Muncie Posted January 22, 2023 Share Posted January 22, 2023 I've got my holden/buick l67 v6 stripped down and I can visibly see some cracking around a few valve seats. Can this be repaired successfully? I have plenty of welding gear and would be prepared to give it a go if it's not too risky. Also prepared to send out if it's a specialist job if you know someone pipe up as I suspect this is a skill that may be dying out. These heads are surprisingly thin on ground as cracks on an L67 3.8 v6 is a given later in life not sure on l36 ecotec suspect wont be much better these days as the vast amount of these engines have ended up skid pigs. There are alloy aftermarket heads but $5k plus for a set is a bit rich. Quote Link to comment Share on other sites More sharing options...
Doug Hill Posted January 22, 2023 Share Posted January 22, 2023 Talk to MPW. Typically you would pin them and not weld them. Quote Link to comment Share on other sites More sharing options...
piazzanoob Posted January 23, 2023 Share Posted January 23, 2023 I would be checking to see if the cracking continues below the valve seat insert which would required getting the head to a reconditioners and getting machined out then following by a crack test. repairing cracked heads isn't a common thing to do now most end up in the bin and find another non cracked one 1 Quote Link to comment Share on other sites More sharing options...
vk327 Posted January 23, 2023 Share Posted January 23, 2023 proflow fab in aussie are machining l36 heads to work as l67 heads now if you get stuck finding a decent replacement 1 Quote Link to comment Share on other sites More sharing options...
Muncie Posted January 24, 2023 Author Share Posted January 24, 2023 On 24/01/2023 at 06:49, vk327 said: proflow fab in aussie are machining l36 heads to work as l67 heads now if you get stuck finding a decent replacement That's an option. I'm not running the blower so can run ecotec heads but want the option of been able to run a second set of injectors for E85 on a separate fuel system or even water injectors. I've looked at 2 sets of heads that we're for sale off an l67 and and l36 both were as chooched as mine so starting get worried about not having a top end for the build. Quote Link to comment Share on other sites More sharing options...
vk327 Posted January 31, 2023 Share Posted January 31, 2023 wouldnt worry about secondary injectors on a 3.8 , modern injectors work well at low pulse widths so not hard to get an engine to idle with a set of 1000cc or 1350cc injectors (at this point you'd lose resolution on the stock delco ecu fuel tables tho) , youd have to be pushing 20 plus psi of boost to even get close to needing that much fuel even with e85 and could run 60psi base pressure if needed a bit extra, more viable option would be a water meth kit which typically run a single nozzle into the intake, either the fancy AEM kit or have done a basic water meth kit before using an AEM nozzle with a solenoid and a tank with an efi pump and regulator on it and a hobbs pressure switch turns on the solenoid as boost comes on 1 Quote Link to comment Share on other sites More sharing options...
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