bevans6

Resistor plugs, caps, rotors etc are there to modify the way the spark duration and strength happens when the plug is fired. A resistor plug will have no effect on when the spark happens, but it will increase the duration of the spark while reducing the size of the spark - same energy, longer time. This has the effect of reducing the RF energy created by the spark, so resistor plugs are required in cars that have computer ECU's, radios, GPS systems, all the modern stuff. You can still get non-resistor Bosch plugs, I buy them from my Formula Ford guy who imports them from Europe directly. They are NLA in North Amercia. The coil sees near infinite resistance (the air gap) until it fires. It creates the plasma in the gap with a burst of high energy, and the plasma has low resistance so the remaining energy in the coil is drained quickly. the resistor simply causes the energy to drain more slowly while still maintaining the plasma path within the spark. If you wanted to experiment with resistor plugs and you had a decent coil, you could open up the plug gap. That would have the effect of increasing the initial voltage hit for sure, and making the spark run at a higher voltage, maybe... If you don't go over 5K in resistance and use a quality wire, no problems using resistor plugs. Brian

Well, I wouldn't necessarily install billet rockers at this point - but I broke a rocker with rather lousy results - a piece of rocker got under a lobe of the cam and punched a nice hole into the waterjacket. Scratch one brand new race head. Anyway, my advice - change the springs to dual springs, they're are cheap and you should be changing the springs anyway at this point, even if changing to new stock springs. If you are taking the valves out anyway, what's the big deal? At your stage of tune and use I'd personally just leave the stock rocker retaining springs in, I wouldn't bother changing to locks on a street car. A failed bolt in one of my rocker locks allowed the rocker to move, which is what caused it to break and ruin my head, so the rocker locks are not without their own risk. I have an Ireland cam, a welded 316 version that they don't seem to sell any longer, it came in a Webcam box. Nice cam, needed oversize eccentrics when it was advertised as not requiring them. Ireland sent them to me, so I was very happy with it all. Brian Brian

I have switched to Pierburg pumps, which are a constant flow pump that are sold by Porsche parts people, and by Redline. Virtually silent, and work very well. I have them on cars with dual 45 DCOE's and 32/36's This is the pump, and the place I got mine: http://www.zimsautotechnik.com/acatalog/Pierburg_Low_Pressure_Fuel_Pump.html Brian

It's normally a phenolic resin composite. Brian

I order mine from http://www.canada-por15.com/ , they are in Stoney Creek and I have had completely excellent service from them. I've ordered from them twice so far. Brian

There are two types of wheel spacers - the flat type with holes, and "hub-centric" type that locate on the hub boss and have a matching boss to center the wheel. I feel that spacers thicker than a half inch need to be the hub-centric type. The hub-centric type could be up to an inch with proper studs. I look at proper studs as a decent upgrade to any system that uses bolts to hold on the wheel. The in-hex at the end has no impact at all on the strength of the stud when properly used. All of the stress in a threaded fastener is taken up by the first 5 to 7 threads, after that the threads are not stressed at all. So just make sure you have 7 threads engaged and you will have maximum strength. Brian

There are two types of wheel spacers - the flat type with holes, and "hub-centric" type that locate on the hub boss and have a matching boss to center the wheel. I feel that spacers thicker than a half inch need to be the hub-centric type. The hub-centric type could be up to an inch with proper studs. I look at proper studs as a decent upgrade to any system that uses bolts to hold on the wheel. The in-hex at the end has no impact at all on the strength of the stud when properly used. All of the stress in a threaded fastener is taken up by the first 5 to 7 threads, after that the threads are not stressed at all. So just make sure you have 7 threads engaged and you will have maximum strength. Brian

Here is another idea - I have idle issues with my M10 engine that are advance related. What my issue is related to is that I want the engine to idle at 1200 rpm. What happens is that the mechanical advance starts around 900 rpm. The engine either drops down to about 800, below where the mechanical advance starts, or revs up to 2000 rpm when the advance starts and the added ignition advance pops the revs up. It won't idle between 800 and 2000. So far it hasn't bothered me enough to fix it. So my thought for the OP is that maybe your idle is related to the point at which the mechanical advance it trying to start to work. I see three ways to fix this for my application - stiffer advance springs so that advance doesn't start until say 1500 rpm, reduce the total mechanical advance allowed so that I have a lot more initial advance at idle, or just lock out the distributor so that there is no advance at all. Cheers, Brian Here's a picture of my car, btw, at Roebling Road a few weeks ago.

When I've used POR15 on bare metal, I've abraded it significantly with sandpaper and used the phos. acid prep solution liberally. It's worked well for me so far. I regard it as brushable powder coat. It works really well on rusted metal, of course, again well abraded and treated with phos. acid. Brian

On match-porting, as long as any step is in the direction of flow (Intake manifold slightly smaller than intake port, header slightly larger than exhaust port), precision matching is irrelevant. In terms of porting your stock head, it's useful to take off or blend any casting marks, smooth out around the guides, make the existing short-side radius into the valve bowl even and smooth, and just generally clean up the rough stuff and the uneven edges without significantly changing the shape of the ports. The stock BMW shape is quite good until you are above 200 hp. Bigger intake valves are fine if you are changing them but for a simple street application the stock valves will be fine. The bump smoothing and blending in the ports takes a couple of hours to do, tops. Brian

It's very common with race cars to reduce the amount of steering lock so that the tires don't rub. I't amazing how little lock you need on a track. With rack and pinion it's easy, I don't know how you'd do it on a 2002. Brian

Kris, I use Odyssey batteries, I get them from http://www.absolutebattery.com/odyssey.htm in Hamilton, they are the Canadian distributor. I use PC 525, PC 680 in my race cars and I have a PC 925 in my MGB. You may get them cheaper by mailorder from the States these days. The PC 680 in my sports racer starts an 11:1 M10 race engine all weekend without recharging, but after talking to the engineers at Odyssey I recharge it with a 10A smart charger at the end of each day. Brian

if you give me the arm lengths at the various holes, the length of the bar, the ID and the OD for the new bar, and the same information for the other solid bars, I will run them through my sway bar program and tell you their spring rates. That will help you decide. Brian

A leakdown tester compares the leakage from the cylinder to the amount of air passing through a calibrated orifice inside the tester. Since there are variables from the accuracy of the orifice, other leak points in the system and the gauges themselves, a leakdown tester is valid in comparison to itself, and not necessarily to any other leakdown tester. One can read a good cylinder as 2% leakage, another one will read 10% on the same cylinder. So what I do is test a known good, fresh cylinder and compare the results of other cylinders to what I know is a good reading on the tester. The other thing a leakdown tester is good for is finding out where a leak is. you can find bad rings, bent valves, blown head gaskets by listening to the air leaking from whatever it is leaking from. You can do a test like that cold, but anything that you think needs any sort of accuracy needs a hot engine. You also need to bring the engine up to TDC on the cylinder that you are testing by rotating the engine in it's running rotation, and never rotating it backwards. That keeps the rings seated normally. If the engine is on TDC it won't rotate under air pressure, but two degrees off and it will. I use 70PSI for my tests, fwiw. Brian

You should be just fine if you simply put a new plug in. The chances of having a damaged piston are very slim, and the chance you irretrievably damaged the spark plug seat are also pretty slim. Make sure the washer is there this time! Brian

The reason you do the valve lash check on a new head is to see if something is going wrong with the valve, the valve seat, the rockers or the cam. I would absolutely recommend checking after 1,000 miles or at the first oil change, and routinely thereafter. I had a rocker lock fail, which caused a broken rocker, which a piece of got punched through the head into the water jacket, which caused a complete new cylinder head and an engine rebuild. I had ample time to catch the failing valve lock (I could hear a change in valve clatter note) but I didn't check in time. All you have to do is turn the engine 4 times and wiggle the rockers, you can tell if they feel OK. Visually inspect, and if one valve has more or less lash than normal, go into the whole routine and figure out why. Brian

I confess that I don't have back-to-back testing results to show you, but I use the newer style seals. They need the valve guides machined down to fit, or use later style valve guides when doing a complete head job, and they are required when fitting any dual valve spring, which makes them mandatory when fitting many performance cams. I have them because I am running a 316 cam in a race engine with dual valve springs. Brian

too low an idle speed, or wrong ignition timing at idle. installing a light flywheel. improper idle mixture. Brian

Aluminium - can be a lot lighter than stock lightened. will be stronger than stock lightened. uses a replacable friction surface, so can be rebuilt. Impresses people who see it before you install it. All round a good - better option. Lightened stock - stock flywheel is a good grade of cast iron, almost cast steel, and can be lightened somewhat with good safety. If you lighten it too much, or in the wrong places, it can explode. That is always bad... You can get it lightened and re-balanced probably cheaper than a new aluminium flywheel. you keep your grotty old ring gear, which may or may not be a problem, or you have to add in a new ring gear to the price mix. You can't lighten a stock flywheel nearly as light as an aluminium flywheel. This rates as a not bad to fairly good option. Race steel flywheel from 1040, 4140 or equivalent steel. Lightest, strongest, coolest flywheel option. Most expensive. Can have the ring gear teeth cut directly into the flywheel if it's a 4140 steel, making it even lighter, more expensive and even cooler yet. Best option for bucks-up guys on the track. I make custom aluminium flywheels for race engines from time to time, I think this is a good way to go. On street cars, I've been known to use lightened stock flywheels on several different cars. On my M10 race engine I happen to have a 1040 steel flywheel in 9" diameter with a 7.25" Quartermaster racing clutch. Very light, small diameter keeps the revs happening, light clutch helps a lot, high on the cool factor as well! Brian

Well, springs. They do tend to ignore common sense and logic. A coil spring is nothing but a torsion bar that is bent into a coil so that the bar twists when you press the coil up and down. Two things (aside from the basic material spec) go into determining the rate of any spring - the diameter of the material, and the length of the bar. The diameter of the bar has a function that mathematically is raised to the 4th power, so a small change in diameter has a big change in rate. The length of the bar has a direct, linear relationship, so if you take a 10" long bar and make it 8", you've increased the rate by 20%. Take this to the world of coil springs, linear springs first. If you take a spring that has say 10 working coils, and you cut one coil off, you've shortened the length of the bar (what you'd get if you uncoiled the spring and stretched it out straight) by a certain amount - about 10%, depending. So you have increased the rate by about 10%. It depends on how the ends of the spring are treated in the install. So yes, shortening the spring does increase the rate of the spring. Progressively wound springs are wound with a varying pitch - lots of coils at one end, fewer coils at the other end. the end with lots of coils is soft - lots of coils means longer bar - and what happens in use if they are designed correctly for the application is they quickly bind under load. As soon as they bind, they are no longer springs but become spacers, so the rest of the spring, which is stiffer because it has fewer coils, is active and the rate will continue to get stiffer or softer depending on how many of the coils get bound solid under use. There are other ways of doing this. If you cut coils off the widely spaced part of the spring, it will get stiffer overall. If you cut coils off the tightly spaced part of the spring, you'll lose the bit that does the initial coil binding to create the progression, and the spring will just kind of get less progressive and shorter. If the fancy progressive spring doesn't coil bind in use, then it's just a fancy single rate spring, because of how springs in series work. Brian

I bought a long block kit, customized to suit my needs (running dry sump so no need for anything related to the oil pump, that sort of thing). Bought valve springs, etc as well. The only thing I didn't like was the cam, but it was exactly as advertised so no fault there, I just ordered the wrong thing. Completely happy with the service. Brian

You don't say what carb you have, but you should always run at least a short stack on any DCOE weber. On the 45, it is needed to hold the venturi in place properly, from what I recall, and it's been years since I had 40's but probably something similar there. Anyway, the 1/2" tall stack will work inside of just about any air cleaner. Brian

You would do well to do a good tuneup on it to start, as noted. I would get a proper dial timing light and set the total advance to 34 - 36 degrees at about 4500 rpm. Then, I'd set the carbs up with recommended jets, same size as Weber 40's. If that doesn't work, I would redo the cam timing, it's likely that a tooth out will cause this. For top end response, total ignition advance is all that matters, so check that and ignore what the timing is at idle for now. Brian

I forgot to add that the cheapest hp is indeed a good tuneup - on a dyno! While I use engine dyno's, a decent chassis dyno operator can help you dial in your jetting and ignition timing to find often quite a lot of HP. 10 % is common, that's 15 hp on a lot of engines, and the cost is about $300. Brian

As a famous engine builder (KD) once said - bigger bangs more often! That means three things (after the aforementioned decent tune-up)... 1. More compression. Get that with mechanical compression, a turbo, your choice, basically. 2. More stuff to burn - fuel and air. Get that with better breathing, cam, induction, exhaust - or with no. 3... 3. More RPM! If you really want more HP, you have to put up with more RPM. In the real world, either turbo it or install more engine - bigger capacity. There is very little you can do to a normally aspirated engine that has much effect without adding RPM's All the cam/compression/breathing stuff is really about is letting the engine run at higher rpm's, which is fine on a race track but often kills street performance. Adding a turbo or adding size is what works on the street. I once compared the dyno results for two engines: I had a 1600cc Ford crossflow, fairly full race, and had about 150 hp at 7000 rpm. The other engine was a Cosworth BDA, 1600 cc and about 225 hp at 9500 rpm. The dyno trace for it showed about 150 hp at 7,000, and my engine made more power below that point - BDA won all the races, obviously! Brian