z20 block z24 head

[onewingedangel690]

I'm a NOVICE. But I have built my Nissan 720 from the ground up. Here is the problem. I had my engine rebuilt they messed up the head and they replaced the head from the z20 engine block with a z24. I had the truck running about 9 months ago for about a day then it stopped. Due to my having to work away from home a lot I haven't had time to mess with it? Is using the z24 head on the z20 block a problem? I bored the z20 block 30 over. and There are no other mods to speak of. I will be switching out the carb to a WEBER 32/36 and there is no electrical to speak of on my truck at all. The compression in my engine is low from what I'm told but it seems to want to start up. Guys you are my last hope give me some advice before i drop in a chevy v6 in it and call it quits. I really want to have this engine I may go to use a z20 head if i can find one in this area. Any help will be greatly appreciated.

[MicroMachinery]

I'm a NOVICE. But I have built my Nissan 720 from the ground up. Here is the problem. I had my engine rebuilt they messed up the head and they replaced the head from the z20 engine block with a z24. I had the truck running about 9 months ago for about a day then it stopped. Due to my having to work away from home a lot I haven't had time to mess with it? Is using the z24 head on the z20 block a problem? I bored the z20 block 30 over. and There are no other mods to speak of. I will be switching out the carb to a WEBER 32/36 and there is no electrical to speak of on my truck at all. The compression in my engine is low from what I'm told but it seems to want to start up. Guys you are my last hope give me some advice before i drop in a chevy v6 in it and call it quits. I really want to have this engine I may go to use a z20 head if i can find one in this area. Any help will be greatly appreciated.

 

You're going to have to provide more information if you want any worthwhile help. "I had the truck running about 9 months ago for about a day then it stopped" isn't going to cut it. Does it try to start? Does it crank? Does it pop? Is there spark? Is there fuel? There's more info needed here.

 

Oh yeah, and by the way, if you're having trouble getting a stock carbureted Z20 motor to run, I would strongly caution you against trying to drop a Chevy v6 into it.

 

Guys you are my last hope give me some advice before i attempt to drop in a chevy v6 in it, get overwhelmed and call it quits.

 

^^Fixed that for ya.

[onewingedangel690]

You're going to have to provide more information if you want any worthwhile help. "I had the truck running about 9 months ago for about a day then it stopped" isn't going to cut it. Does it try to start? Does it crank? Does it pop? Is there spark? Is there fuel? There's more info needed here.

 

Oh yeah, and by the way, if you're having trouble getting a stock carbureted Z20 motor to run, I would strongly caution you against trying to drop a Chevy v6 into it.

 

 

 

^^Fixed that for ya.

 

 

 

yes it has fire. Yes it cranks I rebuilt the engine from the ground up. got it back from the machine shop as a long block rebuild. The problem is the z24 head I think. There is no leak in any of the cylinders. Its reading about 65psi. I need 90 minimum and 120 max for the engine to run. But I have checked everything from the pistons to the rings. Everything checks out. I think there is some problem interchanging the head maybe. I not sure. as for the v6 chevy engine. I have some motormounts that will go in and my step-dad can make an adapter plate to mount it to the 5 speed transmission. I would just really like to get this engine going. I have been having issues with it but I spent the money to have it rebuilt I would like to see it go. I even double checked the timing. Everything is dead on even the oil pump cam. Not one thing is out of whack it seems, it's all by the book. Chilton manual. as for tackling something more I do have others that can help I would just rather not ask my family and do it myself. Its a pride thing. any simple ideas will help me Im out of em and I have been thinking. With no bend valves and nothing else wrong it must be the head. Maybe its not lobed right in top and the piston isnt properly lining up. I am just at a loss I have been working on this project a while and did everything on my own just about. I would just like to see it run lol.

 

There is FUEL, FIRE, AND AIR. no leaks everything the engine needs I did a leak check today. I checked all valves today, I checked all the timing and broke the engine down all the way. sparkplugs are nkg the proper ones for the engine. Checked with the book. different set for intake and diff set for exhaust.

[datzenmike]

There is no leak in any of the cylinders. Its reading about 65psi. I need 90 minimum and 120 max for the engine to run.

 

65 lbs of cylinder pressure is not going to work. It should be 185 or better if rebuilt.

 

You rebuilt this motor??? Was it re-bored to an oversize??? Maybe you should describe what you did and what you had done to this motor.

 

So try again using another compression tester. In other words get a second opinion.

[HRH]

A Z24 head wouldn't be my first choice on a Z20 block. Isn't the height of the cam different on the Z24? I can't remember. Anyway, it still should run. Did you get the chain tight, or perhaps off a tooth? Did you index the cam correctly on the sprocket hole? I agree, if 65 psi, something is not right. If it's even 65 across the board, probably cam timing is messed up, valves bent, or something else. Getting half a tooth off on the chain could do that and it would still run.

 

Do you have any pictures to throw up here?

[datzenmike]

65 across the board means the tester can't go higher and is likely bad!

 

Hey Matt, didn't you have a small chamber Z20 head???? With a tag on it?