The 4BBL M1 does cause a stumble off-idle due to the larger plenum than
the 2BBL version. You running the turtle from Randy Pile in that one or
no?
>From the mods you listed, the injectors are not too small at all - '01+
models use 21# injectors...not the 19# like the older Magnums. As for
the headers/exhaust causing a lean problem, that's only on the older
carbureted engines...fuel injection is excellent in controlling this as
the O2 sensor(s) will help in adjusting the A/F mixture. On the HS
Rockers...what did you set the lash at? (Please tell me these are NOT
the non-adjustable ones.)
Why the oversized 55mm for the 360? 52mm is more than plenty. Sounds
like too much airflow being "gulped" down on a hard acceleration (in
conjunction with the large plenum from the 4BBL M1) causing the
stumble/pop. If you want to compare it to the good old carburetor days,
picture a single-plane manifold with a 950CFM carb on a 350 with stock
heads/cam. Ain't gonna run right and will stumble.
- Bernd
-----Original Message-----
From: owner-dakota-truck@bent.twistedbits.net
[mailto:owner-dakota-truck@bent.twistedbits.net] On Behalf Of Dave
Downing
Sent: Sunday, July 06, 2003 8:03 PM
To: dakota-truck-moderator@bent.twistedbits.net
Subject: Re: DML: Re: Re: what causes intake backfires?
Right now I have a 55mm F&B, 4bbl M1, HS 1.7 rockers & 3" exhaust.
Headers and true dual exhaust are going on next week, followed by a full
Paxton setup. When the Paxton goes on it will be getting dyno tuned, so
I'll find out exactly what's up with the engine and what I need to do.
I've been told that the fuel setup that Paxton uses is awesome and
should be able to handle it just fine. Eventually there will be
heads/cam/forged internals/more boost, but what I'm doing now should
keep me happy for a lil while (it's gonna have to until I can save up
for the next stage lol).
-Dave
""Bernd D. Ratsch"" <bernd@texas.net> wrote in message
news:000501c343eb$3ef51310$030aa8c0@homenet.com...
>
>
> Dave,
>
> If you have access to a scanner (that shows STFT and LTFT), you can
> tell what the engine is doing in regards to the fuel (rich/lean).
>
> What mods are on there right now? (Cam, heads, intake, TB, exhaust,
> etc.).
>
> - Bernd
>
> -----Original Message-----
> From: owner-dakota-truck@bent.twistedbits.net
> [mailto:owner-dakota-truck@bent.twistedbits.net] On Behalf Of
> JAMEPC@aol.com
> Sent: Sunday, July 06, 2003 11:10 AM
> To: aol@dakota-truck.net
> Subject: Re: DML: Re: Re: what causes intake backfires?
>
>
> I agree with Ron, "It may be running lean now....." but of course you
> would confirm that before getting bigger injectors. Most trucks with
> modded trucks
> run fine with the stock injectors. I've heard more stories of people
> getting
> bigger injectors just to find out they're running rich. But that may
be
>
> because it more likely to post negative news for help than successful
> news. James
>
> In a message dated 7/6/2003 6:30:23 AM Eastern Standard Time,
> scsilverdak@hotmail.com writes:
>
> > Dave-
> >
> > It may be running lean now...........
> >
> > You may want to consider upgrading the fuel system with a set of the
> > Lincoln Navigator injectors.
> >
> > Ron-
> > Performance consultant
> > Muscletrucks.net
> > ----- Original Message -----
> > From: "Dave Downing" <ded74@yahoo.com>
> > To: <dakota-truck-moderator@bent.twistedbits.net>
> > Sent: Saturday, July 05, 2003 11:37 PM
> > Subject: DML: Re: what causes intake backfires?
> >
> >
> > >
> > >>Does anyone know what condition would cause intake backfires?
> > >>would it
> > be
> > >a
> > >>condition of retatrded or advanced timing? or could it be lean
> > >>fuel?
> > >possibly a
> > >>vacuum leak? I am experiencing major hesitation off the line
> > >>(engine
> > bogs
> > >>almost to a stall) and intake backfiring.
> > >>
> > >>Any suggestions welcomed
> > >>
> > >>John S
> > >
> > >I'm getting the same thing in my R/T ever since I installed the
> > >55mm F&B, 4bbl M1 &1.7 rockers. Also changed the cap/rotor and
> > >plugs at the same time. Anyone know how you check for a vaccuum
> > >leak? I was thinking that maybe it was cause I'm getting so much
> > >air and the pcm is trying to add
> > too
> > >much fuel. I was going to wait until I got the headers and dual
> > >exhaust
> > on,
> > >hoping that those would lean it out a bit and see if it got better.
> > >
> > >-Dave
> > >'02 FR RC R/T
> >
>
>
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