Just a few pics of my install. Getting tire chirp into 3rd gear...

Going to the dyno Tuesday to see if my lean condition is rectified.

What is a good total advance number for a 340 (@ 6.000 feet)?

Tell us about your engine and what jets are in there. How is it without the powervalve?

Oh wait, thats a 6pk huh? nevermind the powervalve. Sweet setup..

The J head would not be a magnum head. 35 is a very accurate baseline for a SB total and you check that with the vac adv disconnected/plugged & the RPM up to where the mechanical weights/springs wont advance anymore. After checking it then you hook the hose back up.

Doh! I misread your "disconnected/plugged"... I thought I read it plugged in.

On the heads, it's an original 340 T/A block. I always thought they had "J" heads. Where would I look? I do know the intake valves are 2.02's.

Thanks!

The metering plates don't replace the metering block. They replace the metering plates on the vacuum carbs (or on a vacuum secondary carb's bowl).

Ben at ProMax recommended #84 jets. Going to the dyno tomorrow to see if we're headed in the right direction. Previously it was WAY lean when the outboards opened.

I've attached my dyno graph from a couple weeks ago.

Should have another tomorrow afternoon.

I have 84's in mine and it runs great. what outboard springs do you have?

try the long yellow springs and let me know what the result is. I believe my center carb runs 64's

what cam and compression are you running?

Back from the dyno. Here's what I did since the original chart that showed the lean condition.

Installed the ProMax metering plates and #84 jets.

Installed a fuel pressure gauge. With a Carter 120 gph mechanical pump, it reads 8-10psi at idle. At wide open throttle (WOT) it reads 7 psi. When the outboard carbs open it reads 4-4.5 psi.

Used the black (stiffest) vacuum opening springs.

(Now here's a "thing". My timing light showed 42° total advance with the vacuum line pulled and plugged. At idle it showed 35°?!? What's going on there?)

As you can see the power slopes are much nicer curves. The fuel/air is still lean when the outboards open (it is one full point richer than before!)

Hp has dropped from original 225 to 212. TQ has dropped from 242 to 225.

This graph shows:

changeout of the black vacuum springs for the clipped (shortened) yellow springs (the curve is steeper w/the outboards opening about 4,200 rpm).

Hp increasing from 212 to 218 (but still less than original 225). TQ increasing from 225 to 235 (but still less than original 242).

This graph shows total timing reduced to 40°.

We're thinking the primary carb is going a little rich (3,900). Probably going to drop two jet sizes in it.

The outboards are still going way lean with 84's (seen at 4,500). Thinking about jumping 6 sizes richer to 90's.

Hp up to 220 (but still down from orig. 225) and TQ up to 234 (but still down from orig. 242).

With the car running closer to efficient (and safer) burning, why the loss? Thoughts? Other analysis?

Thanks!

"When the outboard carbs open it reads 4-4.5 psi."

I think that this might be too low. 84's seem big for your motor as well.

shortened yellow springs are opening too quick making you go lean. try the long yellow or purples. dont go fatter on the 84's.

Drop the timing to 35 total

btw, the first plot was peaky whereas the later plots rise quicker and flatten out. so even though the peak torque/hp numbers are lower, the later plots have higher average torque/hp and should be much faster.

also, for some reason, my 6bbl has a creep towards lean at the higher rpms. i dont know why. i think its a 6 pack thing

Howdy stranger! Long time no see!

Hey Bill! Yeah, the car's been in the paint shop for almost 2 years (for a 3 month job...) so I've not been doing much. Now it's out and I wanna have some fun, but before it went in, had a "carb shop" adjust it to pass emissions and now trying to straighten all that out...

I've forgotten a lot of this stuff so I appreciate everyone's help and input!

Blessings and T/A Care!
Trip

Are you running a powervalve in the center carb? What is your vacuum at idle? I too had my carbs done at ProMax and I've had to do some "tuning" since I got them back.

Sorry, been away for a while.

I'm running 12 hg at idle in nuetral and 10 hg in Drive (at 6,000 feet above sea level). I have a Comp Cam HE (not XE) 268 (.218° @ .050 .454" on 110°LC) I'm using a 55 Power valve on the center carb.

Since the last dyno, I'm dropping down from 57 jets in the center to 55's.

On the outboard metering plates I'm going up from 84 jets to 90's because it's going way lean when the outboards open.

There's a little stumble off the line. I use a 50cc accelerator pump with the biggest pump cam and I'm out of adjustment so I'm moving my squirter size up from a 37 to a 40.

I'll go back to the dyno and see where we are in a couple weeks.