Crit

iTrader: (6)

Sadly, things do not look good for Homestar Runner. I got a compression test today and my front rotor registers 85, 60, 40, while the rear rotor registers 80, 80, 80.

Now, I really like my 4-port setup and want to keep my carb and everything, so I'm now looking for advice on the most economical way to rebuild what is most likely an engine with a worn rear rotor and a broken apex and stuck side seal on the front. Thoughts? And please don't tell me to go turbo, I'm looking for a simple, carbed little 7 that's gonna stay reliable and fun for many years.

How should I go about getting ready for a rebuild, and how can I check to see what I need? I'm replacing the header this weekend, so I'll try to pinpoint the offending apex seal, but what's the best way to get together all the hardware I need inexpensively?

YapaKanichi

Leave it the way it is and rebuild it yourself, 13b 4-ports with a SP on it are bad ***.

Crit

iTrader: (6)

Specifically, what can I do now to see that I'll have reusable irons and housings and such? I won't drive it until it pops, but can I throw new seals at it and bolt it back together, or do you have to replate the housings and everything?

Jeff20B

iTrader: (13)

I basically threw new seals into both my R5 four port 13Bs. The one I rebuilt last year is strong. The one I rebuilt recently is almost ready to fire up. I just have to mount an E fan and wire up the fuel pump. Both have street ports done with a dremel.

At least your engine has some sort of reading. One of mine had totally flat apex springs and wouldn't idle, but higher RPM was still ok because the centripidal (?) force was enough to keep them against the rotor housings.

BadAssRX-7

well im bad news guy.... i did the test. untill you get the motor open you wont know 100% what does and dosent need to get replaced. the 4 sure items on ANY motor with some miles on it... seals & springs...apex, sides, and corners.. do fd corner springs.. they are better than fc/fb. then you will also need a gasket kit and oil o rings and maybe the metal oil rings. when the motor is opened you can see bearings, housing wear, plate wear, oil pump ect ect. ill start getting you a price list going on basics and full out rebuild

Elysian

centrifugal

Elysian

btw if u wait till it pops u'll be buying new housings where if u pull it apart now u might not have to, tho u probly still have to anyways... i wouldn't wait till it popped if i were u

BadAssRX-7

true, but if 1 housing is dead now id keep on driving...just dont rail on it. and yes if it pops a housing and a rotor will most likly needed

Crit

iTrader: (6)

Is there any way to fix a housing if it's shot, or do you have to pick up a new one? I'm trying to decide if I need to just rebuild what I've got now, or if I've already got one shot housing.

Feds

centripital

cdrad51

centrifugal. And the opposite is spelled centripetal.

Jeff20B

iTrader: (13)

Heh.

Gonna mount the fan now and then wire up the fuel pump. I wonder if this thing will fire up? It's got the rotor set that had the flat apex seal springs. New springs and '74-'75 apex seals (the weird ones) on '74-'75 rotor housings and R5 side plates.

cantstopa-7

pull it apart

cantstopa-7

pull it apart if the intermediate-"plate" housings are bad they can be milled and resurfaced like the heads on a regular engine, the side -or hollow housings that the rotor rides in,are almost unsavable unless youre good friends with a machinist-then maybe you could have it hogged out and a new insert custom made to fit it- but the good news is you probably just need to throw new apex seals in,new side oil rings ,and that stuff, and then go- but the only way to know is to tear the sucker down

Crit

iTrader: (6)

By the way, the inward acceleration needed to move an object in a circle is centripital. The percieved force if you're riding on the object, is centrifugal.

Manntis

"Centripetal" (note the 'e', not 'i') simply means "towards the centre." Most commonly it is encountered in mechanics, as in the force attracting an object to the centre during circular motion. A spinning turbo has no centripetal force as it's attracted to the center by being connected to it physically.

Centrifugal is the opposite of centripetal. On a turbine centrifugal force pulls the blades to the outside. If you grabbed a bucket of water and swung it around in a circle, centrifugal force, not centripetal, would keep the water in the bucket even when upside down (assuming you're spinning it fast enough, or you'll learn a little lesson in gravity)

mwatson184

^incorrect

There is no such thing as centrifugal force, it is a pseudo force. For your bucket of water example. You swing the bucket around, and the bucket is attached to your arm (or a rope), the tension in the rope actually pulls the bucket towards the center of rotation. The velocity is always perpendicular to that force, so it reaches an equilibrium distance from the center of rotation. So the bucket is acted on by a centripital force, and has an acceleration towards the center.

The water stays in the bucket because it always wants to travel in a straight line, but the bucket is always changing directions. Can you actaually name me the force that is pushing the water against the bucket? There isn't one.

This site can describe better than I:
http://www.newton.dep.anl.gov/askasc...0/phy00305.htm

Marques

fatboy7

lol, I knew the moment that word centrifugal was mentioned that this argument would insue.

comradegiant

Tsk tsk folks, has no one taken highschool physics? mwatson has it right centrifugal forces are not real. God I hate being in college, the useless crap you learn...

Manntis

right, that's what I said.

Sure there is - it's an effect of the change in direction, and that effect has been the name 'centrifugal'. As in what happens to material placed into a centrifuge, or with centrifugal motion. Look up the definition of centrifugal. it is not a unique force per se, but the term is a valid label for the phenominon observed.

comradegiant

Its always cenripetal, always. The force of the bucket pushing INWARDS on the water is what holds the water in place. The concept of centrifuge is that there is a force pushing OUTWARDS. Which is incorrect. Therefore, it is always a centripetal force.

Manntis

not outwards, but in a straight line. Take for example the centerfuge used for high-g training. The only centripetal 'force' is the metal arm that attaches the pod to the center pivot. As the occupant is hurled around in a circle his body wants to continue in a staight line and presses down against his seat, the floor, etc.

It's true that the floor pushes back because of the curve, but it's not the only thing pushing or the occupant wouldn't feel the effect. The centripetal force affects the motion of the object, forcing it into a curve, but the object is pushing back - otherwise the occupant would never feel the effect and G-forces would be irrelevant.

In other words, centrifugal force is the reaction of an object in motion against centripetal force according to Newton's law.

comradegiant

Wait... its Saturday... why the hell am I discussing science on a non-class day... See what I mean? Damn college!

comeonstart

Crit

iTrader: (6)

Okay, so can someone point me in the right direction? Where should someone go looking for seals and other rebuild goodies if they're on a budget?