DeTomaso Mailing List: May 2000, Message #122

This also looks like it came only to me, so I'm forwarding them to the list.

Craig

-----Original Message-----
From: Paul E. Roberts Jr. [mailto:paulrob77@earthlink.net] 
Sent: Wednesday, May 03, 2000 4:42 AM
To: Craig Cline
Subject: Re: Persistent miss with 351 Windsor


Another way we determined vacuum leaks, was to get propane with a turn valve and carefully add propane. If the engine smoothed out and RPM increased, this was a good indicator of the lean condition. only works when you have 1 or 2 dead cylinders or a engine scope to read the firing lines. Now
propane will increase the RPM because it adds fuel, so you pull the plug wire with propane,  dangerous, don't have a bunch of propane out there.  Best to use scope where the scope will kill the cylinder.

Paul Roberts

"Paul E. Roberts Jr." wrote:

> Since a windsor engine,  Get one of those smoke machines that help find vacuum leaks. May have an internal leak into crankcase that is leaning out cylinder's to where they do not ignite. Also EGR if it is there, and is opening, and some of the chamber is plugged, can drop all the Ex gases on
> to 1 or 2 cylinders.  It does not take much of a vacuum leak in a vacuum hose or again a cracked manifold or leaking gasket to kill cylinders.
>
> Craig Cline wrote:
>
> > You've got a perplexing problem.  I've never experienced a problem such as yours, but 3 things do come to mind.
> >
> > First, you didn't mention changing the carb, while I don't think it should cause the symptoms you are describing, it can cause some weird problems.
> >
> > Second, you didn't mention changing the cap and rotor, a bad/cracked distributor cap will cause similar problems.
> >
> > Third, I assume you checked the pushrods on 4-8 when you removed the heads, bent pushrods will cause the problems you describe.  I'd pull the valve covers and verify that the 4-8 valves are being activated the same amount as the other cylinders (use a magnetic mount dial indicator gauge).
> >
> >  Craig Cline
> >    1974 Pantera #7352   - the Green One      San Diego, California
> >    1969 Shelby GT-500   - the Red One        E-mail: Craig.Cline@trw.com
> >    1967 Trans-Am Cougar - the Fast One       Work Phone (858)592-3423
> >    1995 Mustang GT      - the Daily One      Home Phone (760)634-3580
> >    1997 Expedition      - the Wife's Bus
> >
> > -----Original Message-----
> > From: Franck DJ (Don) [mailto:DJFranck@equilon.com]
> > Sent: Monday, May 01, 2000 8:20 AM
> > To: Multiple recipients of list
> > Subject: Persistent miss with 351 Windsor
> >
> > Okay,  We have done compression test with a low of 140 high of 150.
> > Done a Leakdown and it is okay.
> > Changes heads
> > Changes distributor
> > Changed Intake manifold
> > Changed Coil
> > Changed spark plugs and wires
> > Triple checked the firing order IT IS CORRECT
> > Changed the Spark plug wires around.
> >
> > After each of these steps, I get the same results.  It now seems to me that
> > the problem must lie in the short block.
> >
> > I still have a very bad miss at idle  If I pull the plus wires on 4 and 8,
> > there is no difference at idle.  This is a 351 Windsor and 4 and 8 are next
> > to each other in the firing order so I get a VERY BAD vibration at idle.
> >
> > It does seem to me the I get the most power from 1 and 5 with progressively
> > less power from both sides as I work my way to the back of the engine.
> >
> > My vacuum is about 19 with a wobble.
> >
> > I have had two suggestions.
> >
> > One - the crank is twisted????
> > Two - I have a bad cam????
> >
> > I figure I can change the cam for around a hundred bucks.  The crank is a
> > different story.
> >
> > WHAT SHOULD I DO???????
> >
> > Don Franck
> > DJFranck@equilon.com
> > 1971 Pantera #1777 /  1969 Mustang Mach 1
> > Wk 713-346-3211 / Wk Fax  713-241-8234
> > HM 281-856-8049 / Hm Fax  281-859-9531
> > http://www.geocities.com/MotorCity/Downs/9415
> > "Some people said it couldn't be done.  What they meant was "They couldn't
> > do it".