Dead old 750 Holley - Resurrected !
Well ! I finally got a kit, and TIME to get this thing done. I've had projects come in, and honey-do's to perform, so here we are !
The tasks today are pretty straight forward... Get some measurements to get some of the guesswork out of tuning, and assembly.
First up, baseplate to body.
Now, @mopowers asked if I intended on converting this carb to 4 corner idle. GOOD QUESTION ! answer, no..
As you see below, this baseplate has an open cavity occupying the space needed to drill idle feed holes at the bottom of the secondaries. (green arrows) As you can see the primaries have. (blue arrows)
HOWEVER: there is small idle feed holes (.022"), on the secondary side, in the same location as the primaries AND transfer slots. (fed via channels in top side of baseplate, see below) I chose to leave these sec idle feed holes at .022".
Moving on...
Observing tradition, I have left out the base screws (red circles), in the event they decide to back out and race their way to a piston. (nice view of the thinned throttle shafts)
I found a potential problem with the primary block/body gasket... No hanging chads in my shop !!!
can't have this come loose and create a shooter issue..
I did find an issue with the PVCR. They were not drilled completely through on one side.
I fixed it.
The balance of the assembly was without incident and straight-forward.
I did want to include one of the measurements I found surprising. Usually the Idle Feed Restriction (IFR) in a OE Holley is .029". This one is .033" Which is about what I would have drilled to for a larger cam motor. (250°@ .050 on up)
Primary:
IFR: .033
PVCR: .061
PV: 6.5 (window)
jet: 76 (OE 75s)
Pri shooter: 031 Generic cam (equivalent to blue cam)
N.S.: .150
Secondary:
IFR: .029 (drilled but not functional to base)
jet: 78 (OE 76s)
PVCR: blocked (OEM)
shooter: 032 Generic cam (equivalent to blue cam)
N.S.: .150
As mentioned in previous the last post, I've added a manual choke:
At this point, I thought I was done but, I discovered Holley doesn't make a throttle adapter for this carb.
So I had to improvise (red arrow) I also spun out a custom KD link (orange arrow)
And here she is !! don't laugh, she's embarrassed about her worn plating..
The bag has the base screws I didn't install, along with the OE secondary throttle opening adjuster.
Now! I've got bad news, and good news. My customer doesn't want it... Moved on to a bigger carb. (440) The good news is, it is now FOR SALE!
Holley 750 4779 (flowed)
Well ! I finally got a kit, and TIME to get this thing done. I've had projects come in, and honey-do's to perform, so here we are !
The tasks today are pretty straight forward... Get some measurements to get some of the guesswork out of tuning, and assembly.
First up, baseplate to body.
Now, @mopowers asked if I intended on converting this carb to 4 corner idle. GOOD QUESTION ! answer, no..
As you see below, this baseplate has an open cavity occupying the space needed to drill idle feed holes at the bottom of the secondaries. (green arrows) As you can see the primaries have. (blue arrows)
HOWEVER: there is small idle feed holes (.022"), on the secondary side, in the same location as the primaries AND transfer slots. (fed via channels in top side of baseplate, see below) I chose to leave these sec idle feed holes at .022".
Moving on...
Observing tradition, I have left out the base screws (red circles), in the event they decide to back out and race their way to a piston. (nice view of the thinned throttle shafts)
I found a potential problem with the primary block/body gasket... No hanging chads in my shop !!!
can't have this come loose and create a shooter issue..
I did find an issue with the PVCR. They were not drilled completely through on one side.
I fixed it.
The balance of the assembly was without incident and straight-forward.
I did want to include one of the measurements I found surprising. Usually the Idle Feed Restriction (IFR) in a OE Holley is .029". This one is .033" Which is about what I would have drilled to for a larger cam motor. (250°@ .050 on up)
Primary:
IFR: .033
PVCR: .061
PV: 6.5 (window)
jet: 76 (OE 75s)
Pri shooter: 031 Generic cam (equivalent to blue cam)
N.S.: .150
Secondary:
IFR: .029 (drilled but not functional to base)
jet: 78 (OE 76s)
PVCR: blocked (OEM)
shooter: 032 Generic cam (equivalent to blue cam)
N.S.: .150
As mentioned in previous the last post, I've added a manual choke:
At this point, I thought I was done but, I discovered Holley doesn't make a throttle adapter for this carb.
So I had to improvise (red arrow) I also spun out a custom KD link (orange arrow)
And here she is !! don't laugh, she's embarrassed about her worn plating..
Now! I've got bad news, and good news. My customer doesn't want it... Moved on to a bigger carb. (440) The good news is, it is now FOR SALE!
Holley 750 4779 (flowed)
