Super unleaded

[v8rumble]

Thought I would try some of this super fuel with the theory that the super fuel might help the higher compression.

Car is holding back under hard acceleration and farting, wondered if it is the super fuel or look elswhere.

Was running not too bad before.

Running 383 totally stock bar an Edelbrock carb.

Any thoughts

[Pete]

It's not the fuel.

My 11:1 engine did not knock on the Dyno at 34 degrees advance on Shell V Power Super Unleaded.

You have other issues - check you ignition timing first.

[v8rumble]

Thanks for the reply

That is what I thought but it coincided with the change so just thought I would check.

Love the car by the way

[Pete]

The fuel you bought may have been contaminated....

[v8rumble]

Ha ha now youn have thrown a curved ball lol

Will have to check the whole system through

[Dave999]

in theory the higher the octane the slower and more controlled way it burns...

so in theory if its burning slower you could have introduced a stumble from and overly rich condition caused by that.

however the difference is minimal so i'd suggest the problem is elsewhere.

new or cleaned and re gapped plugs...start at standard gap unless a special ignition is installed, set timing.

i.e simple things first before fiddling with carbs



Dave

[Dave999]

Just seen its an Edelbrock
get it to drive nice on the primaries only first

the secondaries are tuned (air fuel wise) with either a weighted or spring loaded air flap fandango keep it shut and don't go past the stiff bit on the throttle where the secondaries start opening until primary operation is perfect

from what i remember the weaker the springs on the rods the earlier RICH comes in, vacuum puts you on the fat bit of rod, a lack of it moves you to the thin bit. the rods go through a jet, fat bit of rod limits flow more than thin.
the springs i think push the rods up to the thin bit.... I think....distant past...... i sold my edelbrock to Matt years ago.

use the manual to choose primary and secondary jets and initial start point for rods
or if the motor is mostly standard email edelbrock and ask....

get the rods and jets right first then tune away the Lump with the springs

this will drive you round the bend

its way too easy to be very rich or lean in the middle and perfect at either end

https://www.edelbrock.com/pub/media/wys ... manual.pdf

do timing and plugs first.... and you will need more initial than any book written in the days of 4 star petrol says.. and you may need to limit total advance with a limiting plate in the dizzy FBO and a number of others do a limiting plate for mopar dizzys. the more refined and efficient a motor is the less total advance you need.
the more crap and ethanol addled the petrol is the more initial advance you need and a standard 1968 dizzy doesn't do that without help. modern petrol runs hotter and burns slower than old 4 or 5 star any super blend other than BP has been made super via an additive package that includes more ethanol which is what causes the hotter running

[Steve]

just following on from what Dave has said, worth getting an Edelbrock tuning kit. It has loads of springs, metering rods etc in it and all you need to match your carb to the performance chart in the manual.... after checking the basics as previously stated (timing etc). I paid about £40 off ebay. A quick search popped up a few, but bit more expensive so worth shopping around. RPM do an aftermarket kit too, bit cheaper but not sure if same quality.... These links are based on my 1406 on my 383..

https://www.ebay.co.uk/itm/1487-Edelbro ... SwNSxU0NRR

https://www.ebay.co.uk/itm/Edelbrock-Ca ... SwFV9XzdoG

Cheers Steve