HuD 91gt Posted November 30, 2015 Share Posted November 30, 2015 I've been in the middle of rebuilding my first engine for many months now. I decided to tackle a little bit of headwork on my own. I was having issues lining up the head gasket, and tracing a mark for the fire ring onto the head itself. It seemed to me, if I used the "wear" marks on the head, it would accomplish the same effect. So I did what I could, and tried to take as little material off as I could while still relieving the area. I'm done about 90% of the work I want to do and decided to toss the head gasket on the head to check my work. Still having issues lining up the head gasket (Or doing it properly), I do believe I overdid the unshrouding on one of the cylinders. Is the head junk now? I'm using a Ishono/Stone gasket from MSA. The block is over bored .040". Are there gasket with larger fire rings? Or should I be shopping for a new head and maybe sending it off to one of the local specialists (Or perhaps Hybridz locals). Quote Link to comment Share on other sites More sharing options...
HuD 91gt Posted November 30, 2015 Author Share Posted November 30, 2015 Pictures of my inexperienced work. Quote Link to comment Share on other sites More sharing options...
madkaw Posted November 30, 2015 Share Posted November 30, 2015 You need to fill out your signature or be specific with which block, head, etc. I used the head dowels to line things up. Gaskets come in various hole sizes, so I doubt you've ruined anything. Quote Link to comment Share on other sites More sharing options...
HuD 91gt Posted November 30, 2015 Author Share Posted November 30, 2015 Done and done. It is a stock P90 head I removed off a 120k mile 1981 280zx. It looked awful, but was pressure tested and straight. I have a Colt c542.s cam (280 duration, .510 lift), SI stainless valves, Schneider Springs waiting for installation. Quote Link to comment Share on other sites More sharing options...
johnc Posted November 30, 2015 Share Posted November 30, 2015 Just find a head gasket with a larger OD fire ring. As mentioned above, the head gasket should locate well on the dowels. Quote Link to comment Share on other sites More sharing options...
Xnke Posted December 30, 2015 Share Posted December 30, 2015 (edited) All the inexpensive/over-the-counter headgaskets that I have found have an 88MM fire ring for the L28. I'd love to find a composite, OE style gasket with larger bores! If you do find one, please post back where you get it and what brand it is. If the photo you show is the only spot you missed on, AND the headgasket is aligned using the dowel pins for the head, I'd not worry about it and run it. If it's a MAJOR overage that we can't see in the photo then I'd think otherwise, but that looks like maybe a 0.010" overage? If so or less over a very small area, run it. Edited December 30, 2015 by Xnke Quote Link to comment Share on other sites More sharing options...
HuD 91gt Posted December 30, 2015 Author Share Posted December 30, 2015 My dowels unfortunately went with the block I do believe, which is at the machinist. So I can't say for sure how correct the alignment of the HG is in that photo. As we sit, the head is in a crate and it's ready to be shipped out to Whitehead Performance in Ontario. They said they could repair my damage if too large. Do a more serious porting job and rebuild the head. It was a fun experience, and I think i'd tackle it again but this rebuild is taking far too long and i'd like it out of the way. I'd also practice on a practice head like everyone suggests too!Xnke, I found a list of diameters of the head gaskets available. Most are 89, or 89.1mm. The only one larger that I could find was the MLS gaskets at 91.5mm. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 30, 2015 Share Posted December 30, 2015 Head is not junk. Could weld and fix. I read and was told not to expose anything more than the edge of the fire ring, but don't know if that is passable or not. If you're notching the block to match, you'll have a bit of gasket sticking out which may cost .0000267 hp. Quote Link to comment Share on other sites More sharing options...
Xnke Posted December 31, 2015 Share Posted December 31, 2015 The problem is erosion of the fire ring, not so much that it's in the way. Once the metal ring burns out then the gasket burns quickly...so that's why you don't want it exposed. I'd love to know where to get an 89mm fire ring gasket, all I have in the shop are 88's. Quote Link to comment Share on other sites More sharing options...
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