4k Running 3k Carbie Q's. *urgent*

[rollaresto]

Hey guys,

 

just two quick questions i hope you can help me with!

 

Firstly can anyone comment from experience what a 4k with a 3k head should run like with a 3k carbie bolted on to it. do they over fuel? fart miss etc?

 

reason for question is after an enigne swap we've found that the 4k is running rough as (think it's mainly thanks to faulty points) but yet overfuels and blows smoke as a result in the higher end of the rev range. yet none at idle or during startup, which one would expect from worn valve seals or rings.

 

What should the expected compression be cylinder to cylinder on the above setup be? roughly 120 psi on a used motor?

 

any help would be great guys'

 

 

cheers

[kangaroosa]

In relation the the carby - it should work fine. I used to have a 3k carby on my 4k and then i also had a 4k carby on my Hot 5k. I didnt have any drama's with either setup.

 

Engine running rough could be a leaking manifold gasket, or carby to manifold gasket. Burnt or pitted points would most certainly make it run rough too.

 

If it's blowing smoke - what colour smoke is it? If its running rich, then its going to be black smoke. If it's burning oil, then its going to be a grey/white smoke (in most cases).

 

The compression on my stock 4k was mid 160's PSI after 4 years of giving it hell.

I would have thought 120 is waaaay too low.

My 5K as of last week had 155PSI with bores so glazed that you could use them as a mirror. Hence, even 155PSI is low for 9.5:1 compression.

Edited August 5, 2005 by kangaroosa

[Super Jamie]

if the motor is stock, then you won't have any problems

 

i ran a 3k carb with 4k-c jets on my worked 4k for ages, it pulled 8500rpm no worries. it wasn't ideal, but it worked

 

compression should be 172psi stock, i'd say your motor is in need of a hone and re-ring. but as long as they're all roughly even (within say 10psi of each other) you could use the motor, it just won't be very powerful, fuel consumption will suck, and trying to get power out of it will be a total waste of time

[rollaresto]

Argh!!!

 

thought 120 was too low for a 4k with a 3k head, i'll check it again tomorrow before i tear my hair out.

 

it's blowing blue smoke and it only seems to be when you use the accelerator pump, otherwise no smoke what so ever?? this is why it's got me aboslutely stumped. meh not complaning for a $50 engine.

 

so curiously thou, let say i gotta rehone the block and drop in some new rings, what would be the estimated cost? and could it be done by only dropping out the bottom end with the car up?

 

cheers

 

chris

[Super Jamie]

you'd just buy a wrecker motor with good compression. unless you were going all out totally working a K engine like i did, there's no point in going to the expense of rebuilding it

[mikeys toy[RL]]

i was pushing 230psi with my 3k head on my 4k block

all the "k" enginges over here had flat top pistons, no herons

it would smoke when i revved it, used oil, pinged like hell....that's why i'm selling the head

the alterative would be to get some heron pistons from you guys and replace mine

[mikeys toy[RL]]

that's what i did

[rollaresto]

cheers for your help so far guys,

 

but just to throw a spanner in the works here is what i have discovered lately,

 

after renewing the points and setting the points gap again, i did another compression test, result was approximately, 170 psi with all cylinders roughly even.

 

i assume it's a 3k head given there is no welsh plug in the back of the head but instead a 4 bolt plate.

 

The reason for the engine transplant was that the previous 3k spat the head after the previous owner neglected to use coolant. yet upon some deep arse thought about the problem at hand, the seriously inconsistant idle, i remembered the 3k sounded just the same after i discovered it's faulty head.

 

my assumptions are:

 

the 4k is in realatively good working order for it's age and the lenght of time it's been sitting.

 

given the car is idleing poorly it's carbie related, as it purrs like a kitten at approximately 1500 rpm and above. with serious overfueling above 4500 rpm. and i can only assume with coolant entering the exhaust and intake on the original 3k that this is some how related to the current problem.

 

so, has anyone had experience with moisture in a carbie and if so what was your car's symptoms.

 

and does anyone have a 3k carbie sitting around in good working order so i can test whether my theroy, cash buyer - brisbane :y:

 

cheers

[Super Jamie]

plate at the back of the head just means it's a smallport, it's probably a stock 4k head, being on a 4k bottom end. what's the casting number? between the last two spark plugs i think. we've figured out what some of them are

[rollaresto]

plate at the back of the head just means it's a smallport, it's probably a stock 4k head, being on a 4k bottom end. what's the casting number? between the last two spark plugs i think. we've figured out what some of them are

nick, keen as if you've got one lying around, even a 4k carbie.

 

seems like i'm learning more and more about these old rolla's everyday.

 

i just can't put my finger on what's wrong with the old girl atm, it sounds like a 10a bp idleing, WTF?

[rollaresto]

cheers nick,

 

pm me your contact details, when you check the shed.

 

many thanks