F5 Daytona Coupe-1st Dyno run

[mannyjoe]

I had the car dynoed yesterday as a baseline before any other mods. There are 1100 miles on the motor.
It is a CHP 342 Stroker w/Edelbrock Alm. Performer RPM heads, a RPM Air Gap Manifold and a 600 cfm Holley with vac.secondaries. An MSD Billet Dist. and a 6AL box with a 5800 rpm pill in it. The Holley is straight out of the box with a manual choke and no changes or alterations.
The car has a rather small 9x2 round air cleaner on it. 4 into 2 headers and 4 glasspack style mufflers as was the style on these cars. The best run was with 31 deg. total timing. I would like to achieve 325 to 350 hp at the rear wheels and would appreciate any comments or questions as this is the 1st car I have ever had on a dyno.

Here is a chart of what the last and best run produced (we made 10 more hp with the air cleaner off but I won't run the car on the street that way.)


Here is a graph of the last run.


I would appreciate any suggestions or questions that would help me achieve between 325 and 350 rwhp. in a user friendly manner. Thanks!
mannyjoe

[Scott S]

I am no real expert but the graph looks to me like it was starting to breathe hard. Pretty much what I would expect for a RPM manifold and that carb size.

You didn't mention what cam you were using, that would help.

Scott S

[HighPlainsDrifter]

Hi,
Not bad for 1st run.
You are lean at the carb,go up a jet size in the primaries and put a metering block kit on the seconday's and try again.The AF ratio should be 11.8 to 12 under full throttle.Put a k&n flow top on the air cleaner also. Add 2 degrees timing only after you richen it up.
Good luck,
Perry.

[cleandan]

mannyjoe, the A/F numbers should tell you a bunch. It appears that at WOT (wide open throttle) you are a bit lean. This will hurt max power, cause excess heat, and not allow for full timing. If the lean condition is any worse you get spark knock (detonation) that is not always heard and this is a major cause of many engine failures.
What did the dyno operator say/suggest? (if not much find a different dyno)
The 342 should be able to handle more carb so you may want to ditch the LIST 1850 (I,m assuming here) Holley 600 CFM vac secondary carb. and get something more high performance friendly. I would start by running the carb a little richer. If you have O2 bungs tune with a wide band sensor. Go for idle in the 13-14.2 A/F area, cruise/light acceleration in the 13.8-15.8 A/F area, and WOT in the 12.0-12.8 area. After you get the A/F right you can then add more timing if needed. A total, all in, around 36-38 should be real happy. Adding timing can make the A/F a little more lean so double check this after all the changes. Make certain you have enough fuel volume to keep the carb full at WOT otherwise you will be chasing your tail for tuning. Good luck.

[mannyjoe]

I am having a Holley Spread-bore carb built especially for this motor. This is a 780 cfm. carb with center hung floats and vacume secondaries, I think the List number was 710 or something like that.
I know this seems like a huge jump from the 600 cfm. but the 600 was always intended just to break in the motor and get a few base numbers before we start changing things.
I recently took the car as set up to the dragstrip at Speedworld.
I ran consistently in the low to mid 13's with a very slow (rusty) reaction time. I believe with more practice (or a better driver) the car could break into the high 12's on a consistent basis.
There is a post on the Club Forum for Arizona titled "Wittman on Wednesday?" where I post a few of the details, 60 ft. time, trap speed and ET.
mannyjoe