mk1-forum.net

So after a year or so of collecting parts, my 970s 8 port will be going together very soon. However, being the first 8 port I have built I'm really not sure what cam to use. If I was building a bigger capacity, lower reving engine then I would have a much better idea but I'm stumped with a 999 screamer. Jon Lee at Lynx AE has been fantastic and has helped me hugely along the way. We have discused backing the engine off abit and limiting the engine to around 7500-8000rpm. Not just because of cam choice but also due to the valve gear and pushrods being an obviouse rev limiting factor. Due to it being a competition engine I would like to use 95% of its potential so have any of you guys got any opinions on what I should look out for?

If you build a 999 8-port and limit it to 7500rpm, you will need to be punished!!!!

Vegard wrote:If you build a 999 8-port and limit it to 7500rpm, you will need to be punished!!!!

This is my thinking too!

talk to mike at MBE about cams and never mind 7500 limit - my 1293s fine at 8000 and has been for the last 18 years

pad

7500???


haha

I know someone who used to run a short stroke 8 port and it didn't even come on cam until 6! - he kept it buzzing at around 11-12000 rpm (his was a shorter stroke than yours though)

you should be looking for 8-9 out of yours - as long as the rocker geometry is worked out right you wont have a problem

Would be great to aim towards a 5 figure rev limit like it had when Jon Lee's father raced it Rich. I'd be very happy to see 9000rpm with push rods though! Do Minispares do anything for this kind of engine Rich?

Thanks for your help guys.

I just got some uprated ones off minispares.

wantafaster1 wrote:I just got some uprated ones off minispares.

That's great to know.

http://www.minispares.com/product/Class ... .aspx|Back to

There are a few different designs and also lengths , check them out

with your engine Im 99% sure that you would have to build it with dummy pushrods to calculate the rocker geometry, then get some of the three piece ones made to the correct lengths.

it would be too much to hope that a standard pushrod is going to be correct on a decked block and an Arden head!

[quote="rich@minispares.com"]with your engine Im 99% sure that you would have to build it with dummy pushrods to calculate the rocker geometry, then get some of the three piece ones made to the correct lengths

Anybody know how to bond the three pieces back together? The options are solder, braze, adhesive...?

I think they come with some kind of adhesive fixing the three parts together, but obviously it has to be the right adhesive??
I'm considering solder, any thoughts?

Once they're fitted there isn't enough room for it to fall apart, the valve spring is almost always pushing it into the follower. At the slackest point all you can have is the valve clearance.

But you still have a few thou for the pushrods to fall apart, they need bonding together even though they are under tension.

Granted yes, but it can't fall out of place.

They are bonded, but its not really an issue if they do come loose ( not that they do)

They cannot 'fall to bits'

But the end could get repeatedly hammered into the end of the tube. This couldn't possibly be a good thing.

mk1 wrote:But the end could get repeatedly hammered into the end of the tube. This couldn't possibly be a good thing.

it cant affect anything. they where tested when they where built


interesting enough, a lot of the three piece pushrods used in performance American v8's are run loose with no issues

May I suggest you send an email to David Anton in the USA, my recent dealings with him and David Vizard are very positive and they will be working together to design a camshaft, lifters and pushrods for my 8 port engine. Between the two of them, they have a mountain of un tapped information which I think is slowly being forgotten about these days.

never mind Vizard (has he figured out what torque is yet as all he paps on about is HP) and didnt vizard say they were just over priced fancy schmancy heads which give no real increase in HP over one of his heads

i have 2 piece pushrods in mine, there 18 years old and still totally fine , why go to people in the US when one of the best 8 port guys in the world is in the UK and he will have already done what the yanks are thinking about

Pad

Here you go -



Pad