Thread: stroking a 3.5 motor

Ahhhh, excellent. Thanks for this.

Have just done the 3.5 to 4.2 motor upgrade with my sons Rangie
stroker kit and pistons fitted.
The kit is made by Performance modifications and I am led to believe still availible. From the east somewhere.
Its not a straight out fit as the 3.5 has to be bored 20 thou and parts of the block have to be ground off and lastly the sump will hit the crank so that has to be adjusted as well.
There is a big difference in power.
I have no idea of the purchase cost as I bought this one second hand from someone on this site.
So far so good 20k.
Something else u may consider is to fit bigger liners to the original 3.5 to make it a 3.9. Use 3.9 pistons and have the complete motor balanced.
I have done this twice now with the first one doing in excess of 400k and still going. The other is in my spare room almost assembled all new and ready to go in if and when my motor dies in my Rangie.
Brad

Originally Posted by PLR

sparrow the 3.9 , 4.0 and 4.6 all do it all in the same boat .

Pinning the liners or similar in a 3.5 would may be an advantage

Seems liner shift is the only major problem with them when made into 4.2or.3 ltr

I had the sump off mine (3.5 bored and stroked to 4.3)) the other day to replace the sump gasket and had a good look around..... I cant see how the liners can move DOWN due to there being a step machined into the block at the base of the liner on which the liner sits (on my engine at least). I also cant see how a liner can move UP because of the head sitting on top.
I have heard rumors about liner shift on these engines before and would welcome some comments based on my observations.

Why not just fit a p76 thats what im runing in my rangie and its great tho the 350 option would be nice and cost effective to as a rover or layland will cost **** loads more to get the same sorta tourqe

Originally Posted by Bradtot

Something else u may consider is to fit bigger liners to the original 3.5 to make it a 3.9. Use 3.9 pistons and have the complete motor balanced.
I have done this twice now with the first one doing in excess of 400k and still going. The other is in my spare room almost assembled all new and ready to go in if and when my motor dies in my Rangie.
Brad

But gotta be a post-1983 3.5L doesn't it? Someone was selling one of these on fleabay a while ago so i googled it. A post '83 is known as a "stiff block". The guy couldn't give me the engine number so i left it...

IMHO its not a rover if its not powered by a rover

Originally Posted by PLR

G`day Mark

Yes it will depend on the block

The latest 3.5s were machined so`s the bottom of the liner sits full circle like 3.9s ect but would have to be the last of .

The others may appear that way but only sit on tabs the four middle ones have the least alloy supporting them .

If you have a chance to see one with the crank out and upside down you`ll see what i mean .

When assembled in the factory the block is heated and the liners are fitted at room temp .

When the block cools the liners can and will rise , at the factory before they machine the deck they dont do a final press on the liners .

This can and does leave a space between the liner base and the supports/stops in the block .

The distance is about the same as the thickness of a side rail for an oil ring . Which is also the fix for a shifted liner in a 3.5 . ( 3.9 rail )

This is only a concern after being bored oversize or after being overheated .

One of the main reasons why it is very important not to overheat any V8 Rover engine because they all had the liners fitted the same way .

The 3.9/4.0/4.6 because there is less metal around the liner , crack the block at the same time as liner shift ( maybe ) so overheating them is less forgiving than 3.5s .

I have a 3.5 that one liner has shifted in .

It may be a little unusual but in the head surface there is the shape/ring of the liner imbedded into it .

I have another that all 8 have moved , it is 030 over .

The liners have all dropped as in a space betwwen the liner and the deck .

It got hot a couple of times , the liners dropped but it didn`t worry it , no rattles nothing but the overheating broke 2 rings which gave it low comp on 2 .

Cheers

Thanks Peter - I appreciate the informative reply, even if its not entirely reassuring...
Mines an 85 block. I cant remember whether the liners were supported all the way around, but I think it was just on tabs. Not sure what the overbore would have been to go from 4.2 to 4.3. Is there a definitive test for a slipped liner without pulling heads? It goes Ok but is a bit down on compression on a couple of pots which are around 135psi dry versus the best ones which are around 175. Vacuum at idle is around 17-18" Hg.
It also loses a bit of coolant but I havent totally excluded external cooling system leaks - I am still looking and hoping to find an external leak....

I wouldnt be worrying about slipped liners if it had a Chev in it..........

Not really only noise in the form of a tap or tick .

Heads off obvious , they should look like the liner and deck surface are one in the same , just the liner colour is different . Flat and no obvious sign of a join .

Should be able to run a finger nail over them and feel no difference or catching etc .

No effect on compression .

Depending on the cam ect the gauge reading sounds ok .

Should drop to around 5 and rebound to around 23 with a throttle blip .

If the needle fluxuates at idle may be saying somethings not right .

If the low are side by side head gasket ?

Give it a wet test if you haven`t , best if it doesn`t rise much cos it`s less work to do valves .

If you have a compressor and fitting for the s/plug hole ( can make fitting from s/plug )

When piston in low cyls on tdc with air applied listen at exhaust , inlet , sump for escaping air , tell where fault may be . ex valve / in valve / piston and or rings .

Think 020 is 4.2 and 030 is 4.3

Brad could tell you what his 3.5 was bored to get 4.2 .

Cheers

thanks mudmouse ill give it a go..