JordyKE Posted February 20, 2012 Report Share Posted February 20, 2012 Hey guys/girls Just a quick, and possibly stupid question. Can I run a 4K head on a 5K block, using a 4K cam? If i understand correctly, i will have low compression due to the dished pistons of a 5K. So literally there is no point at all? Cheers. Quote Link to comment Share on other sites More sharing options...
Jono.C Posted February 20, 2012 Report Share Posted February 20, 2012 They made a flat top and D dish 5k. I'd imagine if you got a 5k flat top block (rarer) with a 4 flat top head the compression would be higher. Not too sure about the 4k cam in it, 5k is hydro lifter and 4k is solid, so you'd need to switch to solid lifters to run it. And you can't use 4k lifters 'cause they're too small Best bet is to just buy a complete 5k :wink: Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted February 20, 2012 Report Share Posted February 20, 2012 When I measured my 4K head it had 31cc in the combustion chamber. The gasket occupied 7cc The shallow-dish pistons in a 5K have 6cc in the dish. The 5K cylinder contains 1/4 of the 1496cc, or 374cc. So your compression ratio will be (374+6+7+31) to (6+7+31) Quote Link to comment Share on other sites More sharing options...
philbey Posted February 20, 2012 Report Share Posted February 20, 2012 The shallow-dish pistons in a 5K have 6cc in the dish. Really? Quote Link to comment Share on other sites More sharing options...
JordyKE Posted February 21, 2012 Author Report Share Posted February 21, 2012 They made a flat top and D dish 5k. I'd imagine if you got a 5k flat top block (rarer) with a 4 flat top head the compression would be higher.Not too sure about the 4k cam in it, 5k is hydro lifter and 4k is solid, so you'd need to switch to solid lifters to run it.And you can't use 4k lifters 'cause they're too smallBest bet is to just buy a complete 5k :wink: Alright thanks for that info. The only reason i was asking, is because i have a 4K head which has had work done to to it. And i know it's a really good head, so i was pretty keen to use that. However i will have the 5K head with Hydro Lifters. New pistons with a flat top (if they are even available) i would consider buying? When I measured my 4K head it had 31cc in the combustion chamber.The gasket occupied 7ccThe shallow-dish pistons in a 5K have 6cc in the dish.The 5K cylinder contains 1/4 of the 1496cc, or 374cc.So your compression ratio will be (374+6+7+31) to (6+7+31) Wow, thanks for the info altezzaclub. So to my understanding that's a 9.5:1 compression ratio. That doesn't seem too bad...... But then again i don't know much about that kind of stuff. What do you suggest i do? Run the 5K head and get better compression.. Or just run the 4K head and have that compression? Cheers!! Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted February 21, 2012 Report Share Posted February 21, 2012 (edited) Measure the 5K head combustion chamber with a sheet of plastic and a burette or pipette. You seal the valves with grease, seal the plastic onto the head with grease, and run turps in through a hole in the plastic from the pipette. That will measure the volume in the chamber. The two 5K pistons had quite different heads, so I don't know which you have. Philbey, I'll look it up again... Edited February 21, 2012 by altezzaclub Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted February 21, 2012 Report Share Posted February 21, 2012 http://www.club-k.co.nz/Forums/viewthread.php?tid=7374 From blown 5k Super Moderator <a href="http://imageshack.us/"> Ok the piston on the left is the D shaped piston its combustion chamber area is approximately 22.5cc the piston on the right is the O shaped piston which has a combustion area of around 6cc now if you are using a 3k-b head you should be using the one on the right. Quote Link to comment Share on other sites More sharing options...
TOMMYS Ke 11 Posted February 21, 2012 Report Share Posted February 21, 2012 Hi there all just finished this exact conversion 5k block with shallow dish pistons had 60thou lathed of the top 64thou decked from the block giving us near a flat top ,4k head ,bigger valves, ported,double valve springs with 120lb on the seat and decked to give us 11-1 comp quad kasaki 900 carbys ,reground 4k cam, solid lifters,datsun a12 push rods, ran in and miled tune on the dyno tonight gave us 99.5 rear wheel hp at 6thou revs in 3rd gear. Pretty happy with that and it pulls real hard on the road :yes: :yes: :yes: . Cheers:- Stuart. Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted February 21, 2012 Report Share Posted February 21, 2012 OMG! That is great! JordyKE here's your inspiration! PM Stuart for all the "how-to" questons! http://www.rollaclub.com/board/topic/19886-my-ke-11/page__st__195 Quote Link to comment Share on other sites More sharing options...
philbey Posted February 21, 2012 Report Share Posted February 21, 2012 Interesting. My aftermarket ACl dish pistons were about 8-9cc, that's the only reason I asked. With a dished piston head they were about 12:1 comp. Quote Link to comment Share on other sites More sharing options...
JordyKE Posted February 21, 2012 Author Report Share Posted February 21, 2012 http://www.club-k.co.nz/Forums/viewthread.php?tid=7374From blown 5k Super Moderator Thanks for that. Gives me a good understanding. Hi there all just finished this exact conversion 5k block with shallow dish pistons had 60thou lathed of the top 64thou decked from the block giving us near a flat top ,4k head ,bigger valves, ported,double valve springs with 120lb on the seat and decked to give us 11-1 comp quad kasaki 900 carbys ,reground 4k cam, solid lifters,datsun a12 push rods, ran in and miled tune on the dyno tonight gave us 99.5 rear wheel hp at 6thou revs in 3rd gear. Pretty happy with that and it pulls real hard on the road :yes: :yes: :yes: .Cheers:- Stuart. Alright, so you're running a 4K head on 5K block, just using a 4K reground cam. I have a 4K reground cam which is relatively lumpy, will need to get the actualy numbers of it though. I bought an engine a while ago which came with this 4K head i now have. The work that has been done to it is as follows: -fully race prepet head -3 angel valve job -1mm shaved head -crow cam v8 valve springs -deshrouded portes -ported intake and exhaust So it seems like a solid head, and when i ran it ages ago it was awesome. OMG! That is great! JordyKE here's your inspiration! PM Stuart for all the "how-to" questons!http://www.rollaclub.com/board/topic/19886-my-ke-11/page__st__195 I just had a quick read over this, looks mean, well done to TOMMYS KE11. I'm not in a HUGE rush to get this engine up and going, but i'm trying to get my research down, before i really start anything (espcially with uni starting next week). Thanks for the help. Interesting. My aftermarket ACl dish pistons were about 8-9cc, that's the only reason I asked. With a dished piston head they were about 12:1 comp. How much were thes pistons? Quote Link to comment Share on other sites More sharing options...
tojo2 Posted February 21, 2012 Report Share Posted February 21, 2012 Interesting. My aftermarket ACl dish pistons were about 8-9cc, that's the only reason I asked. With a dished piston head they were about 12:1 comp. possably due to pistons beeing oversized ? More dish added to compensate for added cylindervolume keeping comp ratio same? Just a thought.. Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted February 21, 2012 Report Share Posted February 21, 2012 My aftermarket ACl dish pistons were about 8-9cc, Ah- so people need to measure a few different 5K pistons with the plastic sheet/pipette and publish some actual measurements. 1500cc at 12:1 would be a flyer! Quote Link to comment Share on other sites More sharing options...
Evan G Posted February 22, 2012 Report Share Posted February 22, 2012 I'm building a 5k atm for a mate. std comp for a 5k with 8cc pistons is around 9:1 (i cbf measuring it) ive taken 60thou off the head. HELLOOOO COMPRESSION Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted February 22, 2012 Report Share Posted February 22, 2012 It'll pink on 98 you know... I hope SOMEBODY worked out what 60thou would do! Quote Link to comment Share on other sites More sharing options...
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