----- Original Message -----
From: Tim Ronak
To: Bob Palmer
Sent: Wednesday, June 02, 1999 8:15 AM
Subject: Re: Bob palmer sparkplug fiasco
Robert,
I have seen enough to know that I have not seen it all and it may be that
your engine might like a little extra timing but my gut feeling is that
there is way too much total timing.
I understand that it would not ping when lugging down low as the timing
would only be around 20-22 degrees at 2000RPM but it would eat the engine
really fast at high RPM. Detonation is not necessarily audible as it is a
function of the type of fuel used and it ability to resist preignition. I f
you deliberatly ignite the gases with the piston still accelerating up the
bore it will be fighting the explosion and definitely generate less HP as it
loses energy fighting the pressure of the gases igniting. the other thing
that occurs is that preignition is encountered the rod and crank bearings
may contact the crank throws and mains if the detonation is severe enough.
If you can hear it it is severe enough to do that.
I guess the best thing for you to determine the most effective timing would
be to dyno it and check the numbers. Unless of course you don't mind
changing spark plugs and bearings. (I used to do it weekly on my small block
chevy street car 406", 2 nitrous systems and jet crank, crower 5.85" rods
and Ross pistons 750+ HP from a 2 bolt 400 bolt) It quit being fun after a
while.
Good luck,
Tim Ronak
timinvan@fox.nstn.ca
PS: when i have an opportunity i will key in the dyno results into excell. I
also have flow bench data on our cylinder heads but it is in an old version
of lotus and I am not sure I know where that is. I will may an effort in the
near future to find it as benchracing is almost like real racing.
----- Original Message -----
From: Bob Palmer
To: Tim Ronak
Sent: Tuesday, June 01, 1999 5:27 PM
Subject: RE: Bob palmer sparkplug fiasco
Tim,
Thanks for the quick reply. Would like to see your dyne results sometime,
even if it is for a Chevy. At least some of the results should apply
generally, like the spark plug and ignition type (i.e., MSD, etc.). I don't
blame you for thinking I'm crazy running this much advance. And yes, I need
to quit borrowing my neighbor's timing light and get one of my own; one with
an advance indicator. His has one and says right now I'm at 44 degrees
total. I was as astounded as you are when I first found how much advance
this engine liked - or seemed to. So I rechecked things like - had the
dampener shifted, rechecked TDC etc. Nope, everything checked out. Maybe got
the wrong timing tape on the dampener? Don't think so; it's the same as I
had with the previous 289 heads. And besides, now the timing light confirms
the advance numbers. Wally Cartwright, who had something to do with the
Chittendon drag car and built some of the best small block Fords in So.
Calif. said his motors always ran best at 34 degrees total advance. In my
experience with three or four previous 289 motors, they liked maybe just a
tad more - like 36 degrees. Nothing like this last motor with the 351W
heads. Another thing about this motor; I absolutely, positively can't get it
to ping. Typically, what I do to see how close I am to right is to lug the
motor down and give it full throttle and see if it pings. Even with 10.9:1
compression and 92 octane pump gas, this motor will not ping. What finally
happens is at wide open throttle and very high rpms - ca. 5-6,000 - it
starts pre-detonating. Not a very user friendly way to behave, eh?
Regarding my distributor, it's an ACCEL and it's real easy to adjust the
advance curve. Used to have 20 degrees total advance almost all in by 3,000
rpm. This worked great with my previous engines; 14-16 degrees initial,
34-36 total. I added ten more degrees of mechanical advance so I could lug
it around in stop-and-go traffic and still get the total advance I needed. I
actually tried it with 35 degrees, but dropped back to 30, which seems to
work real well - at least most of the time. When I really run the car hard
I'm at Willow Springs racetrack, which is up about 3,000 feet or so I think.
It runs real strong there. For example, I was keeping right up with a Viper
down the straightaway. We chased each other for about ten laps and called it
a draw. I run about 7,000 rpm or so down the straights. It runs real good up
there, but maybe the altitude is saving me. But, the rest of the story about
when I first got the Tiger back on the street with these heads is, a friend
of mine talked me into going out and watching the midnight drag races. And
yes, I still hadn't put the timing light on it yet. And no, I hadn't at all
planned on doing any racing myself. But as time wore on and my friend kept
egging me on, I succumbed to temptation. I would up beating the best of the
best, which was a Camaro that was running nitrous. I would hear a little
pre-detonation just before I shifted each time, so next morning I get out
the timing light - about time, huh! - and I was astounded that I had more
than 50 degrees of total advance; actually 55 degrees I seem to recall. I've
asked various people if they can explain this and most of the say I'm nuts.
Except Dale Akuszewski, who said he had pretty much the same experience with
his 351W heads. I did a lot of porting and polishing of these heads myself,
and chamfered every edge in the combustion chamber and on the pistons as
well. Don't know if this is a factor, and the chamber design on the 351's
may be more conducive to using more advance, but I haven't heard much about
any systematic differences compared with the earlier 260 & 289 heads in this
regard.
Well, gotta run now. If you have any further comments, I'd like to hear
them
Brgds,
Robert L. Palmer
UCSD, Dept. of AMES
rpalmer@ucsd.edu
rpalmer@cts.com
619-822-1037 (o)
760-599-9927 (h)
-----Original Message-----
From: Tim Ronak [mailto:timinvan@fox.nstn.ca]
Sent: Tuesday, June 01, 1999 3:24 PM
To: Bob Palmer
Cc: Tiger News Group Address
Subject: Re: Bob palmer sparkplug fiasco
Robert,
The Info i gave is accurate and if you would like I could create
electronic versions of the graphs as the only data i have is what was
printed out of the dyno printer. When i have time which may not be too soon
i will be sure to key that stuff in although it is a small block chevy. One
point that astounded me is that you are running 50 degrees of advance with
your small block ford (Can you say P-P-Ping and good bye plugs). That would
create a significant amount of detonation. As i grew up cash challenged in
order to go fast I had to learn all of this stuff myself and I have a
suggestion. I t would seem that your "factory??" distributor has too much
timing built into it to run at the stock 6 degree advance setting and still
achieve aroun 36-38 degrees total timing for performance use. Most of the
performance engines I have played with ..Ford , Chevy, and Chrsley (SP) all
liked between 37-40 Total timing. With the stock distributor having soooo
much timing built in to it (about 32 = 38degrees - 6degrees) in order to
limit the total timing we need to set the initial really low which
definitely impairs throttle response and low RPM performance. Having more
initial timing really helps make the engine FEEL more responsive but it is
bad if at high RPM the engine rattles it's brains out. One of the tips that
I have used is to get the stock distributor recurved to permit 13-16 degrees
of initial with only about 21-22 degrees of timing built into the
distributor itself. This would allow an initial timing of say 16 degrees and
limit total to around 37-38 degrees. (16 initial plus 22in the distributor
would give us 38 total) We found that he extra timing beyond 39 degrees
total did not help horse power as the detonation that it generated started
to erode the any gains low down in RPM. Our small block liked 39 degrees the
best with 16 initial. The other key is to get the distributor to get all of
the timing (at least 17-18 degrees of distributor advance) in mostly by 3000
RPM with maybe 2 or 3 degrees coming in from 3000-6000 RPM. I am not sure
where you live but you should have a performance shop that still understands
the basics and has a good distributor machine. In order to limit the total
internal advance it may be necessary to weld a little on the distributor to
limit the travel for the advance mechanism and then file it out until you
achieve the amount of advance rotation required.
Of course this is all of a mute point if that broken timing light stays
broken. (Get one with the advance knob to facilitate the total timing
adjustment.)
Regards,
Tim Ronak
B382000680
from the frozen North
timinvan@fox.nstn.ca
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