coming along nicely.. like the look of the carbs...what size are they...have you a picture of the flat slide working ..mark
coming along nicely.. like the look of the carbs...what size are they...have you a picture of the flat slide working ..mark
They're 39mm bore. I'll get a picture of the slides fully open - they have a completely smooth bore apart from the needle and a small bridge at the outlet of the needle jet.Originally Posted by madragon199
I've just had a bit of a result when checking the jet sizes. Mains are 175 and pilot is 60 which is where I would've started from anyway (after doing a lot of research). Pilot is possibly a little rich, but the engine won't be idling much or accelerating from idle, and I can always control it with the pilot airbleed screw. Main jets are pretty spot on from what I can gather - haven't checked the needles yet, but can always go leaner or richer to suit. It's all pretty inexpensive stuff, and the carbs were an absolute bargain! They came off a Radical Clubsport racing car (ZZR1100 powered) and are in excellent nick.
Chris.
Here you are. It wasn't easy holding the carbs with the slides open in one hand whilst taking a picture with the other and they may have closed slightly. The springs are very strong and it was hurting my thumb keeping them open.
http://i1286.photobucket.com/albums/...ps6895925b.jpg
Result..thanks mark
Now that is a proper set of carbs, you will have much higher velocity through the inlet system than with larger carbs, a direct straight shot into the ports
I would recommend trumpets with a 90* or full roll back edge but with parallel or very slightly tapered bores and a small flare at the end in order to get the strongest pulse signal for some extra power, it would also be best if you could adjust the inlet length somehow, different length trumpets would do the trick for fine tuning on a dyno/rolling road
The smaller the inlet system CSA the better the port velocity and inlet ramming at mid and high rpm's, you inlet system is going to have a lot of energy behind it ramming the charge at the inlet valves, very nice!
"Horsepower sells cars, torque wins races" - Enzo Ferrari
It's been a while since I posted an update because "real life" sometimes gets in the way of my hobby!
I've had the carbs re-spaced by Allens Performance;
http://www.allensperformance.co.uk/
They've made a superb job of modifying the carbs to suit the Pinto inlet spacing, which meant machining a new throttle spindle, various spacers and fuel linkages. In an effort to save the customer money, and because Keihin stuff is so ridiculously expensive, everything is custom made in their own workshop. I had a TPS mounted on one end of the bank of carbs to suit my mapped ignition system -this actually IS a Keihin item, but pretty reasonably priced and bolts straight on.
Now I have to make an inlet manifold....
The crankshaft is at SEP in Kegworth to have the flywheel double-dowelled. They're more used working on racing bike crankshafts (particularly 2 strokes) but do car engines too. Not a lot of people know that!
http://www.sep-kegworth.co.uk/page1.htm
I like to give these small independent firms a link in my posts - hope no-one minds. Use them or lose them.
If they were going on a bike I'd say Dayammm that's a nice rack but they are gonna look real good under the bonnet!
Allens ARE real helpful and can still get the odd bit of bike carb unobtanium every now and again!
Very smart....like the centre throttle linkage....the bellmouths look way cool in blue...what is the coating.........(thanks for the heads up on the pistons)..
cheers mark
They ain't coated - they're through colour and plastic. FCR41's are red in comparison which fade to a loverly pinky orange!
Looking good! there will be a lot of x-slows getting eaten by this when completed! lol
"Horsepower sells cars, torque wins races" - Enzo Ferrari
When you think of it your bore size is about the same size as a BDG and stroke is far less than a BDA, this thing is going to rev like hell!
Great valve area vs bore size for a 2 valve per cylinder engine, max power around 8K I imagine
"Horsepower sells cars, torque wins races" - Enzo Ferrari
That was always the plan Jason. Big bore, short stroke and deep breathing equals lots of revs and (hopefully) lots of power!
Just catching up with this thread nice work
That sounds like the one.
Not with 1600 shorter rods.....
swept volume = height at tdc - height at bdc * bore/2^2 * pi. the length of the rods only moves this up and down the bore.
Well, unless there's an offset grind involved...
jason is correct, rod length has nothing to do with cc, if you have a 2.0 bore and 2.0 stoke the engine will be 2.0, it doesnt matter which block or rod you haveThat sounds like the one.
Quote Originally Posted by RWD fords rule View Post
Lol a 2.0 pinto bore and 2.0 crank stroke = 2.0L no matter what block it is in
Not with 1600 shorter rods.....
I'm waiting for the crankshaft to come back from having the flywheel dowelled, so can't do a dummy build just yet, but I need to figure out the theoretical depth of valve pockets required in my pistons.
A dummy build of the head shows that there is 5.75mm of clearance between the valve face and the head face on the inlets, and 6.75mm on the exhausts. Now, I've never done this before on a Pinto, but have on numerous Crossflows. Accralite pistons for a crossflow come with valve pockets 8mm deep- which is deep enough for any crossflow race camshaft on the planet! A 244 cammed Crossflow only needs 6mm pockets, and one of my old crossflow race engines running Powermax pistons, a 1FR4 race cam and high-lift roller rockers needed just less than 7mm.
Would 8mm clearance be about right for a Pinto; a bit excessive or not enough? I'm using a Burton BF63 cam which doesn't have massive lift on overlap. I realise that only a dummy build will show me exactly, but I'm just curious to know if anyone has any experience they can share with me so I know what to expect. BTW there's plenty of meat on the JE Piston Crown.
Cheers .
With BF63 in a 2.0 with a 2.0 head skimmed -2.5mm and 136mm rods you need inlet valve reliefs around 1mm deep for a bit of comfort to be able to advance the cam timing if wanted/needed, no need for exhaust reliefs
With a 1600 head the valves are 2mm longer, sitting 2mm shallower in the chamber closer to piston crown, in a 2.0 since the chambers are much smaller the head needs far less skimming so you end up with more or less the same valve clearance, but in a 1700cc engine at a guess you will be skimming the head 2mm or so to get 12 to 1
Also the longer rods and much shorter stroke mean the piston is going to hang around TDC a lot longer than a 2.0 engine, for sure needing larger valve reliefs
Xflows have cams with much lower valve acceleration so comparisons are only a rough estimate
Best to do a dummy build with some xflow rocker shaft springs installed as valve springs for no1 inlet and exhaust valves, time in the cam as normal, place a DTI on the inlet retainer and check what valve clearance you have at TDC, 5* ATDC, 10* ATDC, 15* ATDC etc until you find the closest point, it is usually around 7* ATDC, take not of this figure, then test the exhaust valve same way but starting with 15* BTDC, then 10* BTDC, 5* BTDC etc and take note of the closest reading, then advance your cam 5* or so and also retard it 5* or so, taking note of the minimum clearance at each point
Best power and torque in a 2.0 is made with BF63 set between the 3/5ths inlet (60% inlet 40% exhaust lift at TDC) timing point and equal lift at TDC (50% in 50% ex)
Call the best point 55% inlet 45% exhaust then
Actually you should really check the valve clearance at these 3 timing points, regardless of the inlet full open after tdc method, best power and torque will be within this range and most likely at the 55/45 timing point or 60/40 for a little more low end torque
If at the 60% inlet setting the valve clearance is only 0.30mm then you know you need 2.5mm - 0.30mm = 2.2mm deep inlet reliefs
2.5mm clearance is the minimum I would use, 2mm would be really cutting it fine and asking for trouble imho, 2.5mm is a lot safer
As for the exhaust reliefs check the equal lift at TDC point and if you have say 1.30mm clearance then you need 1.20mm valve reliefs to create 2.5mm total at that setting
Mark the vernier with these 3 timing points so that you know where the limits are when making adjustments on the rolling road or dyno
BF63 has about 3mm valve lift at the equal lift point for reference, RL31 is more like 2.4mm lift at the equal lift point and does not need reliefs in a 2.0 engine even with 11.5 to 1
Sure this will help
"Horsepower sells cars, torque wins races" - Enzo Ferrari
Tbh, I would recommend RL31 for this engine over BF63, RL31 would have a power band of around 3500 to 8000 and BF63 more like 4300 to 8200 but for racing BF63 should work well especially with tight gearing as you have, RL31 would be ideal for rally/race with a wider power band
"Horsepower sells cars, torque wins races" - Enzo Ferrari
The case has altered somewhat since I checked the volume of my worked combustion chambers yesterday. I'm seriously considering what is the best way forward with this build because as it currently stands, the chambers are at 40cc, which when combined with a 1mm gasket gives me a CR of only 10 to 1. Nowhere near enough, and that's with a 1.5mm head skim. If I went the whole hog and shaved another 1mm off, I can get it to nearly 11.0 to 1, but that would require very deep pockets in the pistons, (I don't think the pistons would take it) and is still not enough. So all in all a bit of a cock-up.
I think that I had to do so much unshrouding of the larger valves (45.5 and 38) that it increased the chamber volume too much. My own fault for being greedy... :/ This downdraught head that I've spent so much time and effort on really will only work with a 2.0litre + engine.
So the options are;
Build a 2.0l bottom end for the downdraught head. Tempting...
or... prepare another conventionally ported head for the 1700 bottom end with smaller valves, needing less metal removal and hence a higher CR. It would still go alright, but not the animal I really wanted!
What a dilemna...
One solution is raised top pistons, only way to get decent compression from 1700cc, but at the same time it would be very interesting to see this turned into a 2.0 engine
Building another head would be a lot of hassle and using smaller valves would be a very big compromise, I would rather use the head you have on a 2.0 than go that route
"Horsepower sells cars, torque wins races" - Enzo Ferrari
What is the 1.6 stroke and your piston CH?
What about using a 2.0 crank in your 1.6 block with the short pistons you have and rods to suit?
2.0 Inj rods and crank will clear the 1.6 block, the rods are a close fit to the bottom of the block bores, YB rods will not fit but inj will, I think your pistons will have too high of a CH to fit std length rods, maybe you could fit some of the stronger 1600 rods
"Horsepower sells cars, torque wins races" - Enzo Ferrari
Thanks for your input Jason. I'd thought about that, but it would require a very short rod of about 123mm which I think is too short for the 76.96 stroke of a 2.0 crank. The pistons have a compression height of 31.8mm, so to use them in a sleeved 2.0 block would mean a rod length of 137.5mm, or deck the block and use off the shelf 136mm rods.
You know; the more this project has progressed, the more I'm actually interested in using the downdraught head. It's my baby and I want to see how it performs! If that means going to a 2.0 or 2.1 bottom end, and thus into a less well subscribed hillclimb/sprint class then so be it. I'm really leaning to this idea now...
Have you considered welding the combustion chambers like Vizard and Brookes have done to raise the compression on your 1700cc Pinto? It would be such a shame to throw the Towel in at this late stage.
1300 cc pinto head ?????
re think your cam! an rl31 wont give the same clearance issues and will only want 11.1, i put a rl31 in a 2.2 and power was still going up @7500, so in a 1700 it should go way past that
Last edited by Graham; 08-04-2014 at 16:40.
try finding one! actually i know where there are two, but they are not for sale, tbh i dont think they would be that good for downdrafting the ports being much smaller you will have massive holes to fill.
the dave brooks head i have hear has been heavily welded in the combustion chambers and with some cold weld cast iron rods shouldnt be to hard really
Thanks for the advice chaps. Still looking at all options. The problem with welding the chambers is that my downdraught tubes are glued in with epoxy so preheating the head in order to weld could be an issue.
Exactly, welding this head is out of the question due to the port filler
I would skim the head -2.5mm or even a little more, run the pistons 0.75mm between head and crown with a compressed gasket (with your short stroke and YB rods there will be far less rod stretch at high rpm than a 2.0, so even 0.70mm could be used but certainly 0.75mm is safe)
Use 12mm bike plugs, iirc the difference in CC between std plugs and 12mm heat range 12 NGK plugs is the best part of a 1cc saving there
Use an RL31 cam as it is the the best cam for this application, also needing a lot less valve relief depth
Do your best to get 11 to 1 and have a very decent engine, you will easily achieve 9 to 1 DCR which is much more important than the static compression ratio
The best compression that can be got from a 2050cc engine with a head skimmed 2.5mm and large valves is really 11.8 to 1, so don't be worried about 11 to 1 being too low, with RL31 it will work very well
"Horsepower sells cars, torque wins races" - Enzo Ferrari
At a later date you could always fit a new set of pistons with deeper valve reliefs and a raised crown to get more power but you might as well use what you have for now, the breathing ability of the head will produce decent cylinder pressures from mid rpm's upwards
"Horsepower sells cars, torque wins races" - Enzo Ferrari
Thanks.
A 1mm extra skim (2.5 total) will give 11.0 to1. With the plug mod 11.25 to 1 or thereabouts, so certainly not a disaster. I hear what you're saying about the RL31cam- I was just being too greedy using the BF63. Now I'm thinking of maybe something even less extreme like an FR33 or BF30? Any thoughts? When I first got the car it was fitted with a 2.0l with big valve ported head (45.5 and 38) and FR33 cam which in a car weighing half a ton made it a real missile!
glad your back in the groove on this one, its an interesting angle that wouldn't have been 1/2 as interesting as a 2.0
I would personally choose the RL31, I have used RL31 in a long stroke 1600 pinto for rallying before, with tight gearing it worked well, the head flow of the long stroke is very poor vs your head so top end wasn't really there tbh but your engine will be really rev happy and you could keep the rpm's above 4k probably at almost all times, plus you have a very light car so low end torque below 4k isn't really a must, you could use a milder cam but a lot of top end would be lost, depends on where you need the torque in the rev range to suit your car but my bet would be RL31 making the best combination for your car
It has around 288* to 290* seat with the recommended valve clearance, 244* @.050" lift with lash, 12.7mm max lift, the LSA is around 112 to 113* with std valve lengths or short big valves an equivalent length, with your much smaller chambers there will be plenty of overlap duration to scavenge/fill the chambers at tdc, that kind of low duration and high lift would be impossible with a xflow valvetrain, realistically equivalent to a kent 254 cam's top end and 234 to 244 bottom end!
Heck even a 264 cam only has 12.5mm lift (book figure rather than real with lash) and more duration, that would have more total valve open area but don't forget your inlet valve size is 45.5mm! that would never fit in a xflow bore! 12.7mm x 45.5mm pinto vs more like 12.5mm x 41.3mm or around 43mm max with offset guides
Everything going well I think you will have a xflow eater!
Last edited by RWD fords rule; 09-04-2014 at 12:07.
"Horsepower sells cars, torque wins races" - Enzo Ferrari
Thanks Jason. RL31 it is then!
Good man, great to head it is going ahead, you have a very unique setup there, will probably sound like as well as go like a BDA!
"Horsepower sells cars, torque wins races" - Enzo Ferrari
What about fitting a Borham Works WR 40 Cam, they Rev until the Cows come Home!
Houston ...we have a problem.
So I've now had another 1.5mm skimmed off the head to get the compression ratio up, which makes 2.5mm total. I'm really not prepared to go any more as it's getting a bit thin, and the valves are moving even closer to the pistons. I still only have a 38cc chamber which corresponds to a 10.5 to 1 CR. I can gain 1cc (apparently) by using plug inserts and bike plugs, but will probably lose that when I machine the pistons for pockets. So 38cc it is.
This really isn't where I want to be on a 1700 hillclimb engine, so I'm left with a choice:
Just build the 1700 anyway and use a softer cam (FR32?) which will limit power to XFlow level (!!);
Or turn it into a 2.0 by using a bored out 185 block at 90mm to suit my forged pistons, 185 crank (same as 2.0l) which combined with a longer rod and a slightly decked block will bring the CR up to 12 to 1, which is much more like it. With the down draught big valve head on a 2.0 litre I would expect to see substantial horsepower. Unfortunately this doesn't change the fact that the over 1700 hillclimb/sprint class is rather poorly subscribed, but I could just go out and have some fun anyway.
So I still have a dilemma... and it's doing my poor old head in
remind us, where do the pistons sit in relation to top of the block and what thickness head gasket are you using?
if you have 10.5 you have enough compression for an rl31 to work.
Just looking at compresion 10.5 is with pistons level with block.....if you go -0.5 mm into gasket ..gives you 0.5 clearance on 1mm gasket and takes compresion up to 11.12:1...
Getting closer and would work well on the rl31 cam
it depend on how thick your gasket is. 0.75mm clearance is absolute min between piston and head 0.8mm safer
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