_Remi

What kind of improvement did you feel when you installed it?

Starfury

The improvement comes from correct timing, not the fact that it's a fancy new aftermarket distributor. You could probably recurve your factory distributor and come out with a similar result.

htwheelz67

the edels probably dropped compression and increased flow dramatically. You probably want to add some pump shot and increase initial timing a bit. The best thing you could do is throw in a cam to make the cyl heads work, with the stock cam you probably picked up about 20-25 hp in the mid and upper range but just when the heads start working the stock cam stops working. What rocker arms are you using? If a cam change isnt in the mix then 1.7 rockers could help, even just on the intake side. A cam that increases cyl pressure like the old high energy 260-268 would really help with the compression drop and probably add another 50 hp with those heads.

_Remi

Hi guys,

Update on my problem!

I went to my new mechanic today (Nick Rescino Performance Engine in San Francisco - plenty of good reviews and very nice guys) to have my new MSD distributor installed. That's one of the ready to run. They removed the old one, the reset the timing and I went for a ride to try it. I felt some improvement and the whole feeling was that driving was smoother (but not completely 100% smooth which probably makes sense on a old car). I did not hear any misfire and assumed the problem was fixed.

After leaving them, I took the freeway and enjoyed my new heads and the 40 series Then, for some reason, after the exit, I heard a misfire right after reaccelerating. I was scared but assumed it was random. I parked the car and when I took it back after a couple of hours (i.e. car was cold but not crazy cold, it was sunny today in San Francisco), I had the exact same problems : misfire, car is about to stall, seems to take a long time to warm up, basically impossible to really accelerate. It really reminds me of the worst times when I still had my points. When it gets warmer, it is better (and that's why I did not see it after leaving the mechanic), however, it is not perfect and it was really better before my head swap

At least, we now know that it cannot be the distributor... Any suggestion?

Thanks!

htwheelz67

next step is the carb, I have a feeling your A/F ratio is way off. I would also do a compression check, I would bet your psi will be around 120-130. Once again, what rockers and pushrods are used?

racin66coupe

what kind of carb are you running?

_Remi

Thanks for your feedback!

I run a Holley 600cfm carb that is one year old. It was working perfectly fine before they heads were changed.

I don't know about rockers and pushrod, I just know that while changing the heads, they swith to roller rocker arms.

About the AF ratio, how does the engine being warm reduces the problem?

rmodel65

i wonder if one of your pushrods is too long, letting a valve stay open

_Remi

Is this something that my mechanic can easily check?

My understanding is very basic but because the heads + roller rockers were changed, I can see three main reasons:

- Better flow means a new fine tuning and that is not the case
- Something is wrong with the heads (is it possible?)
- Something is wrong with the roller rockers

I will be using your inputs when I call him today.

_Remi

Another update, I am back from my mechanic.

It is definitely not the timing, they changed it a couple of times and the misfires were still happening (at a specific RPM like 2k 2.5k, not idle). They took my carb out put another one, same thing to it is not the car either.

They came up to the same conclusion than some of you here: it may have something to do with the rockers being adjusted too tight, that's actually there only remaining suggestion

Unfortunately they did not have enought time to check that today, will do tomorrow at noon and I will keep you posted.