Skip to main content

Hello gents.

Well, I am booked for 3 pulls on a chassis dyno next Monday.

The day will begin with the performance shop (Unlimited Performance in Calgary, AB) test-driving my cat to check for hiccups, pings, knocks and bangs emanating from the engine bay. I should be good there as she has been running great since I dropped my power-plant back in a few months ago.

Some minor tweaks (most likely the idle mix, choke, fast idle, etc. for my rebuilt carb and perhaps my timing) may be required prior to setting up the dyno - after which time I am not sure what to expect ...

Here are some things I am hoping to ascertain from this experience:

- optimal air/fuel mix (set up for 3600 ft elevation but comfortable at over 7000 ft in the mountains)
- a completely tuned carb (Holley 735) that will deliver maximum HP
- compression check for each of the 8 cylinders
- confirm the overall engine compression ratio, which I was told was in the 11.5:1 range
- check new plugs (approx 400 miles on my new plugs) for gap and performance
- confirm actual engine RPM's versus what my tach shows (I assume my tach to be light ~ 200 RPM at idle and ~600 RPM when roaring)
- and, most importantly, find out how many ponies are dancing behind me.

As this will be my first time, I am excited to see the results ... but I also don’t want to wreck my cat. Any advice, suggestions, stories, etc. would be appreciated.

Thanks,
EA
#3528
Original Post

Replies sorted oldest to newest

Let me start by saying first that if anything is going to break/fail it will be on the dyno. The dyno puts load on the engine/drivetrain that will typically not be seen in everyday driving. Im not saying anything will break but it will certainly be happy to point out anything you have missed. Be sure your cooling system is working its best. Three pulls wont stress it too much but be aware this is typically the weakest link. Depending on what dyno you are using you could possibly be dissapointed by hp results. My fathers car which has a stout 427 in it only showed 380 hp on a dyno dynamics dyno (which are typically more accurate from what I hear) whereas on a dynojet it showed 440 hp. Also be sure your rear lugs are on good and tight (dont ask). Bring ear protection. Set your rev limiter or if you dont have one be sure to go over your max RPM with the operator.

Blaine
Well, as it turns out my timing was being retarded by my distributor's tired vac advance. I had that replaced and the timing reset to 12 degrees initial (20 degrees mechanical - at 2800RPM). The carb was pulled as the secondaries weren't getting enough fuel. Plugs were gapped at .038" but the technician said that my UR4's are running too hot. Hmmmm ...

My idle mix was a little rich so that was also adjusted ... and at the end of the day we just ran out of time to do the dyno.

I am going to drive her for a few weeks to see if everything stays tight. She's really running great right now and my power curve is very responsive. I was impressed that these guys didn't just toss #3528 on the dyno; rather, they insisted on a test drive and running diagostics so that everything was set up properly before stressing her on the dyno.

Stay tuned ...
Post
×
×
×
×
Link copied to your clipboard.
×