Update on my non-running Z

[jeff1216]

1978 280Z

F54 block with flat top pistons

E88 head

Ported polished oversized valves

Wild cam (stage III)

Arizona intake

Holley 390cfm

A little more info........................I was suprised to find that my 78 had an F54 block.....when I pulled the head off the pistons looked new...very little carbon. I do not know if it has been bored over or not.

E88 head was a lucky find.........I bought all new 280Z valves for it.............the machine shop had me come by...The head looked to be race prepped................Huge intake and exhaust valves.....much larger and thinner than the stock 280 valves.

Installed the stage III cam and heavy springs.

We can get the car to fire when hard and the gas and will run when pumping the gas and keeping the rpm's high. It still sputters un-burned gas thru the carb and will not idle.

Fuel leaking from the intake problem fixed.

I am now curious ..... is it possible that the car is making more power and compression than I thought......Maybe need 110 octane to run? (I say this because I have no idea what has been done to the bottom end.

OR

With the hot cam and HUGE valves....Do I need to re-curve the timing? If so how do I recurve the timing?

I can tell you this............when turning the motor over the compression is so strong that it will almost stop a fully charged battery from spinning the motor on the compression stroke.

Jeff

[kyteler]

Sounds like it could be lethal if it was running, sorry I can't really be of any help, but I'm curious, what CCA is your battery if the compression can almost stop it from cranking?

Go down to the race track or airfield and buy some AvGas chuck it in and see if it makes any difference.

You'd like to think that if it had all that work done to it, if it needed a re-curve it would have been done also.

[kyteler]

I just realised, the Holley comes in 2 390CFM's currently, there's probably been more in the past.

1 has Vacuum Secondaries the other has Mechanical, it could be that your carb is just dumping far far too much fuel into the engine, you may want to get the carb itself checked.

Really I have no idea what I'm talking about Just throwing things out there.

[Ed]

I would venture to guess that you have a fuel problem. If it was the timing you wouldn't be able to keep it running at high revs. And if it was iginition it wouldn't run at all.

[jeff1216]

Ok......here we go

Part of this is my fault for taking the machine shops word......The intake valves were adj. to cold spec..........the exhaust walves were either not opening or barely opening.....I adjusted to spec.

I expected the car to fire right up after that.....NOPE

Now it will not start at all.........................Back to backfiring thru the carb.

I am totaly lost.

[Ben]

If you can't crank it, back off (retard) the timing. It could be too advanced & kicking back on the starter.

One way to check this is to crank it with the coil disconnected, if it cranks fine, then you have a timing issue (perhaps only a few degrees).