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Machine Shop Questions


Guest Stoker3.0Z

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Guest Stoker3.0Z

I bought a L26 for $50 and have since torn it apart and sold what I didn't want and cleaned up and painted the block. It is about to go to the machine shop for magnafluxing and if it "passes" then I'm going to get it bored .40 over. The owner of the shop recommended getting the deck resurfaced before seeing the block. What do you guys think? It costs $125 and I'm not sure if it is worth it. This is going to be a built NA motor later on in its life. I'm just building it to build it. I am also building a L28 Stroker, so it probably won't see much time, i just want to have it around just in case. Would you guys recommend doing anything else to the block while its there?

 

Thanks alot,

 

Stroker3.0Z

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Guest Want aZ

A built NA Motor, I would do the following:

Hot tank & Clean

Magnaflux,

Deck,

Align Hone Crank Journals

Bore if necessary

Hone

 

Just remember to thoroughly clean the block after its return from the shop, Wash down with Soap & Water, and remember to Get all of the oil passages this is important, nothing like putting clean internals in and getting sand in your bearings on start up....

 

after the wash lightly oil

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Decking, magnafluxing, and line boring the crank journals on an L-series block that will only see street duty is unnecessary, IMO.

 

I have re-built about a dozen L-series engines (including two strokers) and I have never had to resort to any of these procedures. The only blueprinting “frill†I do is to have the reciprocating parts dynamically balanced.

 

Block deck unevenness can be measured with a machinist straight edge. If the crankshaft bearings show an uneven wear pattern then you can measure the crank journals (and crank) for straightness (see “How to Modify Your Nissan/Datsun OHC Engineâ€).

 

In the text “The Design and Tuning of Competition Engines†the author states in the excellent chapter on the L-series engine: “The Datsun cylinder block is outstanding for its strength. The quality control is well above average at the [Datsun] factory and align boring and deck milling can be bypassed by a person building an engine on a budget.â€

 

If you want to Magnaflux something, then concentrate on the more stressed items like rods and the crankshaft. Nissan blocks do not have a reputation for cracking (heads, however, do).

 

I have seen a few problems caused by unnecessary machine shop work. Remember the old saying, why “fix†something that aint’ broke.

 

Parts for these engines are very expensive. Save your money for items like a new harmonic damper and new connecting rod bolts.

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Why limit yourself to a 1974 L 26 #P30 block of 2600 CC... Start with the best block:'81-83 280 ZX # F54 block.with stock flat top pistons and a P79, p90 or p 90 a head will give you 8.8:1 compression. The p 90 head flows with larger valves. Without buying a lot of expensive new parts you can swap a lot of good used Datsun parts. Decking an engine sight unseen is crap without any prior measurements first. You can do so much more with the 81-83 blocks not to mention many parts that can be utilzed for performance. Do not underestimate the quality of Datsun engines and parts.

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Guest Stoker3.0Z

The only reason I'm even building this engine is because I got it for $50 and sold alot of stuff off of it and made about $80 (I still the dist., clutch, tranny, block, head, valve cover, ect.) The only things I sold were the crank, rods and pistons, the carbs and intake manifold, and the camshaft. I still have the rest of the engine. I knew it was a good buy so I bought it and now I'm just going to build it for fun. I also have a 1978 FI L28 and I'm going to buy a 1981 L28 Turbo in a few weeks from a guy. Like I said this engine is just being built for fun and possibly to sit on an engine stand in a shop (to be opened soon) so I can tell people that ask what is done to it. Or possibly for a swap into the Z if anything ever goes wrong with the soon to be stroker engine.

 

 

Thanks alot,

 

Stroker3.0Z

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Guest Stoker3.0Z

Thats a really good point. Hanve't thought of it that way. Do you think I should go ahead and get the block bored and honed, that way it will bring in more $$$ or should I just sell it cleaned and painted? The total of machine work won't cost but $125 or so. Thats magnafluxed and bored .40 over. Do you think I would recoup that money or is it not worth the effort?....Thanks alot for all these great suggestions.

 

Stroker3.0Z

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