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Requesting some L-24 rebuild advice and opinion


Daniel Fox

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I will start with what I am working with.

Early 240 with wide ratio 5 speed stock diff but have a 3.9 that I will be installing and the tires are 205/55/15.

Engine is L-24 with 0.30 over flat tops, E-31 head, stock cam stamped "A", 4 screw Z-Therapy carbs still in the box, 6-2-1 ceramic coat headers 2" exhaust 30" glasspack and twin resonator tip, Ignition is stock (points) recently rebuilt with a performance curve by Advanced Distributor. A compression check (warm with plugs out but slides closed) yielded 185 lowest 195 highest.

 

The car was sitting for a few years when I got it and the previous owner had no work done on it. Anyway I went through the brakes, replaced rims and tires, a few other odds and ends and got it running. I took it out a half dozen times, it ran pig rich and burned some oil had a small radiator leak and the three screw SUs were pretty clapped out, the car seemed plenty quick and a lots of fun but I decided pull the engine to clean it up a go through it. The valve guides need replacing and the rockers look pretty bad the cam not too bad but not great. The head itself looks great with zero corrosion. The cam towers are shimmed 0.18.

 

Ok that gets me to my questions which very likely do not require all that information.

 

Should I use cast or bronze guides? and what did the E-31 come with?

Is there any actual power to be had installing 280 valves with zero head work and do you recommend it?

Lastly, and your going to love this one. Can you recommend a conservative cam grind that will take some advantage of the high compression and low gears? Durability is my main concern the car seems very fast as it is, but I have been driving a Type 2 VW daily for 20 yrs.  I will be sending the cam and rockers to Delta in the next few days and I appreciate any input.

Thanks

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Welcome to the forums, and enjoy the ride!  It sound like you got a pretty decent one there, at least mechanically. I don't know if larger valves will be much of an improvement on their own, maybe someone else here can answer. Regarding the cam and followers, I wouldn't recommend re-grinding the rockers, buy new OEM and have the cam reground (if it's a Nissan cam - if not get a Nissan cam that has been reground). There is a guy named "bonk" on fakebook "Church of the L" forum who makes custom cams and is supposed to be good. Talk to him before you do anything with your current cam.

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Thanks for the reply, I have decided to stay with the E-31 size valves and just get nice valve job, as for the cam grind (Nissan cam) I'm thinking the minimum will be 

260/.420" and max 270/.450" (opinions are welcome) a Delta regrind is $100 hopefully they have a profile somewhere in the middle, I will have the rockers resurfaced anyway, at $4 a rocker even if I don't use them they can sit on the shelf with a nice finish. I guess 12 new OEM rockers is to yet to be determined. I have had Delta grind couple inline 6 chevy cams way back when and they were great. I know the valve guide question is pretty mundane but cast are very durable the head now has worn bronze, did they come from the factory with bronze?

 

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