The carb is a two stage design, so it's essentially a one barrel with a secondary that comes on at full throttle. But yes, I do enjoy it and try and go out in it as much as possible - I bought it to drive and not be a show car. For a road engine there are a few simple things. Engine Block They look 10X better in the engine bay on a 1300 or a 1500 than a ZS or Weber and have been around forever. Dealer 3,695 Triumph Spitfire 1500 1978 Triumph Spitfire 1500cc in yellow, has been dry stored. We can rebuild or repair your engine to factory specifications, and in most cases to much better than factory specifications. Engine gasket sets I prefer Payen brand gasket sets when I can get them. Use a wooden, or plastic hammer handle, to tap the top of the piston down into the bore. Which is a big part of a rebuild, You will do this similarly to your crankshaft end float. Started out as just a collection of snaps as I stripped down an engine bought off ebay. This may take several minutes. Current slide {CURRENT_SLIDE} of {TOTAL_SLIDES}- Best Selling in Engine Blocks. This is very important, because if you are not on TDC, all your readings will be wrong. Freshening a carburetor is not as scary as it sounds, and companies like Quantum Mechanics supply the necessary kits. TRIUMPH SPITFIRE 1500 16958 N/A RHD Refcode: 333759 Complete strip down, body spray with new parts and components and rebuilt 12 years ago, engine re. Install the oil pan and gasket. Connecting Rods Triumph For most, dropping off the cylinder head complete to a machine shop is the best idea. There was an article in Classic Motorsport comparing different SUs to different Webers on the same MGB B-series engine. A bit too obvious for me that! Having trouble posting or changing forum settings? Bolting Dual DCOEs on a stock engine would would hurt driveability. For about $400, we sourced a set of these carbs, the proper intake manifold, a factory European exhaust manifold and a downpipe from Quantum Mechanics. xmFnpTdjkUcUnQtjY4A6zvd5f4fG3r3ftcbDZwzrnG90J4oOQ3fXP5leOHPeW4da. No problem. How do we feel about con rod lock tabs? 100bhp should be achievable fairly easily. It went like stink. We also redid the air cleaner with the original black crackle finish. Engines & Engine Component Rebuilding Services. Inferior steel in the crankshaft, narrow bearings and thrust washer inadequacy posed issues for the 1500 and on top of that the single carb is a negative, as your test showed A competitor in my race group used to refer to his 1500 as "Mr Floppy" (referencing the crank, which precluded using high rpm). as perspicacity of this Triumph Spitfire 1500 Engine can be taken as skillfully as picked to act. But now you will know what degree of offset key to order. anglefire is my forum name across all forums I use. In this way, conrods can be made 15% lighter and stronger than the OE ones. A word of caution about decking the block too much: Some engines, such as the Spitfire and Midget 1500 and the later TR6, have necessary recesses around the cylinder bores. TR6 and GT6 Engine. Crankshaft wear: the 1493cc engine fitted to the Spitfire 1500 has problems of its own, as the crankshaft can wear badly, along with the pistons and rings. Differential Mount Set Poly Front Spitfire GT6 . The Triumph SC (small car) engines were never derived fromtractors. ASSEMBLY Yes I know it was built from parts in the 50s and the design never changed. I'm guessing not particularly. This measured sprint took us an alarming 14.7 seconds to completenot very sporting for a sports car. Bottom end I might just get it balanced and reground if needed and look at different pistons and rods but also look at budgets. Fill the engine with all fluids. Protection by optimising the oil supply is another option. The project is really starting to come together now, with the engine soon to go back in. Install the oil pump, remember it is important to disassemble the oil pump, clean the inside whether new or used, lube them, and check the clearances on them per the manual specs. You can get a reaction between different paints causing wrinkling. I don't have a clue what else is in there yet but I intend to pull it down and find out before I run it hard. Timing assembly always replace the chain, timing gear and timing chain tensioner. In this video,. This may seem like a lot of clearance to your machinist who is not used to working with our engines. From the the tight budget, to the all-out approach, I've done it all, and can help you with your project The rubber insulator can crack and wear out over time. Street engines are warrantied for 12 months / 12,000 miles (contact us for complete details of the warranty). This should make for a more spritely drive. Because this CNCengine center also bundles multiple machining operations into one piece of equipment, we no longer have to worry about different individual machines introducing any deviations in tolerances between machining steps. Then rotate the crank til it stops, note the reading on your wheel then rotate it backwards. 5000 rpm may be a conservative limit even for a 1500, but it's easy to see that thelonger stroke engine approaches the 20mps limit far sooner than the earlier engines. (TR6 engine block in the process of being CNCmachined, cylinders being bored). Bearings shouldn't touch surfaces! About the Author: As an engine tuner and builder for more than 30 years, Hap Waldrop is the go-to guy on British car forums. Be extra careful installing the camshaft into the blockespecially with a block that has cam bearing as most nicks and scratches happen during installation. If you can catch a fingernail on the surface of the flywheel where the clutch disc rides, you will need to resurface your flywheel. Bare A-type OD base rebuild pricing is $1650. First, scrape off old gaskets as much as you can, then move on to degreasing. 20 Make sure the piston is marked front and that you are installing it in the proper direction. Which classic roadster offers the best top-down experience? I think that they are 3.67 to 1. quantumechanics.com, Swain Tech Coatings Inc. As much as I would like to say you can leave it all in their hands, you cant. 2,000 rpm. Let the engine run 20 minutes at 2,000 rpm to break in your cam and lifters. My apologies. Initial start up The idea is to remove all the accumulated junk, especially from critical areas like the float bowl and jets. Buy your used Triumph Spitfire motors/engines from us and save time and money. The mean piston speed will be 26.5m/sec. I replaced the original exhaust header with a Pacesetter which increased the pipe diameter to about 2"but have learned there are better ones available. His advice on road cars and racers is often the last word. .0015 to .002 is acceptable. $20.74. Those upgrades transformed my previously 1300 powered car, and it did well at club autocrosses. A piece of angle iron drilled and tapped with a small bolt installed across the bore is easy to make. The last GT6s had a lot of differences from earlier mk3s, I wonder if Triumph went back to tabs? And as my current engine seems to be doing about 28mpg, I'd hate to think what a low efficiency engine is like, i cant find any data readily availablethat explains the last suffix 'E'. But Ive stuck with it for reasons long since forgotten! This guy does a good job of outliningthe issues with the 1500: http://triumphspitfire.rickbaines.com/weaknesses-of-triumphs-1500-engine/. Install the camshaft, front engine plate and cam thrust plate Install a lubed lifter on #1 cylinder intake and then install a push rod into #1 intake lifter. Personally, I'd just check the originals for signs of stretch and reuse them. Triumph Spitfire - Engine rebuild - YouTube Restoration of my Triumph Spitfire showing the newly rebuilt engine by Prather Racing - Kent Prather and myself. But not just any pump--SU carb float valves will allow gas by if it's under too much pressure, so you need a low-pressure pump or pressure restrictor in the system. Check the wiper section of the rocker arm where it makes contact with the valve stem. This pristine car is fa. Manganese bronze guides expand with heat at a different rate than your cylinder head and require more clearance than cast iron guides. But the Spitfire could be easily stroked to 1493 ccto regain some performance. Water pump Be sure to use engine oil with 1200 ppm of ZDDP to insure long engine life. In my post above I was referring to "quality"! If you feel any resistance, make sure the ring compressor is tamped square against the block deck, and if you still feel resistance, you may want to look in the bottom of the block and make sure your connecting rod is not interfering with the crankshaft. Handy Tip: If using an adjustable cam gear, torque the cam retaining nut to manual specs before making your adjustments. The following is a list of new parts I typically include in an engine rebuild. Privacy Policy - Terms of Service - Contact Us, Rare American Sports Car: The Fiberfab Jamaican II V8, Full Documentary: The History Of Land Rover, For Sale: The Triumph Scrambler Stunt Motorcycle From James Bonds No Time To Die, Street-Legal Historic Race Car: A 1962 Semi-Lightweight E-Type, Unusual Project Car: A Brazilian Volkswagen SP2, For Sale: Ferrari F40 Wire Frame Sculpture. In some states, this kind of modification is a no-no. Click & Collect. They could save you a big hassle later. But this is for high revving engines, not road use. The intake will have receded. Replace them. You'd hopethey'd have put them back for the sake of a few pence if they reduced engine failure rates That's interesting, I wonder why they are on my late GT6 mk3? The factory paired these preferred carburetors with a free-flowing, cast-iron exhaust manifold that emptied into twin pipes. Add to Cart. Re the pinking. Bring in the camshaft you are using to insure it fits with the new cam bearings. Search (123\Tune+) For perfect timing. Take the connecting rod, with the cap removed, and the rod bearings installed and insert the connecting rod in the bore. The American exhaust system from the downpipe back will need to be replaced, however, as it wont mate to the European-spec downpipe. You can use new lifters with a used cam but never used lifters with a new cam. Follow the same process with the rod bearings as we did with the crankshaft and plastigauge each journal one at a time. The std stamped on the shells should mean std size. I start with the #1 piston. Trending price is based on prices over last 90 days. Add to Wish List. This number could vary, as long as it is the same exact point before, and after maximum lift. It takes a trained eye to do this procedure. If it is worn, have it replaced as well. Both BC (B series engines) and Triumph (the Vanguard/TR wet liner engine) also used the engines in all sorts of different applications - main vans, boats and tractors, but they weren't designed for agricultural use in the first place. Does anyone have a good engine building recipe I could replicate for my 1500's? This is done to prevent a piston ring from getting caught and breaking during installation. The weber downdraft is basically the same carburetor that was used on early German Capris and Ford Pintos (1970s). Triumph Spitfire 1500 engine and gearbox rebuild We've just finished the rebuild of this fast road engine for a locally owned Triumph Spitfire. It's the 1500cc variant, however, its had some cylinder head work and a fast road camshaft. Some connecting rods will be a press fit type, and not need servicing other than pressing the old piston off and the new pistons on. It should come around the outer edge of your degree wheel, preferably on the top side. Exhaust valves 4>2>1 manifolds easy to source, and the canley single sports box would be my choice. For the earlier 4 cylinder engines we always fit upgraded rear oil seals, an . 21.49. Harlow Private 4,500 TRIUMPH Spitfire Spitfire Perhaps our biggest issue was simply the original setups drivability. To read Haps previous article on engine disassembly and inspection, visit www.mossmotoring.com/disassembling-british-engine, October 16, 2013 @ 2:20 pm I'll be making sure that my new one is as good as it can get to the "best" end of the specs. Get Started Most cam lifters can be installed after the cam, but on the MG and Austin Healey A-Series engine, the lifters have to be installed before the cam is installed. AnglefireSeptember 30, 2017 in Engine. Other Areas of your Engine DO NOT be tempted by an external oil line to the cylinder head. Do this one main cap at time working from front to back being careful to not rotate the crankshaft. All engines are run and broken in prior to installation or shipping to the customer. Ray Ciccarelli, Hello Always seemed like a sacrilege putting a Spitfire engine into a Midget. REBUILT ENGINE UNITS The Roadster Factory offers its own factory rebuilt engines and cylinder heads (see p. 6), and we believe that these units are the best solution available to most enthusiasts who need an engine overhaul. I use .005 before and after maximum camshaft lift. (203) 463-8299 Frequently bought together. sorry real name is Mark - Ill update my signature when I get 5 ! Rocker arm bushings, if needed, Gaskets and the final touches Cloudflare Ray ID: 7a2e7dcb8a2dc2cd The key here is getting the entire setup, including the linkages. The three-main-bearing design did not lend itself well to hard use. Maybe because its the one I raced back in the day, but it always just seemed better balanced than the 1500 for some reason. Install and torque the main caps one at time. A bead blast cabinet is ideal for this job; however a wire brush on a drill, or bench grinder with a wire brush will get the job done. I've seen talk of 100HP from some out there, but I have to admit that the 3 main bearing crank arrangement scares me pretty badly. But do no explore the rev range too often (maybe get a rev limiter!). Install lifters, pushrods and cylinder head. He said he'd had problems with soft lock tabs on other engines messing uptorque readings. WishboneClassics is able to perform certain machining operations on your engine that you cannot have done elsewhere. At TRF, we know every part of the Spitfire 1500 engine intimately, and rebuild them to exacting standards bolts. So I always set timing by ear, drive the car and try to get it to pink. A heat shield is highly recommended for these as well. | From the March 2013 issue The 1500 long stroke is not the best for reliability and can suffer serious big end and con rod failures ifnused in a hurried life It does age quite quickly, upping the power wont help much in reliability Clives the best on this Pete clive Members 5.5k Posted October 1, 2017 For a road engine there are a few simple things. Add to Wish List. (Not for racing, just to bring them into the 21st Century and to get my little Midget screaming down the road). It set the record on 60% nitromethane, naturally aspirated. Some connecting rods have floating piston pins, the bushings will need to be checked for play and wear as well. This website is using a security service to protect itself from online attacks. And it's easier/cheaper than replacing the crank and rebuilding the engine! It is extremely important that the filet radius (the edges of the journal where it joins back into the crankshaft body) is restored when the crank is reground. The problem with the thrust bearing is serious, and every Spitfire (or GT-6, or TR-6) owner should know how to check crank end play. TRIUMPH SPITFIRE MkI,II,III,IV & 1500 (1959-80) FUEL PUMP REPAIR KIT. Took the car out for a ride and have a small backfire after shifting. The Kent fast road grind has a lot of lift but not a lot of duration which keeps the power band from being pushed too high. Buy used Triumph Spitfire motors/engines from our network that offers up to a two-year warranty on qualified units! Our reconditioned full engines have one of the highest rebuild specifications available on the market. I like to start with the center cap. In England, Triumph Spitfire 1500s were sold with dualSUcarbs. A fair amount of work, but nothing too technical, and it saves the engine. It will smooth out an engine and pull locked up hp to the fore. Whilst I don't have a bottomless budget, I would rather spend a few quid more now and not regret it later! Triumph Spitfire, 1962-1981 (Haynes Manuals) $2995. I have 185/60 13 tires which are a little lower so I put TR7 gears in the diff. Add to Cart. I have seen someone fitting an extra thrust bearing by machining the cap to suit - but keep some material for retaining the extra and existing bearings. Most cylinder head parts are inexpensive. I have 3 1500 Triumph engines in RB Midgets I'd like to rebuild and upgrade for greater performance and reliability, to take advantage of modern engine components, the years of tuning and development on this engine since the 70's, and the wealth of engine building experience that has amassed since the engines were introduced. Custom options available from electronic fuel injection. In recent years we have become especially well known for ourperformance Triumph TR6 engines, which put out incredible power while improving durability and eliminating faults with the original design. You need to plastigauge the bearing clearances. I raced both 3 and 5 main bearing MG engines and the 3 mains were dealing with slightly less drag and seemed a bit stronger and quicker revving, but bearing life when run to high rpm was better on the 5 main engines - they didn't get around to making 5 main versions until 1965 and Triumph never did go with 5 mains for their 4 cylinder sports car engines. To avoid offsetting the soon-to-be-realized power gains, make sure the new system is not too restrictive. We're able to bore Triumphblocks to accept cam bearings, we've even produced specialized tooling to shorten the duration of this procedure - which saves you money, because we can do it quicker. Please comment on anything from main studs to cams to roller rockers to engine machining procedures, to compression ratios, to carbs, etc..Please post any good links on this topic as well. This firm finds these parts overseas and imports them for American enthusiasts. WHAT YOU CAN CLEAN YOURSELF This is due to the manifolds available for that adaptation. Fuel pump work good (tested). Grinding off unnecessary mass from conrods, should be followed by polishing and shot peening, which does increase the strength. Proper clearance is required in many areas of your enginepiston to cylinder wall, crankshaft end float, camshaft end float, connecting rod side clearance, and then also things like spring valve lash. I had a re-used bolt shear, causing catastrophic damage, my first rebuild. If the margin (the vertical part of the valve just below the seat sealing area) is ground away during refacing it could leave a sharp edge that can lead to a burnt exhaust valve later on. Useful article on the oil pump too. Bare J-type OD base rebuild pricing is $1399. The car was largely based upon the chassis of the Triumph Herald saloon, but shortened and without the Herald's outrigger sections. British Engine Rebuilder 217-232-7303 Specializing in MG/Triumph 1500 Engines " I will not let you run one of my rebuilt engines in your car if I would not run it in mine. Its really more simple than people make it out to be. Payen gaskets where possible, use the best crank bearings you can find (vandervell but you will have to be VERY lucky) and you WILL need a thermostatic oil cooler, and millers CSS20/60 oil a good idea. Description Triumph Spitfire - Classic Car Fuel Injection Conversion Based on our Premium Vehicle Kit for 2 SU carburettor upto 125 BHP This kit contains all the parts needed for our Classic Fuel Injection system (you do not need to order anything else from our range ) Save around 200 when buying as complete kit By Make sure to clean and lubricate your throttle linkage, too. All rights reserved. Read More 1978 Triumph Spitfire with a Mid-Engine Turbo 1.8 L Inline-Four. Quantum Mechanics offers these as used sets with manifold pulled from old Spits in England. Many parts are available for this engine from aftermarket suppliers. It's currently (As far as I know) standard - though is from a Dolly 1500! Oil pump Valve seals This is a good time to consider a performance cam. I wouldn't bother changing the main bolts either, and I don't think loctite is a good idea. MG Midget Triumph Spitfire Rebuilt 1500 Engine About this product About this product Best Selling in Engine Blocks Speedmaster Pce286.1049 Aluminum Engine Block Ford 351w Windsor 9.500 In. Quickview. TheseSUcarburetors may be older technology, but they have served many owners very well through the decades. Im only really in the planning stages as when I do pull the engine, Id like to do things like make sure the head is lead free - Im told it was done by the guy who rebuilt it before the last guy who I bought it from. Get the distributor modified to match the cam (the Distributor Doctor) and find somebody to set the carbs up on a rolling road. I spoke to the distributor doctor today - after looking at the website - and have ordered a standard replacement dizzy for mine as a starting point because I replaced mine with one from ebay after getting issues (Which I suspect were really down to the carbs) and I am getting some issues with pinking and the like, that could be caused by a cheap chinese one - of course it could be something else, but I decided to start from a good place! Minimum engine rebuild service price is $10,000 USD for a fully rebuilt dyno tested engine package (fully assembled engine, carbs, ignition, exhaust manifold, etc) All engines being rebuilt are torque plate honed for superior cylinder bore geometry and improved piston ring seal Listen out for rattling and blue. You may have seen them at county fairs the vertical velodromes were originally built from old grain silos, leading to the name "silo-drome.". You need to be a member in order to leave a comment. Altering the factory cam timing can be done in one of two wayseither by using offset camshaft keys or with an adjustable camshaft gear. Install the cam thrust plate, timing gears, chain and tensioner (if applicable) following the workshop manual guidelines. That is not true but often repeated. I suggest you guys go read the same thread over on the MGExperience board. Install the piston and connecting rods I'm also probably going to get another engine and after a bit of general inspection (The one I'm going to look at has already been largely rebuilt) and replacing the oil and water pumps - which haven't been done and then swap engines over - it also has a twin exhaust and a 4-2-1 header which is almost new. This engine is almost a direct bolt-in. Inspect your starter ring gear. Most machine shops have a special tool that can cut all three angles at the same time. All in all, even though there are more desirable sports cars out there the 1500 Midget has been a fun car to have owned for the past 18 years. FUEL PETROL PUMP (**See Engine No**) (1970- 74) 20.50. Cover the camshaft journals, lobes and gears liberally with assembly lube. I highly recommend Moss uprated valve seals. Car. I use a Moss high performance Pro Sport model on my MGB racecar and can attest to its high quality. If you find excessive wear your machine shop can reface them. It will be your main point of reference. The MG motor was incapable of being enlarged, just getting itto 1275 had required engineering handsprings (offset conrods? Keep advancing the timing until you do, then retard just enough so you don't get any pinking. Keep your manual close at hand for the assembly stage. Quantum Mechanics, Ltd. Line up the dots on the two timing gears when installing the chain. Your IP: Now that you have found TDC, move the dial indictors outside bezel to reflect zero at the needle point. Remove no more than .010 so that the head gasket will seal properly. MATCHING RED FACTORY HARDTOP. Watch on There's nothing quite like the process of pulling apart, fixing and rebuilding a vintage engine. And here's the reason why. It was beautifully designed by the legendary Italian car designer Giovanni Michelotti, and it also surprisingly sold in greater numbers than any of its rivals between 1962 to 1980. Set up the magnetic base and dial indicator on the front side of the cam, or cam gear, and moving the camshaft front to rear reading the movement on the indicator. And, once you have the engine block on the engine stand, youre ready to dive in. All spark advance is handled electronically. A parts washer makes this job a lot easier, but if you dont have one you can make a temporary parts washer out a 5-gallon bucket and waterbased degreasers. Ray, that is a good point, the wet sleeve motors like the Triumph TR3/$ engines are not a engine I work with. If theres any drawback, its the legal ramifications. Handy Tip: Use a Sharpie to put markings on parts you have already torqued or checked clearance to know where you are in the process. Magnafluxing typically involves applying a fluid, or powder to the crankshaft, then viewing it under a black light. As of March 2007, all of our engine block work is carried out to the extremes of perfection on a CNCengine machining center. This was criticallyimportant asBrazilian automotive, This is a wire frame sculpture of the Ferrari F40 inarguably one of the Italian automakers most important and historically significant supercars. Opening out the oilways in the block, cross drilling and ovalising the orifices are all possible, as is optimising the oil pump. Read the Forum Help (FAQ) or contact the webmaster. I've read that a Newmans mildroad cam is a good option, and payan gaskets are the best, but what bearings and rings? Manganese bronze guides are also available and I almost always use them because they are very long wearing. Can't find a shop that offers a crankshaft nitriding service? One day. You will want to ask around for the shop that has the best reputation for crankshaft work. Zero out the indicator and double check to make sure you are correct. I also experienced the thrust washer failure which ruined the crank so my advice is to keep your foot off the clutch as much as possible. 7500 19.00 21.88 MG MIDGET (late model) TRIUMPH SPITFIRE 1500 MOTOR ENGINE REBUILD SERVICE Refurbished $2,695.00 timwhomi5 (2,345) 99.6% or Best Offer Freight 39 watchers Sponsored New Complete Engine Seal and Gasket Set Triumph Spitfire 1500 MG Midget 1500 (For: Triumph Spitfire) Brand New $59.94 sportscarpartsltd (55,071) 99.7% Buy It Now Free 3 day shipping Flywheel After refreshing the carburetors, the next step is simply to replace the intake and exhaust manifolds with the European-spec pieces. Thank you very much! Oil Pump and Exterior Assembly , Triumph produced the fun and affordable Spitfire for 18 years, during which time over 314,000 were built. It's a surrogate for the actual stress calculation that works out the acceleration of the piston, whichis a LOT more difficult! Deck H $3,341.18 New ---- Used Dart SBF SHP Iron Block 4.125 Bore 9.500 DH - 31375235 $2,999.00 New ---- Used Cut a small piece of plastigauge and place on the #1 journal. 142.132.219.252 Almost 100,000 of these engines were used in the 1973-80 Spitfires, and nearly as many were used inMGMidgets sold from 1975andlater. Thanks Pete and Clive - as I say, I'm not after a racing engine or even upping the power particularly. Apologies, confusion re std. That is as good as you are likely to get it, though DD can of course alter advance curves to suit your engine spec, or go for a mapped ignition! Also worth making sure the crank end float is correct (oversize thrust washers usually required, get them the right way round too). Your connecting rod will almost always warrant big end resizing, and considered a must if you replace the connecting rod bolts. Both BMC (B series engines) and Triumph (the Vanguard/TR wet liner engine) also used the engines in all sorts of different applications - main vans, boats and tractors, but they weren't designed for agricultural use in the first place. A new set isnt expensive. The MG Midget and Austin Healey Sprite High Performance Manual - Daniel Stapleton 2008 Covers all aspects of modifying the MG Midget and Austin Healey Sprite for high performance. Triumph Spitfire 1500 LHD Completely body off restored Triumph Spitfire 1500 LHD. A window into racing in the 1960s | Sebring Special MGBs: How an MG TC gave way to a worldwide British car enterprise. Valve springs, Rocker arms assembly Cylinder head It is a normal practice to oil the threads on all engine high torque bolts to help reach true torque. Lube the rod bolt threads with motor oil or fastener assembly lube, like the one ARP makes, and torque your rod bolts to manual spec. With your choice of advance curves or a tunable unit. Bolting on the new carburetors is easy, and since this is a factory setup, the throttle cable will perfectly join the existing system. Current car: 1980 Triumph Spitfire Past cars: 1975 Triumph Spitfire, 1973 Austin Mini, I prefer tri-metal bearings; they are what the factory originally supplied for many cars. Need oversized lifter / tappet bores? If you're a British car owner that seeks perfection, you will not find another engine rebuilder that is able to produce as fine of finished unit.