Wristpin 400 #26 Posted November 30, 2016 Talking gas flow; while the manifolds are off its worth checking that the passages exactly match the gaskets and head ports - same with the inlets. Back in the day the alignments on some engines was so bad that grinding a bit off here and there was the cheapest extra couple of horses to be found. 1 Stormin reacted to this Share this post Link to post Share on other sites
Stormin 4,458 #27 Posted December 1, 2016 I agree. That's a good idea. You could do the same with the inlet manifold and remove any bumps and lumps from inside if possible. Share this post Link to post Share on other sites
expeatfarmer 591 #28 Posted December 2, 2016 Turns out that "replacement manifold is much worse than I thought, I started to drill along the crack line and more and more of it just fell away in some places it must have been less tha half mil. thick change of plan now fortunately the original manifold is cracked in other places but the back is sound so I have cut the back out and will do likewise to the " new " one and braze it together. Share this post Link to post Share on other sites
expeatfarmer 591 #29 Posted December 2, 2016 Tried brazing and to start with it went well but then loads of contamination came out of the cast and I had to give up. As the manifold would be scrap i thought I would try mig welding it instead, to my surprise it worked well and manifold is now repaired and sealed ready for fitting. Normally cast iron cracks when you weld it but I think a combination of very thin cast, short bursts of welding and lots of patience finally paid off. I will hold back until I actually refit it in the morning and see what happens when it is hot but fingers crossed. 2 Anglo Traction and Stormin reacted to this Share this post Link to post Share on other sites
Anglo Traction 1,016 #30 Posted December 2, 2016 Very nice work on the Manifold sir!. I heard that preheating an Iron casting helps, and the use of Wire with a high Nickel content work very well. Seems you don't need it! . Share this post Link to post Share on other sites
Stormin 4,458 #31 Posted December 2, 2016 Good job Jonathan. Your right about cast cracking when welded. From what little I know, pre-heating can prevent it. I may have a run up tomorrow afternoon. Looking forward to hearing the V8 burble. I'll phone first. Share this post Link to post Share on other sites
Wristpin 400 #32 Posted December 2, 2016 2 hours ago, Anglo Traction said: Very nice work on the Manifold sir!. I heard that preheating an Iron casting helps, and the use of Wire with a high Nickel content work very well. Seems you don't need it! . Both of the above plus controlled cooling - in its simplest form, burying it in dry sand. Also, as has been alluded to, short quick spaced tacks extended and joined in turn contains local heating, expansion and contraction. Share this post Link to post Share on other sites
expeatfarmer 591 #33 Posted December 3, 2016 I should be around Norman. Share this post Link to post Share on other sites