I had an interesting one yesterday with an engine builder with one on the dyno. The build was a 14 to 1 496CID with a Super Vic on on top of a set of 320cc heads that had been ported. The old cam was 740/740 284/294 .050" on a 114. The new cam was 730/700 271/286 .050 on a 109.



Here were the intial results:

Old cam peaks 797/615

New cam peaks 769/704



Comparison Power from new to old

RPM HP Diff Torq Diff

4500 +73.3 +87.5

5000 +69 +72

5500 +53 +50

6000 +21 +19

6500 +11 +9

6900* -26.7 -24 *Peak of HP of both Cams

7000 -45 -34



Now if you are one that looks at averages the new cam is the winner. The problem is the masses look at the Max power and the new cam is clearly the looser. So what to do.



I personally believe I/E ratio because of trends I have seen......this build showed us a curveball and proves there are exceptions.



I told the engine builder to tighten lash equally on the engine.He did and the engine lost power. He then looked at his notes and his best power was made with the intake lash a little tighter and the exhaust a little looser. He went back to this setting and duplicated the the best power pull of the day. He then called us tod discuss what to do next. Fox and I discussed options while builder was on speaker. The builder thought it was the intake, Fox said no the runners CSA was enough for the build. The mystery was it had stopped moving air by 6700.



I proposed to Scott and the builder who did not flow the heads maybe the port is going "dirty" and its not happy. Possibility. Looking at this make of heads the do back up at .700" out of the box. Scott ran the Ghetto math to see the demand change that the new cam had put on the heads. We came up with about 12 cfm. Scott told the builder if you have a port backing up the way to calm it down is to slow the air down. We could try this by making the intake lobe bigger. Told the builder to keep tightening intake lobe and leave exhaust alone.



Late last night I got a text 830HP at 7000 rpm and 730#/ft at 5500. In crease of 61HP and 26#/ft over initial results of my cam. 34HP and 97#/ft increase over the original camshaft. The changes made were .006" tigher intake and .002" looser exhaust. Timing went from a best with 34 degrees to a best with 37 degrees. I did not get a jet change if there was one, but will ask today.



John Reed always preached, lash is the most important tool you have in your tool box. Joe Petelle once told me always remember air and fuel must slow down to turn. This engine proves both of these men correct in my opinion.

 

Wow, thats some amazing stuff and very impressive numbers. What is this engine going in?

 

It is a drag only application.

 

Well with that cr I assumeded so. I meant what kind of car is it going in. C3?

 

Nice, so the next step would be a camshaft with larger intake lobe providing more lift?

 

Bump for interest. Come on Chris!

 

We've updated to W7. I'm in computer hell right now.

The lash adjustment is fine. The intake port needs more area to slow the air down in the port. Customer is going to run it at the track up in Canada and see how she does. Should be a whole new animal

 

LOL, Win 7 is easy. Win 8 will give you fits of rage.

 

I've never ran a solid, but thought that the lash was pretty much set in stone.