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Discussion Starter #1
Need some help! I'm running a 350 SBC with a 671 blower with dual 600 Edelbrocks. The blower is 20% under-driven. I came off the blower base plate to run vacuum to PVC and trans module. The hose to the trans module fills with raw fuel, not totally, but about a thimbles worth. I've got vacuum at the hose with engine running and hose off at modulator. Whats up with that???
 

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You might be condensing fuel into the vacuum leg as it is colder than the engine. You might try running the vacuum line higher than the manifold for a short distance to allow the condensed fuel to drain back.
 

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AKA Lee in KC
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Hey 23T, I'm running the same engine set-up in my 23 T except I'm at 1:1 for about 6# of boost. You need to pull your vacuum signal from above the blower. I'm using the un-ported (lower) vacuum port on the rear (primary) carb (Edel 1405) for my vacuum advance and I'm using one of these to supply a corrected vacuum signal to the modulator on the TH350. I need to adjust the vacuum curve on the distributor a little, but other than that, the bucket is running great. The BDS pressure diversion valve really helps with proper shift points.

If you're ever on the NTBA forums I post there as "Lee in KC."

EDIT: added "1:1 for 6# of boost) and "rear (primary)" carb...
 

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Discussion Starter #4
Vaccum

Thanks for the feedback---I'll move lines from carb plate to the rear port on rear of edlebrock. If that doesn't do it, I'll pick up one of those diversion valves.. Thanks Again guys!!!
 

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AKA Lee in KC
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23T, I mis-read your original post. When you said you were pulling your vacuum off the "blower base plate" I interpretted that to mean the manifold. If you are pulling your vacuum off the carb adaptor plate on the top of the blower, you should be OK. That should be the same vacuum as the "non-ported" signal on the front of the carb and the extra ports on the back of the carb. My PCV is plumbed into the NPT port in the back of the base of the carb, as you are proposing to do it.

Also, you should not have the PCV and the trans modulator sharing the same port or tee'd off the same line. The PCV line is intended to move a lot of air and will not generate an accurate signal. Your trans modulator and distributor can only need a "signal," that is a pressure reading (actually, a "lack of pressure" reading), with very little actual movement of air in the lines. I'm using 3/16ths steel brake line for my vacuum connections.
 

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Discussion Starter #6
XNTRCI-T Didn't express myself very well in initial thread, sorry. At present I'm pulling off the carb base plate at rear. One port for pvc, one for modulator. The pvc line is clear with good vacuum. The modulator line has vacuum and collects fuel in it down at the modulator.
 
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