dont know, a 2.0 i have had loads of 2.0 skimmed 0.100" which is about 2.5mm and a couple a bit further still, i dont see why a 1600 should be any different, the limit probably being the spark plug hole.
with really heavily skimmed heads i use bike plugs, i feel loctite-ing the the plug adapters in place lessens the risk of cracking the head doing the plugs up, with the added advantage of moving the plug tip away from the piston
I managed to resue the 1300 head by sleeving the inlet ports with steel tube, glued in with epoxy. It still left a 35.5mm port.
Unfortunately, I then broke through on one of the throats, so it's scrap! There's no way a 1300 head has enough metal to get the flow that I'm looking for. It would probably be ok on a ......1300! Lol.
I suppose it was a big ask to go from this;
Last edited by Memphis; 21-11-2019 at 11:59.
dave walker once said to me they were great for a 1600, definitely too small for a 2.0, might be ok for a quick 1800 but he wasn't sure on that............
It's been a 5 year itch... but at least I now know it won't work. All it's cost me is a little time as I hadn't ordered any valves, and on a plus point, I'm getting pretty good with a die grinder. All good practice.
So I have another 1600 head to modify, but this time I'm going to get the chambers welded to raise compression, followed by a skim if necessary. It's not cheap, but I've come this far so I may as well carry on! It hasn't been a major priority recently, but that has changed with the purchase of a very nice Pinto powered, live axled Westfield. Ok, so it's not my preferred Sylva Striker, but there are none around at the moment and loads of people after one. This one has been totally rebuilt from a bare chassis upwards, and is perfect for my 1700 project.
Time to get the die grinder out again!
Any news if this project ever got off the ground Chris?Originally Posted by Memphis
Sadly, I have to report that I have done no more to it, and an impending house move means I probably won't get to it for quite a while.
I thought I would ask the question Chris as I got the down draught head I bought off you from out of storage the other day and started refettling it.
I dummy fitted the valves which are 111.5mm length to the head and installed the WR 40 camshaft that's of 1983 vintage. For some unknown reason at the time Kent never gave any timing or valve lift figures, only tappet and the full lift figure for timing it in. I am showing mid 450 thou lift on the inlets and considerable less on the exhausts. I can't help but think with it being a 1600 casting it should have 113mm length valves but that would mean even less lift on the valves. The cam would have been ideal for your 1700 block as it doesn't have massive overlap @ TDC. The next step's to fit the BF 63 and take some measurements.
Now onto compression, I read on one of your previous posts that the chamber volume was 38cc which by my calculations on 2040cc capacity gives me approx 12.5.1 compression which I believe's 1 ratio too high. If I had another block bored and a set of forged pistons which had valve pockets machined in them then that might reduce the comp down to my desired 11.5.1. I didn't really want to go to all that trouble and expence until I found out if the head was a goer or not, my idea was to remove my excisting head and try yours on that engine. I'll keep you informed on any further progress.
I look forward to the progress ��
I don't whether to continue on this thread or start a new one with development work on the ex Memphis DD Pinto head.
to me it makes sense just to carry this thread on
Another day measuring on the DD cylinder head. This time it's with a Burton BF 63 cam dummy fitted. Burton quote timing 44/86 86/44 with 310* duration and 510 thou lift in and ex with 10 thou tappet clearance.
After a number of time consuming checks with 3 different dial gauges these are the figures I have obtained. Inlet valve lift is 515 thou + or - 1 thou across all 4 inlets with the tappets set a per cam grinder. The exhaust valve lift is 504 thou on all 4 valves. The LSA angle on all 4 cylinders comes out at 108* which I am quite pleased with.
The next job was to see what valve overlap there would be with the piston @ TDC. The figures I am going to settle on are 3.3 mm ( 130 thou) inlet and 3.0 mm (123) thou exhaust, that'll give me 2.0 mm inlet and 2.8 mm exhaust before the valve heads become flush with the cylinder head face. This leaves another 30 thou to add to those figures for the head gasket clearance. Unfortunately there's no room for advancing the cam on the dyno as clearances are marginal.
So far so good up to now, I was pleased enough with those figures. I then attempted to cc the chambers with a kit I bough which consisted of a 60 ml syringe and a perspex plate to cover the combustion chamber. I can't help but think the size of the syringe isn't sensitive enough for my needs, maybe a smaller one would be better. I couldn't get an accurate measurement but the chambers are certainly no larger than 38cc. Bear in mind this's a 1600GT casting with smaller chambers anyway, this's going to make my engine a minimum of 12.5.1 on 2040cc, that's one complete ratio above my ideal figure. I just can't see there being enough metal to remove out of the already small chamber to lower the compression. I now have the opposite problem to what the heads previous owner had.
Last edited by Forest_rallying; 31-01-2021 at 18:10.
I'm not sure how much it needs to make up but could you use a thicker head gasket to make up a full point cr reduction you want to achieve?
That's a good suggestion Rob, I thought of that idea but I was hoping to keep my 30 thou squish. I recon I need between 4 and 5 cc to reduce it to some sort of acceptable level. Some people say the BF 63 needs over 12.1 but it's only a Group 1 cam with approx 40 thou more lift and not an all out Race cam.
Very interesting!
Would you really notice the increased squish area of a thicker head gasket? A thicker gasket would also give you more clearance for advancing or retarding the camshaft.
Chris.
Cometic do all thickness of gaskets for Pintos. The one at 0.070" should be ideal.
I have just done a couple of rough calculations on a piece of paper for the Cometic head gaskets, 60" thickness gives me 11.74.1 and 70" 11.34.1 with 38 cc chambers. I need a pipette as a more accurate way of measuring the volume to confirm exactly what the chambers are. Incidentally with a 40" gasket and 10" piston protrusion your 1700 would have been 10.65.1. on my calculations.
I'll give it some consideration over the coming days as to what my next move's going to be before deciding which way to jump, after all there's no immediate rush with us all in this lockdown still.
IIRC 60-80 thou squish is a real no no from a detonation point of view
Sorry, can you explain a bit more? Would 60-80 thou equal 1,52-2 mm (checking I convert correctly) and that would be bad for detonation in a Pinto?
That would sort of mean that if you have pistons that are 0,6 mm from the deck face at TDC, with a 1,4 mm gasket at would be a 2 mm squish.
Looking at decking my block to raise compression a bit and it seems I might end up just around there.
Gustaf
its was in an artificial Vizard wrote years ago, he did a load of testing with various thickness of gaskets, he started with a really tight squish and found opening the squish clearance up mad the engine more detonation prone, despite the compression dropping slightly each time.
with a really small clearance you cant get any spontaneous combustion, as it opens up you are trapping combustible mixture which can be set off by heat or the advancing flame front, when you have a really big clearance you have no squish at all so in reality the squish area is just part of the chamber without any trapped volatile mixture just waiting to go bang
Interesting, thanks. Wonder if I should deck the block a bit more then. I think I have the option to get at least to the lower figures (squish at around 1.4 mm and CR just over 9:1, should be fine in an E85 Pinto turbo.
Gustaf
In that case, if you have access to a lathe, it would be a fairly easy task to machine a shallow bowl in the crown of the piston to fall within the combustion chamber boundary. Assuming the crowns are thick enough.
i just remembered back in the day we always wondered why my bosses RS2000 with around 10.1 cr and mild cam didnt pink, but his transit which was bog standard and low comp did
Maybe slightly different but my mate had a chipped (270bhp) Yb Turbo in a Transit, that bloody pinked too.
I might be wrong actually I can't remember if it had the chip in it or not, it was a long time ago now.
Last edited by rallyrob; 03-02-2021 at 11:47.
That's a sensible suggestion Chris but at the moment I don't want to dish out a new set of forged pistons until I find out if the head casting's fully serviceable or not.
I spoke to a well known Northern engine builder the other day and he said he wouldn't be frightened of running 12.5.1 compression with a BF 63 cam, I would still prefer to nearer to 11.5.1. but still retaining 30" squish. I have just order a burette so I can get a more accurate measurement of the combustion chamber CC than the 50ml syringe I used.
I have now got a burette and done a more accurate measurement than the syringe that I had used. The chamber volume's works out 37.5 cc, that's with 14 mm spark plug insert which I think is of a smaller volume than a std Pinto plug. I am looking for a chamber volume of around 40 cc to get my compression ratio to a respectable level of mid to late eleven to one.
Then there was something blindingly obvious, the 38 mm exhaust valve's are very badly shrouded by the side of the combustion chamber so maybe a little material can be removed from here. I can't remove any metal from the side of the valve because of the head gasket fire ring but I can grind some out on the spark plug side of the head. This was confirmed looking at an old 2.0 Big Valve head I have that was done by Peter Burgess. Whether I can get the best part of 2 cc by working round there only time'll tell.
looking back at the pictures i would of thought you could find an easy 2cc in those chambers
I managed to get a couple of hours measuring the chamber cc and the news's not really what I was looking for. Despite me relieving the chambers around the inlet and exhaust valves I am still struggling to to enlarge the chambers to my desired capacity of 40 cc. The first time I checked them with the pipette I mistakenly though they were 37.5 cc, maybe I was being optimistic but despite enlarging them I have still only got 37.5 cc. With the current figures the compression ratio's working out at 12,76.1
After this head has spent a lot of time waiting to be built I finally managed to get the valves installed today along with the camshaft. The next job's the followers and settings.
The head's now fully built up, only the inlet and exhaust studs to fit and an inlet manifold gasket to make and it's finally ready to be bolted to an engine.
After a lengthy spell off the Pintosports Forum I thought I would give an update on the downdraught head.
The heads now installed on my bottom end that’s fitted with forged pistons and Cosworth Rods, the CC’s 2040. Carbs are 45 Weber’s with 38mm chokes and the head has a BF63 cam of 35 years vintage.
Early trials once I had balanced and adjusted carbs looks very promising, the engine responds very well once the throttle’s blipped. Out on the Road the engine pulls well from 2800 RPM with strong mid range. It’s hard-to say at the moment if it’s the head or cam that’s made the big improvements. Considering the cars fitted with a 4.6 diff and 15 inch wheels I think early indications are very encouraging. At this stage’s it’s difficult to compare with the previous head as that has a GTS 4 cam fitted and 36mm chokes.
The next job’s to get to a Rolling Road to get the fuel mixture checked out and see where we are with power figures.
Great stuff Gary ! . Let me know if your ever “testing” over my way any time I’d love to hear what the intake roar is like on 38 chokes with bf63 💪💪👍 give me some motivation 🤔!.
It’s good to hear from you again Alan. I think the old Girl will pleasantly surprise you with its performance, it has me. I do need to get the main jetting checked out before I give it any serious Rice as I wouldn’t want to do any damage at this stage.
How are you getting on with your build? We no longer have the same motivation that we once had. You are welcome to come and have a look at it one Sunday if you like, that might give you some inspiration to kick back in.
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