Head mods

[old grumpy]

Not sure why you would want to keep the stock cam for any reason with any other mods.

I am so stubborn!!

Actually I am not that stubborn. I just wanted to stretch the point that a more "active" camshaft is not the first and only step but the second together with the headwork.

Some people do actually change camshaft and nothing else

 

[RootesRacer]

Some people do actually change camshaft and nothing else

Yes, quite often its the greatest power output you can change per dollar.

 

[Jim E]

Think the factory inflatted the HP numbers on these engines a good bit or used a "really" well preped engine when they came up with the numbers. As in blueprinted it to within an inch of its life. Just do not see this engine at just over 100 cubic inches making almost 1 hp per CI. Then when you think about the H120 a 1725 rated at 120hp and all the extra stuff it had over a standard 1725 that added up to only a 20hp gain. Then think about the Isuzu Bellet GTR motor which is a copy of the 1725 Rootes motor at 1600 cc except it had a double overhead cam cross flow head dual webers and was rate at just 120hp the same as the H120....

 

[RootesRacer]

Think the factory inflatted the HP numbers on these engines a good bit or used a "really" well preped engine when they came up with the numbers. As in blueprinted it to within an inch of its life. Just do not see this engine at just over 100 cubic inches making almost 1 hp per CI. Then when you think about the H120 a 1725 rated at 120hp and all the extra stuff it had over a standard 1725 that added up to only a 20hp gain. Then think about the Isuzu Bellet GTR motor which is a copy of the 1725 Rootes motor at 1600 cc except it had a double overhead cam cross flow head dual webers and was rate at just 120hp the same as the H120....

Actually the H120 was 105BHP, the "120" was the original goal and from what I recall, to get the 120HP, the impact on low end torque and drivability was too great a compromise for Chrysler so Holbay went back to work creating the version we know of today. Small ports, odd cam timings, very strange DCOE configuration.

Now from what the guys at Holbay told me years ago, the cam profile that gave 120BHP was the cam that became known as the Tornado E128 grind.
Which was available as aftermarket until Holbay closed its doors.

 

[Jim E]

My bad I forgot that, so the H120 was maybe a 10% per factory numbers increase.

 

[RootesRacer]

My bad I forgot that, so the H120 was maybe a 10% per factory numbers increase.

HP wise yes, but the bottom end torque is way mo bettah.

The H120 was designed to make a reliable rally engine that could be abused
but not buzzed.

 

[Jim E]

"mo bettah" have not heard that since I left Hawaii

goes to show it has all been done... Holbay built the type engine I want to try mo bettah bottom end power instead of a RPM motor years ago

 

[SeriesVtime]

Wow - what a surprising array of info from a seemingly simple question - thanks to all that answered!

Not to intentionally re-ignite this discuss, but, I've seen a set of roller rockers, valves, etc.. available on ebay and wanted to know if anybody has thoughts on that package? If this has been discussed elsewhere, my apologies.

 

[jumpinjan]

The roller rockers are good, but I would not use old rocker shafts with them. So, the question is, where does one find new shafts?....at a fair price?
Jan

 

[RootesRacer]

The roller rockers are good, but I would not use old rocker shafts with them. So, the question is, where does one find new shafts?....at a fair price?
Jan

Speedy Spares shows them in their catalog.

http://www.speedyspares.co.uk/ROOTES/ALPINE/alpine%20report.html


P118878 Rocker Nos 2 4 6 8 £7.50
5220124 Rocker Shaft - Front £8.50
P106984 Rocker Shaft - Pedestal £5.50
5220125 Rocker Shaft - Rear £8.50

These would appear to me to be good prices, but that doesnt mean they are available.
Also getting stuff shipped from England these days is getting very pricey.

 

[SIVAllan]

Actually the H120 was 105BHP, the "120" was the original goal and from what I recall, to get the 120HP, the impact on low end torque and drivability was too great a compromise for Chrysler so Holbay went back to work creating the version we know of today. Small ports, odd cam timings, very strange DCOE configuration.

Now from what the guys at Holbay told me years ago, the cam profile that gave 120BHP was the cam that became known as the Tornado E128 grind.
Which was available as aftermarket until Holbay closed its doors.

I don't know the term "Tornado E128" grind, but Coltec (formerlly Holbay??) offers a grind for Alpines labelled on their site as...E128...

Various engines makes

Application Ref. No. Timing Figures (Degrees) Valve Lift (inches) Inlet/Exhaust Cam Lift (inches) Inlet/Exhaust Degrees Period at Crankshaft

Chrysler 1725 E128 35/60 60/30 .465 .330 275/270
http://www.coltecracing.com/camshafts.html#various

I would accept the consensus here on the H120 engine's BHP but hope it's from a dynamo as the info on the net ranges upward to 110 or 120 but it's not clear whether that's at the flywheel, rear wheel, or just what.

I don't see how the improved flow and raised compression could have produced less than a 10 - 15 percent gain over stock BHP - but I'm a rookie at this

 

[RootesRacer]

I don't know the term "Tornado E128" grind, but Coltec (formerlly Holbay??) offers a grind for Alpines labelled on their site as...E128...

Various engines makes

Application Ref. No. Timing Figures (Degrees) Valve Lift (inches) Inlet/Exhaust Cam Lift (inches) Inlet/Exhaust Degrees Period at Crankshaft

Chrysler 1725 E128 35/60 60/30 .465 .330 275/270
http://www.coltecracing.com/camshafts.html#various

I would accept the consensus here on the H120 engine's BHP but hope it's from a dynamo as the info on the net ranges upward to 110 or 120 but it's not clear whether that's at the flywheel, rear wheel, or just what.

I don't see how the improved flow and raised compression could have produced less than a 10 - 15 percent gain over stock BHP - but I'm a rookie at this

The E128 cam is the one I was talking about, the specs shown are the same.

Any factory engine specs you will ever see will be at the flywheel.

If you dont understand how all that work would result in such a small HP increase then you havnt seen the torque curve of the H120 engine.

All things the same, cam shafts let you have power down low or power up high, but not both.
The stock H120 setup has more torque across the board but has it down lower in the RPM band as compared to a stock 1725 cam.

The E128 will put your power up top and will probably get you the 120 HP you think you should have been due with the H120 setup.
The only way to get that kind of power from an H120 engine is to toss the H120 cam in the trash and put in a more "advanced" cam with some duration.

Now thats not to say that there arent folks with H120 setups making 120BHP, they just arent doing it with the "as delivered" H120 cam.

 

[alpine_64]

I don't see how the improved flow and raised compression could have produced less than a 10 - 15 percent gain over stock BHP - but I'm a rookie at this

Allan,

For starters the power figures changed lots over the 50-70's.. the earlier the less reliable and more inflated. They would test engines on a stand with no accesories and exhausts so no reflection of what they do in an engine bay or woth the other parts that would be on the motor.. later they went to more accurate testing methods..

then there is the truth.. ask Jim E.. from all accounts a very quick 4 clyinder alpine that could see others off.. yet 85ish at the wheels.. an honest HP rating.

 

[old grumpy]

This tread is not over yet!

Nobody has mentioned about careful re-profiling of the inlet and exhaust channels, valves and combustion chambers. Well yes, we all have David Wizards book and work accordingly to it, but it is the ultimate?

Considering the talk about shortage of heads I guess not many has cut a head in half to see what can be done.

All this work just to be able to get more (from less?) and using a not-that-hot camshaft.

A lot of work with a small result? Yes, that's the essence of old car ownership

 

[RootesRacer]

This tread is not over yet!

Nobody has mentioned about careful re-profiling of the inlet and exhaust channels, valves and combustion chambers. Well yes, we all have David Wizards book and work accordingly to it, but it is the ultimate?

Considering the talk about shortage of heads I guess not many has cut a head in half to see what can be done.

All this work just to be able to get more (from less?) and using a not-that-hot camshaft.

A lot of work with a small result? Yes, that's the essence of old car ownership

Come on give us some credit here.

Since I was port matching to a twin DCOE intake, and needed to remove a lot of runner volume for the intake runners. I had to cut a head down the middle and down the ports to see the casting section so as not to break into
cooling passages.

One thing I learned is that when you get a good head, get the same casting type for doing the cutting since the castings WERE different between some head types.
This way you have the best possible chance of knowing where the danger zones are.

 

[alpine_64]

This tread is not over yet!

Nobody has mentioned about careful re-profiling of the inlet and exhaust channels, valves and combustion chambers. Well yes, we all have David Wizards book and work accordingly to it, but it is the ultimate?

Considering the talk about shortage of heads I guess not many has cut a head in half to see what can be done.

All this work just to be able to get more (from less?) and using a not-that-hot camshaft.

A lot of work with a small result? Yes, that's the essence of old car ownership

As Jarrid mentioned he has cut a head to check it out, i believe Mike Broome who was in the UK did the same, though Mike had his alpine for sale about 18 months back.. anyone know what happened to it?

 

[old grumpy]

As Jarrid mentioned he has cut a head to check it out, i believe Mike Broome who was in the UK did the same, though Mike had his alpine for sale about 18 months back.. anyone know what happened to it?

What could be found, what was hidden there? A lot of material that can be taken away? On the other hand, it's no use with big runners if bigger valves can't be used.

 

[RootesRacer]

What could be found, what was hidden there? A lot of material that can be taken away? On the other hand, it's no use with big runners if bigger valves can't be used.

Big runners are counterproductive unless you have big cams and big RPMs to back it up.

 

[old grumpy]

Big runners are counterproductive unless you have big cams and big RPMs to back it up.

But I have, but I have!!!

You are of course right. I slipped away from the not-so-hot-camshaft to dreams about big-bore hot more-or-less-racing-engines where small valves are a nuisance.

It's easy to fall into fantasy.

 

[alpine_64]

Things to consider on an alpine, the valave size is limited by the head,

Jarrid had built one with as large a valve as you can go (lapping into each other on the seats) now.. Jarrid.. correct me if im wrong, but in some ways while you get bigger valves they may interfere with the flow in the chamber a little .. but this possible negative is outweighed by their size?

Large inlets require large cams, slightly smaller, well flowed and lightly polished (so you get intake tubulance) runners will perform better than gung ho bored out intakes. Also the revs you need to get to to take advantage of the size will require rolelr rockers or some serious springs as the alpine will bounce or float its valves long before you get peak power.