DearmanKE Posted September 21, 2008 Report Share Posted September 21, 2008 Hey everyone, the 4k in my car is abit tired, but anyway i have another 4k thats don't only 100,000 k's and i wasw wondering if it would be worth taking the head off(no i can't be bothered with a whole engine swap) and getting it decked for higher comp then putting it on my current 4k how much should i get it shaved? would i endanger the valves hitting the pistons if i deck it to much? anyway, your thgouths/advice welcome -Alex (grammar loser) Quote Link to comment Share on other sites More sharing options...
tojo2 Posted September 21, 2008 Report Share Posted September 21, 2008 Change the whole engine. Not that mutch work. By just changing the head you`ll probably be keeping the most tired bits. Shaving the head will increase the compression pressures and therby increase the blowby caused by worn rings & bores. Will also cause more strain on worn bearings ..... How mutch to shave off a head depends on what compression rate you are after, what type of 4k you got (twin squish?) , standard cam? , standard carb set up? , extractors ?, type of fuel you want to run ? . Quote Link to comment Share on other sites More sharing options...
DearmanKE Posted September 22, 2008 Author Report Share Posted September 22, 2008 its all standard, and the reason i cbf changeing the whole motor is, my dad wants the wreck gone that contains the spare motor, and i don't have a hoist to get the engine out. so its way to much effort i probs wont do it, but id stil like to know more about it. thankyou Quote Link to comment Share on other sites More sharing options...
tojo2 Posted September 22, 2008 Report Share Posted September 22, 2008 Once bolts are undone I`m sure you + a mate will be able to lift it out ,using a 2 by 4 and a pice of rope. They only weigh about 100k. :y: I once calculated that a 1.2mm shave gave me 10-1 comp rate on my flat pistoned 4k. Recomend you to stay well below that figure on a worn stock 4k. I wouldnt do it at all with a tired one, but thats me. Quote Link to comment Share on other sites More sharing options...
DearmanKE Posted September 22, 2008 Author Report Share Posted September 22, 2008 yeah, but its attactched to a gearbox, and i really don't have that kind of effort atm lol ok so 1.2mm abit much 1mm be alright? Quote Link to comment Share on other sites More sharing options...
love ke70 Posted September 22, 2008 Report Share Posted September 22, 2008 its all standard,and the reason i cbf changeing the whole motor is, my dad wants the wreck gone that contains the spare motor, and i don't have a hoist to get the engine out. so its way to much effort i probs wont do it, but id stil like to know more about it. thankyou so f@$k off and stop wasting time! but anyway, the whole engine swap is easier than a head swap and why do you think the current motor is getting tired? a whole engine swap without shaving the head would give better results than a half arsed piss poor attempt at decking a head and putting onto a tired motor. Quote Link to comment Share on other sites More sharing options...
Doogs Posted September 22, 2008 Report Share Posted September 22, 2008 The figure I have heard pop up a fair bit is 20thou. I think that gives you 10:1 comp. If you are going to do that you may as well do a few other things while you are at it. From what I have heard just getting a head shave done will not gain you a huge amount. Maybe get the other engine machined and then put that in the car ? Is cost an issue or is effort the problem ? Quote Link to comment Share on other sites More sharing options...
love ke70 Posted September 22, 2008 Report Share Posted September 22, 2008 i think laziness is the key issue. and an inability to read the faq or use the search funtion. but what do i know... Quote Link to comment Share on other sites More sharing options...
Doogs Posted September 22, 2008 Report Share Posted September 22, 2008 Yeah, If you are so lazy why even change the head ? If you are wanting answers to questions you are actually concerned about you should know people here are pretty helpful. (providing you do a little searching first and are willing to listen). Quote Link to comment Share on other sites More sharing options...
Redwarf Posted September 22, 2008 Report Share Posted September 22, 2008 (edited) Take .060 off it and go from there. (Says the man with a head with .100 off it....) And for Christ sake, do some research. Edited September 22, 2008 by Redwarf Quote Link to comment Share on other sites More sharing options...
DearmanKE Posted September 22, 2008 Author Report Share Posted September 22, 2008 Thanks to those who are being helpful, ive used search and didnt find much about if its worth doing or not. To the haters. one of the key words in this subforum is "Discussion" so f@$k off and stop wasting time! rags? Quote Link to comment Share on other sites More sharing options...
Falken_KE30 Posted September 22, 2008 Report Share Posted September 22, 2008 rags? Isn't that a Kids show on ABC?? :y: Quote Link to comment Share on other sites More sharing options...
archangel62 Posted September 22, 2008 Report Share Posted September 22, 2008 love ke70, f@$k off and stop wasting time! Sorry to be blunt. Don't like the thread, don't post. I think raising the comp is one of the best ways to get NA power, if the engine is tired then yes it will speed up wear, but it'll also increase power. Grenade engine for cheap? Still sounds like fun to me :o. I rebuilt a 2lt Gemini engine, upped compression to 10.5:1 by using a different head, and it goes like absolute mad. Ideally I'd say shave the head as much as cylinder clearance will allow, and put it back on the good engine, then swap that, but if you can't do that then it could be a viable option to do as you're saying, heads can be swapped in a day and you don't need an engine crane/etc. Having said that if you want to borrow my crane you can! I didn't think 20thou would do much until I worked it out... 0.020" x 2.54 x 10 = 0.5mm.. Bore/stroke is 75/73mm, each piston is 322.5cc or thereabouts, I haven't been able to find a comp ratio on google for the 4K but I've heard it's pretty high.. Let's say it's 9.6:1, the compressed piston volume would be 33.6cc. Blah blah blah maths, 20thou = 2.2cc out of compressed volume, = 31.4cc, /322.5^-1 = 10.27:1 compression ratio! You could run that with an old school ignition setup, probably even on bullshit 91 octane fuel without pinging, depending on timing... But if you want the most power, aim for 10.5 - 11:1 compression, but no more, and run 98 octane and/or an ethanol mix like E94 (run slightly richer if using ethanol), and set the timing to suit. Another option is to restrict the dizzy's total advance so it doesn't blow its head off at high RPM. If you find out stock compression ratio and tell me what kinda compression ratio you want to run, I'll work out how much to shave :y: If anyone read all that you deserve a cookie, but hey, someone had to do the maths! Eli Quote Link to comment Share on other sites More sharing options...
Toy-Yoda[RL] Posted September 22, 2008 Report Share Posted September 22, 2008 Confusing mathy stuffs Eli I read it all, I got confused, but I stupid, so I can has cookie? CR for a 4k is 9.4:1 BTW....... :y: Quote Link to comment Share on other sites More sharing options...
tojo2 Posted September 22, 2008 Report Share Posted September 22, 2008 love ke70, Sorry to be blunt. Don't like the thread, don't post. I think raising the comp is one of the best ways to get NA power, if the engine is tired then yes it will speed up wear, but it'll also increase power. Grenade engine for cheap? Still sounds like fun to me :bash:. I rebuilt a 2lt Gemini engine, upped compression to 10.5:1 by using a different head, and it goes like absolute mad. Ideally I'd say shave the head as much as cylinder clearance will allow, and put it back on the good engine, then swap that, but if you can't do that then it could be a viable option to do as you're saying, heads can be swapped in a day and you don't need an engine crane/etc. Having said that if you want to borrow my crane you can! I didn't think 20thou would do much until I worked it out... 0.020" x 2.54 x 10 = 0.5mm.. Bore/stroke is 75/73mm, each piston is 322.5cc or thereabouts, I haven't been able to find a comp ratio on google for the 4K but I've heard it's pretty high.. Let's say it's 9.6:1, the compressed piston volume would be 33.6cc. Blah blah blah maths, 20thou = 2.2cc out of compressed volume, = 31.4cc, /322.5^-1 = 10.27:1 compression ratio! You could run that with an old school ignition setup, probably even on bullshit 91 octane fuel without pinging, depending on timing... But if you want the most power, aim for 10.5 - 11:1 compression, but no more, and run 98 octane and/or an ethanol mix like E94 (run slightly richer if using ethanol), and set the timing to suit. Another option is to restrict the dizzy's total advance so it doesn't blow its head off at high RPM. If you find out stock compression ratio and tell me what kinda compression ratio you want to run, I'll work out how much to shave :y: If anyone read all that you deserve a cookie, but hey, someone had to do the maths! Eli Credit for making an effort, but sorry mate: You got the blah blah bits wrong. Take a look at a 4k compression chamber. :o If you want to do this accuratly, measure the cc of the combustion chamber , thickness of your compressed headgasket, and calculate what comp.ratio you got. Then you calculate how many cc you need it to be for your wanted ratio. Subtract and you got how many cc you want to get rid of. Now figure out the surface area of head combustion chamber and calculate how mutch you need to shave. Shizotimang : Your lack of effort and cbf coolness is suddenly becoming contageus. Good luck to you. Quote Link to comment Share on other sites More sharing options...
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