On a crab'd 3.0...how much backfiring is "normal"?

svonkampen · 06:58 PM

Ok when I drive my car in the morning, I start her up and let idle at 1500 rpm for about a minute.......

Then I start driving, and she will fart fat ones for about the first 3 to 5 minutes of driving, then she settles down ..........also if I gun her and then down-shift she will fart quite a bit.........

My heat-exchangers are new ssi's so the problem is not there...Also TRE did a rebuild on the carbs.

Keep in mind that in order to run carb's on a stock 3.0, they need to be run rich.

Is this normal behavior?

thanx,

SvK

svonkampen · 08-26-2005, 06:57 PM

Bob Tilton,

Does your car do this?

SvK

bob tilton · bob tilton's Garage

tansplanting the heart of a beast will involve dialing in little nuances over the course of time as you re-adjust to a new organ.

i had this issue and several others which took about 1000 miles to resolve. my back firing was the result of a lack of back pressure due to the dansk duel out sport muffler. i replaced it with a single out dansk and the problem was solved.

in re: to start-up, the carbs need about 30-60 seconds at 1500 rpm to clear its throat(s) first thing in the morning. it's fine once i take off. all other start-ups are fine.

have you cked for exhaust leaks? i had one at the SSI flange to the muffler flange. Resolved with new gaskets.

how's your engine temp?

svonkampen · 07:55 PM

Bob the surgeon ;-)......thanx for responding

my engine temp gauge is always super low.....maybe broken?

btw, I have single-out Dansk....will check muffler gaskets....

SvK

svonkampen · 08-26-2005, 07:58 PM

"in re: to start-up, the carbs need about 30-60 seconds at 1500 rpm to clear its throat(s) first thing in the morning. it's fine once i take off. all other start-ups are fine."

So when you drive to work and leave car for 8 hours, then start up for drive home,,,,no back-firing?

SvK

bob tilton · bob tilton's Garage

yes - i recall from your pics that you had a single out exhaust.

what you did was a major upgrade with a lot of things done at once. 99% of the work has been completed and only time will tell what that 1% needs to be done.

sounds like it just needs some fine tuning which is to be expected.

what are your thoughts on the suspension?

svonkampen · 08-26-2005, 08:02 PM

Love the suspension.......she is so stable at 110mph........you gonna upgrade?

SvK

bob tilton · bob tilton's Garage

yeah - all other start-ups are fine after the morning start-up which is also combined with a couple days of sitting. it was much like my '83 rx7 which required the same start-up procedure.

dd74 · 08-26-2005, 08:04 PM

On a crab'd 3.0...how much backfiring is "normal"?

"Crab'd"

In this case, I suggest you take your car to one those free clinics; not TRE...

bob tilton · bob tilton's Garage

i can't justify the susp upgrade right now considering everything is new "down there".

my next upgrade will be a LWB ST replica.

svonkampen · 08:57 PM

Wish I could give you more feedback on suspension.....I am not a schooled driver YET....so I take it pretty easy in turns........But like I said , Night and Day difference at high-speed..

BTW Dave at TRE said: "The '68 suspension was just plain awful"

SvK

svonkampen · 08-26-2005, 08:07 PM

I think that includes the prior year as well.......

svonkampen · 08-26-2005, 08:36 PM

ST huh ?

" ST/GT was permitted to run an oversize engine for racing in Group 4, the FIA allowing Porsche to increase bore but not stroke. As a result, displacement was up to 2247cc, bore having been stretched by 1mm (to 85mm), stroke remaining unchanged at 66mm. Designated Typ 911/20, the highly tuned engines were equipped with twin-plug heads, camshafts from the Carrera 6 and special Mahle pistons."

wow.......what color? ;-)

svonkampen · 08-26-2005, 08:42 PM

ST rear...for Surgeon Bob,

bob tilton · bob tilton's Garage

these are my initial thoughts as i have just been having them within the last few days:

1 start with a carerra and backdate it
2 69-73 front fenders
3 plain front bumper (not split S or RS)
4 1 piece rear bumper
5 fuchs up front, minilites in the rear
6 cibie hood lites (2 pair)
7 RS interior with dark green leather
8 slate grey exterior
9 no decals

this would require selling my car and starting new.

svonkampen · 08:52 PM

it will be interesting too see what your car will fetch.....but how will you live without a working Porsche during the build?.....that is just torture. Just a mere 6 weeks without my ride and I was ready to start Prozac...

SvK

svonkampen · 08-26-2005, 09:10 PM

DD74,

heheheehehe...i couldn't figure out what you were talkin' about

"crab'd" ....free clinic ! hahahaha

....but my car is suffering IBS ;-)

SvK

ianc · 08-26-2005, 10:38 PM

So, umm... What happened to the CIS injection that came with the 3.0? You could always 'uncrab' yourself...

ianc

RoninLB · 08-27-2005, 12:30 AM

all below depends on ignition, cam, etc.

the gas has to be in a state for efficent combustion. CHT becomes a factor with a rich idle circuit. I've found that a very rich circuit needs a bit higher CHT than just a rich circuit to preventing start up bs. Very rich needs about 175degF for no bs at all, rich needs about 160degF.

svonkampen · 08-27-2005, 12:36 PM

Ronin,

I have no idea what you are talking about ;-)

Please speak english...so this dummy can understand........

SvK