Oh no Cracked cylinder head - is it terminal?

So I've been looking for a new mechanic after a series of not so great ones. I found one as used by @Tiny-Pie and gave him a small list of jobs:-
1. Adjust the sliding door as I'm sick of it bouncing back (very embarrassing and loud at night lol)
2. Sort the gear linkage, as much as I like stirring a cake I don't get the same enjoyment (or end product) with my gears
3. Check the brakes over, this was what I thought and involved the pads moving in the calipers. Then finally....
4. Sort the timing and stop her popping. I thought as I'd had the twin carbs for a while and have probably done about 2000 with them it just needed a bit of tuning how wrong could I be

It turns out one of the heads is cracked between the spark plug and something else I've forgotten. For about the last year I've heard a noise which I put down to tappets and a kind of sucking/blowing noise - previous mechanics x 2 both said not to worry about it and that's how i've ended up where I am now - somehow I think using the van this weekend is out of the question

Anyway the mechanic is pricing up things and has also mentioned replacing the piston rings or considering 1641 pistons whilst the engine is out ? I'm wondering the following:-
1. would it be better to bite the bullet and get a new engine?
2. Would 1641 pistons make that much difference and how much would it cost to do?
3. How would 1641's affect fuel economy

Yours in optimism

 

1. if the engine is all good apart from one head, no
2. not really from 1600 unless the rings and bores are shagged no idea on cost, depends who rips you off or who plays fair.
3. hardly any.


in my opinion.

 

I'd still use the van this weekend. I mean if you've used it up till now what can go wrong eh?

 

I was asking about the upgrade to 1600 a while ago. In nut shell the response I got is that it barely gives any more power.

Apparently its better to have your cylinder head and inlet manifolds ported/polished and gasket matched. Which means opening up the holes to the same size of the holes in the gasket, and then polish the insides to allow better airflow, then get a better than standard exhaust.

As for cost.. I think the barrels and pistons were about £400ish, then someone's gotta do it. So it's not a cheap thing to do.

 

this.

 

1. No. Just get head swapped (assuming your bloke actually knows what he's doing)
2 & 3. 1641 will make barely any difference: best forgotten.

 

I wouldn't waste your money on Bs & Ps....a hone and O/S Rings perhaps, if bores are a bit worn? plus new gaskets etc., Which head was cracked?....maybe check the oil cooler/surrounding tin ware

 

If only that was an option, unfortunately the engine being in pieces on the mechanics floor kinda prevents it lol

 

Took my old bus to Vanfest at least twice, Scotland twice, East coast, Weymouth then discovered that the lack of power on hills was due to both heads being cracked between the plug holes and the valves, inlet and exhaust! I only found that out because number 3 plug kept coming loose so I torqued it in, as per the Haynes manual and stripped the thread in the hole. I discovered that, when I turned the engine over and the plug shot straight out of the hole!
Cure? Two new heads from GSF.

 

i was going to upgrade to a 1641

 

ive got a spark plug with a stripped thread and somehow its holding in at the minute. Am contemplating what to do, had considered replacement head or even one of those top end re-build kits until i read Zeds comment on another thread which said something like in his experience rebuilding the top end can lead to problems with messing the bottom end up (sorry Zed if I quoted you wrong ) Anyway I thought time ive done that why not just get a recon unit from the engine shop for £750 quid. Cant argue at that price and piece of mind....hopefully.

 

i think the 1641 conversion is fine for the normal 1600 bottom end, if i recall correctly it's only if you start going up to 1776 etc you need to worry about the bottom end.

 

oh that's interesting as ours are cracked in the same place. When we fitted the twin carbs I felt a little increase in power but nothing like I'd been led to believe by various kind souls on here - does this mean by the time it's sorted it may feel a bit nippier?!!?

 

You bought the wrong twin carbs

 

Hopefully. At least you'll have a bit more compression.

 

possibly Woody but I didn't want to have to have a BP tanker follow us everywhere

 

This is different - newish engine with a cracked head - I'd get him to just replace the head, try and find out why it was running hot and carry on.
If your whole engine is tired then yes, renewing the top end will finish off the bottom pronto. In this case at least replace the big end bearings, but even so you might as well go the whole hog and replace all the bearings. lol

 

Do you think its ok to just replace one head, is it best to replace in pairs???

 

Just one is fine but needs to have the same valve sizes as the other.

 

ive got a spark plug with a stripped thread and somehow its holding in at the minute....

is it beyond a helicoil? got to be worth a punt...or have it rewelded/tapped...lot less than £750