CIS to Carbs questions

[mikl911]

Just finished the CIS to carbs conversion but i'm not sure if I need the vacuum line from the distributor or not. I have not had the distributor recurved yet, will it hurt to run it, as is, a couple of times just to check for leaks etc?

[chrismorse]

The vacuum advance is a load compensating device. At part throttle,or light load, the charge density is less than full throttle and by using the vacuum to advance the spark, the engine becomes more fuel efficient.
This will cause no harm to the engine, only a drop in fuel efficiency.
Good luck, that is a nice looking install.

Chris

[mikl911]

Thank you Chris.

[mikl911]

In case anyone was wondering I was able to get the CIS out without removing the motor, just dropped it down about 4 inches.

[zedsn]

Let us know how you like the swap, performance wise and mileage wise, when it is driven for a period of time. I have a RS spec 2.7 and get crappy mileage but my foot is into the floor a lot.

[mikl911]

zedsn, I will. CIS was working great and the 3.0 only had about 1000 miles since rebuild with 9.8, 964 cams and SSI good or bad I should see a difference. My 67 has a 2.7 with the same set up so I'm used to the poor mileage.

[chrismorse]

Theory, done a ton of changes to a lot of cars & trucks,, but have been reading the threads and seeing significant HP and Torque improvement, optimizing, on the dyno. I have changed to webbers, fussed with jetting, but I know I have missed out on a lot of hp, tq, and throttle response.
Get help balancing the carbs, jetting, or the EFI, setting the timing, Christ, I need help choosing a 2 in 2 out for my dead stock, CIS 2.7, I am planning on budgeting real bucks, getting pro help to get it RIGHT.
Got Chris 7's light flywheel, and am planning on a light clutch.

God loves a snappy 6

Best,
Chris

[RSBob]

Originally Posted by zedsn

Let us know how you like the swap, performance wise and mileage wise, when it is driven for a period of time. I have a RS spec 2.7 and get crappy mileage but my foot is into the floor a lot.

Spoiler alert. I have ‘82 3.0s in both my cars and the SC with CIS gets low 20s on long haul freeway driving. The 914 with Webber’s gets mid teens doing the same. Hammering the 914 probably gets me down to the high single digits.

A good friend of mine calls carbs a ‘controlled fuel leak’. Do like the added torque though, but the gas smell in the garage from evaporation from the float bowls is a bit much.

Now back to the thread already in progress.

[mikl911]

chrismorse, you will not regret the lighter clutch and fly wheel the throttle response is very noticeable. Besides gas mileage the only down side to the carbs, I have read, but not notices in my 67, is in top end. I don't know about the rest of you but NY state troopers really frown on you cruising at 110-140. Almost all of my driving is spirited 0-75. When I want the fastest car on the block I'll buy a GT3 or a Mclaren for now I'll enjoy the 1. better torque 2. better look, by far 3. better sound and 4. better reliability the Webers offer. And for those that will ask why not EFI simple, cost, not the cost of a system I had one brand new still in the box and just sold it. The cost of the learning curve mentally and finically, with dyne time ( I'm a little obsessive and would have wanted it to be perfect). I understand carbs and have friends that understand them because we are old lol. My 2 cents.

[Dpmulvan]

Wondering how the drastic weather changes here in upstate NY would affect carbs??

[mikl911]

Dpmulvan no issues. I have heard that altitude effects them more, not an issue in Rochester.

[obscene]

I have a carbed 2.7 and can whole-heartedly agree on both:

1. proper tuning and syncing will help fuel economy tremendously

2. any improvement in fuel economy becomes immediately negated by proper application of the right foot

[JackMan]

I have obscene carbs in a 3.0 . I don't worry about mileage. Foot to floor. Fill up the car every three days.

[SCOTITUDE]

Originally Posted by JackMan

I have obscene carbs in a 3.0 . I don't worry about mileage. Foot to floor. Fill up the car every three days.

Thats what its all about....Fuel Mileage? Really guys? Smiles not miles!!!

[mgatepi]

Originally Posted by mikl911

zedsn, I will. CIS was working great and the 3.0 only had about 1000 miles since rebuild with 9.8, 964 cams and SSI good or bad I should see a difference. My 67 has a 2.7 with the same set up so I'm used to the poor mileage.

I have virtually the same set up except for I have the large port heads. I have struggled with a dead spot, very minimal but still there between 2800 and 3200 RPMS. I have swapped out jets and plugs and have it the best I can get it. One problem may be the 964 cams....they are not the best choice for carbs. Talk to the Cam Doctor.

Enjoy!

[mikl911]

mgatepi I also have the big port heads, did you have the distributor recurved? I had a similar issue with the 2.7 with Zenith carbs it would not idle, hesitated below 3000 rpm but came on strong after that. Switched to webers, same problem until one day I decided to run non-ethanol gas, fixed the issue immediately has been running strong foe 4 years no issues.

[mgatepi]

I actually purchased a new distributor from Clewett Engineering.
After the 3000 rpm lag...hold on! It comes on strong.
Interesting about the gas. I will give it a try.

Thanks!

[mgatepi]

Also, the Clewett distributor does not have a vacuum advance.