Hi Group,
Can someone tell me if the Sprint engine supports lead free 97 octane fuel or do I have to convert the head to lead free? What parts should I change?
I also want to install a TT 10140 Kent cam. I heard that the valve clearance for this cam should be 10 thou, that is nearly half of the normal valve clearance. Can a reduced valve clearance be harmfull to the engine ? And why is the standard clearance so big if not?
Many thanks for all help, Eric
lead free cylinder head
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SPRINTPARTS
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Eric
I have been told that valve clearance with an uprated cam should be 9-10 thou whereas the standard valve clearance is 18 thou for the Sprint. Less clearance means more fuel mixture in the engine and more power but I don't n know if there is a risk to burn the exhaust valves. The racing fraction among us should know.
Also acording to the manual, the Sprint should use 98 octane, will it run with 95 octane or should I retard the ingition (how much)?
Thanks for help, Eric
Also acording to the manual, the Sprint should use 98 octane, will it run with 95 octane or should I retard the ingition (how much)?
Thanks for help, Eric
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Hans ten Broeke
Actually every cam, stock or competition works best with a specific clearance, so the thought you tell us 10 thou for a comp cam is just not precise enough.
With a very extreme cam, for example a Le Mans Spitfire replica, the overlap can be so much that on the required valve clearance the thing would not run below 4000 rpm, now going back to a bigger clearance the lower rpm torque gained considerable and the car became drivable, he lost almost nothing in the top end, but his lap times became competitive.
Work done on our dino.
Every cam should come with a spec sheet, if you don't have one you could look in the data from Cent cams, or call them, we had good experience with there service.
Burning Exhaust valves will appear when the total clearance become negative, w.a.w. that specific valve won't shut anymore.
The very hot gas will escape trough this small gap, the valve on its own can't cool on the seat and gets extremely hot.
If that happen in a very short time you will find a hole in the side of it or worse.
If the engine is well build with a known compression ratio it even could run better on 95,
We did run 2 racing cars a few seasons on 95, now one believed it but is was the trough.
To understand fuel, we did about 150 runs on the dino with 4 different petrols in 95 an 98 ron, with 3 different cars. this was a nice task for one of the apprentices, it took about a week!!
The difference between a 4 and a 2 valve engine was eye opening.
Now we use a far higher comp ratio and use German V power 100 octane.
But If you don't know your comp ratio, and for example in the past the head has been shimmed and afterwards NOT measured the several combustion chamber been equal or made equal, it could be dangerous.
Actually with every aspect with this (rare) engine, just doing something without understanding it and thoroughly measuring and understanding that also you could come in a risky area.
The tolerances from this engine (early 70') is so big that every engine undergoing serious tuning should be treated as a single item.
Just doing the same as your mate did, and he was successfully can easily end in disaster.
--
Hans ten Broeke
De Hoge Esch 49
7783 CBÂ Â Gramsbergen NL
STOC #2830
'92 green topST
'93 red usaST (ex #221) (2005)
'73 CB 750 Candy Glory Gold
'71 Jamathi 50TT -restoration project, but proud to have one-
'78 Maico 370 Enduro Red
'95 CB Sevenfifty Red
'96 SZR 660 Super Mono Orange
'96 CB 70 Dax Red (2000)
and too many cages to mention...
With a very extreme cam, for example a Le Mans Spitfire replica, the overlap can be so much that on the required valve clearance the thing would not run below 4000 rpm, now going back to a bigger clearance the lower rpm torque gained considerable and the car became drivable, he lost almost nothing in the top end, but his lap times became competitive.
Work done on our dino.
Every cam should come with a spec sheet, if you don't have one you could look in the data from Cent cams, or call them, we had good experience with there service.
Burning Exhaust valves will appear when the total clearance become negative, w.a.w. that specific valve won't shut anymore.
The very hot gas will escape trough this small gap, the valve on its own can't cool on the seat and gets extremely hot.
If that happen in a very short time you will find a hole in the side of it or worse.
If the engine is well build with a known compression ratio it even could run better on 95,
We did run 2 racing cars a few seasons on 95, now one believed it but is was the trough.
To understand fuel, we did about 150 runs on the dino with 4 different petrols in 95 an 98 ron, with 3 different cars. this was a nice task for one of the apprentices, it took about a week!!
The difference between a 4 and a 2 valve engine was eye opening.
Now we use a far higher comp ratio and use German V power 100 octane.
But If you don't know your comp ratio, and for example in the past the head has been shimmed and afterwards NOT measured the several combustion chamber been equal or made equal, it could be dangerous.
Actually with every aspect with this (rare) engine, just doing something without understanding it and thoroughly measuring and understanding that also you could come in a risky area.
The tolerances from this engine (early 70') is so big that every engine undergoing serious tuning should be treated as a single item.
Just doing the same as your mate did, and he was successfully can easily end in disaster.
--
Hans ten Broeke
De Hoge Esch 49
7783 CBÂ Â Gramsbergen NL
STOC #2830
'92 green topST
'93 red usaST (ex #221) (2005)
'73 CB 750 Candy Glory Gold
'71 Jamathi 50TT -restoration project, but proud to have one-
'78 Maico 370 Enduro Red
'95 CB Sevenfifty Red
'96 SZR 660 Super Mono Orange
'96 CB 70 Dax Red (2000)
and too many cages to mention...
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Eric
... Still Sprintless.
Sprint shims are the same size as those in one of the other vehicles Rimmers deal with, one of the SD1 variants I think. They are available for that engine in greater thicknesses. Someone will remember which engine before long....
I have a Triumphtune book at home, I'll have a look over the weekend and see if the gaps are stated.
The damage you have seen is interesting if you will pardon my morbid curiosity. If you are using larger than standard shims you must have a reground cam. I hope the damage you have is not a warning of what is to come for everyone running a regrind, if so sprint heads are going to be in very short supply in another ten years.
Tinweevil
I have a Triumphtune book at home, I'll have a look over the weekend and see if the gaps are stated.
The damage you have seen is interesting if you will pardon my morbid curiosity. If you are using larger than standard shims you must have a reground cam. I hope the damage you have is not a warning of what is to come for everyone running a regrind, if so sprint heads are going to be in very short supply in another ten years.
Tinweevil
1978 Pageant Sprint - the rustomite, 1972 Spitfire IV - sprintfire project, 1968 Valencia GT6 II - little Blue, 1980 Vermillion 1500HL - resting. 1974 Sienna 1500TC, Mrs Weevils big brown.
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Eric
Hi,
You are right, the Triumphtune cam is a reground cam as I had to return my old one when I bought it. I think that Rimmers did not do a good job when they rebuilt the engine in 1994 (they probably use an old head) that is why the head failed (after rebuild and until now I covered only 15.000 miles with the Sprint). I measured the camshaft and the diameter of the cams are less than the original cam. So it is logic that I need larger shims. But on the other hand, the cam will not open the valves to a higher degree as the cams are not longer. In my old cylinderhead, the valves sat deeper in their seat than in the new s/h one, perhaps due to wearing.
Thank you for looking in the catalogue for me, perhaps you can send or mail me a copy of the related page.
Eric
You are right, the Triumphtune cam is a reground cam as I had to return my old one when I bought it. I think that Rimmers did not do a good job when they rebuilt the engine in 1994 (they probably use an old head) that is why the head failed (after rebuild and until now I covered only 15.000 miles with the Sprint). I measured the camshaft and the diameter of the cams are less than the original cam. So it is logic that I need larger shims. But on the other hand, the cam will not open the valves to a higher degree as the cams are not longer. In my old cylinderhead, the valves sat deeper in their seat than in the new s/h one, perhaps due to wearing.
Thank you for looking in the catalogue for me, perhaps you can send or mail me a copy of the related page.
Eric
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Hans ten Broeke
About the head, unfortsional I'm not surprised, seen over the years sins 1978 /79 many heads, good and bad ones, but by far the worst rebuild head I've seen some 2 years ago.
This head had done 3K miles and been bought from the company you named as a Full Reconditioned head, in "good" English, Fu..... unbelievable.
Just one detail, almost all seats where put in so angled, I mean not in line with the valve guides, at least a few degrees off, that after the seats where grind, the with of the 45' surface varied from under 1 mm to almost 3 mm !!
But probable the worst, someone just continued to put that head together, again unbelievable.
I hope your not cross with me, but  so called craftsmanship is sometimes very, very, bad in England!! Flame suit on and ducking!
I refused to use this head to build a fast road engine for this man, he had 4 or 5 other heads so after clean and inspect them I could find a non shimmed example what was a good base to start from.
Before, the owner had consult us to measure his car what had new 45DCOE carbs fitted with a reasonable jet setting, max CO at max output around 6%.
The engine did put out around 115 DinHp, actual a joke.
That engine with the new build head and a new cam did afterwards on low compression, so he could use 95 during holidays abroad ext, a healthy 175 Hp
About the shims, we do have a few hundred new thick shims original pact in sets of 5 who have to be grind to sise.
If interested contact me off line.
Hans
--
Hans ten Broeke
De Hoge Esch 49
7783 CBÂ Â Gramsbergen NL
STOC #2830
'92 green topST
'93 red usaST (ex #221) (2005)
'73 CB 750 Candy Glory Gold
'71 Jamathi 50TT -restoration project, but proud to have one-
'78 Maico 370 Enduro Red
'95 CB Sevenfifty Red
'96 SZR 660 Super Mono Orange
'96 CB 70 Dax Red (2000)
and too many cages to mention...
This head had done 3K miles and been bought from the company you named as a Full Reconditioned head, in "good" English, Fu..... unbelievable.
Just one detail, almost all seats where put in so angled, I mean not in line with the valve guides, at least a few degrees off, that after the seats where grind, the with of the 45' surface varied from under 1 mm to almost 3 mm !!
But probable the worst, someone just continued to put that head together, again unbelievable.
I hope your not cross with me, but  so called craftsmanship is sometimes very, very, bad in England!! Flame suit on and ducking!
I refused to use this head to build a fast road engine for this man, he had 4 or 5 other heads so after clean and inspect them I could find a non shimmed example what was a good base to start from.
Before, the owner had consult us to measure his car what had new 45DCOE carbs fitted with a reasonable jet setting, max CO at max output around 6%.
The engine did put out around 115 DinHp, actual a joke.
That engine with the new build head and a new cam did afterwards on low compression, so he could use 95 during holidays abroad ext, a healthy 175 Hp
About the shims, we do have a few hundred new thick shims original pact in sets of 5 who have to be grind to sise.
If interested contact me off line.
Hans
--
Hans ten Broeke
De Hoge Esch 49
7783 CBÂ Â Gramsbergen NL
STOC #2830
'92 green topST
'93 red usaST (ex #221) (2005)
'73 CB 750 Candy Glory Gold
'71 Jamathi 50TT -restoration project, but proud to have one-
'78 Maico 370 Enduro Red
'95 CB Sevenfifty Red
'96 SZR 660 Super Mono Orange
'96 CB 70 Dax Red (2000)
and too many cages to mention...
-
Eric
Hi Hans,
Thanks for reply, I need to measure the clearance to determine the shims I need. I also measured the heads, and I found that the s/h head is as original but my Rimmers head had be reskimmed by 2mm. If I install a thicker head gasket, will the car run on unleaded with the new head? What valve clearance is better, original specification 0,018 thou or 0,10 as I have been told for the Triumhtune cam?
Have a nice Week End, Eric
Thanks for reply, I need to measure the clearance to determine the shims I need. I also measured the heads, and I found that the s/h head is as original but my Rimmers head had be reskimmed by 2mm. If I install a thicker head gasket, will the car run on unleaded with the new head? What valve clearance is better, original specification 0,018 thou or 0,10 as I have been told for the Triumhtune cam?
Have a nice Week End, Eric
O series engines perhaps? As fitted to Marina, Princess, Sherpa and some Rovers in 1700 and 2000cc petrol versions?tinweevil wrote:Sprint shims are the same size as those in one of the other vehicles Rimmers deal with, one of the SD1 variants I think. They are available for that engine in greater thicknesses. Someone will remember which engine before long....
I have a Triumphtune book at home, I'll have a look over the weekend and see if the gaps are stated.
The damage you have seen is interesting if you will pardon my morbid curiosity. If you are using larger than standard shims you must have a reground cam. I hope the damage you have is not a warning of what is to come for everyone running a regrind, if so sprint heads are going to be in very short supply in another ten years.
Tinweevil
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either PM or use Report Post if you see anything you are unhappy with. Thanks.
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Neil907
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Neil907
Unfortunately you are right and I personally feel rimmers are a prime example of this which is a big shame when they tend to be the first place allot of people go for triumph parts. But whilst people continue to buy from them they will continue to produce s##t.Hans ten Broeke wrote: I hope your not cross with me, but so called craftsmanship is sometimes very, very, bad in England!! Flame suit on and ducking!
When I bought some shockingly bad panels off them recently and phoned them up to complain they just said yeah we know they are crap but since you can't get them any where else its tough s##t. I sent them back anyway and found a way around it.