Rebuilt 1275-running a bit "out of sorts"

[ampwhu]

would i be right in thinking the 1275 engine is "taller" than a 948/1098 engine? i mean is the head or block taller?

[philthehill]

The 1275cc and 948cc heads are the same height 2.75" standard.

The 1275cc block is 225mm tall.

The 948cc/1098cc block is 220mm tall.

Therefore the 1275cc block is 5mm taller than the 948cc/1098cc block.

1275cc blocks with either thick or thin sump flanges are still 225mm tall.

The 1275cc push rods are longer to compensate.

You used to be able to get shortened engine mount towers to compensate.
I have never had the need for shortened engine mount towers. There is enough room in the engine bay to compensate for the additional height of the 1275cc block.

[ndevans]

A further 220 miles trouble free running this weekend, 110 miles each way, with a trailer, to do house clearance. The car has now passed the 500 mile mark since the head & new gasket went back on, so I will re-torque it sometime before I next use it.
The car ran smoothly and pulls well, but the weep of oil from the head gasket joint in the vicinity of no 1 cyl on the exhaust side is no better. It used about 500ml in the 220 mile run, which is more than I'd like.
The only other teething trouble is that the choke seems to work it's way out, and has to be pushed back in repeatedly. I looked under the bonnet and pulled it shut with my fingers, but it still worked it's way out again over the next few miles. Any idea why that could be, and how I could fix it?

Cheers N

[philthehill]

As regards the oil leak - Torque the head and see what happens.
As regards the choke cable - Replace the choke cable.

[liammonty]

As regards the oil leak - Torque the head and see what happens.
As regards the choke cable - Replace the choke cable.

I don't think a new choke cable will be necessary with a HIF38 carb. I'll check mine at lunch time but from memory, the 'stiffness' of the choke mechanism (which is totally different to on the HS carbs) can be adjusted.

[liammonty]

Nigel - having refreshed my memory regarding the one of my cars with a HIF38 on it, I'd suggest checking a couple of things:
1. Is the return spring on the choke mechanism present and correctly tensioned?
2. Have you set the resistance in the cable appropriately? On my set-up, there is a small spring clip on the bracket attached to the plate that is sandwiched between the insulation blocks on the manifold. This can be set to exert a given amount of resistance in the cable to ensure the choke stays out where it is set - i.e. it isn't pulled back in by the return spring.

[ndevans]

Nigel - having refreshed my memory regarding the one of my cars with a HIF38 on it, I'd suggest checking a couple of things:
1. Is the return spring on the choke mechanism present and correctly tensioned?
Yes, the spring is there, it's a coil spring wound around the shaft that the choke cam pivots on. Not sure how it's tensioned, how do you check?
2. Have you set the resistance in the cable appropriately? On my set-up, there is a small spring clip on the bracket attached to the plate that is sandwiched between the insulation blocks on the manifold. This can be set to exert a given amount of resistance in the cable to ensure the choke stays out where it is set - i.e. it isn't pulled back in by the return spring.
If yours is the same setup as mine, then yes, I have the spring clip, but as it clamps on the armoured choke cable sheath, I can't see how it regulates the cable resistance.

Edit: a picture says a thousand words, so here's 2:-

IMG_20210124_144112599~2.jpg (1.25 MiB) Viewed 3544 times

IMG_20210124_144203484~2.jpg (1.93 MiB) Viewed 3544 times

[ndevans]

In other news, I swapped the BFY needle in the HIF44 for a BDL yesterday. The result, while not out of this world, is definitely noticeable. The BFY seemed to give plenty of mid-range torque, but lacked a bit in the lower and upper ranges. The BDL seems to even this out, and the result is a more drivable car. It's also a little quieter, but I'm not sure why this would be. It's smoother at idle as well.
I fitted the BFY on the advice of SU, whilst I was rebuilding the carb, but a trawl of various websites and forums revealed the BDL to be the most widely recommended for an HIF44, so I thought I'd give it a try.

Cheers N