Need a little help. I've had my cd 175 rebuilt and now i need to know how to adjust them. When I start the car cold I have to hold my hand over the front carb to get to start even with chokes open.When it warms up with chokes off and the two carbs working independently the front one seems to be doing all work if I engage the rear one the car dies. The front one seems to be sucking a lot of air and the rear not so much. I need a base line to start from. This is a 1969 xke 4.2 Thanks for any input.

Submitted by bblackwell@jcna.com on Mon, 12/20/2010 - 20:22

I would suggest you look for a pretty big leak into the manifold downstream, probably near your front carburetor. There are a couple of breather fittings, plugged casting gate holes, and such to check. It ought to be big enough to feel around for with the engine running when the engine is cold. Often a period of time goes by between removal and reinstallation and you might not have put it all back together correctly.
I did this once with a Sprite about 20 years ago when I switched two caps during the reassembly but I found it pretty quickly. When I put my fingers over both holes, the car ran perfectly. Putting your hand (or the hole) over the carburetor richens the mixture enough for it to run, but the air leaking in somewhere else is leaning it out too much to run when you remove your hands. These carbs do not have that much adjustability.
I hope this helps.
Brian Blackwell
Helotes, Texas - "Where the Texas Hill Country Begins"

Submitted by SE98-32482CJ on Sun, 12/19/2010 - 14:50

Your choke plate is either clogged on the front one or very poorly assembled.It also sounds like the linkage or the ballance is way out--do you have a manual for your car--JCNA sells all you ever need in the shoppe! By the way leading in with SU carbs when you in fact have Zenith Stromburgs makes one wonder--There is very little adjustment if --IF the carbs were rebuilt properly.

Submitted by DavidBarnes71@… on Sun, 12/19/2010 - 08:43

Do not think much adjustment can be done to the Stromberg carbs on the Series II engine. Float level and metering needle are all I am aware of that have any agustment at all internally but I do not think that normally you are supposed to mess with the metering needle. A few months ago my '68 was acting similar to this and I found the problem was an air leak in an obscure spot around the intake manifold. Sprayed carb cleaner around all the intake joints and the idle picked up speed when sucked it in at a leaking gasket. First though I guess you need to make sure the linkage tying the carbs toghether is correct and they are in sync with each other. You probably need the Unisyn tool to check that they are in sync. There is a procedure in the book to do it by ear with a length of hose to hear the amount of air being drawn in by each carb but I never had much luck with that nethod.

David Barnes
'68 FHC