Q420 cams ...
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Post by: Old English White » Tue Jan 29, 2008 10:17 pm
Some of you may have these camshafts in their engine .
So I choose these QED 420 cams , with 1.6/1.4 valves and Q55 springs .
This is the moment to tell me about installation and timing ...
My engine builder is working for the first time with QED's cams and ask me for your advices and said than the valve pockets will need to be deepened to accomodate.
Does anybody know about that !?!
Christian.
So I choose these QED 420 cams , with 1.6/1.4 valves and Q55 springs .
This is the moment to tell me about installation and timing ...
My engine builder is working for the first time with QED's cams and ask me for your advices and said than the valve pockets will need to be deepened to accomodate.
Does anybody know about that !?!
Christian.
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Post by: rgh0 » Wed Jan 30, 2008 12:40 am
Christian
With the right cam base circle, valve length and springs you can accomodate lifts up to around 0.500 inch without deepening the valve pockets.
I have a spreadsheet I use to set up the heads I build. I can send it to you or your provide the data and i can model your head.
With a ported head the metal between the bottom of the valve spring pocket and the inlet tract is minimal so deepening the pocket can give you big problems. ( been there and done that, had to weld it back up)
cheers
Rohan
With the right cam base circle, valve length and springs you can accomodate lifts up to around 0.500 inch without deepening the valve pockets.
I have a spreadsheet I use to set up the heads I build. I can send it to you or your provide the data and i can model your head.
With a ported head the metal between the bottom of the valve spring pocket and the inlet tract is minimal so deepening the pocket can give you big problems. ( been there and done that, had to weld it back up)
cheers
Rohan
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Post by: john.p.clegg » Wed Jan 30, 2008 6:43 am
And as for the timing, the spec sheet states I/L 105 ATDC E/X 110 BTDC
John
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Post by: Old English White » Wed Jan 30, 2008 6:00 pm
john.p.clegg wrote:And as for the timing, the spec sheet states I/L 105 ATDC E/X 110 BTDC
John
John , Rohan ,
Here are the data sheet I get with the cams ...
John , your's is a bit different , isn't it !?!
Rohan , does this help !?! My head is an early type , staying with Weber's 40DCOE , and it had been already ported ...
I just can't read anything about valve spring pocket ...
Christian.
Last edited by Old English White on Thu May 30, 2019 7:35 pm, edited 2 times in total.
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Post by: paros » Wed Jan 30, 2008 6:30 pm
I used the 420 cams in my Elan and was delighted with them.
Ended up with leaner jets than QED suggested and quite a lot of ignition advance
QED supply a valve pack of modified retainers, springs and spring seats etc for the cams that negate a need to counter bore.
The installed length of the spring is 1.150
Cam timing was set at 102/105, the exhaust at 109 was not as good for tractability as when set at 104/105
Inlet ports need opening out to let the cams work and I used 34 mm chokes where I needed good bhp as against torque.
I am slowly building a spare head up which will have the 450 cams - so yes I do like the cams.
They run out of breath at about 7200 but will pull just like the normal cam from low revs.
Hope this helps
Richard
Ended up with leaner jets than QED suggested and quite a lot of ignition advance
QED supply a valve pack of modified retainers, springs and spring seats etc for the cams that negate a need to counter bore.
The installed length of the spring is 1.150
Cam timing was set at 102/105, the exhaust at 109 was not as good for tractability as when set at 104/105
Inlet ports need opening out to let the cams work and I used 34 mm chokes where I needed good bhp as against torque.
I am slowly building a spare head up which will have the 450 cams - so yes I do like the cams.
They run out of breath at about 7200 but will pull just like the normal cam from low revs.
Hope this helps
Richard
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Post by: Dag-Henning » Thu Jan 31, 2008 8:08 am
- did you try the 100/106 setting as specified by QED ?
Dag
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Elan S1 -64/ Elan race-replica 26R / Works Escort TwinCam -69/ Brabham BT41 Holbay
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Post by: rgh0 » Thu Jan 31, 2008 10:18 am
Christian
Setting up a head with non standard valves, cam and springs requires a number of component design selections and assemble measurements to ensure it all works properly. It is not a trivial exercise and I hope my explanation below helps but you need to think through each step carefully as a mistake can be expensive
QED (and the other suppliers) know what works with their springs and cam and other components they supply but they dont provide all the needed data as they want to do the asembly work themselves naturally. Dave Bean is better than most but even he does not supply all the needed data simply in one place to build you own head, but if you know what your looking for you can find most of it scattered through his catalogue
I use the attached spreadsheet to help me with the head design and set up process. If you look through it you will see what data elements are entered due to design selection or measurment and then what is calculated.
The following are key steps in the head set up process.
1. You need more room to fit springs in for higher lift cams. You achieve that by using a smaller cam base circle - 1.05 inch is typically whats needed and longer valve stems - a little less than 4.0 inch is typical and thin steel cam followers with a pad thickness of around 0.15 to 0.18 inches to end up with an acceptable shim thickness and enough room for springs without deepening the spring pockets.
2. You then need a spring and retainer pack that achieves around 75 lb installed load and around 195 lb load at maximum lift. Less than 75 lb /195 lb combination risks valves bouncing off the seats or not following the cam nose at high revs. Going to higher loads up to around 220 lb max lift load risks excessive cam and bucket wear.
3. You need to get the valves set correctly in the head so you have the target distance from cam centre line to the top of the valve. This distance
is around 0.80 inch given all the other components selctions I use. You need to be able to measure this distance accuratley plus also the distance from cam centreline to bottom of spring pocket in order for the spreadsheet to calculate the other values you need. I made up a special tool that sits in the cam bearing tunnel and provides a measuing face on the cam centreline. I have attached a photo of the tool.
4. You then need to detemine if the springs you have selected fit in the space and whether they need shimming to get the target loads, the speradsheet calculates that for you based on spring measured data, you need to measure the Q55 springs or get that data from QED. The Q55 springs should be OK but if they dont work with the above design selections either find another spring or change some other design element slightly. You should not need to deepen the spring pockets to make a .420 lift cam work with the right springs.
5. Finally you need to do a number of clearance checks to ensure it all works and nothing fouls. The spreadsheets checks the common issues with the head itself bur you also need to check valve to piston clearances by a test assembly. Most forged racing pistons you can buy have adequate cut outs but you need to check your final assembly as piston to deck height, head thickness and gasket thickness all have an influence and will vary depending how you select components and assemble the bottom end and total engine.
Personally I prefer the McCoy 450 cam as it essentailly combines the higher lift of the QED 450 cam with the shorter duration of the QED 420 and combined with the right porting it gives you the top end horsepower of the QED 450 with the tractability and torque curve of the QED 420 - best of both worlds!
I will be away travelling for a week from this Saturday so will not be able to answer any questions for a while but hoipe this helps your engine builder.
cheers
Rohan
Setting up a head with non standard valves, cam and springs requires a number of component design selections and assemble measurements to ensure it all works properly. It is not a trivial exercise and I hope my explanation below helps but you need to think through each step carefully as a mistake can be expensive
QED (and the other suppliers) know what works with their springs and cam and other components they supply but they dont provide all the needed data as they want to do the asembly work themselves naturally. Dave Bean is better than most but even he does not supply all the needed data simply in one place to build you own head, but if you know what your looking for you can find most of it scattered through his catalogue
I use the attached spreadsheet to help me with the head design and set up process. If you look through it you will see what data elements are entered due to design selection or measurment and then what is calculated.
The following are key steps in the head set up process.
1. You need more room to fit springs in for higher lift cams. You achieve that by using a smaller cam base circle - 1.05 inch is typically whats needed and longer valve stems - a little less than 4.0 inch is typical and thin steel cam followers with a pad thickness of around 0.15 to 0.18 inches to end up with an acceptable shim thickness and enough room for springs without deepening the spring pockets.
2. You then need a spring and retainer pack that achieves around 75 lb installed load and around 195 lb load at maximum lift. Less than 75 lb /195 lb combination risks valves bouncing off the seats or not following the cam nose at high revs. Going to higher loads up to around 220 lb max lift load risks excessive cam and bucket wear.
3. You need to get the valves set correctly in the head so you have the target distance from cam centre line to the top of the valve. This distance
is around 0.80 inch given all the other components selctions I use. You need to be able to measure this distance accuratley plus also the distance from cam centreline to bottom of spring pocket in order for the spreadsheet to calculate the other values you need. I made up a special tool that sits in the cam bearing tunnel and provides a measuing face on the cam centreline. I have attached a photo of the tool.
4. You then need to detemine if the springs you have selected fit in the space and whether they need shimming to get the target loads, the speradsheet calculates that for you based on spring measured data, you need to measure the Q55 springs or get that data from QED. The Q55 springs should be OK but if they dont work with the above design selections either find another spring or change some other design element slightly. You should not need to deepen the spring pockets to make a .420 lift cam work with the right springs.
5. Finally you need to do a number of clearance checks to ensure it all works and nothing fouls. The spreadsheets checks the common issues with the head itself bur you also need to check valve to piston clearances by a test assembly. Most forged racing pistons you can buy have adequate cut outs but you need to check your final assembly as piston to deck height, head thickness and gasket thickness all have an influence and will vary depending how you select components and assemble the bottom end and total engine.
Personally I prefer the McCoy 450 cam as it essentailly combines the higher lift of the QED 450 cam with the shorter duration of the QED 420 and combined with the right porting it gives you the top end horsepower of the QED 450 with the tractability and torque curve of the QED 420 - best of both worlds!
I will be away travelling for a week from this Saturday so will not be able to answer any questions for a while but hoipe this helps your engine builder.
cheers
Rohan
- Attachments
-
- tool for measuring valve postion and spring pocket depth versus cam centreline
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Example head rebuild.xls- Twin Cam Head Head cam and valve setup
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Post by: Old English White » Thu Jan 31, 2008 12:02 pm
paros wrote:I used the 420 cams in my Elan and was delighted with them.
Ended up with leaner jets than QED suggested and quite a lot of ignition advance
QED supply a valve pack of modified retainers, springs and spring seats etc for the cams that negate a need to counter bore.
The installed length of the spring is 1.150
Cam timing was set at 102/105, the exhaust at 109 was not as good for tractability as when set at 104/105
Inlet ports need opening out to let the cams work and I used 34 mm chokes where I needed good bhp as against torque.
I am slowly building a spare head up which will have the 450 cams - so yes I do like the cams.
They run out of breath at about 7200 but will pull just like the normal cam from low revs.
Hope this helps
Richard
Thanks you Richard ,
I just get the same answer from Simon from QED concerning the installation springs lenght . 1.150"/29.21mm .
I am pleased to read than the head don't need any new mods.
About the rest of your specs , they seems to correspond with that my engine builder is used to see .
The man used to race an Elan , cat. GT , and has just finished his new toy , a 47 but using Piper's cams ...
Don't hesite to give some news about your head with Q450 , these should be my next stage , too , but not tomorrow !
Christian.
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Post by: paros » Thu Jan 31, 2008 2:24 pm
Hello Christian
I was glad my info did not conflict with QED's!
I suspect I ought to know your engine man as I raced Elans in GT's, both with twin cam engine and later a big Sierra Cosworth lump.
I must concur with Rohan on the proper way to do it, but for myself building perhaps one engine a year, I have had to do it all the hard way without nice pieces of kit to measure spring depths. Very envious!
I am pretty certain QED no longer do any machining and so you will not be having problems from them in doing it yourself.
Dag asked if I tried 100/106 and I don't think I did - my notes don't show my ever having done so. Most engine builders here reckon twin cams don't like less than 100 degrees and so I tended to steer toward 102. And how accurate are we really in setting the cams - plus or minus one degree would be pretty good I suspect for an amateur like myself.
As to my current cams these are 450 and they behave much like the 420 but keep breathing beyond 7000. QED gave me a dyno sheet of a 450 equipped engine some 5 years ago, and when I dyno'd mine on a local dyno last January it replicated the QED data almost exactly. I opened the inlets out still further for the 450 cams and followed Rohan's advice and installed the bigger inlet and exhaust valves using the standard sprint sized seats.
The 420 profile is used by other cam suppliers as well, so this is a further recommendation I guess.
Any questions do get in touch
Richard
I was glad my info did not conflict with QED's!
I suspect I ought to know your engine man as I raced Elans in GT's, both with twin cam engine and later a big Sierra Cosworth lump.
I must concur with Rohan on the proper way to do it, but for myself building perhaps one engine a year, I have had to do it all the hard way without nice pieces of kit to measure spring depths. Very envious!
I am pretty certain QED no longer do any machining and so you will not be having problems from them in doing it yourself.
Dag asked if I tried 100/106 and I don't think I did - my notes don't show my ever having done so. Most engine builders here reckon twin cams don't like less than 100 degrees and so I tended to steer toward 102. And how accurate are we really in setting the cams - plus or minus one degree would be pretty good I suspect for an amateur like myself.
As to my current cams these are 450 and they behave much like the 420 but keep breathing beyond 7000. QED gave me a dyno sheet of a 450 equipped engine some 5 years ago, and when I dyno'd mine on a local dyno last January it replicated the QED data almost exactly. I opened the inlets out still further for the 450 cams and followed Rohan's advice and installed the bigger inlet and exhaust valves using the standard sprint sized seats.
The 420 profile is used by other cam suppliers as well, so this is a further recommendation I guess.
Any questions do get in touch
Richard
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Post by: Old English White » Thu Jan 31, 2008 10:15 pm
Richard , Rohan ,
"My" engine man raced in the early eighties a blue pounder Elan S2 , and still prepare some Seven's of the french TOP Lotus Challenge , always near the podium ...
It take me long time to decide him to build "OEW"'s engine , even after having spoken hours before on my desire of a "special" one.
Speaking about QED cams , he was surprised about the dimensions of the Q55 springs ... having 420 lift cams from Piper with Cosworth springs , he has to machine the valve pockets. This for his twincam in the 47 ...
Rohan, your spreadsheet is very impressive and I will show him this master piece . I think its too late for me to use it !?! , no !?!
When we went to QED for buying all the necessary parts as ask by the engine man , we meet Simon and he tell us than QED no longer build engine , but still concentrate on engine parts ...
Everything was on the shelf , and we saw a dozen of heads( for 40 &45 webers) being machined ...
The day after was the Stoneleigh Lotus Fair , and we had the possibility to complete our list with a full set of ...
Cool , no !?! I suppose these are the right one's !?!
Christian.
"My" engine man raced in the early eighties a blue pounder Elan S2 , and still prepare some Seven's of the french TOP Lotus Challenge , always near the podium ...
It take me long time to decide him to build "OEW"'s engine , even after having spoken hours before on my desire of a "special" one.
Speaking about QED cams , he was surprised about the dimensions of the Q55 springs ... having 420 lift cams from Piper with Cosworth springs , he has to machine the valve pockets. This for his twincam in the 47 ...
Rohan, your spreadsheet is very impressive and I will show him this master piece . I think its too late for me to use it !?! , no !?!
When we went to QED for buying all the necessary parts as ask by the engine man , we meet Simon and he tell us than QED no longer build engine , but still concentrate on engine parts ...
Everything was on the shelf , and we saw a dozen of heads( for 40 &45 webers) being machined ...
The day after was the Stoneleigh Lotus Fair , and we had the possibility to complete our list with a full set of ...
Cool , no !?! I suppose these are the right one's !?!
Christian.
Last edited by Old English White on Mon Dec 01, 2014 6:21 pm, edited 1 time in total.
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Post by: rgh0 » Thu Jan 31, 2008 10:37 pm
Piston valve cut outs look fine. I would always do a trial assembly and check clearances to the valves and to the head itself. The top of the intruder may need a little machined off depending on the compression ratio you are targeting and other details such as combustion chamber size, gasket thickness and deck height of piston amd rod assembly.
cheers
Rohan
cheers
Rohan
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Post by: Old English White » Fri Feb 01, 2008 10:18 am
rgh0 wrote:Piston valve cut outs look fine. I would always do a trial assembly and check clearances to the valves and to the head itself. The top of the intruder may need a little machined off depending on the compression ratio you are targeting and other details such as combustion chamber size, gasket thickness and deck height of piston amd rod assembly.
cheers
Rohan
That's right , Rohan,
As the target compression ratio is 10.5:1 (standard conrods & crankshaft), everything will be done as described.
As usual , he said .
Christian.
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Post by: paros » Sat Feb 02, 2008 10:28 am
Good morning Christian
The Q55 springs work BUT need the valve spring retainers need machining on the cotter taper to allow the retainer to be further away from the valve seat. QED include these as part of the valve pack.
There seems very little metal in the 55 springs, but I can say with confidence they were OK at 7700 with Sprint size valves.
I use the same Omega pistons and use a compression that is nearly 13 to 1 with the 450 cams. With the 420 cams I was at about 11 or just over if I remember correctly.
Bon chance
Richard
The Q55 springs work BUT need the valve spring retainers need machining on the cotter taper to allow the retainer to be further away from the valve seat. QED include these as part of the valve pack.
There seems very little metal in the 55 springs, but I can say with confidence they were OK at 7700 with Sprint size valves.
I use the same Omega pistons and use a compression that is nearly 13 to 1 with the 450 cams. With the 420 cams I was at about 11 or just over if I remember correctly.
Bon chance
Richard
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Post by: Old English White » Tue Nov 25, 2014 1:26 pm
Old English White wrote:john.p.clegg wrote:And as for the timing, the spec sheet states I/L 105 ATDC E/X 110 BTDC
John
John , Rohan ,
Here are the data sheet I get with the cams ...
John , your's is a bit different , isn't it !?!
Rohan , does this help !?! My head is an early type , staying with Weber's 40DCOE , and it had been already ported ...
I just can't read anything about valve spring pocket ...
Christian.
Just replace the dead link to image file.
Christian.
Last edited by Old English White on Tue Nov 25, 2014 1:32 pm, edited 1 time in total.
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