i need to the best motor to drop into my 73 z thge old one is shot help please

[Znut73]

i recently went to change my head gasket and found the block had a crack in the cylender wall the head had been rusted right oabove the #1 piston searching for a new motor what shaould i get i hear the 280 block is what to get with it if so will my motor still be carbed need all the info i can get please help want my z back in the worst of ways thank you

[2ManyZs]

If you want the best 280 motor (L-28) try to find an F-54 block with the flat top pistons, you will have a displacement increase while keeping close to your current compression ratio. If you get an earlier L-28 they will have dished pistons and your compression ratio will drop to about 8:1 unless you replace the pistons.

[Znut73]

What type of head do i use with that block and well i still be able to use my carbs with this set up thanks 2manyzs

[Ivan]

P79, P90, P90a, E31 or E88 will all fit I think

[2ManyZs]

If you have the original head on your 73 it should be an E-88. That will be a good choice if you don't want to spend any more money than you have to. You might want to consider a valve job while you have it off, and if you do that, you can put the larger 280 valves in it.

Only head that you might want to stay away form is the N-47 280 head as it had steel inserts in the exhaust ports that tended to disintegrate over time.

Any L-series head will work with very little work. If you have a good head now, all you need to do is swap it and your intake and carbs over on the new block.

[mperdue]

Hey 2Many,

You say these inserts go bye-bye over time? Any idea under what conditions and how long it takes? I've heard they restrict exhaust flow but not that they burn up. NOt that I would change heads any time soon - gotta try this one out first but just wondering.

michael

[2ManyZs]

I'm just basing my opinion on all that I have read. Don't know about how long it takes but it seems to me if they are steel they would disintegrate somewhat from the same sources that cause valve seats to burn up. Heat would be it's biggest enemy since it is right where the hottest exhaust passes through it on it's way to the manifold......

Besides, if they do reduce flow in the exhaust port, why not just find an N-42 which has the larger valves and better ports? One of the good things about the N-47 is that around 79 they started using the hardened steel valve seats, so you could probably find one that doesn't need one thing.........

The N-47 is a round port (exhaust) so it is kind of the black sheep in the L series as nearly all the rest have the square ports. More interchangeability if you have one of the square port heads.

[mperdue]

Mine's not an N47 - it's a P79 but it has the same inserts. It's a long way off but I was gonig to just plunk my engine back in and do any changes later (maybe much later). It was running fine at the time so when I get there I'll probably just want to drifve for awhile.