Thermoquad on 340 (plug photos)

Long post, but... OK, so I was not getting any color on the porcelain and not much on the fuel ring even though the A/F #'s were pretty good. (This motor has always seemed to respond well to more fuel, more carb.)

So I decided to try the Thermoquad a while back. The first thing I noticed was how much more stable the A/F #'s were with the the TQ. And the motor liked the bigger secondaries (440 carb.) In steps I started adding more fuel to the mix. Went to .101 primary jets, drilled the pump nozzles to .031. Played with raising the tree (now at 2 turns up), and also messed with the secondary settings. Learning as I go.

(Only 9:1 but the motor has the iron X heads ported/polished by Bob Mullen in the old days. I added the .526/.546 lift solid Lunati to see if I could use the heads more.)

So, ...and here's the fun! I decided to follow old recommendations from "demonsizzler" that I found on FABO from when he was on here. Also checked the MP bible settings for "Bracket 340 with TQ and LD340 intake." And it really WOKE THIS MOTOR UP!! :D

I had removed the choke before (and it starts just fine for me.) I drilled the secondaries out to .149", kept the same .101" primaries. Drilled the pump nozzles to .038" and opened up the air door to 17/32" from the tower, and set it for very little drop when running. I checked and set the secondary throttle blades to 81* per the manual. and have the air door spring at 2-1/2 turns.

Now I FINALLY have a nice light grey around the base of the porcelain and light black on the fuel ring (flat part). Timing at 19/35. And the motor is finally sounding "happy" like never before. Pulls much harder, breaks loose when I shift to 2nd, etc. Really runs great, ...absolutely no bog or hesitation. The A/F hovers at 13.5 throughout pretty much all conditions. Amazingly consistent. Idle reads 14.5 and WOT is close to 11:1 but plugs look great. I don't know how I can add that much more fuel supply and still have about the same A/F #'s??? Anyway, I am a Thermoquad convert for sure!!!!!!!!!

Thats my report. I added all the info in case it is helpful for someone in the future.