gerg

I thought of that too, but gripping such an irregular shaped body in the vice isn't easy, it would be best to make up some kind of jig for it in that case. Knowing my luck, the body would jump out and Chernobyl itself in the cutter head or something dumb like that

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Ok into it today... After inspecting the threads in the body, I found another one mostly stripped. So I made the leap and punched all of the base screw holes out to take M6 Phillips head screws.
 
Firstly, I made sure all gasket surfaces are flat by hand-filing them down to an even finish, progress shots show how important this is due to casting warpage over time (possibly even during manufacture).
 

 

 

 

 
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Bah ha ha..........that's never happened to me. Not even once....
 
Small drill press mill with a fly cutter, and cross drive table would be nice.

Yup, reckon you're right.  I have watched a guy on Utoob who actually mills the faces to get them flat again, Serious carby guy.! 

I was thinking the same thing Bear, the surfaces aren't machined so maybe they rely on thick gaskets to take up any wonkiness in the as-cast finish.

Holleys in particular have lots of circuits going through tiny passages in the gasket surfaces, so any small gaps between these circuits might have cross-feeding and affect the tune.

For a carby that's made in Japan, I can't say the casting quality is terribly good. Maybe Holley farmed it out to a Japanese factory very early on when Japanese quality wasn't quite what it had become by the 80s. These were a 70s replacement for a Quadrajet so I guess they may have cut corners to get it to market quickly.

I don't really know if making everything dead-flat has an effect on how well it works but I figured it wouldn't hurt do do it right while it's in bits

Those blank holes@gregaust mentioned are the ones that go under the power valve cavities? I drilled and tapped those too so I now have 8 x 6mm screws holding it all together.

Next is assembling the bowls and internals... And buy a wideband kit to tune it

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Master at work. They are shockingly warped, all the ones I've pulled apart.  Maybe that's why the gaskets are so thick.?  😂

Ok into it today... After inspecting the threads in the body, I found another one mostly stripped. So I made the leap and punched all of the base screw holes out to take M6 Phillips head screws.
 
Firstly, I made sure all gasket surfaces are flat by hand-filing them down to an even finish, progress shots show how important this is due to casting warpage over time (possibly even during manufacture).
 

 

 

 

 
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I spent yesterday afternoon making all the engine bay brake lines
 
not bad for a first timer 
 
 
 

Cheers, mate.  I got a new power valve in the Holley kit, but, was interested in the numbers.  
 
I tried my local Adelaide Speed shop (Outlaw), and VPW, nil stock....
 

LOL. Just doing the same thing here.........
 
 
 

Well mum finally arrived with my Holley... imagine a woman in her 60s going through airport security with a big lump of 4 barrel carby in her bag
 
Carby looks good on the outside, throttles are a bit stiff, the lever that's peened onto the throttle shaft is flopping around like a cock in a sock, filled the bowls with wash solvent and worked the throttles, no acc pump working either end, but no obvious fuel leaks there generally.
 
Choke port hadn't been blocked after choke delete, so would have had a vac leak there.
 
Gaskets all came off intact, but there were signs of moisture and dried fuel in everything. Acc pump diaphragms both solid, crunchy and falling to bits. Bowls are a bit corroded but floats and needles seem fine.
 
Someone's been in this carby before, as the jets don't seem anywhere near right for the application.... 57 front, 68 rear. They should be more like 60 front and somewhere in the 70s or 80s rear.l, especially since this one doesn't have a rear power valve so needs extra jetting to compensate.
 
Some missing/bodgy screws in the base plate, missing circlip on the primary pump arm, all choke hardware has been deleted. Also they'd pinched an o-ring on the fuel transfer tube, so it would have pissed fuel everywhere.
 
Primary power valve seized open, and unmarked (likely to be standard 6.5)
 
Throttle shafts seem tight without slop, now freed up with a bit of solvent and working.
 
Overall, it looks like it had done a lot of work then sat around for years in storage, but the biggest issues with it are bad assembly and missing parts, all fixable with a rebuild.
 
Here's what I can see so far:
57 primary jets
68 secondary
25 primary squirter
37 secondary
White primary pump cam
Brown secondary
Unmarked power valve
Secondary blanked off
 
Pinched o-ring

 
Buggered diaphragms

 
Made in Japan!

 
Lots of carbon buildup in the power valve cavity

 
Blanked off power valve

 
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You'll be happy with a warmed over Clevo. Don't overthink it, just carb, cam, inlet manifold, ignition and extractors.
 
Don't rev her over 5 grand, last for years and enough torque to pull a house. If you want to go racing.......well, that's a WHOLE different Cleveland.

Well mum finally arrived with my Holley... imagine a woman in her 60s going through airport security with a big lump of 4 barrel carby in her bag
 
Carby looks good on the outside, throttles are a bit stiff, the lever that's peened onto the throttle shaft is flopping around like a cock in a sock, filled the bowls with wash solvent and worked the throttles, no acc pump working either end, but no obvious fuel leaks there generally.
 
Choke port hadn't been blocked after choke delete, so would have had a vac leak there.
 
Gaskets all came off intact, but there were signs of moisture and dried fuel in everything. Acc pump diaphragms both solid, crunchy and falling to bits. Bowls are a bit corroded but floats and needles seem fine.
 
Someone's been in this carby before, as the jets don't seem anywhere near right for the application.... 57 front, 68 rear. They should be more like 60 front and somewhere in the 70s or 80s rear.l, especially since this one doesn't have a rear power valve so needs extra jetting to compensate.
 
Some missing/bodgy screws in the base plate, missing circlip on the primary pump arm, all choke hardware has been deleted. Also they'd pinched an o-ring on the fuel transfer tube, so it would have pissed fuel everywhere.
 
Primary power valve seized open, and unmarked (likely to be standard 6.5)
 
Throttle shafts seem tight without slop, now freed up with a bit of solvent and working.
 
Overall, it looks like it had done a lot of work then sat around for years in storage, but the biggest issues with it are bad assembly and missing parts, all fixable with a rebuild.
 
Here's what I can see so far:
57 primary jets
68 secondary
25 primary squirter
37 secondary
White primary pump cam
Brown secondary
Unmarked power valve
Secondary blanked off
 
Pinched o-ring

 
Buggered diaphragms

 
Made in Japan!

 
Lots of carbon buildup in the power valve cavity

 
Blanked off power valve

 
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Looks like a very light tidy up, only taking off sharp edges around the bowl, short turn and guide. Still, an improvement on stock for sure.

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🤔 I'm leaning toward the roller... Options soooooo many options.
Maybe I'm overthinking it...A standard 351C will feel like a rocket after driving 3.0 TD Nissan Patrol (daily driver) 😂.

Gerg is right, Vizard is a head working legend.
When you get right into his head work you realize HOW smart he is.
He was into 2L pinto motors in the 70's.

It's not all about just grinding stuff out, any dill with a die grinder can go that... And muff it up.

It's about the approach angle of air and velocity at the back of the valve.
Sometimes metal or resin is added to the port to change the approach angle of the air.
Then you want to go further its valve relocation. That's how it's done properly.

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David Vizard has been a prominent author of performance books since the 70s and is a successful race engine builder and performance guru. He's been around since before aftermarket parts were a thing so knows how to squeeze every last bit of performance out of factory parts while at minimal cost.

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Vizard did an episode on valve shrouding and it's interesting to see his view on it. He takes the bare minimum to achieve the results and no more. It's all in where you remove metal and not how much

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David Vizard has been a prominent author of performance books since the 70s and is a successful race engine builder and performance guru. He's been around since before aftermarket parts were a thing so knows how to squeeze every last bit of performance out of factory parts while at minimal cost.

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Vizard did an episode on valve shrouding and it's interesting to see his view on it. He takes the bare minimum to achieve the results and no more. It's all in where you remove metal and not how much

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The castings from 1970 were average at best, if you stick a standard inlet gasket onto a small port Clevo head you'll see what I mean. I'm not talking full port and polish, just match the inlet port, to the manifold, exhaust port to the extractors, using a store bought gasket. It's not hard work, just a lick with a die grinder, its free HP...
 
Unshrouding the valves is great if you know how, but, not for the beginner. The hours involved in getting all 8 ports to flow similar, and the added weight of cast iron, just cheaper to buy an aftermarket head. They weren't around 25 years ago, so keen builders did what they could. Nowadays you can grab some AFD, CHI, or SCM heads. 

diff ratio dictates the revs at 100kmh  see below. 
 
is it a 3.75 ratio diff ?
2.75 is the highway standard standard gears most LTDs etc got, they'd have you doing about 2250rpm at 100kmh.  (make sure the cam choice is ok to cruise on that if so)
3.7 (not 3.75) would be doing about 3000ish from My calculations at 100kmh.  
 
your 3.75 number doesn't sound anything i've heard before. so probably should confirm what it is.
 
 

Good choice in parts thus far. I would at minimum, clean up the ports on the 2Vs as they can be pretty terrible in the casting. I did that on mine and despite only having only about 3 hours in them, I would guess that they're easily 10% better in flow. A properly cleaned up set of iron 2Vs should be good for 400hp.

Before getting them skimmed, determine what compression you want to run (thus chamber size) and pistons (stock rebuilders or good zero deck ones). The compression number hinges on what cam you are running by figuring out what dynamic compression you actually will have. I have said for a long time, pick your camshaft and build the engine around it.

Upgrade valve springs to suit cam specs, get heads done up and guides machined to suit press-on seals. Up to you if you get the rocker pedestals machined to suit stud mounted rockers, it does allow a bigger selection of rockers but there are decent pedestal mounted ones out there, namely Yella Terra and Scorpion. Stock steel rockers aren't a deal-breaker, they just work the oil harder and can't deal with much above 0.500" lift and/or high spring pressure.

Many folks on here have had good results with the Comp 268 and 274 cams, but for any cam aim for around the 220 mark at 0.050" give or take. I would save up for a retro roller cam in that range only because I've wiped 2 flat tappet cams on my clevo in less than 100,000 km. It's getting harder to find good oil to suit flat tappet cams now.

Your inlet manifold can be the stock iron 4 barrel, but if you can stretch to an Edelbrock air gap that would be a no-brainer. The other good name manifolds are probably only slightly better than the stock one (which isnt bad) but you'll save a lot of weight up top using them. Don't use cheap Chinese ones. They are poorly made clones and they rob the original designers of their hard work. Their cylinder balance will also be poor.

Using the hotrodder's rule for carbys, take target HP and double it to get the CFM you need. So either a 750 vac or pumper will be perfect. These are said to be the sweet spot for size in a square bore carby.

4-into-one headers are obviously ideal but are a tight squeeze in an earlier narrow chassis. Tri-Ys are a good compromise between stock manifolds and proper tuned length 4-1s.

1 horse per cube shouldn't be too hard in this day and age. If you do get it chassis dynoed though, don't be too disappointed by the figures. My 302 gets along ok but didn't even crack 200 hp. I know my cam is drastically holding it back for top-end power but I like the low and midrange it has.

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Hi Bear,
 
Thanks for your input as well,
 
Sorry about the message and then the addition of the topic, Greg doesn't accept direct messages lol, added the topic hoping he would answer.
 
Greg,
 
3500rpm on the highway no thanks😳. I will need to revisit the cam.
 
Great input, I really appreciate it.

I think the 4V issue is on the inlet, not exhaust side. Plenty have done that though, so maybe even that's not an issue as such, but maybe considered just not worth it?

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