both 850mans photos of the grey motor lifters and TimW s photos show you can visually pick it, despite the large radii... again good to know thanks for sharing

Hi MG Rocket,
Sorry I didn't answer your post before this(The Secretary went on strike!) Here's a head I made in 1968/69 when I was playing with sport sedans. The end ports are 1.25" in diameter, offset towards the ends of the head. The inlet ports are 1.375" in diameter. the push rod holes as you can see in the photo had to be offset quite a long way. It actually straightened the push rods up to almost vertical. Which was a good thing. The sides of the rockers had to be machined away 1/8" so they didn't protrude into the port. But finding that round port are not the answer for the mini head. I don't do them like this anymore.





Below is a couple of photos of the end exhaust ports, showing you how the exhaust exiting the port is doing a big swirl and going down to the bottom of the port. This is not ideal. This all stems from the valve seat and just below the valve seat not being correct. This just isn't efficient.





Graham Russell

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"It's better to be not informed than ill-informed"

Thanks Graham for the trouble you go to, to answer questions.
If I'm reading the photo properly....the gases simply do not want to use the top or even the entire
right hand side of the port. It looks like the port would be more efficient if it was smaller, even
after resolving the seat problem. But that I guess would depend upon the revs the motor was designed for.
Great photo btw.

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850man
This is the problem people are still living in the 60s move on things have changed, cylinder heads with the aid of flow benches we have learnt a lot about air and what it does on its journey down the inlet port and out of the exhaust, camshafts have taken a MASSIVE leap forward since the 60s we are now making more hp from road cars with road cams than they were making from race cars in the day, the brown extractors were possibly the best in the day when matched with the likes of the 649 type cams that were only making hp to 7000rpm and they are still a good all round set of pipes but times have changed and so has exhaust tuning, to win races in the 21 century you regardless of the class you don't build motors like they did in the 60s.
Graham Russell

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"It's better to be not informed than ill-informed"

Hiya.

I have a question about port speed, well actually throat speeds.
I did quite a bit of calculations (well my computer) and the port speed at the min CSA for a 1310 race engine (so 5-9K rpm) with a 37mm valve using .86 to .88 times throat x the valve diameter is very high. At 8000 rpm I get 360 ft/sec average. So at maximum piston speed it gets near or over Mach 0.6 ( sonic choke ).

Its mostly theory but using 1D engine modelling (it's a work in progress but I got it to the point where it gets quite near to dyno figures without trying to match them) I did get more power when I enlarged the throat to > 0.9 (0.93 to basically almost no. However this would not give a good port to seat shape and lose flow.

How about using a even bigger valve not because it flows more, but because you can keep the CSA of the throat large enough the keep the speed down while keeping the shape where it need to be ?

I'm using the flow numbers of one of your (GR) heads that lives in Canada for that particular model btw. I need a lot more work on my own stuff to get to those numbers..

cheers

JR

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no time to finish me bleedin car ..
1982 Blue-White Roof.

http://aseriesmodifications.wordpress.com/

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replying to Sir Yun

in regard to bigger valves.. ...from what i recall/glean,many well respected builders have said don't go larger than 37mm, velocity suffers, no space etc
again from recollection, lots have tried but it just doesn't work.... again the thought is flow improves but velocity suffers ..

i can't really comment on the csa %s.. however it seems to me that dcoe45 starting at 45mm down past say 38-40 chokes where it picks up its load and then reducing very gradually (as long an inlet as you can fit) at 35mm may mean that peak velocity until you get to SSR may not be much fluctuation on average..

850man
What would you expect them to say when you ring up about lifters don't buy ours there all rubbish wake up to your self,
As for Rob Selby ask him about the meeting he had with Keith last week, and if you think ANY of these lifters have the correct radius on them Please show us and the rest of the world where we can buy them.
Correct me if i'm wrong but didn't you say you get Clive to grind all your followers, why would you say that if there is nothing wrong with them.
Graham Russell

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"It's better to be not informed than ill-informed"

Hi JR
At 8000RPM using a throat dia of 1.136 80% of the valve size the mean gas velocity through the valve is 280 ft/sec, i'm only using .450 lift in my own engine i've come down in valve lift to try and get more velocity and keep the velocity going through the valve for better filling and finding this is working.
And yes you will find a little more power some times by opening the throat area up to 90% but on the circuit it does not pull out of corners as well with the smaller choke area.
The piston speed is getting up there at 8000RPM 4267 ft /min with a 3.2 stroke but at 9000RPM your up to 4800 ft/min that is starting to get to high with a mini with all the harmonics it gets at that speed
Graham Russell

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"It's better to be not informed than ill-informed"

Ah - just for the record... I have sent samples of properly re-ground followers to various specialists. I am about to receive bundles of followers from the renowned names for re-grinding. As Graham (GR) said - when asking a company selling products whether they have had any issies, they are not likley to say 'yes, we've had all manner if issues with that component type'. Can you imagine the aggro that would cause from customers that have already bought said component from them wanting them replaced or refunded? Now just multiply that factor by the fact the cam follower is probably the first component that goes in to a 1275 block, and so the last one out? And those companies would have no recourse to the manufacturer or supplier as they are adept at pointing the finger at somebody else. It would be a very, very rich person to take them to court over it.

Some years back, fed up of being palmed off by a cam producer I had a fully metallurgicval examination done of a damamged cam. Cpost me £600.... the result? the cam roducer said 'there may have been a problem so as an act of good will they'd replace the camshaft... at their cost price to me'. Never any apology or admission of fault on their part. Always the same with all the followers I have returned over the years too. The supplier sends them back to their supplier who sends them back to teh manufacturer and several months later you get the 'sold thousands, never been a problem'.

Keith - long time no see!

GR & Keith - is there any good way I look at the followers I've had sitting around at home for the last 5-10 years waiting to be put in an engine (happening this Chrissy), to see if they have the right radius on them?

How badly pitted can old ones be before they can't be reground?

cheers,

Jacob

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'72 Clubman Van - 1022cc, 295 head, 731 cam - Daily Driver
'69 Morris 1100 S - Dinged by a bus, in shed under repair
'64 Morris 1100 - Early 1100, long term project

Hi Jacob
If they are not to badly pitted just get them reground they will be fine.
Graham Russell

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"It's better to be not informed than ill-informed"

With new followers, set them face down on a flat surface (a window will do if no other choice as glass tends to be pretty flat). Lightly press one finger on a top edge of the follower to force the follower to sit on the face edge of that side. If you can not get a 0.0025-0.003" feeler blade under the opposite edge, there could be issues with the followers.

Should we start by asking what cam angles different grinders put on their cams?