JCan

A quote from Braap...

Skirkland. Your video is a great representation of what we have been talking about! You found problems with rockers that were dressed. At the time of my build i didnt know how important it was to check this. We will be interested to learn how your head sounds after you start and gap your rockers. Thanks again!

I hate to hijack this thread... but I see an issue that matt might have... Matt. I had the same issue you are having on my build also. Are you sure the clutch is not partially engaged when your foot is off the clutch petal? (Get under the car and see if there is at liest 0.100" play between the slave cylinder and the clutch arm. You can do this by attempting to move the clutch arm with your fingers.) If it is partially engaged, (like mine was). Remove the slave cylinder and reduce the length of the pin that engages the clutch by measuring the distance the clutch is currently engaged. I made this measurement by unscrewing the slave cylinder and measuring how far the clutch pushed it back. I cut ~1/4 inch from the engagement pin at the slave cylinder side, then rounded the cut end such that it was similar to the original surface. I hope this fixes your problem! Jim

Josh. the reason the rocker arms are made of soft metal is so that it will seat into the lash pad. Remember, the old motors had a manditory 500 mile break in time.! Valve seats will wear in first, as they do, the gap gets smaller, then the rocker arms seat, when they do the gap gets bigger. Regarding gapping your rocker arms. Gap your rockers with the motor hot. be careful to gap only the valves which the cam lobe is pointed up (typically you can gap 4 rocker arms at a time, turning the motor 2 times to get all 12 rockers). if you are gapping at 8mils, bring out the 8 mil and the 9 mil metal spacer. when the 8 fits and the 9 doesnt, you have it right. This is time consuming. Once you have finished, your motor should run quiet. I dont believe you have a spring issue, Big springs are designed to work at high rpm not idle. As you drive, your motor will get louder, regap as requried then once at 1000 miles. Good luck!

Leon. The motor looks great! Regarding the alternative methods of priming the oil. I like the idea of pumping (under slight pressure) oil into the block through the pressure gauge. This method does prime the oil pump and will fill the oil filter with oil, but it does not flush the engine and filter the foreign debree out of the oil inside the oil pan. We are talking about esoteric issues. No matter what you decide to do, your motor will start up and run great!

I am sure you know about priming the oil pump prior to first starting the engine, I also expect there is a fancy way to do it that I do not know of... the way we (my brother and I) do it, is messy and time consuming, however it works. I will diagram it here. Once the engine is in the car, and you are nearing starting it, you can remove the oil pump and remove the spindle that turns it. before you do, be sure it is at top dead center, or remove the distributor and mark the spindle location (so that you can reinstall it). Go to home depot and purchase 5/8 inch nylon rod about 3' long. On one end, shape it to look like the spindle rod you just removed. Next remove the distributor and insert the rod through the distributor hole and into the oil pump. It is time to add oil to your car. for good measure, we pour one quart into the front cover (attempting to get oil into the oil pump via gravity). Once the car has oil, you can turn on your ignition and look at the oil pressure indicator. Connect a variable speed drill to the nylon rod and (I think you have to set it to reverse) turn on the drill slowly and watch for oil to emerge out your cam lobes (or oil gallery if you have an earlier z). Once it comes out of the lobes, check the gauge and vary the speed to ensure your gauge is working properly. once complete, remove the oil pump (yes oil will leak all over), reinstall the spindle, reinstall the distributor and you are ready to start the engine. AFter you start your engine, be sure to replace your filter and oil after you have run it for 30 -60 minutes. your engine is full of all sorts of junk from machining and reworking. you will be amazed at how bad it looks! Good luck! Do you think the car will be running by JCCS? I hope to see you there!

Leon. The rear crank oil gasket should fit snug into the block along the outside of the gasket. The inner portion of the gasket has to make a seal on the crank, however because centrifugal force will cause most of the oil to spin away from the gasket, I believe it does not have to be too tight of a seal. Having said that, you can purchase a new rear oil seal for 4.89 plus shipping from Rock Auto. If you are not comfortable with the seal, get a second and see what happens. Good Luck! Jim

Hi Leon. It has been a while, was wondering how your engine rebuild is going?

Madklaw. Its really hard to mis-align valves and therefore I still believe your problem is caused by the person who dressed your rocker arms did it crooked. However... with the small gap you stated above, I would suggest you continue to check it every 200-250 miles or so till 1000 miles as your valves will seat and you dont want to burn them prematurely. I also expect that you will be able to gap your valves at stock specifications after 1000 miles due to the fact that I believe your rocker arms will also seat to the valves. Best of luck!

I wish you wouldn't give up! The tip of the rocker arm, should have a slight crown on it. The purpose of the crown is to ENSURE the rocker arm is both parallel to the cam shaft and touches the valve lash cap at one place in the center of the cap. This is why the rocker arm is made of soft material. AS you break in your motor, the rocker arm will mate to the lash cap as it self grinds down perfectly parallel to the cam. IT is a very simple job, just get 600 or 800 sand paper on a machine and gently grind the sufrace side to side so that you see a definite crown (think of the surface of a 4" diameter sphere. I guess that if you leave your rockers alone then they might eventually wear in to allow you to gap them properly. Best of luck! Jim

Wow... This is troubling. it is clear that your rocker arms were dressed, however it seems like the guy that did it didnt put the crown i the center of the rocker arm to lash. Maybe his setup was a bit crooked? too many beers? I think all you have to do is put a slight crown in your rocker arms to ensure the wear is in the center. Good luck!

Yea you have it. Remove your rocker arms and take a fine file to them and get rid of the edges so that it seats ontop of the center of the lash pad. Good luck!

if your rocker arm looks like the below picture, remove and regrind them such that they touch only in the center of the lash pad instead of on the sides like the picture

okay. you have new lash pads. Did you have your rocker arms (where they seat on the lash pads) reground? If not, Then take a moment, and remove all of your rocker arms, be sure to number both them and lash pads and have them ground. It is simple and will greatly reduce the sound your motor makes. Do you understand where the noise comes from? Basically the plane of the cam is not parallel to the plane on the lash pad made by the two ridges that you did not grind down, this makes it that you can never accurately gap your rocker arms or it forces them to torque as the cam pushes down the valve. get it? take pictures and keep us up to date.

Did you replace your lash pads? Are they square like the ones in the pictures in this thread? Remove 2 or 3 rocker arms and take a look at the wear marks where they meet the lash pad (metal U shim ontop of the valve stem) If they are worn in the center and not on the sides, then all you have to do is remove all of your rocker arms and dress the rocker arm such that it touches the lash pad in the center of the pad (file or grind it with a very slight dome). This solved both Mats and my valve noise. Good luck! PS - My daughter is in her second year at Purdue - Go Purdue!

New toys! I purchased some engine paint from autozone. This paint actually cures above 100degrees. I painted the block 2-3 light coats prior to re-assembly. Be sure to remove the wd40 prior to paint when you do paint and prior to putting the head gasket on permanently. Looks good!

According to my calculations, on my motor, 46cc equates to 9.78 compression ratio and 42cc equates to 10.13. I guess we do not know how much the head was decked prior to milling (I worried about this issue during milling with my head). I agree that you should re-measure the cylinder chambers prior to engine assembly. I am beginning to like copper gaskets more and more. They come in your choice of thickness (.022,.032,.040,.043,.054,.063,.070, .086, .093, and .125 inches), they do not compress, and it allows you to build your motor exactly as you want it (noting that you can increase/decrease the gasket thickness slightly if you are shooting for a specific compression ratio. I purchase mine at Gasket works copper@headgasket.com for $135! Building motors is just fun!

Wanted a set of old school recaro seats. I plan to reupholster them. Thanks Jim 858 204 9422

Leon. Stage 3 cam?!!!!@!@ WOW! Will you have to notch the pistons to accomodate the valves with this 0.490 lift cam? it has a 72 degree valve overlap but should provide excellent torque out through 7kRPM right? meaning that you should be able to race through 8krpm?! Now my question. You have balanced the crank, pistons, flywheel, pressure plate. Are you going to lighten the flywheel/clutch assy? What pulley will you put on the front of the motor? If you look at the stock pulley you will notice that it is drilled (I believe to balance the motor used in initial production). I left mine alone, do you plan to balance this pulley with the crank? It is something I overlooked when I balanced my motor. In my build, I did not use valve spring shims, but purchased new springs from isky. I believe all you have to do is tell him that you have increased the resting spring distance 2mm and he can either tell you that the spring is okay by itself of change out either the inner or outer spring. Note: I used the springs as provided and found no issues (though I have only run the car for 300 miles). I have two felpro head gaskets that I purchased new and used to measure piston to head clearance so therefore they have been torqued down once but have not been run in the car for any length of time. I am happy to mail them to you if you want to use them for piston to head measurements. I also have valve springs (inner outer) spring caps and lash caps from the p90 head i used if you need them. Fun stuff!

Leon. Are you going to adjust the valve to cam lash yourself or have the machine shop do it? If you have the machine shop do it, that means you have your custom cam? Im really excited to learn what you did and how it works! On another topic, I believe you are using tripple webbers right? Are you going to use the stock fuel rail? if so, pay close attention to the return line. I learned (from steve at ztherapy) that the return outlet tends to get clogged (the tube diameter is reduced at the output to set pressure in stock cars). I believe that having gas continuously flowing from the gas tank to the carbs and back helps keep the gasoline cool and helps eliminate vapor locking. Lastly, I am very interested in learning what head gasket you end up using and what you expect your head to piston gap is. Good luck! Jim

I am not a fan of rev limiters. You balanced your engine right? My brother and I (in the day) would race through 8krpm without engine problems. I vote you set it to 9k rpm and go back to your mountain road and try to repeat the backfire. IF you still hear noise, sounds like you can enable datalogging. All in all, it sounds like fun!

Matt - you have a pretty nice setup! I know you have a new electronic ignition, + rev limiter, I also believe you have an electronic fuel injection, lastly we know that a bang in the exhaust is most likely unburned fuel passing from the engine to the exhaust pipe and igniting. Given this knowledge, does your rev limiter stop ignition or fuel injection? IF it only stops ignition (the way they used to work back 1000 years ago when I was a kid), is there a possibility that it kicked in and the unburned charge went from the cylinder to the exhaust pipe? Maybe you can disable the rev limiter and see if that fixes the problem? On the z that I just built, I seem to be having problems with the electronic ignition at high revs. (still debugging) If the above is wrong, do you think you may have the same issue? A miss can also cause a bang in the exhaust pipe. Intermittent problems are the most difficult! Good luck!