this is my latest dyno sheet. does this show u guys any thing? you guys are the experts
http://idahostreetracing.com/gallery/ullose272/dyno_sheet

I take it this is a 350....

Looks to me like it needs more cam. Looks alot like a 929 or one of those generic 204/214 grinds. The torque really falls off bad as RPMs go up; looks like peak torque is at or below 2500 RPM. But it doesn't look like the intake or exhaust is flow-limited (would usually produce a sharper drop-off).

What induction system is on it? What was the fuel mixture readings and the ignition timing in this run?

Those are some impressive rear wheel hp numbers graemlins/thumbsup.gif

Nice numbers You must have some serious traction problems with all that torque down low

Mike

well the specs might suprise some of u.
-355
-~9.6:1
-vortec head
-perfrormer rpm cam 234/244 dur @ .050
-rpm intake/750 vac sec
-1 5/8 headers
the lower # dyno runs were with open exaust and the higher were with 18 in 3 in tourqe tubes.

a/f was at about 12 the whole run. timing was set at 34 where it made most power,

This looks like a typical chassis dyno curve. The initial peak at 2500 rpm is the converter multiplication, the peak at 4200 is the engine torque peak. The large dip at 3300 indicates that the stall speed of the converter could be raised closer to the torque peak for better performance. The small dip at 2700 is the transition of the carb, there's probably a matching dip on the a/f chart.
This cam is still making near-peak horsepower at 6200 and probably will extend upwards of 6500. This graph compares favorably with the Edelbrock dyno test.
This graph also demonstrates the function of the collector extension, significantly raising the torque below the torque peak.
Are you sure your secondaries were wide open? We've seen 20+ hp gains by forcing the secondaries to open at the torque peak.

Originally posted by onovakind67:
Are you sure your secondaries were wide open? We've seen 20+ hp gains by forcing the secondaries to open at the torque peak. Have you seen this with the 750 VS mostly or with other carbs too? How do you go about getting the secondaries to open at torque peak? Is this simply a matter of experimenting with the sec. springs?

put a double pumper on :D

Sorry, I screwed up and looked at the numbers in the middle of the graph instead of looking at the axes graemlins/clonk.gif It makes sense now, with that cam. You can do alot better.

The reason the torque peak is down so low (3700 or so) and falls off so bad all the way up through the range is probably the small headers.

do you think a different cam would help me much? i know its old technology

I don't know about Hydraulic, but a bigger solid cam should help everywhere.

Later
Steve

Have you seen this with the 750 VS mostly or with other carbs too? How do you go about getting the secondaries to open at torque peak? Is this simply a matter of experimenting with the sec. springs?

Mostly the Holley carbs. It's easy to see if the secondaries open all the way, you just look at the lever. If they doesn't open all the way on the first pull, I put my finger on the lever and force them open when the dyno tach gets to about 4500. It's nice to be able to sit on the fender of a car at 100+ mph with the engine working flat out.

The torque curve actually holds up very well as the evidenced by the flat power peak. The header diameter is not as much of a factor as the length. I would use a 1-5/8" x 36" primary with a 2.5" x 14" collector.

I was reading a Jack Burns article on trends in headers and here's a quote:

One of the largest errors street enthusiasts make is in running too large of a primary pipe, and too large of a collector. For example, NHRA and IHRA Stock teams using Burns' headers in H/SA in traditional small-block powered musclecars are running 1.5-inch diameter primary pipes- much smaller than many street machines are trying to use.
http://www.popularhotrodding.com/tech/0310phr_burns/

You would probably get better results from a more modern cam but would it be cost effective?

what about rocker arms. i am using stock gm self aligning rockers. would some comp magnums help at all with there extra stiffness?