3.0 engine build questions carbs/cis

[pete-stevers]

Couple of Qs
what is the displacement capacity ceiling of an 3.0 engine with cis?
And which configurations will run with cis?

how tough will it be to smog(aircare) a 3.0 or bigger displacement w carbs and cams?
(considering the only "aircare" requirements here in BC are emissions only)

Are there any tricks when running a moderately cammed engine with carbs to reduce unburnt gasses in order to pass smog(aircare)?

The car will be run on the street,and touring, maybe auto crossed on a blue moon. Aircare is mandatory every two years, and i think the emissions qualifacations are the same here as across the line.
thanks
steve

[Steve@Rennsport]

Originally Posted by pete-stevers

Couple of Qs
what is the displacement capacity ceiling of an 3.0 engine with cis?
And which configurations will run with cis?

how tough will it be to smog(aircare) a 3.0 or bigger displacement w carbs and cams?
(considering the only "aircare" requirements here in BC are emissions only)

Are there any tricks when running a moderately cammed engine with carbs to reduce unburnt gasses in order to pass smog(aircare)?

The car will be run on the street,and touring, maybe auto crossed on a blue moon. Aircare is mandatory every two years, and i think the emissions qualifacations are the same here as across the line.
thanks
steve

Perhaps I can help,....

1) 3.5 litres with the right fuel distributor and twin-ignition.

2) You can do a 3.2, 3.4 (short or long stroke) or 3.5. Some of these combos require case machining and a different crank.

3) Smog-compliance with ANY carbureted motor can be tough. Its depends on what the CO & HC valuse you must comply with as well as cams and compression.

4) See the above,... LOTS of variables here.

[pete-stevers]

Thanks Steve
I am toying with build up on a early 3.0, and would prefer the simplicity of a cis or motronic set up, but would entertain carbs if there is a way to get them through aircare.
but a set of pmos are spendy in comparision to a stock injection sys and of course money and streetablity(aircare compliance) are two absolutes for a happier marriage

the thought of running a 3.4 on a 3.0 crank( if possible) on cis does tickle my fancy but again i would prefer to run a single plug set up, for simplicities sake.
Is a limiting factor for HP on a cis/ or motronic the cam?

[pcar9119]

i just got done building a 3.0, very mild build. The cis can't handle much. I couldn't get the car to run right with the cis. I'm now in the process of putting carbs on the car. I'm using a set of zeniths 44's, motormeister had all the parts i will need for this conversion. Now i will have the fuel and air i'd require for my motor. Just my experience with the car. Another issue is the minute one of those many vaccume-mechanical issues aris, you car wil become a giant pain in the ass.

[pcar9119]

i meant zenith 40's. duh

[dtw]

Originally Posted by pcar9119

i just got done building a 3.0, very mild build. The cis can't handle much. I couldn't get the car to run right with the cis. I'm now in the process of putting carbs on the car. I'm using a set of zeniths 44's, motormeister had all the parts i will need for this conversion. Now i will have the fuel and air i'd require for my motor. Just my experience with the car. Another issue is the minute one of those many vaccume-mechanical issues aris, you car wil become a giant pain in the ass.

May I humbly suggest typing "Motormeister" into the search box above, before you hand them any of your hard-earned cash.

[MatthewBrum]

i just got done building a 3.0, very mild build. The cis can't handle much. I'm now in the process of putting carbs on the car

If you have not taken the CIS system off I would try working with it to see why it is not working for you. There is a whole lot of info on the forum about testing and set-up of CIS. Once you get the system right I think you will be happy with it.....

[Steve@Rennsport]

Originally Posted by pete-stevers

Thanks Steve
I am toying with build up on a early 3.0, and would prefer the simplicity of a cis or motronic set up, but would entertain carbs if there is a way to get them through aircare.
but a set of pmos are spendy in comparision to a stock injection sys and of course money and streetablity(aircare compliance) are two absolutes for a happier marriage

the thought of running a 3.4 on a 3.0 crank( if possible) on cis does tickle my fancy but again i would prefer to run a single plug set up, for simplicities sake.
Is a limiting factor for HP on a cis/ or motronic the cam?

Smog compliance standards do vary so if they are fairly strict in BC, I would recommend a Motronic engine as the best compromise between improved performance and emissions compliance. Its FAR better than CIS in every way imaginable.

These engines are quite octane sensitive, especially in the larger bore sizes so when someone wants a big-bore engine (98mm or bigger) and performance, twin-ignition is the only thing that permits decent compression with pump gasolines.

The limiting factors are pistons and the single-throttle intake systems which do not tolerate cams with much duration or with narrower lobe centers.

[pete-stevers]

if one was to build a 3.2 or a 3.4( is it recomended/possible to run a 3.4 on 3.0 crank) using a 3.0 block and crank will motronic keep up with the operations of gas ,air and idling even with a lumpier cam
Is the twin plug mandatory for running on street octane gasoline,
or can the a lower cr be used as a compromise in order to mantain a single plug set up?
....or... is running a lower cr too detrimental to performance? and if so what is the performance lost from running single plugs and a lower cr?

i guesse this all begs the real question....
what is the net cost of twin plugging??

[Won]

Steve, a friend of mine has a 3.0 with carbs (Jasper's old blue car) and he got it Aircared. His Pelican handle is "Turbo Den", you might want to send him a PM.

[Steve@Rennsport]

Originally Posted by pete-stevers

if one was to build a 3.2 or a 3.4( is it recomended/possible to run a 3.4 on 3.0 crank) using a 3.0 block and crank will motronic keep up with the operations of gas ,air and idling even with a lumpier cam

That can be done, yes. Camshaft choices are limited by the single-throttle intake systems to either 964, Webcam's 20/21, or equivalent.

Is the twin plug mandatory for running on street octane gasoline,
or can the a lower cr be used as a compromise in order to mantain a single plug set up?

It depends on compression ratio. Anything over 9.7:1 with these big bore engines needs twin-ignition to safely run on pump gas. Keep the CR at 9.5, use conservative timing, and you'll be OK. Its not ideal though,...

...or... is running a lower cr too detrimental to performance? and if so what is the performance lost from running single plugs and a lower cr?

This is a VERY complex subject fraught with many variables,....
CR makes both power & torque everywhere in the rev range. Its only limited by available octanes (and to some degree: engine longevity when the values are high). Lower CR's and single ignition result in reduced torque and throttle response. Some can be gained back with a proper ignition advance curve but this really depends on bore size, fuel octane, outside air temps, and mixture control.

i guesse this all begs the real question....
what is the net cost of twin plugging??

Are you referring to performance or costs?????

[pete-stevers]

No i am looking for the cash cost of converting single to twin plug.( while your in there of course)
....
The motronic engine has a better inj sys, the 3.2 heads breath easier
it might be a better base to build off a 3.2 but the initial cost of a 3.2 in need of rebuilding is much higher than an old 3.0 in the same condition. But the 3.0 has a shorter stroke( and no i can't split for Henries fancy crank)
what value do 3.2 cores trade at?

my goal is to pick the components, including the core
do a total cost for the build up, and acumulate the parts over the course of the next year.

[pete-stevers]

Originally Posted by Won

Steve, a friend of mine has a 3.0 with carbs (Jasper's old blue car) and he got it Aircared. His Pelican handle is "Turbo Den", you might want to send him a PM.

Has he done any mods to the internals or is the 3.0 in stock config with carbs

[pete-stevers]

i have decided to go with a used set of Max Moritz P+Cs
i am thinking of regrinding to a 964
running the stock 3.0 crank+rods
it is a 78 3.0
the heads will be modified to accept dual plugs
possibly a BB dist
and cis
but the question is what can i do to my cis to make it breath better?
are there some good classic threads on this subject?

[longhornchris04]

Unfortunatly, making CIS breath better is generally hard, at least hard enough that you have better/cheaper options. Especially given that you are already starting with the 78 SC (of course Canada should have the ROW model - US 78 and 79 had larger ports than the later SCs).

A regrind to 964 is about as good as you can do with CIS, the larger P+Cs will pull more air through, but the fact remains that CIS will limit you.

I've been surfing the classic threads (debating about starting my own). I've found one of the big reasons why places like Andial do the big-bore CIS is that it will pass the Cali visual inspection... a stock 3.0 and a moded 3.4 or larger would be difficult to tell apart if the owner doesn't say anything. Same with cams and porting out the heads to the 78/79 spec. Its kinda sad because closed-loop EFI would be so much better (environmentally & performance wise). As would twin-plugging (cleaner, more complete combustion) but none of it is CARB approved.

Since you've already said BC requires a sniffer test, but not a visual inspection, ditching CIS is at least an option, as is twin-plugging. Smog will be tough with carbs, maybe impossible if the cam has too much overlap.

If you stick with CIS you should be able to make it pass (see Andial's big-bores... and Cali's tests suck) although you may have to cheat and adjust day-of to get things in check then re-adjust afterward for performance/protection.

If you go EFI and add wideband O2 then you should have no problems passing smog. You can always go EFI later.

[pete-stevers]

i am going to run with cis, and the max moritz pistons
but the resounding question is-what is the best thing to do with the cis?

Are there any cis gurus out there?

Where did Rdane get his cis sorted?

[don gilbert]

this is the best i could come up with to help with the limited air flow on my cis, looks a little goofy i know, but there is a noticeable difference in throttle response, (esp on hot city driving and 60mph +) and for a fact my temp inside my air box dropped 18-20 degrees, that cant be hurting anything, and my engine temps are down 10-15 degrees on the gage, i think thats ok to. this is a prototype, i am know working on a twin inlet/twin scoop for some serious ram air.