HC Head - is it worth the bother?

[Alan Ashton]

I am having difficulty removing the two head manifold studs (see my earlier thread).  I was wondering, before I get to the point where I snap the studs, how much difference it will make to the cars' performance? Just wondering if it is worth all the effort....

Alan

[David Anthony]

I think so. It only added a couple of bhp to my Ruby, but it means I can cruise on motorways at the same speed as lorries, so avoiding the wind buffeting as they overtake.

[Reckless Rat]

Made a considerable difference to my RP which had a LC head. The engine pulls much better in top gear, although it is a bit harsher - you need to play with the timing a bit to find the best setting.

[Bob Culver]

The extra 3 or so bhp is a big percentage increase. Hill climbing in 3rd especially is much improved. But Austins did delay hc until the 3 bearing crank for reasons. The 2 brg engines are distinctly more harsh. And raised cr is severe on the original cranks. Many loads increases in proportion to cr and if you read any elementary text on metal fatigue the effect of a 30% or so increase is interesting!

[Hedd Jones]

To give a bit of realism.
I have a short wheelbase box saloon (RL). 3 speed box. 4.9 rear axle. L/C head. Downdraft carb

I have a long wheelbase box saloon (RP). 4 speed box. 5.25 axle. H/C head. Sode draft carb.

Both have bosch 009 dizzys

I think they cruise about the same speed. Its difficult to tell as i drive harder than the wife so she (in the RP) holds me up, or cant keep up. 

I feel the RP is stronger on hills and is certainly more refined. It will go up hills with its lower axle thay the RL will not despite the obvious extra weight. Ive baulked the RL on a certain hill. Being lighter the RL feels nippier and more nimble. The 3 speed box I prefer.

My gut feeling is the RP probably wouldnt go as well as the RL if it had a L/C head on it (as it should). As it is, on balance it probably goes better.

A RN with L/C head and a downdraft carb is probably not as good as either

[Bob Culver]

Many heads have been planed to further increase power (and problems). Originals nominally 1.5 inches deep. check enough thread on studs.

And somewhat off the subject but the 4.9 cars in 2nd pull about same rpm as 5.25 cars in 3rd. I found on my car with later head and minor mods, with snappy gear change, 30 mph or more could be maintained on many hills whereas previously a tedious (and now dangerous) 20. Ridiculous though it seems today could through the 1960s easily overtake many trucks and busses.

[Alan Ashton]

Thanks for all the info. Think I'll carry on trying to remove the studs.

Alan.

[Austin in the Shed]

Invest in a set of stud removers ,6-8-10-12mm sets.Warm the studs up with a blow lamp,apply Plus Gas tap the top of the studs with a hammer to shock them and carefully try to undo.repeat if necessary.

[John Cornforth]

The HC head overlaps part of the cylinder, so it's important that the pistons don't protrude above the top of the block at TDC, even when there is a bit of whip in a 2-bearing crankshaft. The thin gasket gives some clearance, 20 thou from memory.  I suggest you check that no-one in the past has shaved the top of the block or left out the base gasket.  One way to check "static" clearance is to trial-fit the head without a gasket and use small pieces of plasticine.  Once you have turned the engine over by hand, the squashed material can be checked for thickness in each cylinder.

I found that less advance was appropriate after changing from the LC to the HC head, presumably because the "squish" effect causes more turbulence.

The tradeoff for more power is a slightly harsher sounding engine, especially around 2200 RPM.  Things smooth out noticeably above 3000 RPM, which is my level cruising speed of about 45 in 4th gear. (1936 Pearl)

The 2-stud water branch can be fitted without a gasket if the faces are flat,  Loctite SI 5660 worked well for me.  I recommend 20 to 25 ft-lb as a torque figure for head nuts fitted dry (other opinions are available !).

John Cornforth

[Jeff Taylor]

Invest in a set of stud removers ,6-8-10-12mm sets.Warm the studs up with a blow lamp,apply Plus Gas tap the top of the studs with a hammer to shock them and carefully try to undo.repeat if necessary.

Cromwell have Sykes-Pickavant stud extractor sets 6-8-10-12mm on special offer at £28.78 inc VAT.

I can also recommend Ambersil Rust Flash - a penetrating oil spray with - 40C freezing action - Cromwell have it on special offer at £5.30 inc VAT.

https://www.cromwell.co.uk/shop/hand-too...gLDkPD_BwE

https://www.cromwell.co.uk/shop/lubrican...gLw2_D_BwE

Jeff.