cis to carbs

_deek1954 · _deek1954's Garage

My80 sc has injection problems. High idle 2500 to 2900 rpm. engine wiring problems no current to warm air regulator, cold start , It does start eventualy every time and runs fair.I'm wondering if any one has changed to carbs and what it takes. Emissions are not needed where I live. I have it in the shop now and its ready to pick up. It idles at 1000 to 1200 rpm now, good performance. But I still cant work on it. If I change over I can do every thing myself. Wondering what to do?

Henry Schmidt · Henry Schmidt's Garage

CIS injection when broken down into basic parts is very simple to work with.
If smog is not an issue, simplify the system.
Remove that which is intended for smog or that which could be construed as a creature comfort. All production cars have compromises and if you can eliminate the compromises that don't suit your needs the customized version of your car will be far more enjoyable. An example of simplifying might be to remove the auxiliary air valve and add a hand throttle. This gives the driver rpm control hot or cold and eliminates a lot of plumbing. I am not suggesting that this modification is good for you, just giving you an example.
Educate yourself as to the specific parts of the system and start eliminating that which you deem unnecessary,
Cheers

edgarcia737 · edgarcia737's Garage

Before you do anything drastic, just take a deep breath and get more info. I was ready to yank off my CIS system and put carbs on. But I worked though it and now my motor is kickin' ass.
Feel free to give me a shout.

Ed Garcia
1977 Carrera 3.0
480-200-5778

Kemo · 03-08-2010, 10:55 AM

I just had my motor out due to a few broken headstuds. While I had the CIS off the motor, I basically cleaned everything up as best as I could, got new gaskets and intake runners. Not super expensive or difficult, but it did act alot differently after putting it all back together. starts fine, idles fine. I still have an issue with cool-to-warm idling a bit low and rough which I think is related to the AAV. Nothing I cant live with. Before all this, I had a climbing idle as it got hotter and I would adjust the idle once everything was warm. Unfortunately, the next cold start was hunting and coughing untill all the way warm. One time, I took a plastic bag and put it over the snorkel hole to see if the engine would die...the idle didnt even change. I had good feeling that there were a few leaks in the system

After some reading, I bought a CIS pressure tester from PP and it my pressures were fine. I eventually bought an Innovate LM1 system with o2 sensor and A/F gauge. I was at least able to dial things in while full on hot but the A/F ratio still changed quite a bit depending on the day. After simply replacing all the easy to get to stuff like the intake runners, runner gaskets and what not, I get a good cold start which runs straight up to 2K and settles down to about 1100 after a minute or so and then after about 4 min drops down to about 900 RPMs (this is where its a bit rough) and after full on warmup goes to 975 RPMs. Its not perfect, but its WAY better.
Now a days, my idle changes when I remove the Oil Tank cap to check the oil, which is a good thing from what I hear

I guess Im trying to encourage you to get the diagnostic tools you need to troubleshoot and get it running right. Once sorted, CIS can be very reliable

Kemo · 03-08-2010, 10:56 AM

plus...carbs arent cheap

calling911 · 03-08-2010, 01:45 PM

Quote:

Originally Posted by Kemo

I just had my motor out due to a few broken headstuds. While I had the CIS off the motor, I basically cleaned everything up as best as I could, got new gaskets and intake runners. Not super expensive or difficult, but it did act alot differently after putting it all back together. starts fine, idles fine. I still have an issue with cool-to-warm idling a bit low and rough which I think is related to the AAV. Nothing I cant live with. Before all this, I had a climbing idle as it got hotter and I would adjust the idle once everything was warm. Unfortunately, the next cold start was hunting and coughing untill all the way warm. One time, I took a plastic bag and put it over the snorkel hole to see if the engine would die...the idle didnt even change. I had good feeling that there were a few leaks in the system

After some reading, I bought a CIS pressure tester from PP and it my pressures were fine. I eventually bought an Innovate LM1 system with o2 sensor and A/F gauge. I was at least able to dial things in while full on hot but the A/F ratio still changed quite a bit depending on the day. After simply replacing all the easy to get to stuff like the intake runners, runner gaskets and what not, I get a good cold start which runs straight up to 2K and settles down to about 1100 after a minute or so and then after about 4 min drops down to about 900 RPMs (this is where its a bit rough) and after full on warmup goes to 975 RPMs. Its not perfect, but its WAY better.
Now a days, my idle changes when I remove the Oil Tank cap to check the oil, which is a good thing from what I hear

I guess Im trying to encourage you to get the diagnostic tools you need to troubleshoot and get it running right. Once sorted, CIS can be very reliable

Yep... you bring up a good point.. if you remove your oil cap and your engine doesnt change its behavior (should stumble and hunt) you have major leakage... mine doesnt even skip a beat when I remove the cap.. damnit.. but I have no running issues after screwing with mixture and pressures.. so it must be a consistent leak.

Your whole post is really good... interesting.

_deek1954 · _deek1954's Garage

Thanks after sending the car to the shop and explaining how I could change over to carbs for $1K or so the owner said should cost much less than that and after bringing the idle down to 1000 rpm and increasing mid range power the bill is $950.00 . He did much like I was told remove emissions and other non essentials. But he did say the engine will adjust to high altitude . After I pick up the car I'll let you know how he did. Thanks again.

Kemo · 12:17 PM

Interesting on the $1K for carbs. Can you find out more information about the type of carb kit he would be using? Seems like a very low price for carburetors.

_deek1954 · _deek1954's Garage

Zenith carbs from motermizer. This is just what I read. 3 brands with dist. all ready curved and linkage.

Kemo · 01:14 PM

Oh, Motor Meister. I encourage you to use the search function on this site and review some of the threads concerning Motor Meister.

calling911 · 03-09-2010, 01:39 PM

Quote:

Originally Posted by Kemo

Oh, Motor Meister. I encourage you to use the search function on this site and review some of the threads concerning Motor Meister.

Carbs AND work at MM or just the carbs.. If the thing runs right when he picks it up its still a bargain...

Something stinks though.. A set of used carbs might run close to that AS IS..

Thats a TON of work for $950... Probably not the correct carbs I would think.. Im guessing the bill is gonna be twice $950 minimum...