11 replies to this topic

[Hedgey]

Good afternoon,

 

Currently building a 1310 with a mild modifications and I need to order a new needle.

Can anyone help me with a starting point to get it running? (I will be getting it rolling road tuned when the car is finished and probably upgrade the carb)

 

Spec:

 

• 1275 A series (bored at 1310)
• Kent 266 cam
• Upgraded Cylinder head - (C-AHT135 Road-sports large-bore 'stage 3' spec head. Modified, standard MG Metro spec 1.406"(35.7mm) inlet & 1.151"(29.2mm) exhaust valves, cast iron valve 
  guides, A+ spec stem seals, 200lb (nominal) double valve springs, nominal 21.0cc 
  chambers. Suitable for fast road large-bore engines and lead-free fuel use up to 
  6,500rpm continual peak rpm limit. Has by-pass hose and heater valve take-offs for 
  pre-1992 engine types. Near zero flow-loss from modified standard valves when 
  compared to race-spec valves)
• Aldon Yellow distributor
• Single HS4 carb - (I know I should have gone with a hif44! but I had already rebuilt and cleaned the hs4 carb so need to use it)

Any help with a starting point will be appreciated, WinSU gives A?Y as I haven't registered and I don't know how accurate it could be anyway.

 

Cheers

Elliott

[richmondclassicsnorthwales]

I Hate these starting points because you will now get about 16 different needle types now >???????  Can of worms

 

Get shot of the HS4 and sell it.

 

Put a HIF44 on.   It,s like trying to feed a shark in a goldfish tank,   you need air and petrol

 

Like running a Rolls Royce on Paraffin.

Edited by richmondclassicsnorthwales, 05 February 2019 - 10:25 PM.

[Hedgey]

I Hate these starting points because you will now get about 16 different needle types now >???????  Can of worms

 

Get shot of the HS4 and sell it.

 

Put a HIF44 on.   It,s like trying to feed a shark in a goldfish tank,   you need air and petrol

 

Like running a Rolls Royce on Paraffin.

 

Straight to the point. Fair enough, I know you're right though

 

Elliott 

[richmondclassicsnorthwales]

Black and white with me, no point in spending money tuning up the HS4, paying for a rolling road,then doing it all again with a 44

 

Things are pricey enough, just put the money from the HS4 towards the 44

[whistler]

Try starting with a BDL needle in a HIF44. That's the standard needle for an MG Metro. The RR technician will 'tune' that one.

[Retroman]

The HIF 44 is a better starting point for sure

 

But if you want the standard look / on a budget / limited re insurance the HS4 vizarded is worth considering

 

It will be more than capable of supplying enough air and fuel for your spec

 

The valve springs at 200lb are too heavy for a 266 cam too

[Pigeonto]

You have 35.6mm inlet valves, (That's the OD, down to about 33 actually in the throat)

HS4 is 38mm bore....

If you don't immediately have a HIF44 and want to get on, put in an AAU needle and set the best idle mix by adjusting the jet, see how you go for now.

Remember, HS 4 is only ever going to be lacking when you are on full throttle in the 5000rpm area, and even then that's debateable

**EDIT**, Retroman beat me to it !!  And I couldn't agree more, 200LB springs ? your poor cam lobes :-/ 

Edited by Pigeonto, 07 February 2019 - 10:47 AM.

[Hedgey]

The HIF 44 is a better starting point for sure

 

But if you want the standard look / on a budget / limited re insurance the HS4 vizarded is worth considering

 

It will be more than capable of supplying enough air and fuel for your spec

 

The valve springs at 200lb are too heavy for a 266 cam too

 

Not limited by the insurance but I did want to keep the engine looking standard.

 

You have 35.6mm inlet valves

HS4 is 38mm bore....

If you don't immediately have a HIF44 and want to get on, put in an AAU needle and set the best idle mix by adjusting the jet, see how you go for now.

Remember, HS 4 is only ever going to be lacking when you are on full throttle in the 5000rpm area, and even then that's debateable

**EDIT**, Retroman beat me to it !!  And I couldn't agree more, 200LB springs ? your poor cam lobes :-/ 

 

I think I will look out for a Hif44. I really wanted to keep the HS4 for the originality and rebuilt it before realising it was too small for the engine.

 

I believe the valve springs are actually 180lb not 200lb. Keith Calver made both the head and assembled the engine and never once commented on the valve springs so I'm hoping they are correct for the application.

 

Thanks to you both

Elliott

[Retroman]

PM me for a good recondition HIF44

[carbon]

Elliott - you have not listed the type of rockers you are planning to use.

 

If you use the sintered A+ rockers with the MD266 you willl discover that the top-end power tails off very rapidly, and fitting a HIF44 may not give you much (or any) benefit compared to the HS4.

[Hedgey]

Elliott - you have not listed the type of rockers you are planning to use.

If you use the sintered A+ rockers with the MD266 you willl discover that the top-end power tails off very rapidly, and fitting a HIF44 may not give you much (or any) benefit compared to the HS4.

Sorry didn’t think about the rockers, I’m using 1275 pressed steel rockers. I think my current plan is to start with ‘vizzard’ mods to the HS4 and see how that goes. In time I can change the carb to achieve more power if I need/want

Elliott

[carbon]

The pressed steel rockers are a good starting point, much better than the sintered type.

 

When carrying out the Vizarding mods to the HS4 I would give priority to thinning the throttle spindle and using flush butterfly retaining screws with some Loctite to keep firmly in place. This improves the airflow without upsetting the mixture at any point in the duty cycle.

 

The other Vizarding mods are very likely to change mixture. In my experience streamlining to the throttle body weakens mixture at higher rpm, and radiusing the piston tends to richen up the mixture under acceleration. Doing both does not cancel out the different effects, and a trip to a good rolling road with an operator who understands SUs will be essential if the engine is to be kept in good order.