The whole big gap - high voltage thing started in the late 70's when people were first trying to get quite lean mixtures to run when pollution controls first started to cause issues. Brian

Keep in mind that the air horns for Formula Ford applications require the removal of the choke mechanism. My engine guy tells me that on the dyno they make no difference. We spend thousands of dollars on each incremental horsepower, so if they worked (on Formula Ford engines that use the 32/36 carb) EVERYONE would have one - and no one does... I have a nice one on my shelf right now, come to think of it... Brian

Some, not much. What you get out of there is a combination of blow-by from combustion and condensation vapour burning out of the oil. Brian