doctee Posted April 13, 2009 Share Posted April 13, 2009 Hi All, If I fit twin carbs to my 1300 herald will iI need to change the origianl exhaust manifold for a sports exhaust manifold, also where is the best place to buy a set of recon carbs from, and finaly will it make a lot of difference to the speed, acceleration, etc.many thanks Doctee Quote Link to comment Share on other sites More sharing options...
Clive Posted April 13, 2009 Share Posted April 13, 2009 same exhaust manifold will fit.As to power increase-maybe a tiny bit. The difference btween the herald and spitfire engines includes camshaft, compression, exhaust and the carbs.Andrew Turner sell recon sets, and will no doubt supply a complete bolt-on solution. However there are alternatives. How about using an HIF44 carb (metro etc) on the later dolomite 1300 inlet? and the money saved can go towards a better camshaft, possibly 4 branch manifold or whatever. Just throwing alternatives about.......just don't expect a pair of SU's to make it a different car.Clive Quote Link to comment Share on other sites More sharing options...
Richard B Posted April 14, 2009 Share Posted April 14, 2009 Twin 1-1/4" SU's from an early Spitfire (maybe),couple of bhp and juicier. As Clive says get a good sports exhaust manifold (more value for money), (followed by a K&N?).Don't fit 1-1/2" SU's from a 1500, onto standard 13/60, be well over-carbed! Quote Link to comment Share on other sites More sharing options...
Deleted User Posted April 14, 2009 Share Posted April 14, 2009 I'd agree with Clifty, a modern 44HIF would probably be a better bet Quote Link to comment Share on other sites More sharing options...
doctee Posted April 14, 2009 Author Share Posted April 14, 2009 Hi, Thanks for the information, I think I will go for the twin carbs (as I prefer the look of twin carbs, as I have a pair in pieces. I will phone Andrew Turner today.many thanksDocteee Quote Link to comment Share on other sites More sharing options...
Jonny-Jimbo Posted April 14, 2009 Share Posted April 14, 2009 No noticeable difference from changing to twin carbs on such a small engine. An engine is designed to 'work' with what the factory fit it with, whilst this isn't always the most powerful set up of the engine, it's one that works. Changing only the carbs will result in over fueling, and changing the carbs and exhaust will result in a very marginal gain in power, but probably not noticeable. You'll think you're going faster because of the noisier exhaust and induction noise. Quote Link to comment Share on other sites More sharing options...
herald948 Posted April 14, 2009 Share Posted April 14, 2009 I'm assuming things would be pretty much the same with the 1296 as they are with the 1147. I've driven an 1147 with Spitfire SUs added, but with no other changes to the stock Herald engine. What tends to happen is a bit better response at higher engine speeds (noticeable, but not dramatic), but that seems to be paired with a bit of a loss of lower-engine-speed torque. Raising the compression, changing the camshaft, etc., do much more. For example, compare an early 1200 to a 12/50: about a 25% increase in power that comes mostly from use of the early Spitfire camshaft, etc., but still on a single Solex! Quote Link to comment Share on other sites More sharing options...
Jonny-Jimbo Posted April 15, 2009 Share Posted April 15, 2009 Exactly Andy; just sticking on the twin carbs won't do a thing really - not in terms of making it really drive differently. You've got to do a whole engine build really. If you want it to be cheapish (not sheepish) for a few more horses and a few more torques then you can blueprint the engine and use a Spitfire cam etc, or alternatively the easiest one would be to find a second hand Spitty Mk3 engine.Or, if you want to make more of a difference again just stick a Spitfire 1500 in. That's my intention anyway... find a rotten 1500; engine, gearbox (with overdrive), diff, shafts and brakes into my Herald along with marginally lowered and uprated suspension, but making sure it's still driveable. Quote Link to comment Share on other sites More sharing options...
Clive Posted April 15, 2009 Share Posted April 15, 2009 And JJ, that is my fav. type of herald 🙂 I didn't bother with the diff change or shafts, but a 3.89 diff as in dolly 1500 would give great performance, the 3.63 better as an all-rounder unless it is regularly fully loaded (like my cars often are)My shed currently runs a courier rear spring (with 1" block) and canley 440lb gt6 front springs. Sits about std height at the front, and very slight neg camber (maybe 1 or 2 degrees) but handles very nicely. Of course a swing-spring is the other way to go, but again not so good for loading the car up.Clive Quote Link to comment Share on other sites More sharing options...
Jonny-Jimbo Posted April 15, 2009 Share Posted April 15, 2009 Sounds like a reasonable set up Clive. Don't suppose you've got any photos of your car in that set up you could post or a link to any photos on the net?I haven't decided on what spring rates to go for yet, but I was thinking of going for a 1" lowering block on the back and about the same down at the front, but hadn't decided on rates yet. Quote Link to comment Share on other sites More sharing options...
Matt306 Posted February 1, 2018 Share Posted February 1, 2018 Resurrecting a very old thread.... I have a spitty head on my Herald lump (PO did it, well the valves are certainly Spitty ones double sprung.) Suppose I get a Canleys Mk3 cam and set of Spitty carbs what sort of real world difference would it be. Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted February 1, 2018 Share Posted February 1, 2018 About 10 hp. Perhaps 15 with a 4-2-1 manifold as well.Nick Quote Link to comment Share on other sites More sharing options...
Matt306 Posted February 1, 2018 Share Posted February 1, 2018 Cheers Nick... might keep an eye out...Thinking of putting the spit 3 cam into my mkiv spit engine when it gets rebuilt worth it? Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted February 1, 2018 Share Posted February 1, 2018 It's a good all-rounder.Nick Quote Link to comment Share on other sites More sharing options...
DanM Posted February 3, 2018 Share Posted February 3, 2018 The early MK4spifires had the same cam as the MK3 anyway Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted February 3, 2018 Share Posted February 3, 2018 Quoted from DanM The early MK4spifires had the same cam as the MK3 anyway Allegedly. Ours is pretty early but the cam wasn't the mk 3 grind........ Engine is all mk3 now bar the head, which is big valve Mk IV.Nick Quote Link to comment Share on other sites More sharing options...
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