Lizz

[CatBox]

have you ever checked for coil bind on the springs? 

this is where the valve opens to far and then the spring is forced against itself and then is breaks.

you have to measure the installed height of the spring at full open and full close and then compare those numbers to the numbers for those springs.

you could also check for piston to valve clearance.

on way to check for proper clearance is to put some playdough on the piston and then cycle the engine (fully mocked up with complete valve train) through a couple of cycles while on the stand with a wrench. 

take the heads off and then carefully slice the thinnest spot of playdough and measure the clearance to see if you are to close.


as for this number Scat: C20 277 duration with .352" lift (with 1.1:1)  i believe that number is to small.  .338" X 1.1= .372" lift.  not a biggie probablly a typo any how.

what kind of pushrods are in your engine?

did you step up to heavier duty pushrods when you built the motor?

if not this may be a concern as the stock ones are just that, good for stock.  step up to a better cam or bigger ratio rockers and the stockers might not be up to the task.  Aircooled.net sells HD aluminum ones that i have read that people are happy with. 

this is all speculation on my part from the reading i have done for my own interests. 

perhaps it is time for some outside intervention from one of the others.

shop day?

 ;D

[Smug]

Coil bind and piston clearance have been checked and are fine. BTW still spitting fire out the carb. I am going to try the standard rockers next... As for the rods they are bug pack HP rods. Stock length which may be the core issue.

Again I am still guess so keep firing off thoughts :)

[CatBox]

how would the rods be that issue?

this is a stock throw crank at 69mm right?

if they are stock length then there shouldnt be a problem.  nothing should have changed with what they are doing.  if they were longer than that would just increase the piston speed and not much else.

perhaps you should post this on the DRAMBA and ask about it in the performance forum.  there are some no talent hacks, but alot of quality builders pipe up frequently and they are generally very knowledgeable and willing to help.

they like pictures and your car is nice so they might just help faster....

[CatBox]

ya know i just sat down with a book and some ice cream to do some reading for you and it just came to me.


it sounds like you have a valve that is not closing all of the way.

with all of the equipment changes that youi have made with the same result happening every time, this makes the most sense to me.

new heads....fire breathing carbs

new cam....fire breathing carbs

more new heads...fire breathing carbs

broken valve spring....

Hmmmmm

 ;D

[Smug]

I am with you on the open valve item... The current set of heads are complete from CB the 044 case. They do the valve grind and all of that before they sent them to me.

Leak down test shows that the valve closes. It is not closing at the correct time or I am sparking at the wrong time.

Timing is set for 5 degrees before TDC at 900 RPM
Valve clearance is at .006" cold and yes I set each piston to TDC and set the valve gap individually. 

I keep looking at the timing and wires and this and that. By the way the standard 1.1:1 rockers did not fix it (surprise!) but I had to try.

Doing the basics too; cap, rotor so on. I have that Flame Thrower II ignition and I am about to remove that as well. It's an Easter egg hunt one item at a time until it stops the fire. Then I can put the add on items back on...

I changed the wires and am trying to now run them and not let them touch each other anywhere along the way. I don't know just guess still.

[Kev]

Some of the ignition stuff makes sense.  You must be getting ignition in that cylinder before the intake valve closes all the way, otherwise you would get lotsa noise without the fire.

[Smug]

She's Alive! Ok I still need to put a few parts back and do shake down cruise but it runs with out spitting fire!

Swapped out the carburetors... May have some crap in the others so they will get a cleaning treatment before they ever go on a car.

Big thanks to Mark! he came over the last two nights and walked through things with me. Sanity check for me to have some one else scratching their head.

Hoping to start driving her to work again as soon as Thursday.

[Kev]

poop Hot!  Good Job!

[Kev]

oops I may have been too enthusiastic on that last reply!  Anyways, what was the issue anyways?

[CatBox]

thats Bin'

welcome back to the world of the daily driven bug

[Smug]

Looks to be plugged jets or something of that nature in the old IDF's (carbs).

In the end the motor is probably built to support a daily driver.

Mild cam, mild carbs, mild exhaust and lowered just a little :)

Can't wait to put it all back together and really start driving her. Hoping to focus on some of the house projects so that this winter I can start in on Dixie.