redzedsled

Hello! I bought my sound deadening sheets from Lordco in Canada. They were a ProForm brand and were the perfect size at 29" x 32", with 2 pcs per package. Here is the link to their website: http://www.proformproducts.com/en/products/repair-products/sound-proofing/sound-deadening-sheets/ Regards, Rob

The FelPro head gasket should not require re-torquing I have understood. I was going to go FelPro as well until I talked to Dave Rebello who suggested the 11044-N4221.

I found this very useful calculator for Datsun L-Series Engines. Here is the link: http://www.ozdat.com/ozdatonline/enginedesign/ With all the stock presets (E31 head, P30 block, etc) and a 1.25mm head gasket, it calculates the deck clearance at -0.100 mm (-0.004") below deck. Note the stock Deck Clearance Presets with the different engines, L24, L26, L28 etc. All dimensions on this calculator is in mm. Here is a link to a convenient length converter: http://www.onlineconversion.com/length_common.htm

This is my source for my information: http://www.jspecauto.com/files/jspecautotechcenter11d.htm You did say and I quote "MOST Datsun motors have positive deck height(.020) for a reason" Making mention of other L Series Blocks is relevant in this case.

After reviewing page 126 of the book how to modify DATSUN 510 610 240Z engine & chassis by H.P. Books, it states: "Deck clearance should be from zero (piston flat even with block deck at TC) to +0.015 (out of the hole) with the piston centered in the bore. This assumes that you are using the standard Datsun gasket which is about 0.050-inch thick when compressed." madkaw is right, after some thought, in that I could have gotten away with pistons that were 0.020" out of the hole (0.030" piston to head clearance). At the same time, I went with zero deck height on good advice of others and also because that is the way I uncovered the engine to begin with. If I have zero deck height along with a 0.050" thick compressed gasket, then I have more than Nissan's minimum requirement of 0.035". This is my first engine rebuild, so I am learning alot along the way. Admittedly I don't have the same experience of other members of this club.

I appreciate the mediation... If I am at zero deck height and I have a stock gasket that compresses to, let's say 0.6mm, that is 0.023" piston to head clearance. Perhaps with the new generation of head gaskets perhaps the compressed thickness is about 0.8mm, that is 0.031". If stock minimum clearance as stated by Nissan is 0.035", how could you get any closer than that.

The engine builder used Mitchel specs I believe he said, and insisted on 0 deck height. There is great deal of difference of opinion, for such a small amount of deck height. What's done is done now...

I made a decision based on many people's opinion, including the engine builder, the members of this forum, and people in the business. The builder felt more comfortable turning the piston tops down. I am aware that you can run your pistons over the top and understand that 30 over would be the danger zone. I debated turning the pistons down versus leaving them as is for several days. I made the decision, and now I will have to live by it. The goal of this thread was to inform others who could have potential issues with ITM pistons of their own.

No excuse for me to edit a posting (I changed it back to what is was), but I did later state it was 0.020 out of the hole, that I did not edit. Getting back to the matter I found this bit of info on L Series Engines, very few with positive deck heights. "Assembled stock engine deck height L16 ('68-'73 510 and later years 521pickup) piston deck height: 0.10mm (above block) L18 ('73-'74 610, and 620 pickup truck) piston deck height: -0.55mm (below block) L20B (various '75-'80 610, 710, 200sx, HL510, pickup truck) piston deck height: -0.45mm (below block)" and further... "most of the L, Z series have the piston slightly below the block deck at TDC"

Yes I did. Initially in the first few postings I estimated at 30 over the block and in later posts I stated it was about 20 over the top. Looking at How to Rebuild Your Nissan Datsun OHC Engine book, it states: "although the piston may extend slightly above the block 0.001 for example clearance is required to prevent piston from striking the cylinder". So what is the actual spec on stock deck height, is it really + 0.020? I have read differently.

I respect your humble opinion, but +0.020 deck height is not the standard from what I have known. When I initially pulled the head off the block, the piston at TDC was at the very top of the block, zero deck height and no higher. I have seen in engine calculators online and they suggest that the pistons should be slightly below the block at - 0.1mm, stock for the L24. I have always thought it was the performance guys who wanted the positive deck height and therefore run thicker gaskets to gain the clearance. The gasket I am going to use is about 1.1mm thick so compressed it should be about 0.6mm or so? Nissan's requirement is 0.035" minimum clearance between gasket and piston top. I respectfully take all opinions into account and then form my own decision, so I welcome your comments.

I did say .020" piston out of the hole in my previous posts did I not.

I had the pistons turned down 0.020" and now enjoy zero deck height. Now I can run a stock head gasket, part number 11044-N4221. Pickup the block and and head on Saturday from the engine builders. Thanks to all who contributed, I hope others can gain what I learned from this thread.

There's one listed on ebay right now if you search the part number. Actually there's two, one at half the price as the other, Genuine Nissan.

Here are some pics for you. The far right image is with the new gasket over top the old one for reference.

Oddly enough I did not get it from Nissan, but it does have the Nissan logo on it, with the packaging labeled JMNR High Performance Engine Gasket Made In Japan. The parts guy had 2 on the shelf, so I bought both. I am happy to give to the other one to you at cost if you want it.

Finally found the head gasket that best fits. It is part number 11044-N4221. It is stamped with the Nissan logo with the code NRZ 46F. NRZ stands for Nippon-Reinz and is made in Japan. The firing oval ring measures 89.5mm x 87mm and features the same water passage holes that my original head gasket had. This the best head gasket I have seen for having the same contours as the original. Thanks for all your contributions!

When I advised ITM's Sales Manager of the difference in height, I thought they would have offered a better deal than just a replacement set at cost. Hardly standing behind your product, but when it comes to pistons, there just isn't many options out there. At least there is a simple solution to all of this.

Wow, I have quickly become to listen to what Dave Rebello suggests, so good to hear. Perhaps I need to have the tops turned down so i can get back to 0 deck height. This way I could use a stock head gasket.

Disappointing being that my car has the matching numbered block, if that were the case. Removing block material in a Datsun engine is never a good idea as I have understood. He has stated that he just skimmed the top, and no more than .007". I have faith he is telling me the truth. He did ask me if the block was ever rebuilt before though, but I can't trace any history past 1987 when I first purchased the vehicle. I can tell you that the pistons that came out of the engine were Standard Size and not overbored. There is much to be learned about Deck Clearance in the book "How to Modify Datsun 510 610 240Z Engines & Chassis" (pages 125-126). It is stated in the book that you can have as much as .020 positive deck height, provided your run a thicker gasket such as a Cometic Head Gasket that is .060" thick compressed. So simple math would suggest that if I have + .020" piston out of the hole, and add the Nissan's preferred Deck Clearance of .035", then that would add up to .055". Having said that the Cometic Head Gasket is .060 thick. This would provide the necessary deck clearance I so desire. Is my math correct?

Found a picture of the Nismo head gasket that is NLA, part number 11044-E4620. See pics below.

This story actually runs a little deeper. Initially I had purchased the ITM RY6335-030 pistons (the ones with the valve reliefs). The engine builders installed them about two weeks ago only to find out that they were too tall and protruding through the top of the block also. When I phoned ITM's reseller here in Canada, he promptly phoned ITM and had the Sales Manager at ITM, measure both the RY6335 and the RY2516 on the same wrist pin. He actually showed images of the two types of pistons having a difference in height by about 30 thou (RY2516-030 being slightly shorter). I have to locate his images to show you. So, I ordered the RY2516-030 pistons thinking well this is the cure as the piston height of the RY2516-030 is correct and was going to be a slam dunk. ITM and their supplier in Canada would not allow me to return them, instead offering me a set of 6 at cost plus free shipping. So it is with great surprise that these new RY2616-030 (the ones with NO valve reliefs) are protruding also. Maybe I am not being told the whole story, I am not sure, but I can tell you that there is a difference between the RY6335 and the RY2516 pistons. I am going to leave the decisions up to the builder as to a solution, and see what he recommends. I build websites for a living not engines.

After speaking to Dave at Robello Racing (good guy), he suggested there be at least a 35 thou piston to head clearance with the head gasket compressed. For racing purposes, he did not recommend the head shims, but for daily driver use he said they would be OK. When I mentioned about turning the pistons down on a lathe, he said he has done 100's of pistons this way. He instead recommended a Cometic Head Gasket at about 56 thou in thickness (factory head gasket at 45 thou) in height (Cometic sells them in varying heights) $$$$ He also told me that many guys are running the F54 block with P90 Head with the pistons at about a 20 over deck height with no problems. If my math is correct the pistons are currently sticking out about 18-20 thou.

Hi Guys, here are the numbers on the Block Thickness. The block measured originally at 10.469" and now measures 10.45857". The engine builder is looking into the availability of steel head shims to bring the head up and away from the pistons.

Steve. Very insightful bit of information, I'll get some exact numbers on the positive deck height.