RedRX

Thats interesting about those cam specs. When i did a lifter clean on my engine (which was built up as a rally motor before it ended up in my car) i saw it had billet cams with those numbers on them : 30-70 70-30 , no idea of lift but they look like big wheels compared to standard cams. Unfortunatley i have no idea of how well they work due to low comp in one cylinder from i suspect a leaky valve which is throwing vacuum and mixtures to hell. Next job is pulling the heads to fix that.

Thanx Skip - u just beat me to it. I tried a can of the Subaru upper cylinder foam stuff - no joy. I DO have a check valve in the brake booster hose - no idea of the state of the white cans guts tho.

This engine came from a rally car and has had a number of rebuilds - apparantly including forgies. From wot i saw in the cam boxes we have 30-70/70-30 cams (from thick billet) and high-tensile socketted head bolts. No-doubt the ports have been altered too. Will be interesting to see.

Yes - will do. Curious to see these mythical forged pistons. Thats if I will be able to tell the difference. What do standard turbo pistons look like from the top? Fixing this should also improve the low manifold vacuum problem, which sometimes caused the odd brake 'fail' where the pedal goes hard; and plays havock with the interior ventilation system - accelerate and air goes to feet, back-off to get air in face - wheeeee!

Damn damn damn! After months looking all over the place for the continuing running problems with the RX motor I think i have to bite the bullet and pull the heads. Got around to doing a compression test and low (ie 70-80psi) in one cylinder. No reason to suspect gasket as no water or oil problems or smoke, same goes for rings - so my guess is a burned or slicking valve that wont close. Will need a special allen socket thingy to get the heads off (high tensile bolts with socketed heads) and will get to see what head work has been done on the old girl. At least it explains why i'm not getting the power i should and why the AC always stalls it. Wish me luck!

Finally bit the bullet and had a new exhaust and straight thru muffler fitted from the cat back on my 86 RX Turbo. Ohhh why did i wait so long? Turbo spools up faster, better LOW-DOWN power as well as high end. And the SOUND! This is all the reason u need to have a boxer engine. Deep burbling throb at low RPM, deep snarl at high RPMs, and the best damn sounding growl on the over-run between gears when u push it. I would never try to drown that with a BOV! Its a modest 2 1/4 system without any fart-can exhaust tip - looks bog standard out the rear. So - more power - better economy - no need for stereo - better low-end - dont have to thrash to have a good time. Its win-win!

4wheeln2 - AAaaaahhh. A little light has gone on with your explanation about high-lift/duration cams in performance engines. The engine in my RX was not 'breathed on' but fully rebuilt by rally mechanics (as in they worked for a rally team). When i did a lifter fix I noticed she has 30-70/70-30 degree cams (as painted on the billet). Has NO guts at all off idle and has a massive unburned hydrocarbon count for exhaust gas measures, and a low compression test. Hit 3000rpm and she lifts her skirts and moves. I guess this explains whats going on here!

Hehe - beatcha! I got gas struts in mine. Work great tho getting the right size nuts is crucial so you dont need a panel job on the bonnet. They are wagon struts BTW. When i get some time i'll snap some shots.

Wish I could help, cos my 86RX is doing exactly the same thing. Murphy's law states that it will NOT me the same cause, nor will it be a single SIMPLE cause.... sigh! Let me know if you find an answer and I will reciprocate.

Uh ho, I guess thats why I seem to have no fall-off at the top of the rev range apart from my right foot and sweet f a at the bottom end. The cams in mine are 30-70/70-30 which is a HUUUUGE duration by comparison. I'm sure the old girl will be more drivable once my problems have been sorted, until then my fuel economy will suffer as i regularly have to change up at around the 6000rpm mark to stay on cam!

PS - from what i have read the knock-sensing apparatus is an arcane device with devious signals and mucho filtering to make sense of said signals.

Have done that bushbashr - still spits and farts. Not game to give it a GOOD run without knock-sensor tho

Thanx Skip - your info is ALWAYS helpful. I'll keep you posted.

Hmmm - let me clarify that last question. Does the fact that the timing light misses the odd ignition pulse mean that the PLUG is not firing either? or just that the timing-light pick-up via the clamp to the cable can only catch pulses of a certain strength.

JOsh, Skip and all. The fact that the problem comes and goes leads me to think that there is nothing structually wrong with the engine. The odd times she can run sweet. Interestingly - she runs much rougher with the headlights on; bad earth on the coil? or even a dodgy coil (I thought a bad coil was just that -BAD- not something that caused an intermittent problem. PS - when using a timing light, is it normal for the strobe to flash at an intermittent rate? ie not firing every ignition cycle? I'm wondering if the leads are right resistance.

I have pulled and cleaned flapper and checked the internals under the glued cover - clean - and flapper is free and spring works not checked outputs yet tho need a decent meter

WJM - what were those cam specs again? particularly the timings and durations ie degrees opening/closing for exhaust and inlet.

Its 86 Skip, with flapper AFM, and breakerless disty with separate knock control unit. You replied to a post i made about the single vs twin wire knock sensor. Supposed to be twin wire for this model but i have single wire installed - I tested with timing light and it DOES work - dunno if it's false-alarming tho - i just know it winds back timing when i tap near the sensor with a big screw-driver. I know this problem has to be in the control system somewhere cos the engine was rebuilt only about 500-1000km ago and built to take WAY more boost and revs than i give it. Just this damn missing and choking - geez could even be as simple as a faulty plug or lead, but they are new.

Slowly eliminating potential causes for the running problems - said problems being: sudden choking after engine has reached operating temp (ie - by the end of the street loses all power for a few seconds), constantly missing at cruise, gets smoother during acceleration, rich running, NO power right off idle (ie AC causes a stall even after hot-wiring the idle-up solenoid) and easy to stall at low revs. When she is wound up (2000-3000rpm) she will pull right past 6000, but always feels like something is holding her back. I KNOW this engine has MUCH more to give - built up by rally mechanics - hi-tensile head bolts, BIG cams (which I know affects the bottom end), and god only knows what head-work. The thing is it has been transplanted into this car with its standard running gear and computer. So far i have fixed and checked the aux air valve, the EGR valve, cleaned out the disty, tested the temp sensor (the resistence varies with temp, and it gets 5 volts), the knock sensor works (even tho its only a single wire job when it should be the earlier 2-wire - I tested it SKIP, and wow, it DOES actually knock back the timing). Fuel pump has had output and pressure checked, I pulled all the lifters and freed and cleaned and primed them. Phew! I know i need a decent exhaust but there is an intermittency to the problem so it cant just be a clogged cat. O2 sensor is new and seems to work. DAMN DAMN DAMN - anyone have a clue? I want the girl to sing as she should.

Thanx Skip. I love the way you give all the useful info I needed then say you dont have a clue! Modesty. Hehe - now I just gotta get my hands on a twin-wire sensor. I imagine the KCU would just get gobbleygook from the current sensor.

Riiiight - i take it no-one has a clue?

Jack - that is one of the sweetest stories ever. I guess only people who have had dogs in their life get it. viceversa - i dont think the 'over-reaction' was directed at you - more to those with comments about anti-freeze, pellet-guns, and deliberate run-down attempts. It might seem funny, it might seem cool, and I am pretty sure they were only joking. Better have been

The engine in my RX is supposed to have a twin wire knock sensor. It has the separate knock control unit in the fender (ah - 80s technology:-\ ). It aparantly works by producing and alternating current. Thing is - someone has fitted a later SINGLE wire sensor and simply bodged it by soldering the single wire to BOTH wires coming from the knock control unit. How does the single wire sensor signal knock compared to the twin wire setup? I have removed the green wire from the knock control unit and simply run this to ground and left the red wire conected to the sensor - but i imagine this has achieved little. Funnily enough - i have never had the car ping - let alone knock! Any ideas anyone?

I bought furry dice for a mate when he got his Saab - and he displays them there too.

Hehe - my RX aint lowered, in fact it could do with an extra inch upwards for the tracks. Hey I dont want to talk anyone out of a project, but by the same token I would hate someone to make the car unsafe or undrivable in the pursuit of 'street cred' : life is too short for that sorta stuff (remember furry dice and panel-vans with fantasy murals?).