Bulldog Posted November 27, 2007 Share Posted November 27, 2007 I'd like to have a go at porting my 1256 motor's head. Does anyone have any information on this or can point my in the right direction? Quote Link to comment Share on other sites More sharing options...
Gaz Posted November 28, 2007 Share Posted November 28, 2007 Umm, Leon/Zep mentioned something bout a rally prep manual he has for chevettes. It would prob have this info. Quote Link to comment Share on other sites More sharing options...
Requiemk Posted November 28, 2007 Share Posted November 28, 2007 http://www.sa-motorsports.com/diyport.aspx try find people who have done heaps of porting etc on these engines or engine builders/porters to find out the problem areas. Quote Link to comment Share on other sites More sharing options...
mikuni Posted November 28, 2007 Share Posted November 28, 2007 http://www.sa-motorsports.com/diyport.aspxtry find people who have done heaps of porting etc on these engines or engine builders/porters to find out the problem areas. Yeah agreed. The main problem with these engines is the head, the block, the ports, the cam, the intake, the exhaust...... Quote Link to comment Share on other sites More sharing options...
Gaz Posted November 28, 2007 Share Posted November 28, 2007 You forgot to mention the crank.. lol Quote Link to comment Share on other sites More sharing options...
mikuni Posted November 28, 2007 Share Posted November 28, 2007 lol, yeah I should have just said the main problem with the engine is the engine rather than picking individual areas. Really I wouldn't bother with porting. Perhaps just a clean up of casting marks and make them a little bit sweet, give the head a skim and a nice 3 angle on the valves while getting them reseated and thats it. You're not going to get alot out of the engine without alot of work so you might aswell just tidy it up and save your penny's for something with a little more potential for power. That said, a tidied up 1256 with those twin SU's should pull along a stripped out hatch quite nicely. Won't be fast but could very well embarass afew unspecting victums. Quote Link to comment Share on other sites More sharing options...
Spencer Posted November 28, 2007 Share Posted November 28, 2007 Don't want to put you off or sound like a cunt but weren't you saying an engine swap is out of your mechanical knowledge? Wouldn't be to keen on a port job if thats the case, Unless its just a learning experience and you don't mind fucking it Quote Link to comment Share on other sites More sharing options...
Gaz Posted November 28, 2007 Share Posted November 28, 2007 There heaps of bolt ins for these too isnt there.. Think bedford cause its so bogun fun. Quote Link to comment Share on other sites More sharing options...
Burntrubber Posted November 28, 2007 Share Posted November 28, 2007 Don't bother with porting just put an injected G200z in it I may have one for sale soon Quote Link to comment Share on other sites More sharing options...
Bulldog Posted November 28, 2007 Author Share Posted November 28, 2007 Sorry, I didn't mean to sell myself short and I'm certain I've got the initiative to do an engine swap I just haven't done one before. I'm keen as to do one...just gotta find a cheapy and a 2litre that's the easiest I guess. Quote Link to comment Share on other sites More sharing options...
treggo Posted November 28, 2007 Share Posted November 28, 2007 The 2l conversion is a pretty sweet one. Shouldn't have to hard of a time sorting it out! were abouts are you located? I'm sure some OS boes would come help for a weekend. Quote Link to comment Share on other sites More sharing options...
Guest sexychevette Posted November 28, 2007 Share Posted November 28, 2007 nah fuck goin G series. If anything they are gayer than 1256 stz. Single overhead cam is soooooo mitsubishi. Anyway, herez da mean shit fo you: Don't think you have to go to the 2.3 litre engine. The 1300 Chevette is worth a look. Pentti Airikalla's win on the Welsh Rally earlier this year was more than a well needed tonic for Dealer Team Vauxhall - it also put the Chevette firmly into the minds of people who had previously not given it as much as a second glance when considering a competition car. The Chevette win was the result of six months hard development by the DTV crew at Bill Blydenstein's railway station workshops at Shepreth in Hertfordshire. Dealer Team Vauxhall's rally programme had passed to Blydenstein late in 1975 and by mid '76 he was called upon to switch from the Magnum to the smaller (but surprisingly not much lighter) Chevette. After a somewhat embarrassing debut on last year's RAC Rally the car started the year well, culminating with the fine win in Wales. Suddenly, it wasn't Escorts all the way: the Vauxhall Chevette was a force to be considered. Currently only available in 1256cc form the Chevette is a good and solid car based on Opel Kadett running gear but using the four cylinder engine originally developed for the Viva. Obviously, it has most potential in 2.3litre form but Bill Blydenstein reckons the smaller engined version should not be dismissed lightly. The 1256cc Vauxhall engine has a history dating right back to the HA Viva 1057cc engine of 1965 and therefore has undergone careful and consistent development over a long period of time. It's never been a spectacular engine in terms of competition performance but has now matured into an extremely strong and reliable unit that, despite its six port head design and pushrods, is capable of quite a reasonable power output. People seem to forget that Bill Blydenstein was racing the HB Viva with engines of this type (of varying capacity as development proceeded) as early as 1967 and by the time the unit was replaced by the two litre single overhead cam engine (the Viva GT) was achieving a measure of success. In fact the HB Viva engine had a capacity of 1159cc but Blydenstein raced on most occasions at 1258cc although engines nearer 1300cc were also built. As installed in the Chevette the latest variant of this motor has a compression ration of 9.2:1 and with a single 1.50 CD Stromberg develops around 58bhp at the flywheel which is good for 40 to 42bhp at the wheels of a well sorted standard car. The standard camshaft is that which started life as the '90' engine pack grind in the old SL90 Viva and valve sizes are 34.5mm inlet, 30mm exhaust. The crank runs in three main bearings and has reasonable mains journal sizes of 53.3mm. A 184mm dia clutch is standard fitting. The Viva/Chevette cylinder head is an interesting design. It's a cast iron, non-cross flow type with only six ports - four exhaust and a pair of siamesed inlets. Where it differs from most engines is the the inlets are vertical, the inlet manifold feeding down tho the top of the head. With a full downdraught carburation set up, this is an extremely good design but, of course, the restrictions of bonnet height mean that the production Viva and Chevette have to utilise a cast alloy inlet that curves through a full 90 degrees to place the side draught Stromberg at a relatively low level. As I said, the small Vauxhall engine has undergone quite a lot of development during its long life and the net result is that Bill is quite happy to say the latest versions have no inherent weak points that need to be considered seriously until you get to virtually full race tune. Most of the Blydenstein parts of the 1256cc Vauxhall engine are in fact listed as DTV Sportsparts and therefore available through those Vauxhall dealers who are DTV representatives. The best way to deal with the power side of the engine is to take the unit through what Bill regards as the logical tuning sequence. Although an initial carburettor swap is certainly a nice and easy way to get power. Bill rates a decent cylinder head as being the first stage of any well thought out conversion. His Stage III head which features 36.5mm inlet valves and a first class gas flowing job is likely to put about 8bhp onto the flywheel while the III H head will add a couple more brake horse to that. Blydenstein defends the rather illogical method of starting with Stage III by saying that in his company Stage One and Two heads have always had standard size valves, therefore their Chevette head... etc. The III head has standard exhaust valves, standard compression ratio and (you guessed) standard valve springs. The III H version differs only in that the compression ratio is upped to around 10 to 1 by removing metal from the head face. The standard compression head is, in face, allowed within Vauxhall's standard manufacturer's warranty for new cars although the III H will put the engine out of bounds. Next step is most definitely carburation. The 1.50 CD is replaced by a 1.75 CD which, gives about four brake horse power on top of the head. Fuel economy must, obviously, suffer slightly but having driven a Blydenstein car with head and carb mods and still managed 35mpg everywhere (including a very high speed run to visit another tuning establishment) I don't think there's too much to worry about on that score. At this point the Blydenstein file (Bill has a file for everything) advises fitting Lumenition ignition. No, it doesn't add 25bhp or even keep the windscreen clean but it's considered worthwhile on grounds of total lack of maintenance and a much quicker warm up, resulting in improved fuel economy. Logically, the next step is an exhaust manifold. The four into one tubular system with bore primary pipes gives around two bhp on top of the head and carb. This manifold mates to the standard system although a complete larger bore system is currently being worked on. With head, carb, Lumenition and exhaust manifold any decent Chevette is giving a respectable 72bhp at the flywheel. Although it's hardly anything to shout about, this sort of power coupled to the excellent handling of the car (you can't keep a good Opel down y'know) makes the Chevette a useful 'shopping' car and weekend road rally machine. It's after this that, inevitably, things start to get expensive. You need a better carb, but there's also a crying need for a camshaft change. Bill won't separate the two: the next step is a 45 DHLA Dellorto (or Weber if you have one lying around) along with the CHR-1 camshaft which increases the effective overlap of the old '90' profile by about 10 degrees and adds 0.020 in to the valve lift. Don't ask for more precise timing details because they hadn't been worked out at the time we went to press. What we can tell you, however, is that the Dellorto carb has these settings: Chokes 35 Mains 190 Air Com 200 Em Tubes 777.6 Idle 65 Pump 60 Now the 1256cc engine is giving around 80bhp at the flywheel, which is still not great stuff for a 1300 but is certainly respectable. Vauxhall Sportparts mentioned in the text Part Number Stage III Cylinder head 33/888 Stage III H Cylinder head 33/911 Stromberg 1.75 CD carburettor kit complete 22/844 Lumenition electronic ignition 66/877 4 into 1 exhaust manifold 35/322 Performance exhaust system 34/211 'Crossflow' Dellorto 45DHLA carb kit 22/899 Manifold only from kit 22/899 22/892 Rally type camshaft 33/902 Quote Link to comment Share on other sites More sharing options...
mikuni Posted November 28, 2007 Share Posted November 28, 2007 I think that was written in the late 70's aye. They are still talking about keeping within Vauxhall's manufacturer warranty. Ahwell, 75 odd hp from the 1256 sounds like abit of fun and it doesn't seem to difficult to get there. Quote Link to comment Share on other sites More sharing options...
Guest spaceghost Posted November 28, 2007 Share Posted November 28, 2007 i like that its a good idea but what a lot of effort to get 30hp but hey what else do you do? when he was on about the dellorto do you think he was saying they put one on would you out two ? and that was the last thing they talked about i would've thought that and an exhaust would be first???? Quote Link to comment Share on other sites More sharing options...
mikuni Posted November 28, 2007 Share Posted November 28, 2007 He said early on that you put a 1.75" (??) single SU to begin with and then do the other mods and then towards the end, after the cam you go to a larger side draft. I don't think putting a big webber or dellorto on a standard motor will achieve any advantage, you'd probably loose power on it. Agree on the exhaust though. Surely a nice set of headers and straight through 1.75" would open it up nicely, although the standard system isn't actually too bad on the 1256. All this talk actually kinda makes me want to play around with one again but after all the hard work I'm sure you'd still be dissapointed with the end result after going in something powered by a decent engine. Ahh shit knows. Work the bastard, surpirse us! Quote Link to comment Share on other sites More sharing options...
Gaz Posted November 28, 2007 Share Posted November 28, 2007 Single 45. Twins would drown the thing. Um I got a head here of my old vauxhall which I just chucked in the trailer the other day to go tip.. Want it to play ports with?? In Rotorua. Also what bout the Izusu 1600. Ive driven one of those and it was HEAPZ faster than the 1256.. gbox was way diff tho. Quote Link to comment Share on other sites More sharing options...
CUL8R Posted November 28, 2007 Share Posted November 28, 2007 1.75 SU, I think *think* thats a size the Triumphs use (cept triumphs use two). I know mini's use 1.25 , 1.50 (the later for the 'big block mini's ) Hmm Carb would be an extremely cheap upgrade... even if you re-kitted it it'd cost less than $80... Cheers,Chris Quote Link to comment Share on other sites More sharing options...
mikuni Posted November 28, 2007 Share Posted November 28, 2007 Single 45. Twins would drown the thing. I reckon something like a twinbarrel 35 would be perfect. A 45 would be h000000g. Wasn't it this fella that bought that mean twin barrel Su's that bolts straight up to a 1256 or was that someone else? edit: yup, this and it looks perfect I reckon! So back to basics. ^ That, nice headers with full exhaust system, cleaned up ports, 3 angle valve grind, planed head to about 10:1, cleaned combustion chambers and bigger valves if you want to go that hard out. Valve springs should manage depending on what cam you use. That should get you from 50 to 80 hp and yeah. Then bin it and get an ecotec for 200hp with quads, cams and exhaust Quote Link to comment Share on other sites More sharing options...
Requiemk Posted November 28, 2007 Share Posted November 28, 2007 i reckno a a nice pair of 40mm dellortos would be perfect, i also know where you can pick some up for a fair price Quote Link to comment Share on other sites More sharing options...
Snoozin Posted November 28, 2007 Share Posted November 28, 2007 LOL I know what you paid for em Quote Link to comment Share on other sites More sharing options...
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