SPACK 68 Posted June 12, 2018 Can some one explain, why would you fit DOUBLE valve springs. What is the benefit if any..?..Thanks. 1 CHESTNUTXE reacted to this Share this post Link to post Share on other sites
deankxf 20,266 Posted June 12, 2018 as far as i know, to prevent valve bounce. why do they put heavier springs on boosted engines? 1 SPACK reacted to this Share this post Link to post Share on other sites
Valvebouncer 2,389 Posted June 12, 2018 as far as i know, to prevent valve bounce. why do they put heavier springs on boosted engines? Yes, they prevent getting my nickname .Heavier springs are to help over come boost pushing on the back of the valve and holding it open after the lobe has passed. 2 deankxf and SPACK reacted to this Share this post Link to post Share on other sites
deankxf 20,266 Posted June 12, 2018 ahh yes, that then should only need to be the inlet valves to overcome boost? or does the exhaust get back pressure behind the valve also Share this post Link to post Share on other sites
ando76 4,354 Posted June 12, 2018 See don't be fooled by the double spring debacle. Modern bee hive springs have a much better rate and control over the valve thru the complete range of movement, compared to rock ape old 80's thinking double spring garbage. Now you can get a great single beehive spring that will comfortably handle .620" lift and big duration and roller profiles. Its all about matching the spring to the cam, head flow figures with manifold attached and cam type. Get it wrong and you will waste mechanical effort at best, at worse you will wipe lobs and generally have an underperforming s..tbox. Cam manufactures guidleines are close enough for mild to medium performance applications. 3 deankxf, matt_lamb_160 and SPACK reacted to this Share this post Link to post Share on other sites
ando76 4,354 Posted June 12, 2018 Boosted engines require greater spring control due to a number of factors. Increased cylinder pressure, Increased ex temps being just a few. You also want to look at hardened locks and good collets for serious boosted engines that see decent rpm. 2 deankxf and SPACK reacted to this Share this post Link to post Share on other sites
SPACK 68 Posted June 12, 2018 Good info, thanks guys... Share this post Link to post Share on other sites
slydog 7,873 Posted June 17, 2018 They need to keep the valve under control hence needing duals or tripples with dampers. Modern spring material helps but spring pressure is needed regardless. 1 SPACK reacted to this Share this post Link to post Share on other sites
SPACK 68 Posted June 17, 2018 The reason i am asking, is that, i had double valve springs on, I had the rockers all changed and the MECHANIC, took them off and replaced with NEW single ones, He said " you will never bounce these"..However I found that by the time i got to 1/2 way on the accelerator pedal, the car/ENGINE just ran out of breath, AND i know there is heaps more it could do... Share this post Link to post Share on other sites
Lord_fahrquhar 2,580 Posted June 17, 2018 Sound like said mechanic is a clown. 4 RuralBogan, Outback Jack, SPACK and 1 other reacted to this Share this post Link to post Share on other sites
SPACK 68 Posted June 17, 2018 He was, he wanted my GENIE extractors as well, said HURRICANE were better, I made him put them back on.. Share this post Link to post Share on other sites
ando76 4,354 Posted June 19, 2018 Sounds like you need a good/ different mechanic. 2 SPACK and Valvebouncer reacted to this Share this post Link to post Share on other sites
deankxf 20,266 Posted June 20, 2018 4 hours ago, ando76 said: Sounds like you need a good/ different mechanic. easier than it sounds.. almost easier to become one yourself 2 Outback Jack and SPACK reacted to this Share this post Link to post Share on other sites
SPACK 68 Posted June 20, 2018 That was done a FEW years ago, he use to be at Chermside, Had it changed back, IMMEDIATE difference.. Share this post Link to post Share on other sites
matt_lamb_160 252 Posted July 10, 2018 Sounds like he also wanted your rockers and springs. Mind you, if it had a stock cam, I tend to agree with what he said. It must not have been std. Hurricane do make decent extractors too. Share this post Link to post Share on other sites
SPACK 68 Posted July 10, 2018 No it wasn,t a standard cam, done by TIGHE...Also he only told me after it was all done and back in the car... Share this post Link to post Share on other sites