Common engine assembly errors - and how to avoid them
- Thread starter Keeper
- Start date
Mr T Bucket
Member
I don't know. I wasn't going to hang around for the question and answer session, that's for sure, LOL.
I always put a dab at the corners where the rubber meets the fiber gasket.
Keeper
Active Member
Yeah I think you are supposed to use it ONLY on the corners....lol not on the whole seal......
Screaming Metal
Active Member
When rebuilding your motors, be sure to clean all your threads, and wirebrush your bolts that go into the deck surface, unless they have the sealer from the factory. Some arp's have it....its usually white or gray looking.
Torque your fasteners down in stages. I run mine in with my fingers, then I run them down with a elect. screwdriver with a adapter. Then I use my small air impact on the lowest setting. then my torque wrench.
Not all oil (on the threads of the fasteners) will give you the same torque readings. I use a special lub for such things since I work on very expensive Hi-Dollar racing motors. I also run my fasteners in and out 6 times to remove all the stuff that can keep from getting a nice smooth pull on the threads. Then I clean out the holes with air. On alum. blocks, use a antiseize on your studs, same with your alum. heads where the studs come thru, then under the washers.
On a street motor, things can be done with a light 10-w30. On your connecting rod bolts, a stretch gauge is nice. For me, its a necessity, while you don't 100% need it, its best to have. You can't reuse those rod bolts indefinitely, once they quit stretching when torqued, thats a bad sign. And your bottom end could and probably will come apart. I replace them per rebuild because its simply not worth it.
If you don't have a complete set of mic's, use plastigage for measuring your clearences. But you will need a dial indicator with magnetic base to check your crank endplay. I also keep my cam endplay down also, cause believe it or not, it can cause bigtime sparkscatter, enough to be a major bitch sometimes keeping things timed.
Torque your fasteners down in stages. I run mine in with my fingers, then I run them down with a elect. screwdriver with a adapter. Then I use my small air impact on the lowest setting. then my torque wrench.
Not all oil (on the threads of the fasteners) will give you the same torque readings. I use a special lub for such things since I work on very expensive Hi-Dollar racing motors. I also run my fasteners in and out 6 times to remove all the stuff that can keep from getting a nice smooth pull on the threads. Then I clean out the holes with air. On alum. blocks, use a antiseize on your studs, same with your alum. heads where the studs come thru, then under the washers.
On a street motor, things can be done with a light 10-w30. On your connecting rod bolts, a stretch gauge is nice. For me, its a necessity, while you don't 100% need it, its best to have. You can't reuse those rod bolts indefinitely, once they quit stretching when torqued, thats a bad sign. And your bottom end could and probably will come apart. I replace them per rebuild because its simply not worth it.
If you don't have a complete set of mic's, use plastigage for measuring your clearences. But you will need a dial indicator with magnetic base to check your crank endplay. I also keep my cam endplay down also, cause believe it or not, it can cause bigtime sparkscatter, enough to be a major bitch sometimes keeping things timed.
Screaming Metal
Active Member
oh yes, before I forget. If you haven't checked it already, when you install that new cam, look at your pushrods and guideplates. Make sure your pushing down center of your valvestem. Off to the side will give you alot of wear, possibly snap off your valve.
Even if your just stepping up to a .535 to .55 lift cam, check for coilbind, and for guide to retainer clearence. .535 to .550 gets really close on some motors, so its best to check. Be sure .04 to .06 between coils, if its closer than .035, have your spring pockets redone. Also on the intake seals, be sure theres about .04 between the seal as it sits in the guide and the bottom of the retainer and keepers at full lift. Gte a pin light, rotate the motor on the stand to get a good look.
Use sealer on the screw in studs on the early SBC's, they go into the waterjackets. Just because those pushrods go thru the slots in the guideplates, make sure they don't bind on the side of the pushrod holes in the heads. Inspect them all, both the holes in the heads and the slots in the guideplates for binding thru the cams full lift.
This is even more critical if running 1.65's or higher on the exhausts....
Heres a quick way to check for piston to valve clearence. Take your valvespring down to Fastenal, or WWGranger, get a spring that is the same OD, roughly just a touch longer, get a few of them, they will come in handy.
When you dummy your motor together, install this spring, when your at your highest valvelift, set you indicator up on the retainer and preload it .250. At Full valvelift, stick a brass screwdriver under the rockerarm and pry down. If the spring is really light, you can press it down with your fingers. As long as you have .1 or more between the valve and the piston, your good.
.075 is the least you want, because if you float your valves, it could get ugly.
Remember, this is with all old used gaskets that have been already used and crushed. Assembly like this is part of enginebuilding. Remember to degree & indicate in those cams too....
Even if your just stepping up to a .535 to .55 lift cam, check for coilbind, and for guide to retainer clearence. .535 to .550 gets really close on some motors, so its best to check. Be sure .04 to .06 between coils, if its closer than .035, have your spring pockets redone. Also on the intake seals, be sure theres about .04 between the seal as it sits in the guide and the bottom of the retainer and keepers at full lift. Gte a pin light, rotate the motor on the stand to get a good look.
Use sealer on the screw in studs on the early SBC's, they go into the waterjackets. Just because those pushrods go thru the slots in the guideplates, make sure they don't bind on the side of the pushrod holes in the heads. Inspect them all, both the holes in the heads and the slots in the guideplates for binding thru the cams full lift.
This is even more critical if running 1.65's or higher on the exhausts....
Heres a quick way to check for piston to valve clearence. Take your valvespring down to Fastenal, or WWGranger, get a spring that is the same OD, roughly just a touch longer, get a few of them, they will come in handy.
When you dummy your motor together, install this spring, when your at your highest valvelift, set you indicator up on the retainer and preload it .250. At Full valvelift, stick a brass screwdriver under the rockerarm and pry down. If the spring is really light, you can press it down with your fingers. As long as you have .1 or more between the valve and the piston, your good.
.075 is the least you want, because if you float your valves, it could get ugly.
Remember, this is with all old used gaskets that have been already used and crushed. Assembly like this is part of enginebuilding. Remember to degree & indicate in those cams too....
Mike
Well-Known Member
I recommend checking coil bind clearance on any cam change. And trying to measure between coils can get you into trouble, as most springs do not compress in a linear fashion, from one end to the other. Put a retainer on a valve, install a pair of locks and pull the retainer up against the locks. Measure from the spring pocket to the bottom of the retainer, where the outer-most coil will locate. That number is your installed height. Now, take one of your springs and run it down solid in a vise. Measure the spring and you now have coil bind height. Now, multiple lobe lift by rocker ratio to get valve lift.
Installed height, minus valve lift, minus coil bind height equals coil bind clearance.
For something on the street, I would really recommend more clearance. Try to use .060" as an absolute minimum and you'll likely find better spring life if you are up around .100". Cutting spring pockets isn't necessary, as there are both retainers and locks available to add installed height. But when you start moving the retainer up on the valve stem, be sure to keep an eye on spring pressures, to make sure you are still going to have enough load to control the valve. And be sure to check retainer to rocker arm clearance. Let a rocker contact a retainer and you'll start hearing really expensive noises.
Inversely, if you see spring loads are too low for your application, remember inserting spring shims is going to change your installed height, so be sure to recalculate with the new number, to make sure you are safe. When spring coils start clashing, the surface of the wire gets distorted and you're providing excellent places for fatigue fractures to start. If they are binding hard, you'll start breaking/pulling studs, breaking/bending pushrods and breaking rockers. Material type can have an effect on how well a spring can survive coil clash, but the best rule of thumb is to remove any spring showing signs of clash and throw it as far as you can.
Screaming Metal
Active Member
What Mike Said! - When spring coils start clashing, the surface of the wire gets distorted and you're providing excellent places for fatigue fractures to start. If they are binding hard, you'll start breaking/pulling studs, breaking/bending pushrods and breaking rockers.-
Just as he said, its hard to judge the spring spacing in the coils, not all of them are the same, he and I have been doing it for so long its second nature to us, but you have to be careful here. The first and the last coil of a spring are closer together than the rest of the coils. These will usually start binding up quickly in the program. Like Mike, I believe you need to run more clearence on a street motor. The correct way to figure up Coil spring bind ht. is the way HE said....I stand corrected....its the correct way. I visually check for the binding too, afterwards....I use my handy-dandy lever actuated valve spring compressor that reads pressure as well as ht both open and closed....I just write the numbers down so when I start setting up my installed height.
I usually use a mic to get my installed height and pressure where I need it, but on alum. heads you want to run those spring washers between the head and the spring. The spring will 'unwrap' slightly or rotate back and forth, which can eat up some aluminum.
I use those same washers on my cast heads also, helps the springs hold their tension while swiveling. If that spring does not rotate, it will actually change the spring tension as it opens and closes. A second flat wound dampening spring helps, a perf. 3 spring set is usually not needed on the street, but there are some avail. for streetable cars with huge cams....
YES, I know the retainer and valve can rotate, but under 300 to 500 pounds of open pressure at a 1/2+ lift at 5500-6000 rpm under hot engine conditions, depending on your cam, that valve is only open a part of a second. Valves are suppossed to rotate too, just like lifters. They don't always do so, so I give them all the help I can.
We mounted a head on a motor, exposed a pr. of valves out from under the valvecover, and was using the spintron to observe the movements. You would be suprised of the harmonics involved, and the movement the springs have....
Mike is correct to say don't let that retainer hit the rocker....big MOJO Messup!
Just as he said, its hard to judge the spring spacing in the coils, not all of them are the same, he and I have been doing it for so long its second nature to us, but you have to be careful here. The first and the last coil of a spring are closer together than the rest of the coils. These will usually start binding up quickly in the program. Like Mike, I believe you need to run more clearence on a street motor. The correct way to figure up Coil spring bind ht. is the way HE said....I stand corrected....its the correct way. I visually check for the binding too, afterwards....I use my handy-dandy lever actuated valve spring compressor that reads pressure as well as ht both open and closed....I just write the numbers down so when I start setting up my installed height.
I usually use a mic to get my installed height and pressure where I need it, but on alum. heads you want to run those spring washers between the head and the spring. The spring will 'unwrap' slightly or rotate back and forth, which can eat up some aluminum.
I use those same washers on my cast heads also, helps the springs hold their tension while swiveling. If that spring does not rotate, it will actually change the spring tension as it opens and closes. A second flat wound dampening spring helps, a perf. 3 spring set is usually not needed on the street, but there are some avail. for streetable cars with huge cams....
YES, I know the retainer and valve can rotate, but under 300 to 500 pounds of open pressure at a 1/2+ lift at 5500-6000 rpm under hot engine conditions, depending on your cam, that valve is only open a part of a second. Valves are suppossed to rotate too, just like lifters. They don't always do so, so I give them all the help I can.
We mounted a head on a motor, exposed a pr. of valves out from under the valvecover, and was using the spintron to observe the movements. You would be suprised of the harmonics involved, and the movement the springs have....
Mike is correct to say don't let that retainer hit the rocker....big MOJO Messup!
Screaming Metal
Active Member
I usually use a mic to get my installed height and pressure where I need it, but on alum. heads you want to run those spring washers between the head and the spring.
Spring Washers=shims....Tomato, Tomoto....
Spring Washers=shims....Tomato, Tomoto....
Screaming Metal
Active Member
How many of ya'll have gone to rebuild a motor, do everything right, go to put the cam in, scratch the hell outta a cam bearing, you try everything to get her to spin free....its just too tight, so its back to the machine shop.
Been there, done that. The long bar that you can screw to the front of the cam in place of the gear helps, but those nice sharp lobes still nick those soft bearings. I used to lay the block standing up, before going up on the stand, that helps, but if you have to remove it as I've had to do 100's of times....you still gotta pull it.
Well, because I got all riled up one day, I made a tool, that I use during every install. Its not that hard to make.
Get a piece of 1/2 x 2" flatbar, going across just under where the cam bearings are, to each side of where the timing cover bolts down. fasten it down with 2 bolts on each side. After cutting and making this, it looks like a H bolted to the front of your motor. Either put the cam in or out ( do this before you pull it out, makes it easier not to mess up bearings and cam....) so that the cam is sitting on the last 2 journals of the cam. Get a piece of 1 1/2" angle iron the length of your cam (get your buffing wheel, make sure you have all the crust and scale off the angle, put some oil on it), before clamping it under the cam, and slide it so it hits the crossbar of your 'H'. Weld the angle onto that piece of flatbar. Now, you'll have to flex your tool up or down some to where it fits the cam evenly.... when you get it to where its perfect. add a couple of gussets to keep her from sagging!
Next time you go to change your cam, bolt this on, slide her out, carefully, now your not having to hold all the weight of the cam....just wiggle it a little, sliding it out, your cam bearings will thank you! Sliding it in is just a little wiggle as you slide thru the journals. Its not a 100% lineup, its as close as you want to make it but its really close, and makes the job easy.
Been there, done that. The long bar that you can screw to the front of the cam in place of the gear helps, but those nice sharp lobes still nick those soft bearings. I used to lay the block standing up, before going up on the stand, that helps, but if you have to remove it as I've had to do 100's of times....you still gotta pull it.
Well, because I got all riled up one day, I made a tool, that I use during every install. Its not that hard to make.
Get a piece of 1/2 x 2" flatbar, going across just under where the cam bearings are, to each side of where the timing cover bolts down. fasten it down with 2 bolts on each side. After cutting and making this, it looks like a H bolted to the front of your motor. Either put the cam in or out ( do this before you pull it out, makes it easier not to mess up bearings and cam....) so that the cam is sitting on the last 2 journals of the cam. Get a piece of 1 1/2" angle iron the length of your cam (get your buffing wheel, make sure you have all the crust and scale off the angle, put some oil on it), before clamping it under the cam, and slide it so it hits the crossbar of your 'H'. Weld the angle onto that piece of flatbar. Now, you'll have to flex your tool up or down some to where it fits the cam evenly.... when you get it to where its perfect. add a couple of gussets to keep her from sagging!
Next time you go to change your cam, bolt this on, slide her out, carefully, now your not having to hold all the weight of the cam....just wiggle it a little, sliding it out, your cam bearings will thank you! Sliding it in is just a little wiggle as you slide thru the journals. Its not a 100% lineup, its as close as you want to make it but its really close, and makes the job easy.
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