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Discussion Starter · #1 · (Edited)
Currently got my 2.5 x25xe stripped down and I have a 3.2 block I was going to put the heads onto but then I realised the 3.2 gaskets are
round as opposed to 50p shaped on the 2.5 ( I didn't even think the obvious here but not the issue )
I then realised that the pistons in the 3.2 are flat whereas the 2.5 has reliefs for the valves.
My question is will I need to get valves from a 3.2 to fit or will the 2.5 valves be okay without hitting the pistons?
Your help is appreciated as always.
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Discussion Starter · #2 ·
Just been back put to garage and the 3.2 flat pistons have a 2mm gap to the top of the head when TDC and the 2.5 has 0 if not slightly proud of the head when TDC. Therefor Is it safe to assume it should be fine without changing any valves or pistons? Also after hours of searching for info I see there's a corsa on engineswapdepot.com/?p=60685 with the same setup and judging by pics it seems the same flat pistons.
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Is it safe to assume it should be fine without changing any valves or pistons?
looks ok to me ' by eye ' but youll be best off measuring it, just to be sure.

if youve got a vernier caliper, you can use the stick end on it, as a depth gauge.

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if you measure the deepest point in the valve cut out, looks about 2.5mm-ish (at a guess) ... and then measure the edge of the raised section of the piston, above deck height, looks about 0.5mm ish (at a guess).

then you can subract that. (2.5 - 0.5) and youll be left with the [below deck depth], to compare against the 3 litre measurement.
im guessing itll be somewhere around about 2mm, total guess.

also that flying saucer shaped hump, in the middle of the piston, is something to consider, as the Z32 piston is 7.4mm wider than the X25.
easy way to visually check, is flip one piston upside down, and center it ontop of the other one, to check where the hump starts, in relation to the cut out.
 

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Discussion Starter · #4 ·
Heyo nova, yeah first thing I thought is I need a vernier. The pics were bad as phone was dying when I took them. Really needed an answer to be fair as I was frustrated. I will get a vernier and measure as you say the depth of the cut out on the 2.5 pistons and along as the 3.2 is same depth across the board then I guess i will be alright. Now I need to figure out what to clean the outside of the block and heads with. It's about to get messy :ROFLMAO: I need to go update my thread as where I hosted my images i am no longer with. Was paying £20 a year for years to hist website storage and email but suddenly its £80 **** that but now all images need reuploaded
 

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I will get a vernier and measure as you say the depth of the cut out on the 2.5 pistons and along as the 3.2 is same depth across the board then I guess i will be alright. Now I need to figure out what to clean the outside of the block and heads with. It's about to get messy
if you dont have one, you could probably get close enough measurements, using a little wooden cocktail stick, marked with a fine point pen.
it wont be as accurate as a digital vernier, but if ones 3mm, and the others 2mm, youll be able to see that by eye, via the mark on the stick.

i'd cover the top of the block with masking tape, or something, if i were you, so no crap gets down the oil ways, bores, or coolant channels, then you can go to town, with wire brush, or whatever cleaning method you fancy. good to leave the oil filter on as well, stop any cack getting in from that side
 

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Astra G 3.2 V6, Vectra Hearse 1.8
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Discussion Starter · #6 ·
I have a vernier on its way,hopeflly here after weekend. Yes I have everything covered in tape at the mo, all is well thank you for reminding me regardless it is much appreciated. I will update here when vernier arrives and see what is what
 

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I thought using the 3.0 block is easier for the 2.5? and 3.2 block is easier for the 2.6 as a conversion, could try a 3.0 block but probably would be hard to source
 

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Discussion Starter · #8 ·
Hi mate yeah finding a 3.0 hasn't been easy. I found one a couple years ago at a local scrappy...I went back to get it and they had closed up and sold the land fml. It seems all the v6 the blocks are pretty much the same apart from capacity obviously. I also apparently can't get fibre gaskets for the 3.2 so I have metal ones. Never used them before. The block seems straight. I will have to get the feeler gauge out with my straight edge but will be a couple days as I'm sick as a dog. Fingers crossed they don't leak. I will post the rests of the micrometer when I get to it
 

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Discussion Starter · #9 ·
Well I managed to just about get out of bed today and measured the best i couldwith my striaght edge and vernier.
This is the closest I could get I reckon So seems like I should be safe enough to fit without fear of bending valves?

I do find it weird how the x25xe pistons sit so proud whereas the 3.2 sits so low down at TDC

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seems like I should be safe enough to fit without fear of bending valves?

I do find it weird how the x25xe pistons sit so proud whereas the 3.2 sits so low down at TDC
That pictures a bit fancy.
Fizz the graphic designer.

Should be alright.
After the head bolts are torqued up, and the cam belt is on, I'd turn the engine over slowly, a whole bunch of times, just to make sure there's no contact. Always best to play it safe.

Talking of cambelts, what belt do you need for that mix of parts. would it use the 3.2, or the 2.5, or would it need a size in the middle.

The raised crown on the 25 piston, is for a higher compression ratio. It's a group 'x' engine. I forget the ratio. (10 point something). Where as the 32 is an 's' rated engine, slightly lower comp. (9 point something)

I've got a feeling the smaller sized cylinder heads, from the 25, will probably make the 32 higher compression than standard, which should give you a little bit extra power and torque.
 

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Discussion Starter · #11 ·
Fancy shmancy lol. Yeah I like to try make things clear especially when it comes down to this kinda thing,but thanks for noticing my draftsman skills.
Yeah was gonna turn by hand a few times just to make sure. It seems like the crank is same place as the other but I will pop my old belt on first to find out and also measure from center of crank to all cam gears.
I have seen the few posts i can find about this that apparently it gives the extra power lower down which would be great.
Gonna do updates in my regular thread from now on. Thanks again yal
 
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