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hey guys, has anyone done this? ie RB20 head on a 30 bottom end? im aware the the smaller ports and valves wont make as much power per psi as a 25/26 head, i assume the chamber diam might also be wrong but im sure it could be ported out a touch to suit. i would think this combo would make awsome low down torque, especialy if it was fitted with twin t28s etc

is there a reason it wouldnt work that im not seeing?

cheers in advance

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just went a laid a 30 headgasket over the 20 head and it all lines up, headbolts are the same, the chambers are about 3mm out but that would port out very easy, the water galleries are out but could be lined up too. are the cams the same length? would the belts line up?

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Has been done, there was a blue over silver VL Calais years ago, one of the first 3 litre twin cam conversions, JET 88C I think it was...guy thought it was a 25 head from memory but later found out it was a 20 head when it didnt make as much power as they expected on a given boost level.

Single cam head FTW if its in a VL :) Guys have made over 500rwkw with the single cam.

Edited by NSNPWR
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Thread closed. Believe it or not, but since SAU started more than 7 years ago, this topic has been discussed before.

Please use the search function in future. It may be found here:


While we understand that it can be frustrating to have your thread closed - Please consider that other members may feel it to be disrespectful and selfish of you to post a simple question, without using the search feature to review the wealth of information provided by said members over the years.

If you still feel that this action is unjust, then please PM me and we can discuss it further.

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