The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: 60 blue flash on 26.07. 2011 10:32

Title: 1960 iron head tuning
Post by: 60 blue flash on 26.07. 2011 10:32
Hi Guys

After a good weekend at the 1000 bikes festival at Mallory park i feel i need to increase the performance of my 1960 flash.
At the moment i think we have the 7.2 pistons, 356 cam? and run the std carb for that year.

I have a couple of spare iron heads,  could someone please advise the best route to increasing the power by a small margin as i dont want to loose the charms of a std A10

Trev
Title: Re: 1960 iron head tuning
Post by: t20racerman on 26.07. 2011 11:16
You can always improve the gas flowing of a head - both iron or Ally. This involves cleaning up the gas flow, reducing the spare metal around the valve guides etc. You don't have to be radical. This will often help to make them run cooler too

Not a job for the amateur though  - there are some very good companies that can help. I used 'The Cylinder Head Shop' down in S London. They did a superb job on my ally head.

Adrian
Title: Re: 1960 iron head tuning
Post by: olev on 26.07. 2011 13:07
There is nothing wrong with your frame or gearbox, Trev.
but, if you are serious and want to run at the front of the pack, drop a triumph into it.
sorry fellas.
Title: Re: 1960 iron head tuning
Post by: Triton Thrasher on 26.07. 2011 15:53
i feel i need to increase the performance of my 1960 flash.

Or, in other words, you've got it running well and reliably and want to alter that situation.
Title: Re: 1960 iron head tuning
Post by: bonny on 26.07. 2011 17:43
What sort of speed will an iron head golden flash run along at comfortably ? Surely 70 mph should be no problem for it ? Might altering your gearing rather then tuning help ?
Title: Re: 1960 iron head tuning
Post by: t20racerman on 26.07. 2011 22:45
Or, in other words, you've got it running well and reliably and want to alter that situation.

Hell yeah! Been doing that for over 30 years.

I used to have an iron head on mine - loved it. Got an alloy head, loved it more. Got my head gas flowed, bigger carb etc, loved it even more! Nothing wrong with looking for a few more bhp and torque...
Title: Re: 1960 iron head tuning
Post by: mike667 on 27.07. 2011 01:40
I am sympathetic - and curious as to others input on this..

 i had my 61 iron head A10 out for a drive up the california coast this past weekend  - just getting to and from the scenic route required time  on los angeles freeways -  yikes! While the bike is very comfortable at the 50-60mph mark, trying to keep from becoming a hood ornament on a Cadillac escalade  was a uncomfortable situation - very buzzy about 65 and above - and while not "its going to throw a piston" buzzy it did make me think of ways to lower the rev's a bit to go 70+ comfortably while staring in my rear view for the guy going to put me in the intensive care unit - hate to think the A10 is a "bar hopper" in los angeles....
Title: Re: 1960 iron head tuning
Post by: t20racerman on 27.07. 2011 08:54
I am sympathetic - and curious as to others input on this..

 i had my 61 iron head A10 out for a drive up the california coast this past weekend  - just getting to and from the scenic route required time  on los angeles freeways -  yikes! While the bike is very comfortable at the 50-60mph mark, trying to keep from becoming a hood ornament on a Cadillac escalade  was a uncomfortable situation - very buzzy about 65 and above - and while not "its going to throw a piston" buzzy it did make me think of ways to lower the rev's a bit to go 70+ comfortably while staring in my rear view for the guy going to put me in the intensive care unit - hate to think the A10 is a "bar hopper" in los angeles....


You could try gearing it up a bit first and see how that goes. It might improve things a little as the standard gearing is quite low and wasn't designed for freeway cruising at 70mph+.
If you do this and find it flat, and struggling to maintain a decent speed, then you know it is time to get a little work done. Gearing up though must be the first step as whether tuned or not, you need lower revs at higher speeds to cruise comfortably.
Title: Re: 1960 iron head tuning
Post by: 60 blue flash on 27.07. 2011 09:22
Thanks to everyone who replied even the funny ones.
I have a 20T gearbox sprocket and im happier with the gearing and 60mph cruising is more relaxed.
The engine feels bullet proof after Mallory and no oil leaks from the top end.

My main question was regarding tuning the spare head a little, and gas flowing as suggested by t20racerman may well be an option

Any thoughts on bigger valves on this head still keeping the btm end the same?

Trev
Title: Re: 1960 iron head tuning
Post by: muskrat on 27.07. 2011 10:56
G'day Trev,
                how fast do you want to spend?
You could put in RR/SR valves in 67-0968 = 1.41" ex 67-0967 = 1.38" with a bit of seat and port work to run a 30/32mm carb. Bump the comp up to 8.5:1. Lighten the valve train components, balance everything, the list goes on and on.
Then you'll have to make it stop, more $.
Cheers
Title: Re: 1960 iron head tuning
Post by: A10Boy on 27.07. 2011 11:57
Why not get hold of an alloy head, paint it with cylinder black [or not] and fit that? easy to reverse if you dont like it. If I remember correctly, apart from the comp ratio and the head, the 1960 A10 is upto super Rocket spec, so fitting the alloy head should make a difference.
Title: Re: 1960 iron head tuning
Post by: wilko on 27.07. 2011 18:36
If you hop it up, you'll have to gear it up anyway to take advantage? It would still be doing the same revs at a given speed.Gear it up a couple of gearbox teeth if possible. What's the biggest engine sprocket available? Get a spare one rebanded.
Title: Re: 1960 iron head tuning
Post by: Triton Thrasher on 27.07. 2011 21:07
If you narrow the power band by tuning for power, you might not get off with higher gearing.

Get the power first, then get gearing to suit.
Title: Re: 1960 iron head tuning
Post by: Rocket Racer on 05.08. 2011 06:58
I agree with Andy, why not keep the iron head std and sort a much lighter alloy head which instantly takes weight away from the bike.
All depends on budget really.
Another option is just fitting a 357 cam would also help it rev and you could leave the top end stock. Many choices to follow.
For street use I wouldnt be looking for hi comp pistons
Title: Re: 1960 iron head tuning
Post by: dpaddock on 12.09. 2011 01:14
If you fit an alloy head, remember to lengthen the rocker box studs.
Note that you won't get much improvement with the 357 cam unless you rework the iron head to RR/SR porting dimensions.
Title: Re: 1960 iron head tuning
Post by: A10Boy on 12.09. 2011 13:55
I agree, you could loose power in low to mid range due to greater overlap.