Good morning all, I am on my way to Oklahoma tommorrow and on my return trip I have the opportunity to pick up a complete 77 L28 engine with 44,000 miles on it for "free" in Sioux Falls. I tried searching advantages of the F54 over the N42 block. All I know is the F54 net HP was 145 ponies compared to the 135 ponies of the N42. The F54 also has the siamese cylinders where the P30 and N42 blocks were not and had coolant flow between cylinders. My intent is not to build a radical powerhouse but would like to build a block that will be stout when you stomp on it for autocrossing and Z-speed fun and have compression in the 9.0-9.5:1 range. I have two E31 heads but would keep my eyes open for a P90 head and use flat-top pistons.

My question for this great group of knowledge is should I hold off and keep seeking for a F54 block or will the N42 hold up to the build?

Thanks to everyone for their input in advance.

Newtonhubcap

The N42 is a fine block......many prefer it (Eiji at Datsun Spirit does). Either will work for any application even though some claim more strength in the F54. Use what you've got IMO.

I am getting an N42 block/N42 head engine built up by Datsun Spirit right now. I am going to throw a set of triples on it and run about 9.5:1 compression with a decent cam. I will let you know how it turns out. Money has been sent, so it is only a matter of time before I get her breathing fire.

One question though, with my 9 lb flywheel, I am going to need a new clutch....I may have to do some searching in the drivetrain section.

Eiji just installed a 9 lb. Flywheel on a his 280 driver on my lift a couple weeks ago. He went back with the stock clutch. With stock, you know what fits with what. KISS is a good practice. You won't need a high performance clutch with what you're building IMO, but ask Eiji.

All I know is the F54 net HP was 145 ponies compared to the 135 ponies of the N42.

The engine block had nothing to do with that. Either block works just fine, get the one that's in the best shape.

The N42 cylinder bores will stay rounder and have a very slightly better seal then the F54 until you get over 400hp. Then the F54 does very slightly better. But Leon's right, pick the block that's in the best shape and that's not necessarily the block with the fewest miles on it.

Japanese people loves N42 since it's solid and most durable for bore up over F54.

http://blog.livedoor.jp/datsunspirit/archives/50678547.html

Just want to say thanks to everyone for their input. After reading all replies, I decided to pull the trigger. So, on our return trip (spring break) from Oklahoma, my daughter and I made the run to Sioux Falls SD to get the motor. When we got there E. had the motor hanging on the hoist so all we had to do was back up to it and slide it in and shake hands. Within in 30 minutes we were back on the road heading to Wisconsin. Overall, I feel it was well worth the 900 mile day trip to get a fairly low (44,000 miles) clean-complete motor for free! A big Thank you to E. for the motor.