Liners or scrap?

[JJDraper]

Just been reading the chat about blocks and wall thickness and had a thought. My original block (681F) is on +60 pistons.. Lots of miles on them now (100k), slight wear lip at the last head gasket change, but still lots of compression. I need to think about what happens next? At 84mm, can the bores take liners without breaking through? The block is otherwise sound and matching numbers with the car (and head!) so I would like to keep it that way. I guess the walls must be reasonably thick to have lasted this long, but I have no idea of the block stamping on the front face as I have never been that far in 15 years of ownership!

Jeremy

[StressCraxx]

There should be plenty of material remaining for installing sleeves. A competent machine shop can do it. New sleeves will have a superior surface for new rings and pistons.

I have sleeved two Kent Formula Ford engines and the results have been excellent.

[alan.barker]

I seem to remember that liners used in the past were stepped liners for a Mercedes 140??? but i'm not sure.
They need to be shortened of couse and scallops cut.
You could then get nos standard pistons which are cheap from Miles Wilkins or SJS
Alan

[stevebroad]

If the walls are thick enough to take liners without breaking through then the block will take another bore easily. Liners are used when there isn't enough material left for another bore. These are called wet liners as they form a complete bore wall with none of the original remaining so they are in direct contact with the coolant.

Dry liners, as the name suggests, don't break through into the water jacket. They are used to change the bore material (eg in an aluminium block or to replace cast bore with a Nikasil lined one)).

[StressCraxx]

If the walls are thick enough to take liners without breaking through then the block will take another bore easily. Liners are used when there isn't enough material left for another bore. These are called wet liners as they form a complete bore wall with none of the original remaining so they are in direct contact with the coolant.

Dry liners, as the name suggests, don't break through into the water jacket. They are used to change the bore material (eg in an aluminium block or to replace cast bore with a Nikasil lined one)).

Dry liners are preferred for simplicity and reduced chance of a coolant leak. Liner metallurgy is superior to the original block.

[stevebroad]

If the walls are thick enough to take liners without breaking through then the block will take another bore easily. Liners are used when there isn't enough material left for another bore. These are called wet liners as they form a complete bore wall with none of the original remaining so they are in direct contact with the coolant.

Dry liners, as the name suggests, don't break through into the water jacket. They are used to change the bore material (eg in an aluminium block or to replace cast bore with a Nikasil lined one)).

Dry liners are preferred for simplicity and reduced chance of a coolant leak. Liner metallurgy is superior to the original block.

Agreed, but if the OP has taken his block as far as it will go, liners will almost certainly break into the coolant jacket.

[rgh0]

I dont think I would bother trying to put wet liners in a Ford block. Cheaper to buy a new block than buy the liners you need and do the machining needed. I also dont know of any that have been tried or done successfully so your out at the bleeding edge trying to build a wet liner 1500 Ford block. The blocks were not as stiff as desirable so I suspect you would find the centre main would rapidly depart the rest of the block with wet liners. You also have the issue of the oil cross drilling between the 2 and 3 to contend with.

Nothing is impossible, it just is not an economic proposition, and high risk, but after 4 or 5 tries and $15k you may get it right with wet liners or maybe not and you prove its impossible

Putting dry liners in a 1500 block is a question of remaining wall thickness and bore you want to build the engine to and that takes some detailed bore wall thickness measurements to determine if it can be successfully done based on how much risk you want to take.

In general you want at least 2.5 mm wall thickness at the thin spots with a minimum of 1 mm for the finished liner and 1.5 mm for the remaining bore wall. That is the absolute minimum IMHO and failure is always an option at those thicknesses in a standard road car depending on the casting integrity and i would not try it in a developed engine without a lot more wall thickness

cheers
Rohan

[stevebroad]

I dont think I would bother trying to put wet liners in a Ford block. Cheaper to buy a new block than buy the liners you need and do the machining needed. I also dont know of any that have been tried or done successfully so your out at the bleeding edge trying to build a wet liner 1500 Ford block. The blocks were not as stiff as desirable so I suspect you would find the centre main would rapidly depart the rest of the block with wet liners. You also have the issue of the oil cross drilling between the 2 and 3 to contend with.

Nothing is impossible, it just is not an economic proposition, and high risk, but after 4 or 5 tries and $15k you may get it right with wet liners or maybe not and you prove its impossible

Putting dry liners in a 1500 block is a question of remaining wall thickness and bore you want to build the engine to and that takes some detailed bore wall thickness measurements to determine if it can be successfully done based on how much risk you want to take.

In general you want at least 2.5 mm wall thickness at the thin spots with a minimum of 1 mm for the finished liner and 1.5 mm for the remaining bore wall. That is the absolute minimum IMHO and failure is always an option at those thicknesses in a standard road car depending on the casting integrity and i would not try it in a developed engine without a lot more wall thickness

cheers
Rohan

Can't argue with any of this. I had my 1600 block linered to take 85mm +60 pistons and they all cracked around the top within a few miles. May have been a crap job, but I went back to a thick walled block and standard 85mm and a long throw crank.

[rgh0]

Blocks that can take a 85mm bore are few and far between and take careful machining to get them robust enough to last !

I have a couple in my stock I have found after lots of thickness checking of lots of blocks. One is reserved for that big bore, long stroke, McCoy headed 200 hp road engine for my Plus 2 that I keep promising myself I will build once I finish all the other projects I want to do !

I also have had a couple of 85 mm bore engine blocks that I built and that failed back in the days when I competed in Marque sports cars racing in the 80's before I got into historic racing when this sort of mod was allowable and i did not know as much about what worked and what did not

cheers
Rohan

[2cams70]

Please see attached some pictures of an original Twin Cam Hepolite dry liner with bore finishing dimensions and fitting instructions. The cylinder bore diameter for accepting these sleeves is 3.375" (85.725mm). By my reckoning that leaves around 1.5-2.0mm thickness of the original bore material left after these sleeves are fitted.

Sleeve fitment should not be too much of an issue provided machining is done correctly. The steel of the sleeve is stronger than the original cast iron and should therefore be better at withstanding the hoop stresses imposed by combustion. With the bore machined back to the original 82.5mm dimension the total wall thickness is back to original but with the steel reinforcement of the sleeve. There is a reduction in the strength of the block in tension however. On the cylinder head side the tension forces imposed by the forces of combustion are taken by the cylinder head bolts and the female threads for these are attached to the outer walls of the block itself and not the deck so not much of a reduction there. On the main bearing side there is a reduction because the attachment of the mains caps via the cylinder walls to the top of the block is reduced significantly. Maybe the dreaded high strength Loctite could help a lot here between the liner and the remaining cast iron ! Has anyone experienced mains failure on a linered Twin Cam block ?? Crossflow experience does not translate to Twin Cam experience unless the crossflow is running at bore diameters the same as Twin Cam because the crossflow will always have a thicker wall given that the OD of the bore casting is largely the same across all kent blocks.

The original Hepolite dry liners liners have been reproduced by Westwood - see attached link. QED have both thin an thick wall liners. The thin wall are probably the same as the Westwood liner. The thick wall are for bore sizes larger than standard. The thin wall liners must be replaced when worn, they can't be bored to a larger size.

http://www.ebay.co.uk/itm/Ford-Lotus-Tw ... xyNepRnLAL

[alan.barker]

I seem to remember that there were some blocks with liners fitted from new
Alan

[rgh0]

I seem to remember that there were some blocks with liners fitted from new
Alan

Yes I have seen original blocks that had one or more liners from new. I presume Ford recovered faulty machined blocks with liners

cheers
Rohan

[rgh0]

Please see attached some pictures of an original Twin Cam Hepolite dry liner with bore finishing dimensions and fitting instructions. The cylinder bore diameter for accepting these sleeves is 3.375" (85.725mm). By my reckoning that leaves around 1.5-2.0mm thickness of the original bore material left after these sleeves are fitted.

Sleeve fitment should not be too much of an issue provided machining is done correctly. The steel of the sleeve is stronger than the original cast iron and should therefore be better at withstanding the hoop stresses imposed by combustion. With the bore machined back to the original 82.5mm dimension the total wall thickness is back to original but with the steel reinforcement of the sleeve. There is a reduction in the strength of the block in tension however. On the cylinder head side the tension forces imposed by the forces of combustion are taken by the cylinder head bolts and the female threads for these are attached to the outer walls of the block itself and not the deck so not much of a reduction there. On the main bearing side there is a reduction because the attachment of the mains caps via the cylinder walls to the top of the block is reduced significantly. Maybe the dreaded high strength Loctite could help a lot here between the liner and the remaining cast iron ! Has anyone experienced mains failure on a linered Twin Cam block ?? Crossflow experience does not translate to Twin Cam experience unless the crossflow is running at bore diameters the same as Twin Cam because the crossflow will always have a thicker wall given that the OD of the bore casting is largely the same across all kent blocks.

The original Hepolite dry liners liners have been reproduced by Westwood - see attached link. QED have both thin an thick wall liners. The thin wall are probably the same as the Westwood liner. The thick wall are for bore sizes larger than standard. The thin wall liners must be replaced when worn, they can't be bored to a larger size.

http://www.ebay.co.uk/itm/Ford-Lotus-Tw ... xyNepRnLAL

The OD of the bore castings is very variable in all the Ford blocks from the earliest 116E to the last 701M or 711M. The minimum individual bore OD I have measured is around 88mm and the maximum around 92 mm. There is no way to identify which blocks have thin or thick walls based on L or Not L, block casting types such as 120E or 701M etc or date of production or T numbers that I have been able to identify. The average is around 90 to 90.5mm. The new cast blocks being produced by Ford Motorsport are close to this average and appear to vary less than original blocks based on the small sample I have measured

People make lots of claim that various blocks are better with thicker walls (e.g. 701M blocks or L blocks) but I have never found this to be substantiated in my thickness measuring. I have never measured any of the AX blocks from South Africa which people claim have thicker walls but I doubt they are any different as the casting technology used does not really allow systematically thicker walls.

Finding a block with all 4 of the bores down at the 88mm minimum is rare ( I have an L block with a split bore like this) simlarilyfinding all 4 of the bores around the 92mm maximum is rare ( I have a couple of these).

You need to check any individual bore you want to liner to see if you can get the liner in without ending up with to little remaining wall thickness. If you have an 88mm OD bore that needs to be linered you will end up with an inadequate remaining casting wall around 1mm wall thickness assuming you can centre the liner in the casting which is not always possible depending on the existing bore and how well its centered to begin with. If you have a "normal" bore casting OD in the 90 to 90.5mm range and can centre the liner then you can liner it and have enough wall thickness ... just

I have seen a number of blocks suffer cracking around the centre mains. This was due to corrosion in the water jacket side at 83.5 mm bores in racing engines. Linering the centre No 2 and 3 bores would have a similar effect and potentially lead to similar failures in a racing engine at least.

cheers
Rohan

[peterako]

Hi Jeremy,

My Twink was at +40 (I think) and I decided, for multiple reasons, to reline and go back to standard.

One of the main reasons was that relining + standard pistons were much cheaper than rebore + over-sized pistons.

I got the liners on eBay ( ):
http://www.ebay.co.uk/itm/Ford-Lotus-Tw ... xyNepRnLAL

Pistons from SJ Sportscars.

It's a few years ago, but worth a try.

Engine is running well many 1000's of miles later.

Best of luck!
Peter

[alan.barker]

+1
nos standard pistons are very cheap and no problems for normal driving.
I deglazed the standard bores on my Sprint and also fitted nos standard pistons from sjs.I have driven many miles and no problem
Alan