4k Mods

[78corolla]

hey all I'm only new to the forum and corollas, i own a 1978 4 door with th 1290cc 4k motor and 4spd manual

looking to spend about a grand max on it just wanting to know what mods are the best bang for buck and

any places to get parts. motor is 100 percent stock and has 120k on the clock

 

-Aarron

[7shades]

Better carby (weber etc) set of headers, 2" exhaust. That's about all you'll need/want to do.

[SLW42]

As mr shady said better carby, extractors and 2inch or 2.5inch max exhaust, and if you want to go the extra mile throw a cam into it and get the head ported and polished and it should scoot quite nicely

[78corolla]

As mr shady said better carby, extractors and 2inch or 2.5inch max exhaust, and if you want to go the extra mile throw a cam into it and get the head ported and polished and it should scoot quite nicely

 

where is a good place to source a cam? what grind would you reccommend? yeah was going to take the head off and give it a clean up, and have been checking out ebay for a carby seems to be a few good buys on there. was going to machine the flywheel a bit too

[altezzaclub]

I'd get a sports air filter first, as I think the stock filter setup is restricting the carb a lot. You'll need one anyway so try it first and spend the grand on other things. You might find the stock carb does everything you need once it can breathe properly.

 

I'd back you on flywheel lightening, head cleanup & skim, cam (you'll need to decide what sort of revs you want to use before you decide on a cam), extractors and a 2" exhaust.

 

I'm running twin SUs, head skim 15thou or so, Crow mid-range cam, (606) extractors and a 2" resonator going into an inch &3/4 system. Seems to all work well and is very civilised.

Edited August 23, 2010 by altezzaclub

[78corolla]

I'd get a sports air filter first, as I think the stock filter setup is restricting the carb a lot. You'll need one anyway so try it first and spend the grand on other things. You might find the stock carb does everything you need once it can breathe properly.

 

I'd back you on flywheel lightening, head cleanup & skim, cam (you'll need to decide what sort of revs you want to use before you decide on a cam), extractors and a 2" exhaust.

 

I'm running twin SUs, head skim 15thou or so, Crow mid-range cam, (606) extractors and a 2" resonator going into an inch &3/4 system. Seems to all work well and is very civilised.

 

how much clearence is there? how much can i skim off the head before running into clearence issues?

[altezzaclub]

How much of a hard time do you want to give the rings & head gasket, and are you happy to run 98octane all the time.

 

15-20thou will set you on 95 octane, but you can go higher OK.

 

I use the 10% ethanol 95 octane, cheapest for as long as the Govt is stupid enough to subsidise it, and I haven't had problems anywhere.

 

Clearance will also depend on the cam you get- a lift of over 0.4" means new valve springs, and the further the valves come down the closer to the pistons they get.

 

Do you want a 3500-7500rpm screamer, or do you want to drive it in daily traffic?? The rev range you want it to work in will be the first thing to decide.

[78corolla]

i don't mind having to run bp ultimate as i do anyway. its not my daily driver but i still want it to run decent.

heres the mods i wanting to do

 

-lighten flywheel (don't know how much i can do this)

-skim head,port/polish, new valves (is their a size best used)

-stronger head gasket (don't know which one is best)

-cam upgrade

-carby upgrade (was thinking weber)

-extractors

-2" exhaust with one muffler

-thermo fan (remove clutch fan)

 

is there anything else thats simple to do or is any of this not recommended...

[Grand Master of Awesome]

spend $300 on a 5k, then do same list of mods you've already said.

[altezzaclub]

:jamie:.. Destroyer is right, unless you have a brilliant set of rings and bearings in the 4k, you might as well do up an average 5K and get a better motor.

 

A couple of Kg comes off the flywheel, the 4K only weighs 8kg I think and mine is 6kg now.

 

Changing valves is probably quite expensive, but a cleanup and a skim always works. I opened the ports up to match the Lynx manifold for the SUs, but the Webers work on the stock manifold so its no good getting too carried away.

 

Head gasket- I'd use Toyota. Buy an aftermarket gasket set if they're cheaper (I'm sure they are!) but buy a factory head gasket. Same with oil filters.

 

Cam- if its not a daily go for a mid-range to top end. Get some fun out of it if you don't need to crawl through traffic. Other guys on here will know some good cams, but here is the table I looked at. I picked a lift of 0.4" so I didn't have to chase new valve springs, but Holden 202 springs allow more lift. Look up the manufacturers as these are only the mild-mid range cams.

 

Weber is the cheap option. It will be jetted to suit the chokes in it, but those chokes might not be ideal for your motor.

 

Extractors are still being made, so you can get them new. ...and put a 2" resonator in it! You will be fedup with the noise and drumming after 6months and hating it if you don't.

 

Thermo fan is a nice idea, on my list for 'one day...'

[78corolla]

picked up a spare fly wheel to get machined. a brand new set of hm headers, thermo fan, a ported up head from a speedway car and cam to suit, a carby with a bigger throat and new head gasket, my total costs so far are 320 dollars going to put it all together in a few weeks time and make a 2" exhaust with one muffler

[altezzaclub]

Measure the volume of the combustion chamber and work out the compression ratio if the guy you bought it off wasn't dead sure of it.

 

You might be running a hand-grenade that was built to do a maximum of 15minutes hard driving and all above 3500rpm! We had a couple of those in rallying and went through a string of head gaskets.

 

You just need a bit of plastic sheet and a burrette, pictured in here-

 

http://www.rollaclub.com/board/index.php?showtopic=42407

 

If its over 10.5 to 1, certainly over 11 to 1 you might want to run two head gaskets or see what some of the guys on here think.

[e70van]

with my 4k i cut the airfilter "lid" right up, ran 98, advanced the timing and got rid of the mechanical fan. run a thermo instead.

 

i also looked into an electronic dizzy (off a 7k?) and at bosch GT coil, but i got a 4age instead :blinks:

[altezzaclub]

What sort of difference did the air filter mod give van?

 

Did you just leave the top circle sealing against the filter top??

[Twinky]

There is a far easier way to do that with far less dicking around, there is a mushroom type pod filter with a flat rubber at the top centre. Drill a hole in the centre and slide it over the carb.

Easy as, sounds nice too. I can post some pics if you would like.