Question: How to adjust cold enrichment on early FI

[PeterR]

First of all I am new to Rochester mechanical fuel injection, but I'm trying to learn. I have an early "360" model FI unit on my '57. I just got the car two weeks ago and it was running very rich when it came off the transport trailer. Subsequently, I found the spark plugs to be totally black with carbon (I replaced them). I checked all the spark plug wires and they were fine. I would like to ensure that cold enrichment is set properly (the black plastic cover was loose so the setting is uncertain). The black plastic cover has multiple rich-lean index marks on it, but I see no obvious corresponding index mark on the cold enrichment housing. I see a couple of scratches on the flat horizontal surface, but nothing that looks like an intentional index mark. And there are no marks on the vertical side of the housing. So how does one set the cold enrichment if there is no index mark on the housing? If there is supposed to be an index mark on the housing, is it on the side or top surface? If you're looking at the housing from the left fender, at what position on the clock should I find the index mark (with 6 o'clock being closest to the left fender)?

Thanks,

PeterR

 

[Tom Bryant]

Hi Peter,


Welcome to the CAC.

It's been a long time since I played with one of these. I suggest a very good book that covers all of the FI units up to 1962 by model and covers the cold enrichment system in detail. It is the "Corvette V8 Complete Owners Handbook" published by Floyd Clymer It's long out of print but they show up on Ebay and Amazon occasionally.

I'll read through mine today and see if I can come up with some answers to your questions.

Tom

 

[Tom Bryant]

That was fast. I found it.

1. With the engine off and cool, disconnect the rubber sleeve from the cold enrichment housing signal boost tube and install a short length of rubber hose over the tube such as windshield washer hose.

2. Crack the throttle valve as necessary to place the throttle tab just on the high step of the fast idle cam, then close the throttle.

3. Holding the trip lever against the counterweight tab blow into the hose while listening at the air meter. If choke rod (fuel enrichment rod) length is correct, slight air flow should be heard. Repeat check but with throttle tab on second step of fast idle cam. No air should be heard. If necessary, bend rod as required to shorten or lengthen rod in order to meet the above requirements.

This method doesn't seem to need any markings on the housing. We used to use this book to set up FI units back in my younger days and it always worked.

Good luck.

 

[Tom Bryant]

I see in some of the pictures that there is an index mark on the housing at about the 7 o'clock position. I'll have to read further on this. Got to go to work now. It may be easier for me to scan this and post it.

Tom

 

[PeterR]

Thank you, Tom. I will definitely look for the Clymer book. And thanks for the procedure. If it worked in the old days, it will work now. I will give it a try. Pete

 

[PeterR]

Tom, I removed the black plastic thermostatic spring assembly and found that the end of the spring was loose and not anchored between the two internal plastic bosses, so it would not have worked properly. Also, one of the external electrical wires was connected to the wrong one of the three hold-down screws, thereby interfering with the link to the fast idle cam. All in all I think it's going to work better. I also located a copy of the Clymer book from an Amazon seller ($7.98 including shipping for a nice copy). Thanks again for the help.

Pete

 

[Tom Bryant]

Glad to help. It's great that you found the book too. The FI section is good reading for anyone with one of these units.

Tom