Tuning for altitude

Chevy55 · 06-02-2022, 07:09 PM

Here's an excellent article from David Reher, Reher-Morrison Racing Engines.
https://rehermorrison.com/tech-talk-...-with-bad-air/

GTX JOHN · 06-03-2022, 02:52 AM

I run 6 Degrees more timing in Denver than Wild Horse in
the wagon.

GTX JOHN · 06-03-2022, 03:05 AM

First pass ever in Denver = I shifted from 1st to 3rd because it was
so long in 1st gear - I thought it was already in 2nd gear.

Darcy Clarke · 06-03-2022, 07:49 AM

One thing I found out a week or so ago is be prepared to turn your fuel pressure down. I ran at Boise with both cars, same fuel and ignition systems and the Stocker Ran good the Superstock was 3 tenths slow. I chased my tail changing everything I could and a good friend I texted said lower the fuel pressure. I did and my 60 foot went from 1.35 to 1.26. Both cars run the same carbs, same fuel pressure but obviously the Superstocker is more sensitive due to the power level. I have passed this along to as many as I can.

6254
A/SA SS/EA
Darcy Clarke

Ralph A Powell · 06-03-2022, 08:04 AM

Do both have carb’s?

Darcy Clarke · 06-04-2022, 05:18 PM

Quote:

Originally Posted by Ralph A Powell

Do both have carb’s?

Yes they both have the same carbs.

Ralph A Powell · 06-06-2022, 08:08 AM

When I was working at the Ford Text track in Dearborn we would go on test trips to Denver where Ford had a small facility at Colorado Springs th do high altitude testing on fuel systems and brakes. At that time Ford had High Altitude kits for carb usage over 5000 ft sign included inmost jets,power valves and dist springs. They were in the parts catalog at Ford dealers.

Tom Meyer · 06-06-2022, 09:59 PM

I think Daves car is a 66 Chevelle 283/220 stocker. The carb on this combo is 485 cfm 4gc maybe with a cast iron 459 intake? Not alot of air flow. Back in the day my SS 283 with the same carb responded to leaning it out with jetting. The 2 plane intake with small lift cam will not have as good as fuel signal in the boosters as my SS motor. Also if he is running a glide with the one gear change, it may respond to higher rpm on the shift. But it is what it is. Good luck. Tom

Eric Bell · 06-03-2022, 11:07 AM

Quote:

Originally Posted by Darcy Clarke

One thing I found out a week or so ago is be prepared to turn your fuel pressure down. I ran at Boise with both cars, same fuel and ignition systems and the Stocker Ran good the Superstock was 3 tenths slow. I chased my tail changing everything I could and a good friend I texted said lower the fuel pressure. I did and my 60 foot went from 1.35 to 1.26. Both cars run the same carbs, same fuel pressure but obviously the Superstocker is more sensitive due to the power level. I have passed this along to as many as I can.

6254
A/SA SS/EA
Darcy Clarke

Darcy.........try that lower fuel pressure at sea level as well.

rod · 09-05-2022, 07:41 PM

thats funny John.

06-02-2022, 07:09 PM	#1
Chevy55 Banned Join Date: Nov 2014 Posts: 324 Likes: 625 Liked 179 Times in 89 Posts	Re: Tuning for altitude Here's an excellent article from David Reher, Reher-Morrison Racing Engines. https://rehermorrison.com/tech-talk-...-with-bad-air/

06-03-2022, 02:52 AM	#2
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,737 Likes: 2,813 Liked 2,489 Times in 699 Posts	Re: Tuning for altitude I run 6 Degrees more timing in Denver than Wild Horse in the wagon. __________________ John Irving 741 Stock 741 Super Stock Last edited by GTX JOHN; 06-07-2022 at 01:41 AM.

06-03-2022, 03:05 AM	#3
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,737 Likes: 2,813 Liked 2,489 Times in 699 Posts	Re: Tuning for altitude First pass ever in Denver = I shifted from 1st to 3rd because it was so long in 1st gear - I thought it was already in 2nd gear. __________________ John Irving 741 Stock 741 Super Stock Last edited by GTX JOHN; 06-07-2022 at 01:42 AM.

06-03-2022, 07:49 AM	#4
Darcy Clarke Member Join Date: Mar 2008 Posts: 202 Likes: 22 Liked 529 Times in 36 Posts	Re: Tuning for altitude One thing I found out a week or so ago is be prepared to turn your fuel pressure down. I ran at Boise with both cars, same fuel and ignition systems and the Stocker Ran good the Superstock was 3 tenths slow. I chased my tail changing everything I could and a good friend I texted said lower the fuel pressure. I did and my 60 foot went from 1.35 to 1.26. Both cars run the same carbs, same fuel pressure but obviously the Superstocker is more sensitive due to the power level. I have passed this along to as many as I can. 6254 A/SA SS/EA Darcy Clarke

06-03-2022, 08:04 AM	#5
Ralph A Powell Member Join Date: Oct 2017 Location: Bay City Texas Posts: 389 Likes: 2 Liked 225 Times in 136 Posts	Re: Tuning for altitude Do both have carb’s?

06-06-2022, 08:08 AM	#7
Ralph A Powell Member Join Date: Oct 2017 Location: Bay City Texas Posts: 389 Likes: 2 Liked 225 Times in 136 Posts	Re: Tuning for altitude When I was working at the Ford Text track in Dearborn we would go on test trips to Denver where Ford had a small facility at Colorado Springs th do high altitude testing on fuel systems and brakes. At that time Ford had High Altitude kits for carb usage over 5000 ft sign included inmost jets,power valves and dist springs. They were in the parts catalog at Ford dealers.

06-06-2022, 09:59 PM	#8
Tom Meyer Senior Member Join Date: Aug 2003 Location: Pierce NE Posts: 936 Likes: 78 Liked 354 Times in 120 Posts	Re: Tuning for altitude I think Daves car is a 66 Chevelle 283/220 stocker. The carb on this combo is 485 cfm 4gc maybe with a cast iron 459 intake? Not alot of air flow. Back in the day my SS 283 with the same carb responded to leaning it out with jetting. The 2 plane intake with small lift cam will not have as good as fuel signal in the boosters as my SS motor. Also if he is running a glide with the one gear change, it may respond to higher rpm on the shift. But it is what it is. Good luck. Tom __________________ Tom Meyer 5240 SS Stock ???

09-05-2022, 07:41 PM	#10
rod Member Join Date: Dec 2009 Location: Kingman, NW AZ. in the middle of the longest stretch of Route 66 Posts: 315 Likes: 0 Liked 20 Times in 15 Posts	Re: Tuning for altitude thats funny John.