Marina Roadster

[lil_red_roadster]

Re: Marina Roadster

There's your answer...put the Ford setup into the Roadster

[cameronfurnival]

Re: Marina Roadster

hahaha - look, it took three gallons of vaseline and a large mallet to get it in there - it aint coming out!

[andyf]

Re: Marina Roadster

There was a piccie I saw recently of the solution...buggered if I can remember which thread though.
Thin airbox across the carbs with a central take-off to a remote filter. I did knock something similar up ages ago so here's a picture of that...however the takeoff I used (or more accurately the aperture into the airbox) didn't flow enough air over 3500 revs.
I gave up twins shortly afterwards
AAA needles are, IIRC, the suggested ones for HS4 when running K&N filters.

[ATTACH]5673[/ATTACH]

The air box looks too small to me I would make it wedge shaped to fill the available space so that the air can flow through it nicely.

[DamnedFrog]

Re: Marina Roadster

Hello Andy.

The volume of the airbox, if there is one, is decided with the resonnance frequency of the enclosed air volume in mind, along with intake pipes length, and the chosen rev of the engine where power would be emphased.

An air box is usually sized and shaped so that the alternance of positive and negative pressure waves resulting of the openning and closing of intake valve should be zeroed around carbs intake at a given frequency, so that air can flow in easily. In addition of that, the geometry of the airbox matters, to make pressure waves of different intake encounter and sum to zero at precise locations in the box.

Of course direct intake carbs dont bother with that, but the length of the intake pipe has an effect on the power curve, because of wavelengh pressure waves in gaz column. Long pipes give a better filling at low revs (torque) and short one at higher revs (max power).

What I see on the picture may be rather named a "flat air duct" than an "air box" and IMHO is the worst case: pressure waves bouncing on the flat surface, and with such a little clearance probabely giving a nice pressure lock on the central airduct. Hence IMHO the problem at 3500.

I agree with you: here I would suggest the biggest airbox as possible and a tangential fresh air duct near the battery.

Regards
Christophe.

[cameronfurnival]

Re: Marina Roadster

well I ordered some ally sheet to have a go at improving Jez's design with a larger, wedge shaped box. Hopefully I will get round to making it over the winter. Meanwhile the third set of carbs has gone on - and its still too rich. I thne found that the spring on the adjusting jet nut was binding preventing the nut weakening the mixture. All is now well and the carbs are balanced and mixture seems good too. Its not very easy to start though.
After I wound it over on the starter it kind of dug in a bit, like something was binding. Unusual, never did that before. Then on startup a belch of smoke came out from the rocker cover! I nipped off the filler cap and no binding noises and a much faster spin over. Its never just one simple thing is it!

[cameronfurnival]

Re: Marina Roadster

I gave up with the cold air box idea. Instead, that's on the back burner and I popped on a couple of pancakes with stub stacks inside. The drive is actually really good now, tractable and responsive with over 75 possible before the wind removed my eyebrows. Here's some pics... first shows the old HIF6s on a standard heat-shield (painted red) and then there is the HS4s on my own heat-shield:

carbsO.jpg

carbs1.jpg

I removed the piranha ignition system and replaced it with an accuspark set up (hall effect rather than light beam and chopper), new coil plugs leads and dissy included. There was nothing wrong with it so if anyone wants a complete electronic ignition set up on a 25D dissy let me know.
I have also started to clean up the ally bulkhead and hand stripped the rocker cover and gave it a lick of paint.

[andyf]

Re: Marina Roadster

Looking at your pics (very nice by the way) reminded me of some advice that my uncle gave me when I was building my car. He told me not to chrome the rocker cover because it keeps the heat in, he advised that I paint it black instead.

[cameronfurnival]

Re: Marina Roadster

Hi Andy, the rocker cover was originally a chromed one - but the chrome was all blistered as the rust was coming through so I rubbed it down and sprayed it wheel silver. I intend to paint it red eventually

[stevejgreen]

Re: Marina Roadster

Looking at your pics (very nice by the way) reminded me of some advice that my uncle gave me when I was building my car. He told me not to chrome the rocker cover because it keeps the heat in, he advised that I paint it black instead.

Cant help but think that all those B series and A series engines with polished alloy rocker covers, including me, must have got it wrong!

Best thing to do under the rocker cover is to fit a tuftrided rocker shaft. It stops many rattles, the wear on the underside of the rocker shaft is often missed. But don't be tempted to try to re-bush the rockers yourself unless you have the correct sized reamer.

[andyf]

Re: Marina Roadster

It was the original chromed version that got me thinking. In most cases it's probably fine but if you're suffering overheating problems it may be something to think about, if someone has the time and the inclination a back to back test would be interesting . BTW red would probably be a good colour since you want to maximise the infra-red radiation.

[cameronfurnival]

Re: Marina Roadster

Civic Rad: Right, so now its running nicely and I can see the nights drawing in its time to think about fitting that honda civic rad. Before I start it would make sense to ask if anyone has a picture or any advice?
the rad comes with a nice big fan and shroud which I'm hoping to keep.

[stevejgreen]

Re: Marina Roadster

Civic Rad: Right, so now its running nicely and I can see the nights drawing in its time to think about fitting that honda civic rad. Before I start it would make sense to ask if anyone has a picture or any advice?
the rad comes with a nice big fan and shroud which I'm hoping to keep.

here or there

[cameronfurnival]

Re: Marina Roadster

Thanks Steve. I have some ideas from that article but would like to try and keep the fan and shroud. Will see how it fits in due course! I think I will try to weld a couple of pieces onto the side of the rad to make some brackets rather than bolt through the fins.

[greyV8pete]

Re: Marina Roadster

Hi Cameron. Re earlier post about carb intakes have just seen the following in Nov Classics Monthly mag.

http://www.webcon.co.uk/shopexd.asp?id=44

They are not just mesh covers but incorporate a filter mesh too. Peter.

[davidmartin720]

Re: Marina Roadster

Just a thought on changing Carbs, doubles for singles etc. On my Herald 1300 which was Stage 3 road spec, I had No1 piston break between the piston rings twice. After the second happening, the local engine machinists looked up in their "Bible" and said it gave the symptons as running far too lean. It transpired that a previous owner, trying to make the engine run smoothly,asked somebody to sort it out. Not knowing it was tuned, they changed the twin carbs for a single to make it run better !!!! Instead of changing the carbs, I put the engine back to a basic 1300. I am well pleased with its performance as I use it as a "Fun" car. David.