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10/02/2005 16:24:43   Jon   Does anybody have an idea where I could get hold of the Ford/Saab V4 engine & transmission engineering drawings? I would like to model the entire engine & transmission in CAD (computer aided design) with a goal to :
1. redesign the cross over manifold for road use (the existing very rare manifold only really being suitable for 7000+rpm rally use). I would either have it fabricated or cast depending on interest.
2. redesign a new free flowing cylinder heads - just for fun!! They would have to have another inlel manifold which I could also design - ho hum.
3. design a new crown wheel & pinion and third gear suitable for modern road use.
11/02/2005 08:03:42   Richard   I have seen a iso cut away drawing, but it would be rare to find any engineering drawings, we would usualy scrap them rather than let them go out of the company.

Answers to points

1, you can use a cross over manifold for the road, no problems and with a std cam, you would want to run twin 40's on something like 30 - 32mm chokes. The reason for not doing this is cost for little performance gain and more fuel consumption. The carbs cost 300 plus new each and a downdaught is easyier to set up correctly.
CT made a manifold which has smaller ports than the Saab item which would suit lower rpm and lower air flow (Alec has a photo of my car with this on it I think).
I have seen people mill the top off a std manifold and weld alloy ports to take twins.

2, You problem here is the heads need to have room for the rocker gear and push rods associated with them, they limit what you can do with the inlet ports. You will see how close they are to the inlet wall and the fact that one inlet sweeps round one of the pushrods. The exhaust is open to twin porting, which helps the engine rev. It would be interesting to look at the length of the twin header primary tubes on the twin exhaust system as they are a bit short on the Saab rally system.
Could be an itea to look at the weak points rods, balance shaft bearings, rocker gear on high reving engines and the fact that a std rocker arm will wear the valve guides as it does not push in a liner motion (see roller rockers). Timing gear is a weak point, general oil flow through the engine and cylinder head sealing on competition high compression engines (see copper rings, copper head gaskets and Wills gas rings).

3, Something like a Sonet c & p would be good for modern use. Third gear is probably the best gear in the box! Have a look at what Saab did, they did more gears than just spec 1 and 2, they did a spec 3 and more, but these were just for the works. If you alter one gear you will need to alter another as the gears are in pairs on different shafts. Best bet is to get a duff box and pull it apart to see how it works. What would be good is to look at the pinion bearing itself, a Saab weak point. It backs off and needs re-shimming. Also maybe look at gearbox case expansion. I have seen on other gearboxes external cages built to stop key bearing positions moving with big horse power.

Hope this is of use

11/02/2005 08:33:50   Richard   Oh just noticed Alec has posted the photos in the gallery.  
11/02/2005 09:55:33   Senor Burt   Jack Lawrence of MSS in the USA has developed a modified twin-choke carb manifold that has the carb mounted in a better position for optimum flow.
It's a standard manifold that has been cut out and the 4-bolt mounting welded in a different position to the normal twin-choke manifold so each choke feeds 2 cylinders. It's used with simultaneous opening carbs like the 40 DFI etc.  
11/02/2005 15:05:08   Jon   Thanks for your advice and comments. I guess I'll have to find an engineer who works at Ford Europe for the drawings.

Richard, nice photos of your car. Check out what I've done to mine :

1. I have a 28/36 carb with twin exhaust port heads and a 7.6 cam. I get about 90bhp at 5000rpm at the wheels - the engine keeps pulling until I chicken out to save valves etc. I'm quite happy with the max power but was looking at improving the low end air flow without compromising the high end (which comes in around 4000rpm like a turbo :-) ). The main reason for redesigning is for fun really, in reality I'll probably just fit some ali pipes to a manifold that I've milled the middle out of, creating a downdraught arrangement (as said, cross over is expensive) dragster style - especially as there's lots of bonnet height to play with. I would also like to keep a modest carb too.

Richard what sort of power did you get with the setup in the photos - and was it drivable!!

Thanks again both of you for the info.
11/02/2005 16:28:02   bill rawles   Hi Jon.

I like the sound of your exhaust man in Crewe. Is he willing to do another/more of them or was it a one off for you?

I've just finished the loose ends on a gearbox conversion on my car - steel casing (a bit heavier but eliminates the flexing), combination of stage 2 and standard gears to give 1, 2 & 3 close ratio then a jump to 4 as a cruising gear. Final drive is a 9;36 (4.0;1) which gives 21mph per 1000 in 4th.

A standard engine might bog down a bit with that but as long as you're tuned its great!

I have an 1800 conversion which is giving 99bhp @ 6000. The most worthwile modification I've done was have a 3d programmable ignition system fitted.

Presumably you are somewhere not too far from Crewe, I'm in Wilmslow, drop me a line if you would like to meet up to compare notes.  
11/02/2005 20:54:46   Jon   Hi Bill,

I also like the sound of your gearbox conversion! I presume the casing is from an older model?

Dave Brooks did my exhaust as a one off, but if you give him your car with the engine in it I'm sure he'll gladly do another. Like I said in the other reply, it's costly. I paid 900, but I far as I'm concerned is was well worth it - it still looks brand new after 5 years. Dave also helped me alot with advice and machining of my engine.

I'm from Chester but live near Paris now. I'll try and drop you a line next time I'm over - send me your tel number via email?

14/02/2005 07:48:06   Richard   Well it goes better than the Andrew street rally car until about 5500rpm then the rally car goes a bit better. Basically its down choked (35 chokes in 40s)for low grunt and is perfectly drivable with power from 2500rpm to 6000rpm on a 7.6 cam. If I go to larger chokes (need to use 45s) the top end will be better and I have a feeling that it will be better than the rally engine which has 147bhp. Its close at the moment between the two and I have all the interior and glass in the road going white car.  
14/02/2005 07:52:16   Richard   Gearbox, mine is a spec 1 and 1/2 spec 1 with spec 2 drop gears which give you higher 1, 2, out of the spec 2 combined with 3, 4 out of the the spec 1. Basically it gives you 2 and 3 very close. I use std crown and pinion. No good for motorways but good for competition and twisty lanes.  
14/02/2005 10:43:10   Richard   Have you seen the twin down draught inlet manifold that was sold back in the day. It ran two 40 down draughts, but each choke fed its own cylinder.  

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