perf-list-digest Friday, December 11 1998 Volume 01 : Number 168



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Ford Truck Enthusiasts - Performance
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In this issue:

RE: FTE Perf - Long rods and more.
FTE Perf - 429
FTE Perf - Roller Rockers?
RE: FTE Perf - 429
RE: FTE Perf - Roller Rockers?
RE: FTE Perf - Roller Rockers?
Re: FTE Perf - Roller Rockers?
Re: FTE Perf - 429
Re: FTE Perf - Roller Rockers?
FTE Perf - Roller Rockers?
Re: FTE Perf - Long rods and more.

=======================================================================

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Date: Thu, 10 Dec 1998 11:52:43 -0500
From: Sleddog
Subject: RE: FTE Perf - Long rods and more.

nice post Muel,

just wnated to add something about the dynamic compression. dynamic
compression changes constantly. when the volumetric efficiency is
increased to say, 105%, the dynamic compression ratio is actually higher
than the static compression ratio.

when VE gets this high, over 100%, it is because of intake & exhaust tuning
appropriate for a particular engine. as an engine, even a more stock
engine, goes through the different possibilities of rpm, throttle position,
temperature, etc, the dynamic CR will change from lets say, a very low
value at deceleration, to a high (possibly higher than static CR) value at
the engines best operating rpm and wide open throttle. the best operating
rpm would be decided by the intake, exhaust, and the head/valves. this
includes the shape, size, and length of each. (this is ignoring the
smaller deviations made by different rod ratios and such, their effect is
smaller than the afore mentioned parts)

The cam would need to be matched to the other parts for this rpm for max
power. when everything is matched and done right, efficiency over 100% can
be achieved, creating more than the static CR. years ago, it used to be
thought that only top notch engines like formula one or such could achieve
these kinds of VE. This really isn't true anymore. with standard
aftermarket parts, and a talented builder VE's this high can be achieved by
many more people.

although i have no proof of this, i think my engine is capable of 100% or
maybe a hair over VE in my puller. the engine certainly was choked with
the small carb, that at 80% should be enough. at 100% it needs over 1200
cfm. and a very similiar engine it appeared to operate also carb limited
with a smaller dominator (1050cfm IIRC) and woke up with a bigger
dominator. my point being, if it can use more carb, it must be operating
at a level that it needs that much more, and the math shows that the VE
would be very close to 100%.

i think i am rambling now.

sleddog

- ----------
From: Chris Samuel[SMTP:fourmuelz email.msn.com]
Sent: Monday, November 09, 1998 10:48 PM
To: A Perf-List
Subject: FTE Perf - Long rods and more.

This took all night to go across town!
So. Then I rewrote it and added to it and... for what it'z worth here ya
go!

When describing the intake characteristics of the long rod engine I
incorrectly said something to the effect that the Maximum Velocity of the
Intake Charge occurs at +\- 79? ATDC. WRONG!

The Maximum Piston Speed occurs about here, not the Intake Charge speed.
The
Intake Charge speed occurs after this point. This is due to the inertia
effect acting in the Intake Charge: "A body at rest tends to stay at rest."

As I described earlier the Long Rod causes the piston to dwell at TDC. If
this dwell effect in fact happens and nothing else changes then the
acceleration of the piston must be higher through the remainder of the
stroke.

Why?

When a crankshaft makes one complete revolution at a given speed the piston
must travel a distance of the stroke twice; once down and once up in a
specific amount of time (RPM). If the geometry is such that the piston
spends more time approaching and departing TDC then it has less time to get
to BDC; the total amount of time being constant. This then requires that
the Piston accelerate faster during the remainder of the stroke.
If the piston acceleration is higher during the middle of the stroke and we
have the valve open as close to maximum lift as we can at the same time.
And the intake system optimized for this effect we can draw in a greater
quantity of the intake charge thereby potentially making more power.
Couple
this to the effect of getting more pressure acting on the piston during
combustion. This higher pressure due to the increased dwell time at TDC
and
you can see the advantages to the long rod.

The catch here is that the Intake Closing Event of the Camshaft must be
later in the cycle to get the full value of the increased Intake Charge
velocity. Here again due to the inertia effect on the intake charge: "A
body in motion tends to stay in motion." Unfortunately as the Intake valve
is closed later the Effective Compression Ratio is reduced. The Effective
Compression Ratio in conjunction with the amount of Intake Charge
determines
the pressure hence power produced.

Effective Compression Ratio is not the same as the Calculated Compression
Ratio. To find the Effective Compression Ratio (sometimes called Dynamic
Compression Ratio) you must NOT use the full swept volume of the cylinder
but the volume that remains after the intake valve closes. For example
suppose that we had a "perfect" engine.
The intake valve opens exactly at TDC and closes at BDC. We can easily
calculate the Compression Ratio by using the full stroke length. But in
the
real world to take advantage of the inertia in the Intake Charge we leave
the valve open after BDC to allow the Intake Charge to continue to ram it
self into the cylinder and we close the valve at say 10? ABDC. The
Compression Ratio is now calculated the same way less the amount that the
piston had moved above BDC (10? Crank Rotation). If I just did my math
right that would be a reduction in the stroke length of 0.0304 on a 4.0"
stroke at 10? ABDC.
________________________________________________________________________
____
_____
Stroke Rod length Max Piston Velocity Max Piston Acceleration
3.5 5.954(351W) 95.24 6728
3.5 6.58(400M) 94.63 7961
________________________________________________________________________
____
_____
Stroke Static CR Rod Lnth. Int.Cls. Eff. CR Dr. 0.05
3.5 9.0 5.954 29?ABDC 8.59 204(M-6250-A331)
59?ABDC 7.31 234(M-6250-A334)
________________________________________________________________________
____
_____
I would be remiss if I did not point out that by changing "only" the
connecting rod length; due to the change in the geometry; the Effective
Compression Ratio will be less. 29?ABDC a change from 5.954 to 6.58 will
reduce the Effective Compression Ratio by 0.01 which is not enough to
notice
on the dyno or track.

FWIW
Ever wonder why a long duration camshaft requires a higher Compression
Ratio. The longer Duration of the Camshaft reduces the Effective
Compression
Ratio so you must build in more static Compression to compensate.
Ever wonder why retarding the Camshaft-Crankshaft phasing can increase the
bottom end power? You just closed the intake valve earlier and raised the
Effective Compression Ratio.

The intake closing point is one of the most important indicators in where
an
engine will build power and is critical to whatever rod you run, and must
be
changed when the rod length is changed. How did I get here??

Ok I got-ta stop!

I think that I just said it correct! Of course I thought that the first
time
too!

Later.
Muel

PS: Ol' Sleddog is being modest the Spread sheet is good! I used it in the
above example.


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Date: Thu, 10 Dec 1998 11:26:50 -0800 (PST)
From: Chuck Stephens
Subject: FTE Perf - 429

I currently have 2 429s,a 69 with a CR of 11 or 11.5 to 1 and a 73
with a CR of 9.5 to 1. The difference is in the heads.........Chuck



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Date: Thu, 10 Dec 1998 13:33:58 -0700
From: Neil Johnson
Subject: FTE Perf - Roller Rockers?


Ok guys, got I question for ya, I have a 72 F-100 that I'm rebuilding the
390 for. Here's what I've got so far.. I'm sitting 401 c.i.d. Edlebrock
Performer RPM intake--750 Holley--Lunati Bracket Master 2 cam...Duration
.050 230/230
Gross dur 292
Gross lift .544
Lobe Separation 109
I have stock heads for now, but they have a lil porting done to them. I
went to a 427 valve size for the intakes, they were pretty ugly. So here
comes the question, with that kind of cam, would it be best to go w/ roller
rockers, or would it be best to stay with the mechincal ones that I have
now? Would I have to "adjust" the rollers more? I would greatly appreciate
any info!!

Corbin


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Date: Thu, 10 Dec 1998 15:35:42 -0500
From: Sleddog
Subject: RE: FTE Perf - 429

deck height on the blocks was also increased as well as the chamber volume
of the heads.

so when rebuilding for a higher CR, the heads and the block can be milled.
the later blocks are IIRC .020" taller. the heads ranged from around 73cc
to almost 100cc. i have a set of 1973 heads that should be slightly over
90cc i beleive, but actually measured almost 100cc.

i think the casting and machining on these heads was not real precise, and
many parts went thru with a very high difference in actual dimensions.

deck height of the blocks sems to be a bit closer to being what it should
be on most blocks i have seen, but they may also have already been machined
once since ford built them many times.

sleddog

- ----------
From: Chuck Stephens[SMTP:chuck73507 yahoo.com]
Sent: Thursday, December 10, 1998 6:26 AM
To: perf-list ford-trucks.com
Subject: FTE Perf - 429


I currently have 2 429s,a 69 with a CR of 11 or 11.5 to 1 and a 73
with a CR of 9.5 to 1. The difference is in the heads.........Chuck



_________________________________________________________
DO YOU YAHOO!?

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------------------------------

Date: Thu, 10 Dec 1998 15:45:04 -0500
From: Sleddog
Subject: RE: FTE Perf - Roller Rockers?

i am a little confused, as the FE uses shaft mounted rockers. i was not
aware that there was any roller rockers around for the FE. lifters maybe,
but?

anyway, the stock rockers are good for that size cam IMHO, but i do
recommend the adjustable rockers even if it is a hydraulic lifter cam.

that size cam with shaft rockers shuold be no problem. seen FE's with C/C
292 profiles run the stock rockers no problems.

sleddog

- ----------
From: Neil Johnson[SMTP:mustang sedona.net]
Sent: Thursday, December 10, 1998 3:33 PM
To: perf-list-digest ford-trucks.com
Subject: FTE Perf - Roller Rockers?


Ok guys, got I question for ya, I have a 72 F-100 that I'm rebuilding the
390 for. Here's what I've got so far.. I'm sitting 401 c.i.d. Edlebrock
Performer RPM intake--750 Holley--Lunati Bracket Master 2 cam...Duration
.050 230/230
Gross dur 292
Gross lift .544
Lobe Separation 109
I have stock heads for now, but they have a lil porting done to them. I
went to a 427 valve size for the intakes, they were pretty ugly. So here
comes the question, with that kind of cam, would it be best to go w/ roller
rockers, or would it be best to stay with the mechincal ones that I have
now? Would I have to "adjust" the rollers more? I would greatly appreciate
any info!!

Corbin


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------------------------------

Date: Thu, 10 Dec 1998 15:37:24 -0600
From: William S Hart
Subject: RE: FTE Perf - Roller Rockers?

At 02:45 PM 12/10/98 , you wrote:
>i am a little confused, as the FE uses shaft mounted rockers. i was not
>aware that there was any roller rockers around for the FE. lifters maybe,
>but?
>
A company just came out with an ad in Mustang Monthly advertising these,
they looked pretty interesting.


Just my 2cents

Bill

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------------------------------

Date: Thu, 10 Dec 98 18:47:46 PST
From: "Doug Ridder"
Subject: Re: FTE Perf - Roller Rockers?

There are two different brands of adjustable roller rockers available for=
the FE that I know of.
1st Harland sharp makes a set that are about a reasonable as I know of =
you can get them through summit.
2nd Dove manufacturing makes probably the best set available but if you =
buy the rockers, shafts, and end stand supports to really make the set =
up strong it will cost over $1000 just for those pieces.

Sharp also has some heavy duty shafts but they don't make the end support=
s. If you are worried at all about the strength of the rocker I think =
you should deffinately get the heavy duty shafts because I have heard of =
people breaking off the ends of the shafts with big cams, right past the =
last mounting post. As of yet I have never heard of anyone talk about =
breaking the rocker itself.

I currently run a hydrolic cam with about 236 degrees of duration .050 =
and about .565 lift in my 390 puller. I have been running the factory =
origional rockers and shafts in it for two seasons and haven't had any =
problems yet (knock on wood), however, the only reason I haven't gone to =
roller rockers is the price.

If I were to ever put a solid lifter or roller lifter cam in it I would =
definately use the heavy shafts and rollers because I think they are a =
little harder on the rockers as compared to the hydrolic lifers which ten=
d to not follow the cam profile as well.

Doug
- ----------
> At 02:45 PM 12/10/98 , you wrote:
> >i am a little confused, as the FE uses shaft mounted rockers. i was =
not
> >aware that there was any roller rockers around for the FE. lifters =
maybe,
> >but?
> >
> A company just came out with an ad in Mustang Monthly advertising these=
,
> they looked pretty interesting.
>
>
> Just my 2cents
>
> Bill
>
> Auto Links http://www.ford-trucks.com//lc/lc.php?action=do&link=http://www.public.iastate.edu/~wish/cars.html
> '73 1/2 ton 4x4 Ford http://www.ford-trucks.com//lc/lc.php?action=do&link=http://www.public.iastate.edu/~wish/Trucks/truck=
.html
> '96 Mustang GT http://www.ford-trucks.com//lc/lc.php?action=do&link=http://www.public.iastate.edu/~wish/Cars/mustang=
.html
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Date: Thu, 10 Dec 98 18:53:55 PST
From: "Doug Ridder"
Subject: Re: FTE Perf - 429

As far as I know the stock head chamber volumes we 73cc on D0 and earlier=
heads including the cobra jet. 92cc there after D1 and up including the=
police interceptor head. And somewhere in there they started making a =
97cc head in the newer stuff. But I have now doubt that you can find a =
wide range in variance.

- ----------
>
> deck height on the blocks was also increased as well as the chamber vol=
ume
> of the heads.
>
> so when rebuilding for a higher CR, the heads and the block can be mill=
ed.
> the later blocks are IIRC .020" taller. the heads ranged from around =
73cc
> to almost 100cc. i have a set of 1973 heads that should be slightly =
over
> 90cc i beleive, but actually measured almost 100cc.
>
> i think the casting and machining on these heads was not real precise, =
and
> many parts went thru with a very high difference in actual dimensions.
>
> deck height of the blocks sems to be a bit closer to being what it shou=
ld
> be on most blocks i have seen, but they may also have already been mach=
ined
> once since ford built them many times.
>
> sleddog
>
> ----------
> From: Chuck Stephens[SMTP:chuck73507 yahoo.com]
> Sent: Thursday, December 10, 1998 6:26 AM
> To: perf-list ford-trucks.com
> Subject: FTE Perf - 429
>
>
> I currently have 2 429s,a 69 with a CR of 11 or 11.5 to 1 and a 73
> with a CR of 9.5 to 1. The difference is in the heads.........Chuck
>
>
>
> _________________________________________________________
> DO YOU YAHOO!?
> >
> =3D=3D FTE: Uns*bscribe and posting info http://www.ford-trucks.com/faq=
.html
>
>
>
>
> =3D=3D FTE: Uns*bscribe and posting info http://www.ford-trucks.com/faq=
.html


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------------------------------

Date: Thu, 10 Dec 98 18:59:12 PST
From: "Doug Ridder"
Subject: Re: FTE Perf - Roller Rockers?

Have you allready machined the heads to accept that intake valve?

If so why did you elect to go bigger on the intake side and what are you =
using this engine for?



- ----------
>
> Ok guys, got I question for ya, I have a 72 F-100 that I'm rebuilding
> the
> 390 for. Here's what I've got so far.. I'm sitting 401 c.i.d. Edlebro=
ck
> Performer RPM intake--750 Holley--Lunati Bracket Master 2 cam...Duratio=
n
> .050 230/230
> Gross dur 292
> Gross lift .544
> Lobe Separation 109
> I have stock heads for now, but they have a lil porting done to them. =
I
> went to a 427 valve size for the intakes, they were pretty ugly. So her=
e
> comes the question, with that kind of cam, would it be best to go w/ =
roller
> rockers, or would it be best to stay with the mechincal ones that I hav=
e
> now? Would I have to "adjust" the rollers more? I would greatly appreci=
ate
> any info!!
>
> Corbin
>
>
> =3D=3D FTE: Uns*bscribe and posting info http://www.ford-trucks.com/faq=
.html


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------------------------------

Date: Thu, 10 Dec 1998 19:06:08 -0800
From: George
Subject: FTE Perf - Roller Rockers?

Excellent comment. Many people, myself included, have put a lot of research
and heavy gold into street engines and then compromised them by using
hydraulic lifters to avoid the maintenance of valve adjustment.

George Miller

If I were to ever put a solid lifter or roller lifter cam in it I would
definately use the heavy shafts and rollers because I think they are a
little harder on the rockers as compared to the hydrolic lifers which tend
to not follow the cam profile as well.

Doug



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------------------------------

Date: Thu, 10 Dec 1998 22:49:26 -0800
From: "Dave & Debby Anderson"
Subject: Re: FTE Perf - Long rods and more.

>nice post Muel,

I agree, very well written.

Sleddog - I picked up your rod ratio spreadsheet some time ago but until
recently haven't had been able to spend any time with it. I haven't tried
to understand the formulas just yet (wish I'd paid more attention in
geometry class all those years ago) but in comparing the calculated values
of two different rod lengths I'm seeing that piston velocity is the same at
0, 90 and 180 degrees and piston acceleration is the same at 45 and 135
degrees, regardless of rod length.

The greatest difference in piston velocity is at 45 and 135 degrees, when
acceleration is equivalent. Since the return stroke from 181 to 360 is a
mirror image of 0 to 180 it would appear that the longer rod increases
piston velocity from 90 deg ATDC to 90 deg BTDC with a corresponding loss in
the 90 degrees both before and after TDC. I'll chew on this a while longer
but for now I gotta admit it doesn't make sense. I would think that the
effect of the increased rod length would cause the same dwell at BDC as it
does at TDC and the acceleration increase would have to occur between these
two points, reaching a maximum at 90 and 270 degrees. Am I misreading the....


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