Engine will only run above 4000 RPM. Carbs or timing?

[grannyknot]

Hey Bart, they said the carbs were shipped on the 15th so with any luck I'll see them next week, I'm certainly ready for them.

And Bart this is for you, I pulled it off the original motor and cleaned it up just in case I need it.

[bartsscooterservice]

Hope you get it running now.

[PastorMike]

Chris,

I think that many of us are eagerly awaiting the results of the ZTherapy carbs. If they don't solve the problem, I know that someone will finally figure it out. I believe that then your idea of a spreadsheet will be in order.

Mike

[grannyknot]

EUREKA, IT IDLES !!!!

Thanks a lot everyone, see ya.

heheheheh, just messing with ya.

I received the carbs last Monday and bolted them on, no difference, no change of any kind.

This morning Laverne, a Z engine guru and member from Ont.Z Club came over at 9am and we spent until 2pm re-trying

everything I've been doing over the last couple months, Laverne found that the oil pump/distributor shaft was one tooth

advanced. To my eye it looked exactly like the photo in the manual but it wasn't, I was so happy we found something wrong that I didn't mind at all feeling the fool. So we fixed it and tried it again, it made little to no difference.

Then Laverne noticed that the distributor that came with the engine had the base plate from another year and was not allowing full adjustment movement, he also noticed it was missing a plastic locator that keeps the cap from turning.

So some slop could have been introduced there, after compensating for those faults the engine still would not idle.

We stood there for a long while shaking our heads, I mentioned that I had tried the distributor from the 2.4L but it had not made any difference but Laverne said "What do we have to loose?" So we installed the old dizzy with the Pertronix magnetic pick-up and it started idling roughly, while Lavern tweaked the carbs I breathed in the sweet smell of exhaust loaded with raw un-burnt gasoline...intoxicating!

So, what was the fix? It could be this is one of those Z's that refuses to run with a HEI ignition module, or a combination of that and the oil pump/distributor shaft was one tooth off. It could also be that the old SU's although good enough for a tried old 2.4L were just too far out of adjustment for this healthy new engine when I tried the old distributor the first time. Whatever the answer is I'm glad it's over, Not very satisfying for you sleuths who helped so much but I really do appreciate all your help.

The Cheeseburger Demon Squirrel Award goes to.... you guys figure that out. I started working on it tonight, I should have it together in a couple of days.

Chris

[beermanpete]

Awesome! It sounds like a lot of liitle things that added up rather one single problem.

[madkaw]

Not a real definitive source of the issue, but it sure sounds like timing way advanced maybe? There's another thread going on that has haunting similarities.

Glad you get to move on!!

[EuroDat]

Grats Chris. You finally got the bugger going;). No real "That it" answer, but more a combination of things which make it harder to diagnose.

Now you can enjoy it before the summer is over:cool:

[madkaw]

Chris,

You kind of threw us a curve ball. You never mentioned that you removed the oil pump during engine swaps- which I wouldn't have assumed since its not necessary. Since you said the motor ran great before hand we were all thinking of things you might have touched, but I didn't figure on the oil pump.

Anyway, it made for interesting reading

Edited June 29, 2013 by madkaw

[Zed Head]

Going to the most basic of basics, you should have been able to choke off the air supply to control idle speed. The engine will only spin as fast as it can pull in air to burn. The fact that you couldn't get the idle speed down suggests that you had extra air coming in from somewhere. The only air supply the distributor might supply would be from the vacuum advance canister, leaking. Just a thought.

[grannyknot]

Chris,

You kind of threw us a curve ball. You never mentioned that you removed the oil pump during engine swaps- which I wouldn't have assumed since its not necessary. Since you said the motor ran great before hand we were all thinking of things you might have touched, but I didn't figure on the oil pump.

Anyway, it made for interesting reading

I never removed that oil pump, the engine would have run for the PO with the oil pump shaft in that position, weird,

perhaps the distributor faults didn't have as much effect as I thought. I'm still trying to figure out what I did wrong when I swapped the 2.4L distributor into the new engine the first time. I'm pretty sure I wired it the same as it is now but I've always been bad with my notes. But from what I remember I didn't keep the old dizzy in very long once I found that the engine wouldn't fire up, I should have pursued it a little longer, that and taking proper notes would have saved me lot of headaches.

[madkaw]

Hmmm, that is weird

[colinc]

Chris,

I agree with the Captain "two heads are better than one". As I mentioned in post #15 there are some great people in our local club that may lend a hand (don't get me wrong,the knowledge base on classiczcar is phenomenal but its hard to fix something you can't see). I spent 6 hours with ont240 the other day while he worked his magic on some crap rebuilt carbs i got on eBay. After stealing parts from my old carbs he actually got these things to run extremely well.

Just a thought.

I told you laverne (aka ont240) was the guy to call. He has an incredible amount of knowledge and just never gives up until the job is done. Can't wait to see a video of the car peeling out of your driveway.

Edited June 30, 2013 by colinc