> I've had to disconnect the vacuum advance pipe from the Holley 390cfm to the
> 35DM8 dizzy as there's just too much advance on part throttle (40-60mph) and
> the car jerks violently.
What rpm does your 40-60mph speed correspond to ?
Are you using the ported vacuum source which is on the metering plate ?
If you use the vacuum source at the base you will get too much vacuum.
> I've tried various idle advances and 6 BTDC seems best,( with the vacuum
> line off), throughout the rev range on steady throttle but it feels a bit
> sluggish accelerating.
The normal bob weights allow a nominal 26 degrees mechanical advance
which will give you 32 degrees total timing. This is pretty close to
optimum (which is normally reckoned to be 34 degrees total timing). The
standard springs bring this in too slowly though with max advance not
reached until 4000-5000 rpm. Real Steel sell a Moroso spring kit that
can be used to adjust the rate of advance. Best performance is obtained
with the timing all in by 3000-3500 rpm. I have tested a couple of
DE8 distributors and they never seem to give the full 26 degrees of advance
with the standard springs.
I assume you have a standard cam ? Most modified cams give the best idle
at 14-16 BTDC. If you recurve the distibutor to limit the mech advance to
an additional 18-20 degrees and use the right springs to bring this all in
by 3000-3500rpm it makes the engine a lot more responsive.
There is a book called something like 'How to Modify and Power Tune
Distributor Based Ignition Systems' by SpeedPro that explains all this
in detail.
> Last bit, are the 35DE8 and 35DM8 vacuum advance units the same?
I don't know, but again I have tested a number of vacuum modules on the
DE8 and their advance varied a lot. Some capsules produce as little as
10 degrees and others produce 15+.
Ian
P.S. I'm new to this list and find the setting of the 'reply-to' field a bit
confusing - on all other lists I have used it is set to the list rather
than the person who sent the original.
--
"He began by pitying him for his sufferings, while exhorting him to rejoice
in them, since it was the will of the Lord." - Flaubert (Madame Bovary)
Ian Crocker ian@btcase.bt.co.uk http://www.geocities.com/MotorCity/9190/
--
"He began by pitying him for his sufferings, while exhorting him to rejoice
in them, since it was the will of the Lord." - Flaubert (Madame Bovary)
Ian Crocker ian@btcase.bt.co.uk http://www.geocities.com/MotorCity/9190/
|