to advance or not to advance

[bemiller]

I put the .557 mopar cam in my dart last season and I have no complaints for it. But I installed it retarded .5 degrees. Well after a full season of racing I figure its now 2 degrees from stretch. Well my question is I have one of those desktop dyno programs and it says if I advance the cam 4 degrees total it would pick up .20. I guess the reason is the MP cams run alot of duration? Does this sound correct. I'm planning on putting one of the 6 degree keys in. Can someone please explain why 4 degrees advance can make my car faster and why would MP tell everyone to install it 0 advance, because in my world two tenths is alot of power for $6 worth of key.

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Check out http://www.donet.com/bemiller/ and let me know what you think!!

[billyclub]

Bemiller,
Typically Mopar recommends their cams be installed 2-4 degrees advanced. I just went to look in the Mope catalog, but they took out all of the descriptions for the 99 catalog. (just one more reason not to buy from them) If I recall, that one should be ground on a 108 & installed on a 106. Advancing the camshaft 4 degrees usually increases torque with a corresponding decrease in hp at peak. In addition the effective RPM range for the cam will move about 400 RPM down. This often helps cars that are a little lacking in converter or gear (or even CR) for a specific combo.

[340king]

You may have to check what the program is calling advance. In some programs, the total advance is based on equal lift(assumed single pattern profile) at TDC overlap or dual pattern equivalent(theorectical lift difference). The advance is total cam rotation required to get to the difference in lifter height required for the particular camshaft design you have chosen. In other words, some cams installed straight up 0° are listed in the computer as having 4° of advance. This advance is cut into the camshaft. I don't know if your Mopar Performance cam has this advance in it from the factory.

In Engine Analyzer, it lists the total advance from theoretical(equal lift or eqivalent). This can be confusing at first. I am not familiar with Desktop Dyno, so I can only speculate as to how it displays the info. I just wanted to pass on what I have learned about the programs I have use

[Marc]

When we run baseline tests on MP cams we always start with the cam straight up. NO advance. We very rarely (twice) advance or retard them. We've always gotten the best results with the cam straight up. Just thought I'd let you know. Good luck!!!

[mopar_nerd]

By the way, any ideas why a degreeing wheel has to cost so much? I mean, you don't use them so often that it's really worth it...(if you're not a racer). Could anyone tell me how many degrees one step or tooth on the cam wheel will make?

[bemiller]

Actually the mopar degree is only like $12. That's pretty cheap in the grand scheme of high performance.

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Check out http://www.donet.com/bemiller/ and let me know what you think!!

[Glen440]

Two years ago I played with the cam timing in my 8-1 comp 400 with the .528 Purple shaft. with five degrees advanced the car ran
consistent 13.8's. I then retarded it with a
6 degree bushing, It ran consistent 13.2's.
I went to the 8 degree bushing and it ran the same. I didn't realize that the bushing does double what it says. I didn't use a wheel on it except for when I installed the cam for 5 advanced. I wish I could of tried
right on centerline. This was in a car weighing 3750 without driver. I personally have had no luck advancing cams, they seem to make more power retarded. It ran a 13.14 in may and in september it ran a 13.15. I drove it everyday as my only car From April to November. The motor didn't slow down with wear.It had over 60 passes at the strip and beat on the street every day. I noticed the chain stretched the first time I went to the track in April. After 6 passes it went 2 tenths faster without tuning.
As for moving the cam or crank a whole tooth
I think it would be around 18-20 degrees. There is a reason they sell bushings.

Glen440

[Christopher]

I use the same cam in my old 440 engine,and I installed it straight up and it ran 11.30's in my Demon,so I never messed with it after that.

[bemiller]

I was playing with the engine program again and I finally figured out why it wants me to advance cam 4-6 degrees... because the rear tires I'm running are so tall 31*13 Mickey Thompsons with 4.56 gear. Does this sound right to anyone? Says the car should run 11.20's after I port heads and advance cam. If its as accurate as last year I'll be impressed. Said 11.73 and best et was 11.73@112 just luck? We'll see. IF ANYONE WOULD LIKE TO TRY THE PROGRAM I'M PLAYING WITH ITS CALLED DRAG STRIP ANAYLYZER AND ITS A SHAREWARE VERSION SO I'LL E-MAIL IT TO ANYONE INTERESTED. It fits on a floppy so isn't that large.

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Check out http://www.donet.com/bemiller/ and let me know what you think!!

[Christopher]

I'm using a 13x31 Firestone on a 12" rim with a 5.12 gear.This is way too much gear,and I'll be dropping down to 4.88's sometime this year.(after I get a spool and axles)I don't agree with the other posts about RPM being wasted with stock heads and valves,(not saying anyone is wrong)but on the 70 Road Runner with the 383,we started out shifting at 5500,then 5800 and finally 6500 over the course of years of racing.The lower RPM's were due to the fact at that time the "Bird" was my Dad's way to work and back.But the car responded to the higher RPM and actually wanted more.We even tried 6800 and one time 7000 rpm and that's where it didn't make any difference.

[ChristianCuda]

bemiller
I would like to take a look at that software. Would you email it to Christian.J.Knudstrup@esc1.net?

Christian

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68 'Cuda 383
Working on adding EFI

[mopar_nerd]

You can actually download it from performance trends site---> http://www.performancetrends.com/

[cruzerjd]

Tried the software and loved it. It shows that my m-body should be capable of running low 15's to high 14's without much work. According to the data I have, I should be running low 16's, we'll see this spring, but it is really cool. cruzerjd

[bemiller]

mopar nerd- that is a different program, please if you want the shareware software I have go to my website and e-mail me. that way I just have reply and I know the address will be correct, plus it is alot easier for me. I think I'm getting racing fever again...must race soon...go away snow!

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Check out http://www.donet.com/bemiller/ and let me know what you think!!

[bemiller]

If anyone remembers this post I have an update. I installed a 4 degree advance bushing. Then once I got everything back together I decided I should probably make sure it was right. After degreeing cam found the 4 degree bushing moved it to 105 degrees, origally was installed at 108.5 degrees so it was correct. Advanced 3.5 degrees, I figure I lost .5 degrees in chain strerch over last season. I'll post the performance change in about a month...that is when the car will ready.

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Check out http://www.donet.com/bemiller/ and let me know what you think!!