Thoughts on Intake Valve Timing 3 degrees retarded
#1
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Thoughts on Intake Valve Timing 3 degrees retarded
Just finishing the build on my LSJ engine. It has a new cylinder head, supertech valve springs, comp cams stage II cams, new rollers, new lifters, forged diamond pistons & rings, TVS, custom headers going into a 1986 Lotus Esprit.
The stock motor in the Esprit was around 215 HP and 215 foot pounds. So the LSJ will be a significant upgrade. Not looking for the ultimate in HP or performance, as the transaxle will be the weak link.
So will be using a conservative tune
Just completed the valve timing (thanks to Mr Belvedere on his suggestion for using solid valve lash adjusters).
I found I can get the Exhaust side to be spot on with Comp Cams specs. Exhaust was 41 BBDC and 9 BTDC w 212 duration at .050 valve open/close. Lift was .419. Valve centerline was 115 degrees (specs were the same)
The intake was 3 degrees retarded. Intake was 1 ATDC and 22 ABDC with 211 duration at .050 valve open/close. Lift was .423. Valve centerline was 105 (specs were 2 BTDC and 29 ABDC with 210 duration at .050. Valve centerline 103 degrees).
So my Lobe separation angle is at 110 degrees (spec is 109).
Question: any risk to running this way? Not looking for the ultimate in HP, so am wondering if I can just use this as is (versus getting/making an adjustable cam gear for the intake side). Would this have any Significant or noticeable impact running it just like this? Looking for any thoughts or inputs that people may have
The stock motor in the Esprit was around 215 HP and 215 foot pounds. So the LSJ will be a significant upgrade. Not looking for the ultimate in HP or performance, as the transaxle will be the weak link.
So will be using a conservative tune
Just completed the valve timing (thanks to Mr Belvedere on his suggestion for using solid valve lash adjusters).
I found I can get the Exhaust side to be spot on with Comp Cams specs. Exhaust was 41 BBDC and 9 BTDC w 212 duration at .050 valve open/close. Lift was .419. Valve centerline was 115 degrees (specs were the same)
The intake was 3 degrees retarded. Intake was 1 ATDC and 22 ABDC with 211 duration at .050 valve open/close. Lift was .423. Valve centerline was 105 (specs were 2 BTDC and 29 ABDC with 210 duration at .050. Valve centerline 103 degrees).
So my Lobe separation angle is at 110 degrees (spec is 109).
Question: any risk to running this way? Not looking for the ultimate in HP, so am wondering if I can just use this as is (versus getting/making an adjustable cam gear for the intake side). Would this have any Significant or noticeable impact running it just like this? Looking for any thoughts or inputs that people may have
#2
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As a side comment, I found that the cam sprockets have some degree of rotational "slop" ( that is, the keys on the sprocket have clearance in the slot on the cam so that there is some "rotational adjustment). I found that the I could vary the timing by a total of 5 degrees at the crankshaft on both the intake and exhaust. My readings above are at the most advance portion of this rotational clearance. If I positioned the cam sprockets to the most retarded position, I would get around 5 degrees retarded change to the above numbers
#3
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iTrader: (3)
when you torque the gears the play in the tooth should lock in and the play will be gone and yes you can run the intake cam e degrees retarded the cam timing changes as the engine warms up anyway and the hotter it gets the more it changes are you in the states or over the pond
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Medida
2.0L LSJ Performance Tech
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05-23-2018 03:48 PM