Thomasi Posted March 4, 2013 Share Posted March 4, 2013 Okay, so I have a few questions regarding the beautiful 4age. If I want to replace my bigport with a smallport, will I need a completely new loom or are the looms rather similar and only require a little tweaking..? Obviously a smallport would bolt in where my bigport has been, but would a 20v Silvertop 7rib block bolt directly in..? Theoretically speaking, would a 20v Silvertop block, 20v conrods, 16v pitsons and a bigport head bolt right up and fit directly into where my average currently bigport sits?? Any answers would be greatly appreciated. Cheers. Quote Link to comment Share on other sites More sharing options...
bigmatt4 Posted March 4, 2013 Share Posted March 4, 2013 looms are different enough not to bother modifying ie injector plugs distributor map sensor instead of AFM no tvis some have injector resistors better off with a smallport loom and ecu. yes the blocks have the same mounting points. 16v head will fit on 20v block late model 100kw smallports have the 7 rib block larger journals and pins also oil squirters in the block for the pistons pretty much a 4agze without the pistons of charger so i would go smallport. Quote Link to comment Share on other sites More sharing options...
Vintage Grumble Posted March 4, 2013 Share Posted March 4, 2013 One thing you may want to check out, 20v have a huge oil drain on one side of the block, and it sticks out quite a bit, 16v dont have this, i'm not sure a 16v head would cover this properly? (not that i've ever looked into it, but something you may want to check) Quote Link to comment Share on other sites More sharing options...
ryanfels Posted March 4, 2013 Share Posted March 4, 2013 You can use a bluetop ECU if you cant find a smallport one, you just end up having the TVIS kind of kick in at 4000rpm Quote Link to comment Share on other sites More sharing options...
Thomasi Posted March 4, 2013 Author Share Posted March 4, 2013 Okay cheers for all your knowledge boys!' Quote Link to comment Share on other sites More sharing options...
Thomasi Posted March 4, 2013 Author Share Posted March 4, 2013 Okay cheers for all your knowledge boys!! Quote Link to comment Share on other sites More sharing options...
Vintage Grumble Posted March 4, 2013 Share Posted March 4, 2013 You can use a bluetop ECU if you cant find a smallport one, you just end up having the TVIS kind of kick in at 4000rpm My 86 had a small port red top running off a big port blue top ecu when I got it, it was kinda shit TBH, soooooo gutless under 4g. Quote Link to comment Share on other sites More sharing options...
ryanfels Posted March 4, 2013 Share Posted March 4, 2013 Pretty much but thats standard with 4ages anyway 1 Quote Link to comment Share on other sites More sharing options...
kpr Posted March 5, 2013 Share Posted March 5, 2013 16v head on 20v block is no worries. run a 20v block and 16v piston with smallport head in mine 20v block you have to use 20v sump as the 16v one is different. but there is actually more clearance with a 20v sump, so no worries there. there are some other small differences between the blocks like the odd threaded boss is different. but again nothing to worry about if you are using a smallport head on anything other than a smallport block. you will want to either drill the block to take the external oil drain, or weld a fitting on the sump. you can block the external drain from the head. but if you're planing on driving it like a 4age, (rev the shit out of it) use it! best to run the ecu and loom to suit the head you are using. as you will lose half the benefits of changing to smallport head. but as others said bigport stuff will run it, just wont bet the best Quote Link to comment Share on other sites More sharing options...
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