[promptcritical]

Originally Posted by Dragncar

Thing is, pretty much all 455s with iron heads fall flat at 5200 RPMs. I have a well ported set of HOs that are already done like what the OP will end up with. My car ETs best when I shift @ 5200-5300 RPM. Just can not get enough air through them. Been a great engine though, retired it after its best ET to date, 10.84 after 28 years.

More cam maybe?

[AG]

I shift my 335 cfm E heads at 6600 rpm because they should be. I could shift at above 7000 rpm but it'snot going to make the car quicker.

[ponjohn]

Originally Posted by AG

I shift my 335 cfm E heads at 6600 rpm because they should be. I could shift at above 7000 rpm but it'snot going to make the car quicker.

Have you tried shifting at 6k rpm? ( Curious)

[Dragncar]

Originally Posted by 68azbird

So how do my 220 cfm 164cc D ports spin up to 7000 RPM and still pull?????

They don't. Its placebo. Shift it at 5300, it takes 200RPM for the tranny to get it done so you shift at 5300 to get a 5500 RPM shift, and you WILL go quicker.

[Dragncar]

Originally Posted by gtofreek

And your street car runs 11.40's in Phoenix with crap gas and only 9:1 compression.

My HO is 9-1 CR, runs on 91 crap gas and runs 10.80s @3500lbs shifting into high gear by the time I make 175 feet.

[Dragncar]

Originally Posted by promptcritical

More cam maybe?

I run a Harold UD solid roller, just under .700 lift, .264-.271 ish. Its not small.

9-1 455 HO pump gas is my wheelhouse. I am not saying I am the fastest 69 GTO with a HO, but I do not know of any off the top of my head that have been quicker than 10.84 at 3500+ lbs. I am sure they exist, but they are not falling off trees either.
Thing is, its a TRW engine.If I had modern pistons and V pump I bet I could get 10.60-50 out of it.
Dan Whittmore ported the heads, ha is as good as there has ever been at the iron head, PMD block Pontiacs. He was Jim Butlers machinist way back.
You can get a bit more flow out of RAIVs but 300-305 is about it before they piss water. He is the one who explained the shift points and why. Did what he told me too, runs quick and has not spun a bearing in almost 30 years of running the piss out of it.

BTW, I would love to see a dyno sheet of a iron head Pontiac 455 pulling to 6800 RPM.

[Cliff R]

Quick ET's are more a product of traction and leaving really hard that cylinder head flow. It's not even really much of a player at the launch RPM for most street cars. Years ago we installed a stone stock set of #46's with small valves and 30 degree intake seats. They only got better springs and screw in studs. They went on a 455 build with a 247/254 @ .050" Crower cam and the engine pulled very hard well past 5500rpm's and pushed a pretty heavy 1981 Firebird to high 11's at the track without much effort.

My car hooks solid and leaves well. It has 295cfm KRE heads on it but really doesn't care where you shift it at far as ET is concerned. The difference between shifting at 5000rpm or clear up at 5800rpms is about .03-.04 seconds and less than 2MPH trap speeds.

This happens mostly because I'm running a really tight converter and 3.42 gears so it "hangs" out quite a while in low gear and at lower RPM's till we get the car moving pretty good.......FWIW.......Cliff

[slowbird]

Originally Posted by Dragncar

My HO is 9-1 CR, runs on 91 crap gas and runs 10.80s @3500lbs shifting into high gear by the time I make 175 feet.

Go to Phoenix and let us know how your car runs!

[Dragncar]

Originally Posted by slowbird

Go to Phoenix and let us know how your car runs!

Ah I knew you would show up here. Cars from here lose less then a tenth going over to Redding, where its HOT. We have a group that has family in Phoenix and race both places. Cars lose a bit, so what. Its bracket racing.

You peeps have raced plenty of 455s with iron heads. Care to share shift points, where they run best at ?

[slowbird]

Originally Posted by Dragncar

Ah I knew you would show up here. Cars from here lose less then a tenth going over to Redding, where its HOT. We have a group that has family in Phoenix and race both places. Cars lose a bit, so what. Its bracket racing.

You peeps have raced plenty of 455s with iron heads. Care to share shift points, where they run best at ?

Your track is 30ft above sea level, not hard to make a car look fast when you race in mineshaft air every weekend! Redding is only 500ft above sea level. Most everyone else is 1000+ft and then throw in crap air and things really change.

[Dragncar]

Here is had Dan explained it to me. 455s have a long stroke and that gives them great piston/ring speed. The pistons are pulling down very fast at a given RPM compared to other makes. Combine that with trying to suck all that air through the small holes that Pontiac ports are, kinda small bore and what you get is the pistons starts pulling away from the best push from expanding gasses past 5800. Sure, you can rev them higher. But Pontiacs with iron heads are still kinda lazy rev,ers, mid range torque beasts.
Tune for it, gear for it and get the right converter.

Big top end changes all that. But its a fools game to think you can spin up a 455 with PMD heads unless you do serious modifications.

[Dragncar]

Originally Posted by slowbird

Your track is 30ft above sea level, not hard to make a car look fast when you race in mineshaft air every weekend! Redding is only 500ft above sea level. Most everyone else is 1000+ft and then throw in crap air and things really change.

You did not answer the question.

Medford OR is another local track. 1300+ feet, in a hot b!tch of a valley with berms down both sides. So they lose a tenth, tenth and a half, big deal.
So I go up there and run a 10.98.I am good with that.

Getting sick of the "mineshaft air" bull sh!t. So when I get the 461 High Port pump gas engine in are you going to talk junk about whatever it runs ? Then the 540 Gabby engine too ??

[slowbird]

Originally Posted by Dragncar

You did not answer the question.

Medford OR is another local track. 1300+ feet, in a hot b!tch of a valley with berms down both sides. So they lose a tenth, tenth and a half, big deal.
So I go up there and run a 10.98.I am good with that.

Getting sick of the "mineshaft air" bull sh!t. So when I get the 461 High Port pump gas engine in are you going to talk junk about whatever it runs ? Then the 540 Gabby engine too ??

What question?
So those of use that loose 3tenths for mine shaft fall air to crap summer air don't know what we're doing. You'll loose a lot more than a tenth or .15 if you ever run in some crappy air

[Stan Weiss]

Anyone look at time area? Anyone plot head flow against camshaft (Yes you need to have a Cam DR file)?



If atmospheric conditions don't really effect HP very much. Why use a correction factor when dynoing an engine?

Stan

[Dragncar]

Originally Posted by slowbird

What question?
So those of use that loose 3tenths for mine shaft fall air to crap summer air don't know what we're doing. You'll loose a lot more than a tenth or .15 if you ever run in some crappy air

Stop putting words in my mouth. I did not say "anyone" who races in crappy air does not know what they are doing. Cars that race at sea level is the gold standard, thats what your car runs. We all know cars slow down in bad air, its not a knock on them.

Now the question in all this, and I asked for your considerable expertise on shift points for a good running 455 with iron heads. I say shifting at 6500 out of 1st or 2nd is lunacy for the vast majority.

[Steve C.]

When to shift
http://www.datsuns.com/Tech/whentoshift.htm

Optimum Shifting Point Calculator
http://www.bgsoflex.com/shifter.html

The Optimal Shift Point
http://www.welltall.com/ymc/discovery/car/shiftpt.html



.

[Steve C.]

Years ago Cliff Ruggles was kind enough to send me a Q-jet carb to try on my car. For interest we wanted to make a few back-to-back runs to compare with my Holley HP950 carb using a Performer RPM intake at the time. This leads to a tale about shift points that relates here....

That particular 462 combo when first built made peak power on the engine dyno at 5800 rpm. At that time with this street combo in place the car was not being seriously raced and was seldom on the track, but when it was the shift light had a 6000 rpm shift chip installed. We never spent much time trying to optimize shift points, shifting at 200 rpm over peak power rpm seemed to work out ok. However before Cliff sent the carb to test we made a cam change with 6 degrees less intake duration. With the Holley carb in place on the first run the car was shifted at 6000 rpm..... it only ran 11.77 at 114.10 mph.
Ouch, it was a dog !
The reason, we had forgotten to change the shift chip and the engine was now making peak power at a lower rpm with the smaller cam. So we then changed to the only other shift chip on hand at the time, it was for 5400 rpm. We then made another run with the Holley carb but this time shifting at the lower rpm resulted in a 11.54 at 116.73 mph time. Never did try to optimize it as we were there to do a carb test, I'm sure it would of picked up some if we played around.

( And a fwiw, Cliff's modified Q-jet performed very well shifted at the same 5400 rpm with a 11.64 at 115.59 mph. I'll suggest it had more in it as well had we tuned a bit and tried different shift points )

.

[gtofreek]

You know, my customer started this post in the street section because they thought it would be nice to show this build as it progresses. It is for a street car, but seems it has turned into a pissing match about when to shift a 455 in a drag race scenario. WHO CARES! That is not what this thread was started for. If it was, it would be in the race section.

BTW Dragncar, 68AZbirds 455 heads do actually only flow in the mid 220's. They are #16 D-ports. I know because I did the valve job and flow tested every port. Also his car does not have a roller cam in it. It has a Harold Brookshire flat tappet cam in it. It also has dished pistons and is 9:1 and a true street car. I've personally seen it run 11.60's in the dead of summer in Phoenix with pump gas and boiling the fuel to the point where it only had about 1-2 PSI of fuel pressure at the end of the track. It's run 11.40 with a little better air, but Phoenix never really has great air, and Tucson is even way worse as our track is at 3075 feet, and our air quality is usually in the 5000-7000 foot range.

[promptcritical]

Originally Posted by gtofreek

You know, my customer started this post in the street section because they thought it would be nice to show this build as it progresses. It is for a street car, but seems it has turned into a pissing match about when to shift a 455 in a drag race scenario. WHO CARES! That is not what this thread was started for. If it was, it would be in the race section.

BTW Dragncar, 68AZbirds 455 heads do actually only flow in the mid 220's. They are #16 D-ports. I know because I did the valve job and flow tested every port. Also his car does not have a roller cam in it. It has a Harold Brookshire flat tappet cam in it. It also has dished pistons and is 9:1 and a true street car. I've personally seen it run 11.60's in the dead of summer in Phoenix with pump gas and boiling the fuel to the point where it only had about 1-2 PSI of fuel pressure at the end of the track. It's run 11.40 with a little better air, but Phoenix never really has great air, and Tucson is even way worse as our track is at 3075 feet, and our air quality is usually in the 5000-7000 foot range.

Thank you Paul.

[glhs#116]

Yeah. I keep coming back to this thread hoping that it has returned to talking about (and maybe some pics of) this build.

Sam