Project Seat 124 2000cc

[litoslit]

Hello Guy:

First of all, I congratulate you about your website and your great knowledge. It's a pity for me, I'm so sorry, meet you now; after I have made my engine. In this moment I can only contrasted your opinions and experiences with mine own.

I would like you take a look at my project and you give me your opinions and tips about the construction of my engine.

Excuse me, I know some sent data are rudimentary and the same about my English.

2L 8v Fiat
Compression 11,5:1
Bore 84,60mm
Cam Abarth Gr. 2 350º Adjustment of valves 0,01mm
With 11mm valve lift
Diagram 48 67 56 47
4-2-1 exhaust manifold
38 mm exhaust valves
45 mm intake valves
Forged Pistons
Forged rods
Crankshaft and rods are balanced independently and married together
Weber 45 DCOE

Questions

1. What is your opinion about measures in the admissions and exhaust ducts?.
2. Which could be the measures the collector admission that until is without made?.
3. I would like you give me the following data about my carburetion 45DCOE?.
? mm chokes
? emulsion tubes
? main jets
?air correctors
? idle jets
? pump jets
4. What do you think about HP and torque?.
5. If my project was wrong (same data), a correction with low cost, will be possible?.

Thanks a lot for your kindness. Yours;


Fdo.: Carlos Mateos

[Guy Croft]

Carlos, hi!

thanks for joining and buying the GC 8V Head prep DVD!

The only remark I'd make is it's not necessary to go quite so big on the ex port, 35mm dia at exit would be big enough, but it doesn't matter really.

You asked:

1. What is your opinion about measures in the admissions and exhaust ducts?
2. Which could be the measures the collector admission that until is without made?.
3. I would like you give me the following data about my carburetion 45DCOE?.
chokes
emulsion tubes
main jets
air correctors
idle jets
pump jets
4. What do you think about HP and torque?.
5. If my project was wrong (same data), a correction with low cost, will be possible?.

The intake manifold, well for 45 DCOE you might like to use the GC M131, that has the same diameter as the std head at the entry joint, 36mm and is certainly big enough. For the ex, I would suggest the new GC spec short-primary setup:

Primary pipes: internal diameter 1.5"(38mm) length 25.6"
Secondary pipes: internal diameter 1.75" (45mm) length 7.1"
Link the pipes 1&4, 2&3.
The pipe length is:
Primary: head face to entry to collector joint
SY: exit collector to entry final collector joint.
The tailpipe ID should be 2" and the silencer (muffler) should be a George Polley AX891 (see: http://www.polleysport.com, it's not shown yet on their website, just order by email. The lowest cost and BEST muffler around for that motor).

I have added a cam timing download into which I have put your cam timing figures. Are you sure the ex timing is 56/47? Because that gives a very late ex closure (very clsoe to TDC compared with say 100-102 deg and lot of ex lift on the overlap, your figures are showing ex FL at 94.5 deg BTDC. Although I'm not saying it won't work - it might - the lift at that setting could be huge, maybe too much for practical fitting really. There is information on cam timing in the GC V/W (virtual workshop)

I would have expected 66/47 but you can download the Excel file and take a look. My diagram indicates that you inlet full lift is 99.5 deg ATDC which is good. For a comp engine I would certainlly time the cams to give full lift at around 100-102 deg if the valve reliefs in the pistons are deep enough - you need 2.5mm vertical clearance at closest proximity. If not go towards the later inlet opening and earlier ex closing eg: 104 -108. But I know now that by 110 deg you will can lose a lot of top-end driveability (the power curve doesn't stay flat). I say this now because I've got a lot of feedback and software simulation now indicatiing big gains in the torque curve from extra overlap and narrow lobe centreline angle (ie: cams nearer 100deg FL)

chokes 40mm
emulsion tubes F16
main jets 145 or richer 150
air correctors 170 or leaner 175
idle jets 55F8
pump jets 45

The fuel pump should be a Facet Silver Top Competition spec and NO regulator. It does not need a regulator and I would use the comp spec rather than the Fast Road spec because that motor is going have a high fuel demand. On no account use the Red Top - it will lift the float needles off their seats.

You don't mention valve springs. Whatever you are using - if not GC triple damped springs - get rid of them and use mine. I don't usually say this on my site because I try to keep it non-commercial in the forum, but I'd hate to see you 'drop' a valve with those nice cams, and I don't have any confidence in any other spring set.

That motor should give 148lbf ft torque at about 5600rev/min and 188+bhp at 7400. It should easily pull way over 8000.

I hope this is helpful and if you need to know anything else, let me know.

GC

[litoslit]

Hello Guy,
I regret not having responded sooner.
Thank you for your advice,
I think and answer,
I believe that I am wrong in my data regarding the exhaust cam
I fail to find the Excel file cam timing, you can get a link?
My adjustment of valves is 0.40mm AD / EX 0.50mm this is correct?
I can put pictures of their valve springs?
Sincerely Carlos Mateos

[Guy Croft]

Hi Carlos

Sure you can post a photo of the springs, but unless I know who made them I can't give much advice about them, but I can say from experience that a lot of TC people bend valves on non-GC springs, perhaps more so than any other cause of engine failure!

Here is the cam timing article in text only, and here is the link (photos there as well)

phpBB3/viewtopic.php?f=3&t=213



GUY CROFT RACING ENGINES
Fiat/Lancia TWIN-CAM
Cam timing and fitting data and dry-build piston-valve checks

**** With a TC you should set the cams up with the head off ****
If you do it on the engine you will bend a valve for sure

General
Nominal cam lift can be measured by putting cam between revolving centres or on V blocks, and rotating cam with dial gauge on cam profile. Subtract clearance to give true lift in running conditions.
The base circle diameter many competition cams is less than std so thicker shims / top-hat shims or cam tower machining may be needed, though when the valve seats are blueprinted (ie: opened out) the valves go deeper into the head and this takes up some of the clearance - without resorting to massive shims. Shims thinner than 3.25mm must not be used or the cam nose will hit the bucket. Use new cam setting shims! Cam housings should be brush-honed at 180 grit silicon carbide or cleaned with fine Scotchbrite and then Jizer or Gunk or similar & detergent with hot water. New seals should be used. If you’re re-using old cams, polish the journals with fine Scotchbrite. If you are fitting head to a previously run block make sure there is no grit/muck from cleaning the block face in the 6 oil feeds in the block. Seal them off if scraping or rubbing down the block. Dirt in these galleries will go straight into the cam journals and seals on start up, causing scoring and seal damage. Head and block need to be flat in all directions to 3 thou or better. You can survey them with a good quality straight edge and a feeler gauge. After installing cams in their housing bolt the cam pulleys in place. Make sure the back of the pulleys does not foul the cambox or the seal, there is end float on the cams and the castings do vary in length. If the pulley is too close, get it machined on the back. Bolt each cambox to the head with new gasket and shim up close to the final setting. The gasket will settle 2 thou overnight, so when it has settled, slacken the cam box bolts fractionally and retorque before final shimming. You can do cam timing whether the head is shimmed up or not, but if the shims are tight, the cam may be hard to turn.
Never turn a TC cam unless you can see the valves especially on a big-valve conversion – the valves may clash and bend. If in doubt remove or slacken off one cam box.

Step 1 – establishing Full Lift (see also photos in rear of Kent Cams book if supplied)
There is a dwell phase around full lift of several degrees on most cams, to hold the valve open at full lift. A reground cam of same lift and duration as a billet cam will have a nose of much reduced volume and flow and a smaller dwell period. To begin with a protractor and dial gauge (with scale big enough to accommodate cam full lift) is needed to establish the centreline of the full lift position, as this will be the datum from which the cams are timed. The cam does not need to be shimmed accurately up to do this.
To establish full lift turn the cam with dial gauge on the valve to approx visual full lift - then turn cam anti-clockwise till lift reads say, 9mm, or some other fixed point on the cam flank say 0.5mm lower than full lift. Make sure the cam does not rotate of its own accord. Then stick a large diameter protractor (you can get them from stationery shops) to the rim of the cam pulley with Blu-Tack, bolt a sharp-tipped pointer to the head and set the pointer to zero degrees. Then turn the cam the other way – clockwise, thru full lift and back down to the same point on the opposite cam flank and read the degrees. True full lift is halfway between 0 and this reading. Swing the cam to and fro and check that true full lift is exactly in the middle of the dwell phase.
Mark full lift on the rear cam journal relative to the housing, say with 2 scribed or pin-punch marks painted white – this gives you the FL reference point, which is useful if you want to check the cam timing later with the engine built and the belt on. The same method as determining the centreline of FL is used to determine true tdc on the crank – using a protractor on flywheel, a fixed pointer and a dti on no1 or 4 piston.
Make sure you bolt a tdc pointer rigidly to the block and aimed at the flywheel or front pulley - before you fit the head. Once the head is on you will struggle to find true tdc with accuracy otherwise.

Step 2 - Cam timing – how it’s done
Cams rotate at ½ crank speed. The engine rotates clockwise viewed from the crank front pulley end. TC cams are always set up on No.1 cylinder, with the valves on the overlap phase (inlet opening, exhaust closing) – not the compression stroke, although when no1 is on overlap, no 4 will be on compression (both valves closed).
The cam degree setting at tdc, relative to cam full lift, will be ½ the crank degrees at which you want full lift.
So if you want cam full lift (see below) at 110 crank degrees the inlet cam will need to be set at 55 cam degrees before cam full lift (no 1 lobe) at tdc and the exhaust 55 cam degrees after cam full lift.
EG: In the above example –
For the inlet cam turn the pulley anti-clockwise 55 cam degrees from full lift to put it before its full lift posn.
The exhaust cam should be rotated clockwise 55 cam degrees from full lift to put it after its full lift posn.
Mark the tdc posn with a red mark on the cam relative to the white mark on the housing.
The values full lift, timed-in degrees and lift at tdc with the cam shimmed up should always be recorded for dyno reference. You can check and adjust the cam timing on the engine – but only with the belt final fitted and ONLY if you have adjustable camwheels.

Step 3 – Dry-build
With non-standard cams I always recommend dry building and measuring the clearances using modelling clay in the valve reliefs. It's not enough to say 'there's plenty of clearance' - you need to record what it is. This needs to be done by turning the engine over 2 revolutions by hand, with the cam belt fitted, before final bolting the head down. Plasticine is an ideal material, and it helps to spray the valves with silicon rubber lubricant to prevent them picking up the clay.
Note that the valve positions relative to the valves are not symmetrical on pistons 1 & 4 on the early (pre reversed port head) TC. The inlet valve will always be closer to the piston during its cycle than the inlet cam. The more that’s machined off block or head (or if the pistons are run proud of the block face), the less radial clearance you’ll get.
Ensure 80-100 thou” vertical piston-valve clearance (measured diagonally - in the plane of the valve axis), and 60 thou radially – from the valve circumference to the wall of the valve relief. How much additional clearance beyond valve full lift you allow in the vertical plane between valve and piston depends on your confidence in the valve springs. Radial clearance is affected by piston - bore clearances and guide wear.
Some comp cams have as much as 5.5mm lift at tdc (on the overlap) but cams with 3.5 mm or less lift at tdc and can often be fitted without the need for deeper valve reliefs.
BUT - don’t forget that in the first 20 or so deg after tdc on the inlet stroke the inlet valve tries to overtake the piston, so to be on the ‘safe side’ don’t base your estimate of valve relief depth purely on the lift at tdc – the valve does move closer to the relief. It's no good just dropping the valve thru the guide onto the piston at tdc and saying 'OK, I've got 4mm vertical clearance', for one thing it's going to be a lot closer in the true cycle, and for another it doesn't tell you the radial clearance. As many engines bend or break their valves from low radial clearance as any other cause. Generally closest proximity is around 15-18 deg. If you are contemplating swinging the cam timing on the dyno it is imperative that you ‘map’ the valve lift around tdc, eg clearance from piston at 110/108/106/104/102 deg etc.

It's worth mentioning that if you think that the piston valve reliefs (cutouts) might need machining to complete the build, and BEFORE you build the head up, use an old valve stem ground to a sharp point as a punch to put down thru the valve guide to mark the valve centres on the pistons. The pistons must be held in the centre of the bores by packing them with thin card, otherwise the slop between the piston and bore will totally upset the valve relief machining. This can later be used for flycutting the valve reliefs to make them deeper or wider. Also make sure, that when you offer up the head to so this marking-out that the gasket and gasket locating dowels are in place.

Lubrication and running
Oil the cam and cam tower (or box) bearing housings and rear thrust faces – front and back - at the build stage. The biggest cause of cam lobe damage is dry-scuff or low-speed running after start up. Damage can be caused to the cam journals especially at the front end if the oilways in the block or head are contaminated, this will cause scoring to the housing and cam - and may cause even a new cam seal to leak.

Old cams re-used:
Fill the cam boxes with engine oil just before cranking so that the cam lobes are not spun dry. Moly grease is also a good lubricant to smear on the cam lobes but don’t use on deep-drilled or cross-drilled cams or if you are going to leave the engine standing for months – it dries out.

New cams:
You must use a good quality special cam lubricant (most cam manufacturers sell it) and pour it over the cam lobes just prior to cranking and start (cam lube will typically be a zinc dithiophosphate compound)

All cams:
Fill all the oil system accessories, filter, lines, cooler etc and crank up oil pressure on the starter with the plugs out with the cam box covers off and make sure oil is pumping into the valve train before starting the engine. It should prime up in 3 bursts of 7-10 sec cranking and in not more than 20 seconds overall. More than that and it's never going to get oil pressure. If the engine has been standing for a long time (months) you may have to prime the oil pump by removing the filter housing and injecting oil down to the pump.
With new cams it is imperative to run the engine at 2000-2500 rpm for 10 minutes to allow the cams to bed in - before allowing the engine to return to idle (750-850 rpm). Obviously timing and fuel system have to be very well set statically to permit this without overheating or stalling/flooding the engine.
Remember that the cam boxes on the TC will empty completely if the car is driven up a ramp onto a truck or trailed on the way to a race, so they will start bone-dry and wipe out the cams, whether they are cast iron or steel. Not good. Refill them!

Cam timing figures – what they mean
Typical competition cam example:
Quoted timing 40/80 80/40. These degree figures are crank degrees and mean the following:
Inlet opens 40 crank deg before tdc and closes 80 after bdc
Ex opens 80 crank deg before bdc and closes 40 after tdc
Overlap is sum of 40 + 40 = 80 crank degrees
Duration of both cams is 40 + 80 + 180 = 300 crank deg
Full lift (FL) is at (300/2) – 40 = 110 crank deg.
Thus inlet FL is 110 deg after tdc, ex is full lift 110 deg before tdc.
All cams I know of for the TC are symmetrical (same shape of open and closure flanks) and this maths can be used on any of them.

Common TC timing and full lift posn
131 1600 & 2 liter 5/53 53/5 (114 deg)
105 TC 10/48 53/5 (109/114 deg)
130TC 7/51 51/8 (112/111.5 deg)
Lancia Beta 2 liter 13/45 49/9 (106/110 deg)
Lancia Vx 13/39 37/3 (103/107 deg)
(Incidentally the true durations of the TC cams are longer, these figures are quoted with an industry standard wide running clearance which assumes no flow at very low lifts).

Don't blame cams from a reputable supplier if you cannot get the power you want
The performance (area under the torque curve) of an engine, ignoring mechanical losses, depends how well the whole spec is integrated. The camshaft is just an opening device. Here are some of the main parameters that determine power:
- Exhaust port and manifold length, diameter and manifold configuration (4-1 or 4-2-1)
- Inlet port and manifold length, diameter and rampipe length
- Head airflow inlet and exhaust – encompassing valve size and discharge coefficient, and port shape and size, combustion chamber shrouding
- Cam profile (lift by degrees) and camshaft timing (ie: FL posn)
- Bore and stroke
- Compression ratio
- Ex silencer back pressure
As a general rule you can set FL of inlet and exhaust cams anywhere between 100 and 113 degrees. Inlet and ex FL do not need to be the same. The cam timing will define the torque characteristic and altering it from any stated spec is not necessarily be a bad thing, but dyno development is needed to optimise it. It is not necessary to run like-for-like inlet and ex cams, indeed with supercharged or turbo engines it’s a bad thing. Blown engines should always have less lift and duration on the ex than inlet. A 16v Integrale for example, depending on boost, can develop well over 450bhp/400 lbf ft with as little as 11mm inlet lift, 8mm exhaust.

[litoslit]

Fist of all, thank you very much for your help and dedication in resolving my doubts. it has been of great help
could you tell me which is the minimun possible roominess (i dont know txe exact word) between the levy and the saucer, for admision and exhaust in mm? Sincerily.

[Guy Croft]

Carlos, hi

not sure what you mean, I understand completely that you are not familiar with the English words.

levy and the saucer:

Do you mean?
1. distance from spring cap to platform
2. Camshaft setting clearance
3. Piston to valve clearance

or something else?

A picture might help..

G

[litoslit]

Guy Hello, I regret my poor English
My question
Bolt the cams to the head and shim the cams at 0,mmAD? 0,mmEX?
Max / Min ?
Thank you Guy.

[Guy Croft]

Sure Carlos, no worries!

Shim - cold:

inlet 0.4mm +/- 0.05
exhaust 0.45 +/- 0.05

GC

[litoslit]

Thank you Guy. Greetings.

[litoslit]

Hi Guy again. First of all thank you for all the help you are giving me.
I`d like you to ask you:
According to the estimation you did about the power of my engine, i`d like to know, How much power will I have if we take down the compression ratio to 11,00:1?
What kind (configuration) of combustion cam , will be the suitable when retouching it to take down this compression ratio?.

[Guy Croft]

Hi Carlos,

you won't notice any difference at all on that engine going from CR 11.5/1 and 11/1 and you don't need to change the cams,

GC