bore out a 4g32 saturn by 0.75mm safe?

[driftforlife]

im thinking of getting new pistons for my 4g32, i just thought if im getting piston rings i might as well get pistons too
the ones im looking at getting are 0.75mm oversize.
can the saturn 4g32 cope with that and can it even go that far at all?

thanks

[kodos]

Yep, pretty sure thats just third oversize.

[shuggy]

yeh 1mm is what the manual classes as max but i beleive 1.5mm is the max as RPW states.

[tandanus]

All true AFAIK. But if you only need rings and a hone, why buy pistons? If your rings have broken you'll need a rebore and pistons. Otherwise probably not.
T.

[driftforlife]

ok, thanks for the information, i guess i'll go ahead with it then.

yeh i know tandanus but i thought if i'm going to get work done in there i might as well do some performance stuff too

thanks

[gaz914]

You can use 4G37 pistons and go up to 1700 cc.

cheers
Gaz

[shuggy]

i read up that the piston height of 37 is different to 32. In this case u would either loose compression or smash valves.. Anyone know anythin about this?

[driftforlife]

i have already found pistons designed for a bored out 4g32, that's why i asked, sorry.

[Rally_2.6LC]

4G37 pistons can actually allow you to go to 1770, thats the biggest (without stroking) u can go in a 4G32.
I need a rebuild and was thinking the same thing as driftforlife.....if u rebild y not improve. I was going to go 0.30 oversize flat tops and new rings but due to having no money I might just go new rings and hone and put some money into the head and the twin webers I want......that or registering the LC rally car.



Cheers Matt

[Torana68]

37 pistons are too high for a 32 you have to machine them down and i havent heard anyone who has done it who was happy (ie too much compression and I think someone went too far and they broke in use)

[shuggy]

37 pistons are too high for a 32 you have to machine them down and i havent heard anyone who has done it who was happy (ie too much compression and I think someone went too far and they broke in use)

thats exactly what i thought..

[topps]

im kinda new here but can you at least give me some hints?

how about a 4g32 head sitting on a 4g37 block? will the piston hit the valves?
im running on a 4g37 but i have damaged the 4g37 head so i want to use my spare 4g32 head.
im not sure if the pistons will hit the valves or will have hi or low compression.
what i have done so far is fit in the 4g32 head(without the valves) to the 4g37 block and rotate the crank pulley. so far no problem. but im not sure if i try it again with the valves on. Hoping it would not be hitting each other.

Thanks!

[shuggy]

this works? considering the valves are smaller im guessing it wouldnt be very benificial tho?

oh and welcome to the sait mate

[topps]

thanks for the welcome.
i really have not tried it yet. i am still in the process of cleaning the 4g32 head.

but from the discussions i have read here, some are suggesting to use 4g37 pistons and rebore their 4g32. unfortunately the 4g37 pistons are too high for a 32 and needs to be machined down.
so why not use a 4g32 head and put it in a 4g37 block so we wont need to machine down the pistons? me thinks the 4g37 block is almost like the rebored 4g32 block with 4g37 pistons.

possible?

[shuggy]

well yes i suppose the stroke is the same, its just the bore that is different.. it has a bore/stroke that is squarer than a 32 (76/86 vs 80/86), its just will the head fit on the block?

[topps]

the 4g32 head sits perfectly on the 4g37 block. everything is the same except for the larger waterport hole in the 4g37 head. also the shape of the head of the 4g37 is kidney shaped as compared to the hemi look of the 4g32 head.

do you guys see any issue that the valves will hit the piston? what can you suggest i do to test it out without damaging any parts?

im thinking of bolting the head to the block with the valves on then rotate the crank pulley. if they hit each other then its not possible? LOL

[shuggy]

yeh thats pretty much the only way.. you could use a ruler and measure how far down the valves come and then compare that to the piston height for obvious problems, if its not obvious they wil meet then test it out? maybe rim the valve in red chalk so you can see if there is contact?

[topps]

yeah thats it. the red chalk technique!
im thinking of stuffing kid's clay on the valve before i bolt it to check if it will hit.
i guess the chalk method is easier and cleaner.

btw 4g37 head on a 4g32 = low comp
4g32 head on a 4g37 = high comp??

thanks again mate!

[C_Fernance]

Measuring them with a ruler is about as dodgy as it gets.

Try putting a piece of blu-tak or playdough on top of the piston, dummy assemble the engine and turn it over a few times. Take it apart again and measure the thickness of the compressed blu-tak/playdough. Then you know exactly how much clearance you have.

[topps]

thanks again.
do we have standard clearance between valves and pistons?
or as long as there is a clearance between them, then its ok?

sorry for asking too much sh!t, its my first time working on an engine and i have nothing but the internet as reference.
have my buddy to work with but he knows toyota stuffs.

[oldn64]

When building a I will not go any closer than 150thou. Any closer and you will find things get close with carbon layers and wear. I have built a 4g32 with 80thou clearnace but this did not last too long. Valves eventually hit pistons

Cheers

[topps]

@ oldn64
did you measure the clearance also using the playdough method?
thanks sir!

[oldn64]

@ oldn64
did you measure the clearance also using the playdough method?
thanks sir!

I have used pastigauge and plastisene and both seem to work as good as each other. You do really need to be super accurate but you use it as a guide. I usually measure before machining and calculate what I want off and then after machining. This way I know not too much will be taken off, what this means is that you end up going through 3 head gaskets. I have seen guys do it without a gasket and measure and calc as if gasket is in there to save the extra expense but at the end of the day I want to know it is right. Just gives better piece of mind...

Cheers

[topps]

thanks mate.

i'll measure out the clearance and post it here for anymore inputs.
im just hoping that there would be no detonation due to high compression.

[LEE]

ok 1770 cc from a 4g32 is possible you use max oversize 4g35 (if you can still find them) , we used to bore 4g33 (1400) to 1600 using 32 pistons ,My god how time flies ,this was the norm in the eighties

[toruhiwi]

Thanks for that confirmation Lee, regarding boring 4G33 to 4G32. I seem to recall this was possible.
It is exactly the question I was asking in another thread last week......

As I understand, fitting a 4G32 head to a 4G37, or conversley overboring a 4G32 and using 4G37 pistons and the 4G32 head, will give a compression ratio in the region of 11.5:1 to 12.0:1.
An appropriate camshaft grind is advisable to reduce the chance of preignition...

Roger

[topps]

what cam profile should i use then?
cam 6? i tried to see what camshaft i have on my head and it just states a "2R" not sure with that though.

forgot to tell say that the 4g37 sits on a 1987 lancer. *weird*
http://i284.photobucket.com/albums/ll35 ... C03813.jpg

[shuggy]

2h is the cast marking, you need to look on the end of your cam at the back, there will be a small number stamped

[LEE]

ok so you are using a belt drive motor by the looks of things - there is no big cam available that will reduce 11.5 to 1 static from the factory thats easily available , custom Ivan Tighe , or kelford and with that you will need the head ported to flow , a intake that can support the flow , and exhaust that wont impeed the intake , head , and cam , expect a 300 deg to wash off enough to run pump fuel , and dont expect it to be a great daily either

[topps]

ok so this is what happened.
i tried to test fit the 4G32 head on the 4G37 block.
at camshaft and crank shaft TDC , i tried to turn the crankshaft several times.
on the 8th revolution the crankshaft was stucked in the BTDC mark. it can neither be turned clockwise or counter. but the cam shaft was still set to TDC.
by this time the 1st and 4th piston should be the one on top, and valves in the 1st and 4th rockers should be near/almost close.
im not sure what is the cause of the stuck up.

do i need to change timing belt since im still using the old 4g37 timing belt? both has 122 teeth me thinks...