I am running a S4 TII block w a RB Dellorto sealed up for blow-thru.

I can't seem to get the hot side of the stock S4 turbo to stop glowing. The exhaust manifold glowed when I had it set-up in naturally aspirated form as well & before sealing any boost leaks on the carb.

The motor was JUST rebuilt by myself, compression is good 95 all around. It glowed before the rebuild as well. When I put the new motor in I made sure all points that could cause a vacuum leak were FOR SURE sealed to try to rid this problem but with no luck...??

All I am doing is cruising around the block, no boost, and rpm's below 3k.

All the jetting on the carb is still the same from Racing Beat.

Any ideas...???

 

Been doing some searching on timing and found this....

"ROTOSPEED - what i found worked best using a dizzy on a boostd applacation is to set the timming at 0* at idle with the vac unhooked, than connect the vac line to MANIFOLD vac. iirc vac advance is 10* and mech advance is 10*. This will give you 10* at idle/low rpm 20* under cruse and the boost pressure retards it to 10* when your under boost. i found this to work very well for power and fuel econemy, way better than the locked dizzy a lot of people use.

A lot of people here will repeat what they heard... Us dizzy has vac advance and jdm 12at dizzy has boost retard... This is wrong. They may have differant advance curves but any one that gets both dizzys next to each other on the bench as I have can see what they do and don't do. Then they will understand what I first posted, what the 12at dizzy does is de-advance the timing the same way a usdm dizzy will when connected as I described."

Also found these old notes from talking to Robert @ RS. Main air jets bigger + air bleeds smaller = fatten up power band.

Which goes along w what my pops seems to think... go bigger on the main jets to richen up during cruise. My wideband is showing #'s in the 15+ area during slow mph, low rpm, no boost cruising.

I'm open to any ideas or input at this point, so please chime in w even the slightest thoughts.

I've chased many many problems so far I feel like I'm so friggin close.

 

righto

lets clear some stuff up..

whoever you quoted above has poor grasp of what is manifold vacuum
and what is ported vacuum as delivered from the phenolic spacer under a nikki carb

two different things
the ORIGINAL vacuum supply that EITHER of the quoted dizzies used had no vacuum at idle

and when you hook a 12at ( genuine boost retard dizzy with double acting diaphragm )
it will advance during off idle ( vacuum is now applied ) , it will retard to the base setting
( just like the NA dizzy ) when you push to WOT
and then the 12at dizzy will retard the ignition a further 6-8 degrees , while the NA dizzy sitts stuck on the base setting

this is easily proven by blowing 8 psi into either dizzy vac pot



the s2 rx7 manual quotes things as ( and this is the important bit,, pay attention )

i quote-

paying attention.. fig 5-31 gives you the big clue

for x axis is clearly says distributor revolution


if you have payed attention this far,, is becomes apparent fig 5-31 is giving us a description for what happens on a distributor graphing machine

the significance?
a distributer moves at HALF crank speed ,, movements on the distributor are DOUBLE at the crank


AND SO - fig 5-31 tells us
that max centrifugal advance occurs at around 1750 distributor RPM... or 3500 rpm crank
and at that point the leading timing has moved 12.5 degrees ( distributor ) and 25 degrees ( crank )
and the trailing has moved 13 degrees ( distributor) and 26 ( crank )

if you realise this engine came with the fawn pulley , which is marked for 0 and 15 ATDC

then it tells you the stock NA 12a engine runs to 25 BTDC at 3500 rpm


dont blame me// im just quoting the mazda book , i know how a graphing machine works
and i understand the difference in port vacuum, purge air, and manifold vacuum

as for the 12at/

well that engine runs the black pulley, it is timed at 5 ATDC leading and 20 ATDC
and this dizzy has just a bit more centrifugal advance , and by experience
( i have had,, and modded many over the years )
this dizzy,, and the GSL-SE dizzy ( another black pulley ) tend to make closer to 30 degrees advance
,, and so end time to around the same 25 degrees BTDC
it will retard under boost,, and not just fall back to the base timing

for your issue,, im thinking timing

and it may pay to just lock a spare dizzy , and use it timed to around 18- 20 BTDC
( this will compromise the off boost cruise power but will amount to about the right retard for 5-7 pounds of boost )

i expect the glowing should back off a bit,,
but if it does not then i would get the infra red thermometer on each runner to see if you have jetting/ inconsistent mixture issue one runner over the other

 

Thats way too lean pal.

Safe boost should have you in the 12's and 13's. The richer you are, the lower the number. 15 is lean. Even for NA.

Fatten it up, you'll be just fine.

 

Sounds like the RB Dellorto was setup for a 12A and that would explain the extra lean condition
for the S4 13B you are running now. Look at the Gruntled.com - Home site for clues on NA jetting
for 13Bs and go from there. Other clues that its very lean are light or white deposits on the
spark plugs and no black deposits on the inside of the exhaust tips.

 

Thank you for the food for thought from those who posted.

I tinkered around some this morning. I ordered a few sets of idle jets a few months back. RB gives a 75, so I bought 80, 85, 90, 95, 100. I went straight to 100 just to see if it made a difference and idle smoothed out BIG time, responsiveness improved BIG time, and slow easy pedal cruise I'm in the 12's.

Now at least I can break in my motor.

I have two locked distributors. One I did myself and one I bought off someone here in the classifieds. When I look at both distributors side by side, when I line up the dimples to stab, the pickups for each is pointing differently...?? (I used the same dist for the photos just to make sense of what I'm explaining).

 

one dizzy is welded at fully mech advanced position
other is welded at the normal rest position

doesnt really matter, or the dimple,, as basically both have to be dropped in one tooth away from dimple to achieve the 18- 20 BTDC position

by timing it,, you cancel out the differences,, one base will be set further to one edge than the other

PS
until you are sure you boost control is working,, you may wish to try 15 BTDC during setup , and then push up to 18 or 20 once you confirm the boost is not going beyond 7 psi

if it is, then you basically have to pull one degree off the max timing position for every extra psi

 

Thanks Bumpstart for your help.

I'm so glad I finally have my father's full undivided attention in helping me as well. He really knows alot (Chevy guy). And with his help I feel I cover more ground in a day then I would by myself in 6 months. Two sets of hands really help as well.

We were brainstorming ideas tonite and he seems to think since the Dellorto ran like a champ without changing any jets from RB on my old 6port, using short RB upper and lower intakes... & in this set-up I am now using the much taller and longer stock S4TII lower intake manifold, no wonder it's running lean (even running w no turbo / na form). He says it'd be the same effect like adding a 1" spacer on a Holley.

A bunch of air bleeds and Main jets are on order. They're coming from Italy so I'll post back w results in about 2-3 weeks.

 

Why does nobody make the damn things here in the US?

There's probably 5-6 different vendors making "brands" of holley/edelbrock carbs out there. You'd think as popular the weber/dell are in america that there'd be some business capitalizing on it here...

I'm going to order a bunch of brass stock and start making nikki/weber/dell jets.

 

I like getting them from the UK ( Dellorto and weber carburettors online ), a little closer and ships faster too.

 

I been using this guy...

alfa1750 | eBay

It might be shorter. He marked me shipped next day & that was 1/06/15. I picked up the boost prep gasket kit prior from him too.

 

Jets and Air Bleeds arrived today. 6 days = not bad.

 

turbo glowing to me would be a timing issue.

 

I have a crank angle sensor so I might not be much help, but I have been in this situation before with the turbo glowing. My timing was in the 20 before tdc range and it was glowing with a high rpm idle, I adjusted timing to 5 after tdc and the glowing when away and idle dropped to normal level.

 

Dellorto parts availability: The shop I go to in southern california had a good inventory last I was there a few years ago. The owner would fly to Italy and come home with a suitcase full of Dellorto parts. They're simply only manufactured on the other side of the planet. With the euro being devalued maybe he'll do that again. I know they do ship, may be worth a shot to call them:

European Motorworks
13224 Prairie Avenue
Hawthorne, California 90250
Telephone (310) 644-8038
(800) 722-8678 in U.S.
Fax (310) 644-8042
Hours:
8 am - 5 pm PST, Monday through Friday
9 am - 2 pm PST, Saturday

I've had a header glow if there was a very weak spark, and lots of unburnt fuel going out the exhaust port and igniting in the header. Or... overly rich which does the same thing (unburnt fuel).

 

1. Car idles amazing. Wideband reads 11.3 - 11.4 steady.

2. It revs with no load / neutral perfect.

3. I got it to where it stumbles if you don't play the pedal right on slow acceleration / getting moving.

4. Cruising slowly at about 2.5 rpms the wideband is all over the place (11-15's) dependent again on playing the pedal right.

5. I got into boost very briefly (2 seconds or so) and wideband is steady in the 10-11 area pulling great.

6. Timing is locked @ 10L 5T, on the money everytime I check.

7. Turbo is glowing ALOT less but still glowing when doing # 4.

8. Idle jets are up'ed to 100 from RB's 75.

9. Main jet is up'ed to 250 from RB's 230.

10. Main air corrector is down'ed to 130 from RB's 230.

I'm done for tonight. If I play w things w out my father's guidance I take two steps backwards instead of making progress.

 

Halle mother flipping lujah...!!

Glowing is GONE...!!!

Bigger idle jets. Biggest size able to be ordered (100) drilled out another step on my baby drill bits.

Everything is in the 10-11 range. Idle, cruise, boost.

 

Its good to hear. You should document this for anyone that wants to use a Dell for boost.

Also send an email to the gruntled page owner with the details. He'd probably be glad to post it
up for others to reference.

 

Well don't jump the gun tooo fast like I did. Light cruising around the block and the glow is gone. I took her to the car wash last night which is about 5 miles away and when I got there, whata' know. Turbo was frigging glowing. I'm definatly on the right track. She drives MINT. I've been reading alot on another turbo forum and the general consensus is timing always being tooo retarded, too rich or too lean. Maybe now I'm too rich...? I'm going to take apart the intake/s & fuel injection plugs to make SURE again... I have no vacuum leaks. I'm grasping for ideas here.

 

10-11 range at idle and cruise is too rich in my opinion. That is why your turbo is glowing.

And of course I could be totally wrong. I've only been at this turbo game for like a year. But what a year!

 

Same here. I learned soooo much over the last year or two. Jeff, does your turbo glow at all...?? Just cruising around, no boost...??

I advanced the timing to 15L - 10T and I made it to the parts store (2 miles away) w a very faint glow. I don't want to advance much more then that...?? or can I...??

She feels soooo smooth & responsive to drive.

 

Glowing parts is bad. Keep the timing where it is and use a smaller idle fuel jet. Try to get in the mid 12's or preferably in the 13's on freeway cruise. Just because there's a snail on there doesn't mean it needs to be super duper rich at idle or cruise?

Just curious, Do you have an intercooler?

 

leave the timing at 15 BTDC.. this gives you the correct retard for hi comp rotors for 10 psi boost and maybe as much as 12 psi

if you have higher boost than that you should retard the base further

if you have 6-7 pounds of boost at WOT and no more then you can sneak it up to 18 BTDC

 

Drivefast, No intercooler. I'm plumbed right off the turbo directly in to the bottom of a RS box.

Bumpstart, my timing is exactly where you suggest....?? Some advance definatly reduced the glowing a lot. I'm at 18* L & not getting into boost at all. Still have a mild glow @ easy cruising.

 

18 degrees is kind of a lot with no intercooler. I'd be worried about popping the engine. I only have 10 degrees of advance with a 10 degree split. The dizzy is semi-locked so I don't have to worry about too much advance at low RPM and idle (static timed/stabbed at 0 degrees).

The engine has S4 NA 9.4 CR rotors and no intercooler. I've never heard the dreaded marbles rolling around in a coffee can sound, and hope I never do.

My idle and part throttle cruise in vacuum is around 13. My idle likes 12.2 best but will idle well from 11.1 to 13.6ish. Any leaner and it complains. Earlier in the year I'd seen as lean as 12.3 to 12.7 in boost and I was concerned so I took steps to fatten it up. My in-boost is anywhere from 11.something to 10.0 now - kinda hard to stare at the wideband in boost because it likes to go sideways.

The turbo doesn't glow as far as I know. I tend to not drive it at night though. The iron exhaust housing hasn't changed colors or anything so I assume it hasn't gotten hot enough yet. No bluing, in other words.

I think your problem might just be the carb. The issue with 2bbl carbs is their limited range on a rotary. You either have good low and some midrange, but not much up top. Or you have good midrange and high end, but low end suffers. And because these carbs have no secondaries, the mains need to be tuned for boost to keep things rich enough for the engine to live, but then your cruise ends up super rich killing your mileage. They also tend to throw fireballs which for some is cool, but pretty wastefull.

I keep a short list handy of everyone who's tried a boosted 2bbl and given up because they just don't work very well:
•ioTus (who sold it and got an NA 6 port and is now MegaSquirting)
•hyper4mance2k (who sold it and did an NA IDA on a big streetported 6 port)
•PercentSevenC (who traded the parts to me for an FD engine and MegaSquirt swap)
•CodeBlue (who bought the ioTus car, rebuilt it, and has since sold it)
•Zaridar (who kept popping 12As and then tried an injected 13B which also died but wasn't his fault this time).