engine builders advice needed -

[ditz]

I've got an old f4r laying around which i've had for a while, which i think origionally had head gasket problems.
i've already had the head off it and rebuilt that, i was just going to sell the head but im now wondering as a bit of an evening project i may just rebuild the whole engine.

problem being - on the bottom end number 2 cyl (and as far as i know this is the only one) is stuck in the bore, and the bore above it has started to rust.

obviously its impossible to say without seeing it wether i can save it, but based on experiance of this sort of problem am i likely to get away with just getting it honed or would i be looking at a rebore with oversized pistons?
cheers

 

[Jam182]

Hey ditz.

It really does depend on the damage the rust has done to the bore surface.

What i would do is after you've broken the engine down have a go at the bores with a decent hone tool, see if it comes up well. Don't hone it too hard compared to the other bores tho, just give a nice even working over.

If the bore surface is still a bit doglike you have your answer, a slight overbore will be neccessary. I don't know what the situation is with oversize pistons/rings is for f4r but it's a regularly tuned and common enough engine so you should have no trouble.

Do you know why the engine had hg probs by any chance?

 

[ditz]

well i got the engine complete plugs in it, inlet plenham on it and exhaust manifold on it
when i took the head off recently, number 2 combustion chamber had alot of rust deposits and it was only really that liner that looks to have suffered,
i think its unlikely water has gotten in by any other means.
im yet to put a straight edge across the head as i was going to get it skimmed anyway to clean up the surface but i will look in to it.

its got a cracked sump also, so obviously the first thing i thought when i got the engine was oil starvation.
but the cam journals/cams etc look brand new no scoring what soever, had a peek at one of the bigend caps and they are fine too.

think i'll start stripping it and see what i find

 

[Jam182]

The block and head are gonna need skimming that's for sure, just to someway ensure that the hg doesn't blow again when you rebuild the engine.

The water in the bore was probably the coolant infiltration from the hg blowing.

Hopefully the engine didn't MASSIVELY overheat as it will have destroyed the heat treatment on the head and you'll have to get a replacement, this is quite rare tho so i wouldn't worry. If you want to check it you'll need to get a local engineers to check the head versus a another sound f4r head with a hardness guage.

Did the engine get removed from a car and then sold to you? Or was it out and sitting around? If so the cracked sump could be from careless handling, or accidental droppage S) so oil starvation may not have been the issue.

Obviously despite this double check all of the bearing and journal surfaces thoroughly for signs of wear or scoring just to be safe and double double check the crank for cracks or wear.

I cut my teeth on all alloy FR/Rally and Race Hillman Imp engines so i knows what i'm talking about when it comes to HG failures!!

 

[sideways danny]

I'd see it as an opportunity to go for high compression pistons and get some oversize forgies if it was me

 

[ditz]

i think you may be on to something re the cracked sump jam -
i'm going to bring it home tommorow and get started.

i am starting to think along these lines danny - how much am i looking at for a set of pistons?

main problem being - where i work i dont really get involved in bottom end rebuilds - we tend to get a headgasket/snapped belt/valve job every other week on average but the last couple of garages i've worked in the most involved bottom end job i've done is changing conrods etc.

its one of the reasons i'd like to have a go, i've got no experiance (and frankly wouldnt know where to start) with things like measuring bearing clearences and thrust races on the crank etc etc

what sort of machining costs are involved with boring/facing the block, bearing in mind the machining place i use atm charge £41 inc vat for a head skim?

cheers for the help

 

[chrisdoc]

first thing id try mate is pouring a can of coke into cyc 2 to try free it off , if your re building make sure u replace the big end bearing a main bearing itll save you trouble in the future , p.s u wnt be able to get a block skimmed clean it but get head done also one thing i did was to get the valve seats recut at the same time

 

[ditz]

you can get a block skimmed!
the heads off so i've just soaked it in plus gas and im going to press the piston out tommorow.

all bearings etc are getting changed i'd never rebuild an engine without doing that


i've already built the head, im fine building heads valve seats didnt need cutting i just lapped them all in polished the flutes and a mate of mine cleaned the ports up a bit.

 

[sideways danny]

a good engine building manual would be ideal to have a read of, checking clearances is time consuming more than anything, with decent equipment and the knowledge to use it right (plastiguage, feeler gauges, etc) it's not hard really. A good machinist you trust, and decent quality parts (bearing shells etc) is essential or you'll get no-where fast. I've used the same machinist for 10 years now and trust them completely

A good engine reconditioner will have tollerences to check crank journal sizes against, and re-grind if necessary (not normally needed unless the journal is scored) buy bearing shells of the corresponding size. Once you've got these bits you need to do a dry build to check tollerences in situ, then strip down, make sure it's all clean and do a final assembly.

Ring gaps are checked by fitting each ring to each bore one at a time, squaring them up (use a piston with a ring in 2nd gap then push down until the ring sits on the block face, the new ring should be squared up) for gap size you need to refer to manufacturers specs, rings can be adjusted with a fine file but it's important to keep the faces square and even, a grinding tool for this job is ideal.

thrust clearance is a case of fitting up and torquing down, then levering the crank fore and aft whilts using feeler gauges to measure the gap between the crank face and the bearing, this can be adjusted if it's too tight by removing material from the back of the bearing (non contact surface) with fine emery/wet'n'dry on a piece of glass (for flatness)

That's a very quick basic rundown, I've probably gone through it a bit quickly TBH but it gives you an idea

 

[ditz]

thats alot of help mate cheers, its like anything else really i suppose - got to dive in and have a go to learn!

 

[ben_p]

i have a BE on 26k £100

 

[ditz]

want to rebuild it fresh really mate, would be defeating the object just buying one.

right, i've stripped it tonight. turns out it wasnt stuck in a bore at all, the bores came up a treat.
it had spun 3 (!!!) big end bearings, the fcukers welded themselfs to the crank had to split one in half to get it off.
surprisingly enough though it looks to be the only damage done - bores still had honing marks even before i touched them, main bearings perfect, cam journals and cams perfect, etc etc.

so the crank needs grinding - how would i go about sourcing/ selecting oversized bigend shells?

cheers

 

[sideways danny]

machine shop should be able to help you with shells, where in essex are you? be aware that if the bearings have spun, the rods wont be much use now.

 

[ditz]

rods look fine, no scoring what soever, i've just been having a look at it and im not entirely sure they have spun, as all the damage seems to be to the crank.
i'll take some pics tommorow.

im in romford - we have been using a place called tk engineering for head skims etc, but gosnays is closer to me ( you may have heard of them)

 

[Fred@BTM]

IIRC 172 shells are a t**t to get hold of in any size other than OE, i maybe way off

 

[sideways danny]

IIRC 172 shells are a tw*t to get hold of in any size other than OE, i maybe way off

AE do .25. There's 2 different types of shell and rod too, one that has retaining tabs and one without. Think the tabbed shells are same as F7

 

[ben_p]

IIRC 172 shells are a tw*t to get hold of in any size other than OE, i maybe way off

AE do .25. There's 2 different types of shell and rod too, one that has retaining tabs and one without. Think the tabbed shells are same as F7

you mean tangs? if you could only get a shell with a tang on to fit, then you would need them removing at a MS

 

[LJColeman]

i know this is really digging up a grave, but if fitting oversized 84mm pistons, what head gasket would you use? as surely that will need to be oversized too ? and does anyone have any more info on bottom end bearing shells after having the crank reground? any help would be much appriciated, thanks

 

[Dan519]

the hole in a standard headgasket is bigger than the bore already. Think it's 85mm

 

[EVOgone]

Its only 83.5mm

Would have to get a Cometic etc as they do upto 84mm.

 

[Chip-mk1]

BTW 84mm isnt common on an F4R, normal oversize is 83mm

 

[EVOgone]

BTW 84mm isnt common on an F4R, normal oversize is 83mm

Yes agree, just referencing you can get upto 84mm dia.

 

[Dan519]

BTW 84mm isnt common on an F4R, normal oversize is 83mm

well that's just not true at all.

 

[Chip-mk1]

the hole in a standard headgasket is bigger than the bore already. Think it's 85mm

No its not 85mm, try again, lol

Its only 83.5mm

Would have to get a Cometic etc as they do upto 84mm.

Cometic is 84.5mm

IIRC the standard one is 83.8mm

BTW 84mm isnt common on an F4R, normal oversize is 83mm

Yes agree, just referencing you can get upto 84mm dia.

Yep, readily available from all the suppliers of forged pistons I know but with the wall thickness being quite small to start with you kind of need a good reason to go that far generally speaking hence most people stick to the 83/83.Xmm oversizes, means standard gasket (which is better than the cometic I would argue in terms of the form of the compression ring) still works fine and also means you can still get another rebore or two out of it again if you need to. Not that another standard block is exactly hard to come by.

well that's just not true at all.

Coming from the man who thinks the standard gasket is 85mm im sure thats worth listening to, FLOL

 

[Dan519]

you're just wrong. You've built one forged F4R. Get off your pedantic high horse. I've used 84mm Pistons plenty of times as have others.

as for not knowing every last measurement by heart while i'm sitting watching the olymipics.....lol, yes good arguement. I don't keep a headgasket and calipers by my bed you tool, hence why I was clear about my post not being exact, the point was it's bigger than the piston/bore size

I deliberately don't memorise these things too closely to make myself check and not assume tollerences.

 

[Chip-mk1]

I've used 84mm Pistons plenty of times as have others.

Have you used them on the standard head gasket then Dan?
If not why did you not use the standard gasket?

the point was it's bigger than the piston/bore size

Bigger than standard yes, bigger than the 84mm you think is common I dont believe to be true though, although im quite happy to be corrected on that if Im mistaken, ive only built a few of these particular engines myself anyway so wouldnt claim to have encylopedic knowledge of them like I do with some other engines.

I deliberately don't memorise these things too closely to make myself check and not assume tollerences.

Flol @ that, tolerances to me are things like piston to bore clearance, not the headgakset IIRC being over a mm smaller than you think and hence too small for the pistons you apparently use all the time.


TBH Dan since I slapped you down when you were trying to belittle someone that raising the CR couldnt possibly increase the amount of power from an engine from the same set of injectors (TBH Im still genuinely gobsmacked that anyone who claims to be capable of tuning a car doesnt even know the basics like that about how an engine works and that more CR will increase power at high RPM when the diminishing induction stroke timebase means that VE will be naturally tailing off) which he was of course completely correct about in the first place as he obviously knows a lot more about engines than you do, but you tried to "put him right" from your misunderstanding where you just didnt actually understand the concepts at all it just seems like ever since then you just desperately want to disagree with me just for the sake of it, which looks very petty of you IMHO
http://www.cliosport.net/forum/showthread.php?617769-Cat-438-Camshafts/page2

I'd be happy to wager if we contacted a few of the piston suppliers for these engines they'd tell you 83mm was more commonly requested than 84mm, but even if its not, its a pretty silly thing for you to be trying to "win @ the internet" over, LOL

 

[LJColeman]

Thanks for the help guys, thought this would be the case, was just too lazy to dig out my old gasket to check !!

 

[EVOgone]

Chip Cosmetic hg's can be purchased in different sizes that's my point, never seen a 84.5mm one advertised but that's not to say they don't do one.

 

[Chip-mk1]

Different thicknesses too which can be useful cr wise.

 

[Fred@BTM]

you 2 should hug it out!