SteveK

Anyone any ideas

What is the maximum amount that a flat top piston can protrude above the deck at TDC After installing my pistons I am seeing a positive height above the deck of between 0.008 and 0.010 of an inch (8 and 10 thou). I am using a fel-pro gasket that, uncompressed is 50 thou and compressed should be 40 thou. Does 40 thou - 10 thou (30 thou) = trouble or will I still have enough to give adequate piston to head clearance and tight enough to give a good squish area. If this is a problem would I be better for safeties sake to us a slightly thicker head gasket ?? Once again Phred if you’re around I would really appreciate your input Ta

Phred Thank you for a comprehensive answer to my questions. I am certainly more comfortable now with the 20 thou gap than when I first saw it. Incidentally I spoke to Total seal yesterday who are willing to make a gapless chrome moly top ring set for me --- not cheap though -- I am just deliberating as to which direction I should take. .

Yep, first phone call I made and the answer was "I should be OK" hmm didnt like the word "should" kinda lacked conviction.

Can anyone tell me (from experience) what the acceptable piston ring gap should be on an L28 with standard sized pistons Have read all the books (How to rebuild, Haynes etc) and it varies from 9 thou to 18 thou, however I am just installing new rings on some dished pistons and without gapping them I am seeing 20 thou on both top and bottom sets. The bores look good (86.02 - 86.03 mm max and practically no taper) with cross hatch honing marks clearly visible (engine has only done 5K since last rebuild) old rings show 22 thou and car made 158 Bhp at the wheels when last dyno’d. Moving on from this has anyone used total seal (or such like) gap-less rings ??? Phred it would really be nice to get your input here if you are around Regards

Thanks Toystory -- read it and most respondents don’t agree either Arizona car have a vested interest in selling them don’t they BTW if Holley 4 barrels work so well why do so many "real" race cars still use triple webers or fuel injection with throttle bodies or haven’t they figured things out yet As one person says

And possible lack of horse power !!!!Single downdraft carb installs will never be as efficient as a side draft set up due to the sharp turn at the botttom of the manifold As for cheapness a decent pair of 2nd hand SU's will surely only be a fraction of the cost of a complete new setup.

Listen to the Phred what he doesn’t know about engine building could be written on a matchbox in poster paint. Hey Phred if your around are Nismo exhaust headers any good ? I have an MSA jobbie that is of average build quality and trying to match the ports up is difficult at best and in some cases overlapping my exhaust ports by quiet a few mm I wondered whether to persevere or cut my losses and start with a better quality unit.

I have this edition (its a Brit mag) and it is fairly good although it does (wrongly) give credit to Albrecht Goertz for the design of the Z The Z club of GB in conjuction with Carl Beck (cheers Carl) has sent a response to Practical Classics in order to set the record straight Steve Kiddell Editor Z club magazine

Yes you can but just based on atmospheric and compressed readings only--- it wont be accurate and will just give you a range, figure on dividing the PSI by 17-20 for a ball park. If you have more data such as cam timing etc then the picture gets more accurate

Hi Alan -- just PM'd you

zhead240 They will get close to 30 mpg in standard form but when you start to modify and tune them for power, gas mileage suffers. Each to their own really, you can stay with a cast iron exhaust manifold, twin SU's and 150 BHP at the fly wheel (if your lucky) or you spend zillions of pounds, every waking moment and end up with a wonderful smile every time you pass a d*** wad in a BMW who thinks he drives the be all and end all of motors -- personally being able to do the best part of 100 in 3rd is a thrill on its own. Think yourself lucky, I live in the UK where petrol is about $6 per gallon but the buzz it get outweighs the cost every time

I am working on a write up for the UK Z site but Here’s a heads up John Wilcox has a multi million pound business solely dedicated to precision race engine building and the scientific analysis of the entire process. They will not generally do rolling road testing for any old jo bloggs (saxo owners be warned) The way I found out about them was through Duncan Pearcy from the Z farm who built my engine, he mentioned that Dominic Frattaroli has been to them for many years. So I phoned Wilcox’s and chatted with the receptionist whom I thought was very knowledgeable -- She turned out to be the Wife of the owner (her name is Rita and she is absolutely brilliant) I almost went through an interview on the phone. She told me the waiting list could be several weeks, which didn’t deter me so we continued and I booked in Five weeks later (I was running my engine in so no big deal) They spent 3 hours, they tested several sets of jets (on triples so x 3) optimised fuel flow, fuel air ratio, and ignition for best power, economy and drivebility, found me 25 hp extra and flattened the torque curve off. They called this a “rough” set up. I then got a guided tour of the site by Jon Wilcox and it blew me away Having had 25 years in engineering I hadn’t seen anything this good since my days in a research establishment for the National coal board. They have a full machine shop, electronics workshop, engine build clean room, 1000 bhp sound proofed water dyno and NASA control center, 225 hp eddy current dyno and the rolling road. But be warned, whilst testing they will not let you anywhere near the rolling road area as it is regarded as confidential, they develop for many high end applications and companies so have to preserve client confidentiallity. This was the hardest thing for me as I (like all of you) am protective towards my car. They definitely get big thumbs up and were not that expensive, considering the expertise that was at my disposal. The most important thing is that I trust them and the figures, they are one of the few dyno’s that is used to test and develop engines for major motor companies and as such stand the best chance of being accurate (as much as could be). Their figures are the ones quoted in book and manuals. They ship engines all over the globe – if they can’t do it, it can’t be done I am proud to say that my car has been tuned (no matter how mildly) by these guys. Once again Eric sorry for hijacking

Hey Eric How are you doing Glad to hear that your new settup is woking out Just to let you know that your carbs are also running on a newly built L28, N42 big valve head, stage II cam, Vernier pully And it has just been dyno'd by one of the most reputable competition engine builders in the UK (Wilcox race engines) Bear in mind these guys develop for Truimph motorcycles and Rover cars and build $20,000 upwards race engines for many people across the globe 160 BHP @ 5500 at the wheels (somewhere around 200+ at the fly) A flat torque of 170 ft pounds from 2500 to 5500 All they had to do was change the main jets from the 115' s that were in them when you sent them to 120's I am still running the original 30 mm chokes

280zx Fever Those results you posted, 500 newton metres of torque equates to in excess of 340 foot pounds -- bloody hell, the BHP seems odd though

3 hours!!!! You Aussies always did has a strange perception of time, bit like the Rugby really You need to win a very important match and you dont start playing until a year later Anyway joking aside, I would rather overstate the job than understate it and raise hopes. greyghost I agree with you on your comments sir, but it doesnt make the task any easier and its still a kack job and is no fun unassisted, particularly for the uninitiated.

About 75 No seriously I have had the gearbox (transmission to you lot) In and out more times than I care to remember due to incorrect bearing carriers clutch issues two changes of engines and whatnot It’s a depressing job Personally I wouldn’t attempt it alone and would pressgang a friend or family member to help So depending on your set-up and assuming you don’t have access to a lift and you have help, this is how I do it, others may have better advise and or different methods and I accept no responsibility for bad language, divorce, busted knuckles or busted car. Remove internal trim around gear lever Remove gaiter Remove gear lever retaining pin (good time to check the plastic bushes) Drain oil from box (several pints of gear oil in your hair when laying on your back, really spoils your day) jack rear of car as high as a trolley jack will lift (still wont be enough) Place axel stands underneath suitable rear strong points Remove exhaust section Unbolt rear sway bar (prop wont drop without it) Unbolt prop shaft UJ at diff end Remove prop shaft Place jack under gearbox for support (I also place a small bottle jack under the engine) Disconnect speedo cable Disconnect reversing switch Remove gearbox saddle mount assembly Unbolt clutch slave cylinder Unbolt gearbox from engine gently separate the two, supporting the gearbox at all times on the jack Be very very careful not to let the input shaft take any weight as it can screw it You will have to twist the box whilst pulling apart at it will not directly drop due to bell housing clearance issues When reassembling buy a clutch alignment tool and check the pilot bearing in the flywheel Personally I would rather bum shuffle naked over broken glass and salt before attempting to pull the box from mine again – in fact when putting my new purpose built 2.8 in and encountering a clutch issue upon firing it up for the first time I pulled the engine again rather than drop the box I hate the SOB job Anyway Have fun Swear alot, drink beer and succeed Let us know how it goes

Hi Alan Couldn’t help notice your pictures and post on the MK63 calipers etc I am looking to do a brake upgrade at some time What’s the availability of the Mk63 caliper and appropriate vented disc in the UK like? Regards Steve

Here's one for you (more of a story than anything) Anyone had the bonnet release cable snap on them. Mine did yesterday at 07:30 in the morning as I was due to go to a race meet Ahhhhhhh It snapped right at the nipple on the bonnet catch (didn’t know it at the time). Conundrum: how on earth do you get the bonnet open if that happens? :mad: Answer:- Jack the car up, crawl underneath, reach your hand up on the starter motor side, underneath the catch mounting bracket there is a hole (bout 1.5") if you have long relatively slim arms you can just get you finger into the hole and operate the catch. Has to be the most frustrating thing that has happened to me so far, mainly because the engine was quiet warm, it's dark, its tight and I'm late. Next problem is how to repair said cable (here in the UK that sort of thing isn’t easy to obtain) on mine the very last inch had thinned and snapped leaving the nipple separated from the cable I used a copper ferrule from an electrical crimp, crimped it on using a quality ratchet crimping tool, then melted some lead around it to form a blob which I them trimmed to match the original nipple. Don’t know how long it will last but the cable doesn’t, A. look easy to obtain, B look easy to replace. What a bloody fiasco

Nice one

Interesting that I am running a lightly modified L24, mild cam, 6 into 1 header, triple webers and 280 distributor (nearly 180 at last dyno visit) I have just moved from a MSA 2.5 inch "turbo" system (yes we get them in the UK) to a custom stainless 2.25 inch with a single "straight through" rear box and square tip -- I will bet on a buggers bum that my RWBHP has gone up, the car feels generally more torquey and pulls far better from low revs, I have also lost a misfire I had at around 5.5 - 6K. Oh and the exhaust note has changed from a harsh wail to a more colourful deep "TVR" tone -- (not that you guys know what a TVR is) which is far less wearing on a 40 year old set of ears. So in my very humble opinion I also feel that a 2.25 is better suited to a "street" L series So in the immortal word of the human torch FLAME ON

Carl Just out of interest, why wouldnt you recommend webers for a 240Z ?

Hi 1971rb26dett "When you raise the piston in one carb the engine is only running on the other one" are you sure (how do single carb installations work then) I always thought that buy lifting the small plunger an 32nd or so you were artificially leaning out the mixture (reduced vaccum across the venturi) so making a weak mixture weaker or a rich mixture closer to the norm. That carb is then adjusted so that the effect is minimised then the same is done to the other Quoted from a Jag based site, corroborated by an MG owners site As I said if lifting the plunger disables the carb how do single SU installations get tuned up (they still have the plunger)

Thanks mdbrandy It wasnt clear to me what 280zgod had or had not got, so it was a point of elimination which is now eliminated.

FI systems generally have a lamda sensor (O2) installed early on in the system (usually around the collector), most aftermarket L series headers dont have the threaded hole and it has to be added -- did you do that or was it already installed and if so did you fit the lamda sensor. Without the Lamda sensor the ECU cannot get an accurate read of the mixture burned and as a result cannot alter the mixture to suit.