Author: midnight340

Finally got warm enough that I got around to graphing my timing curve. 340 with MSD Ready-to-Run distributor, 2500 PTC converter, 4:10 gears.

Right now timing is at 18/34, (may bump it a degree two.) I’m thinking maybe I should bring the curve in a …

Hi all, glad to check in here. Longtime 340 fan. Typical guy, I’d rather talk about my motor than myself. So here goes:

Mine is originally a ‘73 block, cross-over oiling done old days by Larry Atherton’s shop in LA, X-heads port/polish by B…

What is a good way to track RPM for tuneups? I have a good tach inside, and a good non-dial back timing light.

Is there a decent handheld tach for a reasonable price? I have one of those old Actron tach/dwell meters, but it doesn’t have the RPM ra…

So I rebuilt a ’73 Industrial TQ with 1-1/2″ primaries. Walker kit from O’Reilly’s, choke pull-off from Mikes. Sitting on a TQ adapter on LD340. (Cc’d 9:1 compression 340, headers, Lunati solid lifter cam, MSD ignition, etc.)

I modified a set of rods to 67/52/42. Replaced .098 stock jets with Carter .101’s. Drilled pump nozzles to .031″ and put a slightly heavier, longer spring rod spring in. I am running no choke (tied open.) Rods are adjusted 4 turns up and air door is set at…

Thermoquad on 340 (plug photos)

NOTE: PHOTOS WILL FOLLOW!
i needed different rods than what was in my carb in order to fatten up the mix some. A 9000 series emissions era parts carb had some very lean rods which were 67/57/54 when measured.
I modified them to 67/52/42.

I found out …

View attachment 1715424985

Thought I’d post one version of a home made Thermoquad adjusting tool. I had the fittings in a drawer, so… Used it yesterday, easy to hang on to, and was pretty easy to make.

UPDATE: Vacuum Leak??? (all details in my thread “Thermoquad help questions.”)

Thought it best to start a new thread here.
In my last post I was getting very low vacuum with this freshly installed 850 cfm Thermoquad 6518S I rebuilt, using a Walker kit and new pull off from Mike’s. I used a Mr. Gasket adapter to my unmodified LD340 intgake. Driving with vacuum gauge inside, I was getting 5-6 in/hg with gauge T’d off the rear pull-off port.

Forum member lemondana saw that my Mr. Gasket…

Thermoquad low vacuum readings