Thread: 2.25 tuning questions

The ignition questions you ask depend upon the compression ratio and whether it has been modified but the standard ratio is 7:1 or 8:1. If you can't find an 8 stamped on a boss on the head near the exhaust manifold then it will be 7:1.

My workshop manual says 3 deg BTDC for 80-85 octane fuel but seeing that isn't available anymore, 6 deg BTDC is a good starting point for 90-96 octane. Adjust it under load in top gear until it pinks by advancing, and then retard the spark with the fine adjustment on the distributor, until the pinking disappears.

Strangely the book doesn't recommend a spark plug type or heat, but it should be in the handbook if you have one

Cheers Charlie

The problem with the dual throat Weber is that it is quite rare here in Oz.A dual throat Weber was used on the 2.5l engine in the early defenders and those never came here. There is at least one other dual throat Weber that I have seen used in a kit (in the US from memory) but they really don't appear often here. Therefore it will be hard to find anyone who knows how they should be jetted for a 2.25l. It also depends what mods have been done as that may well change the required jetting. Maybe get it on a dyno or at least get it tuned by someone who knows how to tune carbies (and that is a rare breed as well).

Cheers,

TimJ

My IIA has a twin barrel weber on it and as far as I know its got the original jets. Do the extractors make a big difference cause I've got a genie extractors and I'm wondering if it is worth fitting, and does the fan give you extra power?

Originally Posted by Series3 GT

My IIA has a twin barrel weber on it and as far as I know its got the original jets. Do the extractors make a big difference cause I've got a genie extractors and I'm wondering if it is worth fitting, and does the fan give you extra power?

Seems to go ok for a 2.25,bought it like it is so cant compare to standard.On a good day it will do 75 by the speedo with 31" tyres.Having trouble getting float level right.I think the carby is off a cortina,because it had a ford air cleaner on it.

what model weber is it?

The Weber doesn't give any troubles if you run a fuel filter, I'm interested in supercharging a 2.25 petrol, maybe you should look at that and maybe fuel injection to get maximum power out of the little 4cyl.