21 replies to this topic

[kyle9832]

I have asked a question like this before about the hs4 but I have found that I have a crack in my hs4! I have no idea how! but I picked up a hif44 at an autojumble that is in good condition, I am just wondering what needle and spring I would require as a starting point in my engine, specs as followed

12g295 head 32x29 valves gas flowed and polished (24.5cc chamber)

kent 276 cam

+60 flat top pistons running 10:1 c.r

alloy inlet manifold

csi electronic distributer

1.3 roller rockers

lightened flywheel

fully balanced crankshaft

 

any suggestions would be great!, this will be a starting point and will be taken to a rolling road session as soon is I complete the restoration:)

[Bubblebobble]

Ive actually got Vizards book open at the moment with its needle charts . What size is the carb  ? Fot 1-1/2 su its blue spring with a e3 needle or e31 .

 

Thats based on  998 cooper , modified head and semi race cam .

[Cooperman]

An HIF44 is like an HS6 which is a 1.75" diameter carb. It is really a bit too large for a 998 unless you are going to be keeping the revs between 5000 and 7500, which is unlikely with your spec. A 'full-race' 998 could just about run one.

Ideally you should swap it for an HIF38.

[kyle9832]

Well i dont really know what im going to do then, i have a lot of other things now that need alot of money spending on them, now another carb! , well i guess its got to be done!

[Cooperman]

A few owners need an HIF44 for their 1275 engines because they only have an HS4 or HIF38.

I'm sure there is someone on here who will do a direct swap if you ask.

You will struggle to prevent an HIF44 from over-fuelling if fitted to a 998.

[lawrie124]

I have a HIF38 for sale

 

http://www.theminifo...f38-l40-posted/

[kyle9832]

so if I am using a hif 38 what needle would I require, or is it the same as the hs4 needle recommended?

[Spitz]

Would be the same as HS4 needle profile.... both are 1.5" carbs  ( or 38mm )

[kyle9832]

just one thing before I definitely have to purchase a new carb, I know I have been told that hif 38 would be a lot better and I will definatley follow this if it makes a drastic difference but I have just been comparing needle profiles and a bdd needle is not that dissimilar to the e3, the closest I could find anyway! I could lean the mixture out on the carb a bit and might help even more but please correct me if im wrong would this work and not effect the performance too much? I do not want to have to buy another carb when I will only loose 5hp or so using the hif44, I have the hif44  ram pipe now and that wasn't cheap so just want to make sure. I don't want to go against your opinions but im on a budget...:)

[Cooperman]

With the modified specification you have a rolling road session will be necessary to get it right.

You will also need a different distributor, probably an Aldon 'Yellow' to obtain the correct advance curve for the cam, head and C.R. you are running. The advance with a standard dizzy will not be right.

 

It is hard to see how an HIF44 can be made to work with a 998. The larger diameter will cause very low airflow volume through the carb and this will make running difficult, especially at normal road revs. You would be making problems which will be difficult to solve and you will almost certainly be spending more than the cost difference of swapping the carb for an HIF38 on a longer rolling road session.

 

Classic cars are not cheap, even though they are slow.  .

Edited by Cooperman, 19 January 2015 - 05:03 PM.

[Bubblebobble]

just one thing before I definitely have to purchase a new carb, I know I have been told that hif 38 would be a lot better and I will definatley follow this if it makes a drastic difference but I have just been comparing needle profiles and a bdd needle is not that dissimilar to the e3, the closest I could find anyway! I could lean the mixture out on the carb a bit and might help even more but please correct me if im wrong would this work and not effect the performance too much? I do not want to have to buy another carb when I will only loose 5hp or so using the hif44, I have the hif44  ram pipe now and that wasn't cheap so just want to make sure. I don't want to go against your opinions but im on a budget...:)

Its not just to do with the needle , its the choke size thats to big , which you cannot change , so which needle is irrelevant .

[kyle9832]

ok then cheers for the help, if I cant get a hif 38 would a hs4 be ok?

[Cooperman]

An HS4 on a good alloy inlet manifold would be vastly better and much cheaper & easier to set up than an HIF44.

 

From you spec you should expect to get around 65 bhp at 6200 rpm so long as it is all nicely builty and well set-up with a 1.5" carb, that's an HIF38 nor HS4 (or even twin HS2's).

 

Are you fitting a lower FDR to enable it to stay 'on the cam' through the gears as it will be a bit 'lumpy' with a 276 in a 998 with little 'grunt' below about 4500 rpm.

[kyle9832]

An HS4 on a good alloy inlet manifold would be vastly better and much cheaper & easier to set up than an HIF44.

 

From you spec you should expect to get around 65 bhp at 6200 rpm so long as it is all nicely builty and well set-up with a 1.5" carb, that's an HIF38 nor HS4 (or even twin HS2's).

 

Are you fitting a lower FDR to enable it to stay 'on the cam' through the gears as it will be a bit 'lumpy' with a 276 in a 998 with little 'grunt' below about 4500 rpm.

fdr? (still getting to grips with these terms ahah)

[Cooperman]

Final Drive Ratio.

With a 'hotter' cam, the power & torque bands are much narrower, and especially so with a 998. So the final drive ratio (FDR) needs to be lowered to keep the engine still giving good power at the point of changing gear.

For your engine I would recommend a 3.44:1 FDR, so first of all count the teeth on the crownwheel and divide that number by the number of teeth on the pinion. If it is not 3.44:1, then find a 3.44 set and fit it.

What you don't want is an engine which goes to quite high revs in one gear, then 'bogs down' when you change up. in such cases a standard car will be quicker through the gears.