wankel=awesome

So I was playing with my 85 today...

I know with my modded nikki I always had a bit of smoke on decel after a hard run. (WOT from 0-80mph, then let off in gear) but today I had a regular smoke screen behind me for about 2 car lengths.

The smoke is gray in color, not especially thick in density.

Car is not consuming coolant, or engine oil.

WOT AFR's are between 12.1:1-12.5:1 from about 5k rpm to 7500.

Is this normal? I cant say I ever noticed it this bad from my Nikki, or Dell. Current carb is a 465 Holley.

This summer it did this a few times but I thought it was because my secondary jetting was overly rich. Maybe it is again, but the engine seems to like the 12.5:1 area for torque and horsepower.

Car is a 1985 GSL.

'74 ported R5 12A

RB long primary exhaust

13 lb RB flywheel

Stock ignition (other than iridium plugs)

Stock exedy clutch.

Oh, and its premix. No OMP... Cant really think of anything else thats relevant...

wankel=awesome

I guess ill add that im used to it blowing a couple fireballs on decel, not the gray smoke. in this case there werent any fireballs at all.

Too lean?

Jeff20B

iTrader: (13)

Never seen gray smoke on decel, only white smoke (blueish?) caused by oil getting past worn oil seals in early non nitrided engines. I've only seen gray smoke on hard accel from a friend's poorly set up Camden with a Holley. Not super thick like yours, and filled the whole street for like two car lengths too.

Maybe try a different carb? Or maybe your oil seals are needing a little attention. Ever had the irons resurfaced? If so, they're junk. Or are they early non nitrided R5? If so, start looking for some nice Y plates or something.

wankel=awesome

They are R5 irons, but they came from pineapple racing almost 10 years ago... I always thought they were nitrided. Its been many years since it was apart. It runs like a top, and like I said, it doesnt really consume engine oil.

And it doesnt do it any other time! Only closed throttle situations from 6k rpm on decel. AFTER redlining it through 1st, 2nd, and 3rd. Any other engine decel scenarios dont yield smoke.

If the seals were worn wouldnt it smoke while im just driving the car?

Edit, my Nikki did this a little bit too, same scenario. Just not as bad. They are both vac secondary, with the pcv valve mod.

Jeff20B

iTrader: (13)

Hmm, being a pineapple engine, I'd say they were resurfaced.

If you've ever seen any of Rob's videos, he was a real stickler about having absolutely flat irons in every rebuild. That, obviously to him, always meant a resurfacing job, which also meant extra money coming it. It also led to engines that smoked well before they should. Then his excuse was always something like "the engine's best miles are already behind it, so we're just working with what it has left". Yeah, right.

Of course I could be wrong. I'm not there to observe the engine, nor to tear it down. But my best guess is oil seals. It could be old dead o-rings or flattened springs. Or probably simply too much wear beyond factory spec which could be caused by resurfaced irons. Or any combination. There can only be so many causes.

I always say when in doubt, tear it out. Rotary rebuilds are no more complicated than a carb rebuild. Only the parts are bigger and heavier. Hmm, I suppose you need more infrastructure such as an engine crane (unless you're strong) and an engine stand (unless you have a 5 gallon bucket). And I suppose you need a 54mm socket or a chisel. Maybe a few other rotary specific tools, but I can't think of any at the moment.

As for your specific question, it won't smoke that much just from regular driving. You'll tend to see more smoke at startup, sometimes while accelerating hard and usually while decelerating from high RPM where there is a lot of vacuum and a lot of time to pull oil past the seals.

What is the PCV valve mod?

wankel=awesome

lerThe PCV valve mod is the addition of a PCV valve (2002 hyundai accent valve) to a rotary.

It just goes between the oil filler neck and the intake manifold (or vac source).

It keeps the lung butter out. Its been there since I stripped my Nikki and started getting lung butter...

Anyways, I just started the car and it does have a little "smoke" from the tailpipe when the choke is engaged. After the choke comes as it warms up there is not even steam visible.

It just smells like gas to me, certainly not a burning oil or coolant smell.

I also had a buddy follow close to me while I was driving it hard and it didnt do it at all until I started engine braking from very high RPM's. And then it only actually made "smoke" if I had been at WOT and literally just backed out of it.

So, to me it looks like a lot of unburnt fuel coming from the engine when the throttle is closed. The RB carbs "kill bleeds" are filled with solder so the booster has no way to prevent fuel siphon on decel. My question is why isnt it lighting off in the pipes? Unburnt fuel in excess usually = belch of fire.

Meh. The compression is awesome, power is awesome, its not using oil or coolant and since I switched back to rubber accel pump diaphragms from the GFLT type it has no cold start issues.

I'm keeping my eye on the oil though, seeing as its a logical place for the engine to wear at this point.

Jeff20B

iTrader: (13)

Ah, cool. I've added a Fram FV333 PCV valve to some of my builds. They seem to work pretty well on old school manifolds with what appears to be a PCV valve but apparently is an altitude compensator. When the plastic tube breaks off due to age, you install a hose or a steel fitting or any number of other ways to get the Fram inline somehow. The results are pretty good. Prevents moisture under the cap.

Just a note on a turbo setup is I've used the same alt comp fitting on the manifold for the boost gauge and BOV. It works great for those but now I don't have PCV anymore. Still figuring out what to do to prevent the wonderful water under the cap. With a turbo, a lot more moisture gets up there due to a normal bit of blowby -- the turbo obviously makes it more pronounced. It's like soaking wet after a 15 minute drive. PercentSevenC just used a cap with a hole drilled in it for a 1/8" NPT 90 degree fitting, but we later took the fitting out so the hole was like 21/64". Kinda big, and it worked. I don't like the thought of dust and sand particles getting in, or I'd do it too.

Sounds like your engine is ok for a while yet. I'd just use it and maybe keep the conditions where it produces a smoke show, to a minimum.

Speaking of Holley accel pump diaphragms, my RB Holley 600 has one that appears to be meant for marine use or something because it doesn't leak and is kinda stiff or rather kinda lazy. It leads to an anoying lack of accel pump shot unless you really stab the gas pedal fast. There is like no fine-touch driveability like what I've come to expect from Nikkis. However a couple other Holleys I've tried have had nice crisp accel pumps, but they tend to dry out and leak if they sit for any length of time after having had gas in them. The RB carb never leaks regardless of how long it sits. I assume RB used this tougher accel pump material to better withstand OMP oil they have plumbed into the primary float bowl. Is there any truth to this theory? What are your thoughts?

Sounds like your carb's solder filled bleeds are what the problem was. I recall my friend's RB Holley 550 would backfire a bit after he would let off. He said it did that because the carb would "dump a bunch of raw fuel" which always confused me. Why would a carb dump of a bunch of "raw fuel" at any time let alone on heavy decel? Maybe it was just a quirk of the Holley? Or maybe the idle circuit was drawing a ton of fuel through it due to high vacuum?

wankel=awesome

RB uses the black rubber type that was used by OEM's for many years. They are awesome. The "green" or GFLT pump was designed for modern gasoline and even alchy .
They suck. Bad. They are too stiff and the material seems to be very temperature affected. When cold, (below freezing) they virtually freeze and are unusable until the engine warms up a good bit. When hot they get very thin and stretch out a ton. In fact, while doing testing this summer on accel pump cams I kept getting mixed results in terms of cc's of pump shot from the green pumps.

For instance, one test was 24 cc of pump shot for the green cam in the no. 1 position off idle. By the end of a long drive when the carb was more or less heat soaked, it was a 19 cc shot. After sitting for a few hours it was a 14cc shot.

Thats awful. So unless you replace them every couple of weeks, the green pump diaphragms (GFLT) are terrible. Maybe its 2 cycle or MMO that does this to them. All I know is the black rubber diaphragms arent affected at all.

Edit: Btw the green pump diaphragm is included in Holley rebuild kits. Thats how they find their way into carbs that dont need them.

Jeff20B

iTrader: (13)

I think my carb has the black one. I'll have to see if I can look up past the lever. Hmm, maybe the RB is stiff because it sits for long periods of time. At least it never leaks!