36 replies to this topic

[tb205gti]

I'm building a new engine for my Innocenti, and I'm looking for some input from you guys on the carb side og things as I have a few options.

 

Engine will be a 1275 with 276deg cam, cambelt, MegaJolt, CooperFreeFlow (or should I go for LCB instead?) + RC40. Compression will be 10,5:1 static. Head is a slightly ported bigvalve 940 with double springs. IIRC diff is 4.133 on standard A+ ratios. 10" wheels.

 

 

Now I have three options for carbs.

 

1) 2x HS2 with MED Stacks and foam filter, on an original (ported) manifold

 

2) Weber 40mm with 36mm chokes and short trumpets fitting without any body modifications

 

3) 2x HS4 with MED stacks and foam filter. Manifold not bought yet

 

The car is the occasional "fun" car, I'm not relying on it as a daily driver I only drive it occasionaly when I need to have "fun".

 

What would you recommend? I'd expect a realistic peakpower to be around 80-85bhp.

[Spider]

I gotta say, I'm probably pretty boring here, but for that, I'd go with a single HIF44. Yes, it doesn't look as great, but much easier to set up and live with. It will perform perfectly with that set up.

[nicklouse]

as above a single HIF44 with a sorted manifold. but if it has to be one of the 3 I would say that 3 would be almost as good as a single HIF44.

[richmondclassicsnorthwales]

I'm with Moke on that too really,  HIF44

 

Less fanying about !

Edited by richmondclassicsnorthwales, 15 March 2018 - 09:54 AM.

[dotmatrix]

I definitely also like the HIF44 a lot as above, but regarding your three possible options, option 3 will look most right but you need to find the right rolling road guy for setting it up, option 2 most rolling road guys working with old cars will be able to set up a weber carb, but not a lot of them can set up a SU carb. That is my experience anyway.

[Turbo Phil]

Unless you're modifying the bulkhead to fit the Weber on a decent manifold I wouldn't even consider fitting it.

Phil.

[tb205gti]

HIF44 is not an option - I do not own noe :)

 

Turbo Phil: I'll try to get some pictures of the carb and the manifold. It actually looks quite ok. The trumpets are too short - but that is a tradeoff since I do not want to cut the scutte. :)

 

If I were to go with option 3 - what springs and needles do I need to look at as a starting point? I Believe they are fitted with "ABE" needles right now, and the springs look "original" (No color coding on them)

[nicklouse]

if you are not cutting the bulk head then the weber is just not worth it you may as well fit a single HS2.

 

if you have all those carbs get them sold and HIF44 it.

 

but back to you question on set up Vizard has a list in the big yellow book.

 

but before that make sure all is good and the drop rates are correct and the same but as they are that old I would be wary of wear on all pivots etc.

[hhhh]

For some reason Vizard didn't include single 1-3/4" SUs in his needle charts.

[Icey]

I agree with Nick. If you own all three already, sell them, buy a HIF44 and spend the rest in a rolling road session.

[Spider]

If you were really hell bent on one of those options, then for a road car, I'd say Option 1.

 

In the mean time, off load options 2 and 3 and buy a HIF44, manifold and air filter for when you've had enough of the twins.

 

Then after swapping out, off load the twins. You'll not only end up with a much better set up, but money in your pocket.

[Chris.Williams]

I have option one on my car now, was setup on a RR, ran like a champ, engine produces 84bhp at the fly.... After a month I had to start adjustments, and it would always run out of top end.
I would run a single in the future, easy setup, minimal fuss, half the cost eg needle not needles, Spring not springs blah blah.
Looks like a nice spec engine, it would be a shame to not use all of its potential.
Hif44 or chop and weber/manifold to suit.
Good luck.

[carbon]

I'm running similar spec 1293 with MD266 cam using Minispares '1.5' forged rockers, Maniflow freeflow, twin box RC40, compression 9.75:1 static. Head is a slightly ported big valve 940 with double springs. Old school 25D dizzy with modified advance and 4-11-7 vacuum can. Diff is 3.1 on standard S/GT ratios and 10" wheels. I always use the Shell V-Power 99 octane with Castrol Valvemaster.

 

Carbs are twin HS2s, with usual Vizard mods, twin K&N cones upside down on the alloy elbows, QA needles and old red springs with 10 weight oil in the 8103 dampers. I'm using an old fabricated steel inlet manifold, very simple one with about 1/2 inch balance pipe.

 

This pulls very well all the way through rev range. It used to run out badly at the top end, but that was when it had the A+ sintered rockers fitted. Not a problem since these were replaced with the Minispares '1.5' rockers, but took a while to get the ignition timing right (slightly more static advance and a lighter primary spring were needed).

[richmondclassicsnorthwales]

Twin HS2 look all very nice,but it's all the faffing  and fanying around keeping them tip top

 

I have gone both ways with twins on HS2 and HS4 and single 44,   choice though really is yours,   You gotta live with them

 

Every 3 / 6 months checking the balance against mixture and tick over,,    Oh no,,   You will develop back ache at an early age

 

You will be walking with a hunchback  !!!!!!!

[absx2]

A few years ago i was lucky enough to drive a BRG mini that was previously owned and built by Bill Richards, a seriously quick mini that would rev out in the blink of a eye.

I was told it was 130 BHP and it certainly felt like it and all on a HIF44.