6 replies to this topic

[1977 Loud_Mini]

Hi all just a quick question about carbs. I now have a 998cc engine with rebuilt 12G295 cylinder head, flat top pistons, duplex timing chain, electronic ignition and i think 1.5 titan roller rockers (they are red and have silver tubes inbetween with black parts where they bolt). There is loads more compression than on my dished pistoned 998 as it nearly ran my was a struggle to turn over. I was wondering what size twin carbs would best suit this spec engine, either 1.25" or 1.5"? At the moment it has a 1.5" single hs4 carbs and standard exhaust with single box (i will be getting an LCB system to suit the 998 though).

[blacktulip]

twin hs2 should be bang on.

[1977 Loud_Mini]

Great thanks, thats just what i was hoping as i prefer the look of HS2's to the larger HS4 twin carbs.

[Big_Adam]

Aren;t 1.5 ratio rockers a bit much?

Anywho, if you looking to save a bit of money try nabbing a Vizard yellow book and modifying the carb with slimmed butterfly and spindle. It's quick, fairly cheap trick and works pretty damn well.

That said, twin carbs IN GOOD CONDITION are loverly.

[1977 Loud_Mini]

Yea i have been thinking of getting Vizards book and doing some modifications. I'm not sure if my rockers are 1.5 or 1.3, because i have looked on google etc and found red ones from i think Minisport at 1.5 and others the 1.3 rockers are red so i don't know which ones i have, they are TITAN. All i know is the car is lumpy at idle and when slighly revved (timing is spot on).

Edited by 1977 Loud_Mini, 19 February 2010 - 10:42 PM.

[_mini1000_]

...slimmed butterfly and spindle...

can these be bought off the shelf or do you have to modify the originals?

[Big_Adam]

Yea i have been thinking of getting Vizards book and doing some modifications. I'm not sure if my rockers are 1.5 or 1.3, because i have looked on google etc and found red ones from i think Minisport at 1.5 and others the 1.3 rockers are red so i don't know which ones i have, they are TITAN. All i know is the car is lumpy at idle and when slighly revved (timing is spot on).

You REALLY should get the Vizard book, you'll love it for anything your thinking of doing in the future. Covers N/A and all aspects of building (right down to bolts and pushrods and which are best) as well as turbos, super chargers and NOS applications.

But, 1.5 rockers as I recall will be a tad too much for a small bore loosing you something like 5~10bhp I recall, I'd have to look it up to be sure so don't quote me on it.

...slimmed butterfly and spindle...

can these be bought off the shelf or do you have to modify the originals?

Modify, takes about 60seconds with a saw. The way I did it was buy a rebuild kit and get my eye in on the old parts, then do the new ones. Only real problem I had was the Vizard guide says to use pan head allen bolts. Which my nut and bolt shop had none, so I had to improvise with some washers and orginal screws. And locktight thread locker.