Replacing CD 150 in '69 Alpine

[Shannon Boal]

Maybe folks who have done this will appear and chime in....but, you could slice both and mill so that both slices are flat; any place the thickness is equal. Mount dial indicator to crankshaft, mount alpine bell-slice to engine, Volvo bell slice to Alpine slice loosely with clamps and indicate center bearing bore of Volvo bell slice to zero run-out by tapping back and forth. Drill and pin slices to fix position, and instruct itinerant weldor to join them. After you have done this job a dozen times, it will be simple......

Some wild thoughts have passed through my mind, but were quickly discarded. For openers, the input shaft is about 3/4" SHORTER than the Alpine bell. That pretty much eliminates mating the Volvo bell to the Alpine engine. Also makes making a special plate to go between the trans and Alpine bell. The only viable method would be to graft the small end of the Volo bell to the Alpine bell, which could be shortened enough to compensate for the shorter input shaft. I can shorten then, no problem. Whack them off on the bandsaw and clean them up on the mill. How to properly align them for welding, well I don't have a clue where to start on that problem. Maybe make a plate to bolt onto the engine end of the Alpine bell. The plate would engage the pilot bearing. Set the Alpine bell on the Volvo trans, positioning it to align the Volvo pilot with the Alpine pilot bearing, then weld. Much easier said than done. The Volvo trans weighs nearly a hundred pounds. Oh yes, I can't weld worth a crap, not to mention welding Aluminum. May have to make a plate to set between the two halves in order to mate widely differing shapes. I'm pretty sure that all of that could be done, not at all sure I could. Especially the welding part. Maybe if an itinerant welder happened to appear.

Bill

 

[Bill Blue]

Maybe folks who have done this will appear and chime in....but, you could slice both and mill so that both slices are flat; any place the thickness is equal. Mount dial indicator to crankshaft, mount alpine bell-slice to engine, Volvo bell slice to Alpine slice loosely with clamps and indicate center bearing bore of Volvo bell slice to zero run-out by tapping back and forth. Drill and pin slices to fix position, and instruct itinerant weldor to join them. After you have done this job a dozen times, it will be simple......

How about if I make a shaft that screws into a base plate and is 90 degrees with the plate. Knock the oil seal out of the Volvo bell, insert special spacer that mates with the base plate mounted shaft. Drop the Volvo bell piece onto the shaft, letting it self center. Drop the Alpine bell onto the shaft - it self centers onto the Volvo section, waiting to be welded and the whole thing would be portable! Probably not as accurate as using an indicator that would be inaccessible.
Bill

 

[Shannon Boal]

Well, the crankshaft will have no wobble, though it will have a bit of end float; so it is a good place to mount indicator. (Maybe a magnetic base on the flywheel?)The transmission will not be present, so the indicator can be read through the bellhousing center hole, as you indicate the run-out of same. Also, to follow up, the indicator can come out through the bellhousing center hole, and "sweep" indicate the rear face of the bellhousing. (thinking of distortion from welding plus any other errors.) I think you could be out of square by 0.004" and off-center by about the same, and still work OK. I welded and machined a the rear face of a MG TC block, got it crooked by maybe 0.020", and it worked....not my finest hour!

How about if I make a shaft that screws into a base plate and is 90 degrees with the plate. Knock the oil seal out of the Volvo bell, insert special spacer that mates with the base plate mounted shaft. Drop the Volvo bell piece onto the shaft, letting it self center. Drop the Alpine bell onto the shaft - it self centers onto the Volvo section, waiting to be welded and the whole thing would be portable! Probably not as accurate as using an indicator that would be inaccessible.
Bill

 

[Shannon Boal]

Here is a nicely written article (with pictures!) https://www.holley.com/blog/post/ho...and then check concentricity every 90 degrees.

Well, the crankshaft will have no wobble, though it will have a bit of end float; so it is a good place to mount indicator. (Maybe a magnetic base on the flywheel?)The transmission will not be present, so the indicator can be read through the bellhousing center hole, as you indicate the run-out of same. Also, to follow up, the indicator can come out through the bellhousing center hole, and "sweep" indicate the rear face of the bellhousing. (thinking of distortion from welding plus any other errors.) I think you could be out of square by 0.004" and off-center by about the same, and still work OK. I welded and machined a the rear face of a MG TC block, got it crooked by maybe 0.020", and it worked....not my finest hour!

 

[Bill Blue]

That is a lot work as I have no intention of removing the engine and placing it on a special built stand. I'd prolly send the completed housing through the mill for a cleanup cut and depend on the assembly fixture to determine if the pilot bearing is aligned with the flywheel. With any luck, the Volvo trans is a ball bearing model. It is old enough.
A very important thing that has not been mentioned, the interchangeability of Alpine bell housings. I know the '69 engine is canted over ten degrees. I can accommodate that while mating the two components. But does it matter if the housing is for a non Series V ?

Bill

 

[husky drvr]

But does it matter if the housing is for a non Series V ?

Bill,

Also keep in mind that the '69 bell is ~ two inches deeper than a series Alpine bell, as well as canted.

 

[Bill Blue]

Don, was totally unaware of that fact. I was thinking of using a Series bell. But the bell length is determined by the Volvo input shaft, which is about the length of the Series Alpine's. It would also move the shifter forward 2", very bad news. This presents a lot to think about. A real problem I have to work around is that I have no decent space to work on this car. It is too wide to get through the basement doors.
Bill

 

[Bill Blue]

In the meantime I've completed running the zillion combinations of jet sizes and mods.

The winners are:
Plug the Enriching Circuit
Plug 3 of the 4 progression jets, use only #1
Longer Emulsion Tube with extra air holes
Air jet - .085"
Main Jet - .076"
Intermediate jet - .031" Any size greater than .026" would probably suffice.

It still runs rich, but quite a bit leaner than when I started. If I lean it out any more, WOT @ 4000RPM goes lean. The carb is basically a piece of crap that either runs rich or does not run at all. I guess that is to be expected in a carb designed to produce max power in an air cooled engine in which running lean is a death sentence.

But it did wake up the old iron head! If we can't live with the mileage I suppose a sniper will be next.

Bill

 

[Shannon Boal]

Fantastic effort, Bill! Not many good side-draft carbs out there.....

In the meantime I've completed running the zillion combinations of jet sizes and mods.

The winners are:
Plug the Enriching Circuit
Plug 3 of the 4 progression jets, use only #1
Longer Emulsion Tube with extra air holes
Air jet - .085"
Main Jet - .076"
Intermediate jet - .031" Any size greater than .026" would probably suffice.

It still runs rich, but quite a bit leaner than when I started. If I lean it out any more, WOT @ 4000RPM goes lean. The carb is basically a piece of crap that either runs rich or does not run at all. I guess that is to be expected in a carb designed to produce max power in an air cooled engine in which running lean is a death sentence.

But it did wake up the old iron head! If we can't live with the mileage I suppose a sniper will be next.

Bill

 

[Bill Blue]

For anyone thinking of using one of these carbs, be aware it has no power circuit. That means it cannot cruise at a lean condition, then dump in gasoline when needed for increased power. Maybe that is what the Thunder Jet does, but their web site contains very little information, just claims. You end up tuning for the lowest rich tune that will produce power under load. Tune for an economical cruise, you end up with no power @3,000 rpm and up and not good driveability.. The stock low speed circuit gives very rich low speed cruise when it is tuned for smooth off idle performance. Tune for power and you get good driveability and crappy mileage. How crappy, I don't know. Will post that info when available. All in all, a tuning nightmare. Reminds me of the line Johnny Cash sang "And I put on my cleanest dirty shirt".
Bill

 

[260Alpine]

Bill, This article may give you some ideas:

GRANNYSSPEEDSHOP.COM

 

[Barry]

Deleted for brevity

It still runs rich, but quite a bit leaner than when I started. If I lean it out any more, WOT @ 4000RPM goes lean. The carb is basically a piece of crap that either runs rich or does not run at all. I guess that is to be expected in a carb designed to produce max power in an air cooled engine in which running lean is a death sentence.

But it did wake up the old iron head! If we can't live with the mileage I suppose a sniper will be next.

Bill

A Sniper should be a lot easier to tune and should provide a lot better drive-ability. Is there a down-draft intake manifold that is readily available and suitable for the tilted engine setup in the fastback?

 

[Bill Blue]

My only concern about using a sniper is it's size. I think it might be too large to smoothly handle low speed operation of the 1725. Don't understand why a Snuper would have to be installed vertically. Why not use it as a side draft? There isn't a float bowl, is there? Any downdraft manifold for this head would probably not compensate for the 10 degree tilt. The engine in this series of cars was supposedly tilted because of clearance issues. If so, I doubt those issues disappeared. But that may be a bunch of crap, made up by people who knew nothing. Just saw a tilted engine and said "Look, they tilted the engine because there wasn't enough clearance."

Bill

 

[260Alpine]

Bill, they make a small Autolite 1 barrel Sniper now. It has been used as a side draft successfully in MGB's.

Holley Sniper EFI 550-552 Holley Sniper EFI Autolite 1100 - Gold

 

[Barry]

Bill,

No idea if a Sniper will work in a side-draft orientation. There are no float bowls, but ... Checking with Holley might be a good idea.

The Sniper EFI Autolite 1100 has a 1-7/16" throttle bore and a single 100 lb/hr injector that supports up to 175 HP. I don't see any reason why it would not work well for your application.

Very complete instructions here: https://documents.holley.com/199r12047.pdf

 

[260Alpine]

Here is a pic of sidedraft on an MGB:

 

[husky drvr]

Bill,

For a suggestion a bit off the wall, why don't you consider converting your CD carb to be a TBI with a single injector. Then you could drive it with MegaSquirt. If you pull the vacuum piston and fuel bowl parts, you would have a larger 1.5 inch throttle bore and a lot of empty space in the carb body to refill. Think it's been done by someone, as well.

The Sniper is probably rated about 350 CFM @ 3 inches Hg. to support 175 HP.

If you rerate that airflow to the four barrel restriction level of 1.5 inch Hg., then it would only be considered to be about a 250 CFM unit. The Rootes 1725 at 6000 RPM at 100% would need about 185 CFM. Since the fuel metering is controlled electronically by fuel pressure and not different gradients of atmospheric pressure, and your engine maintains a healthy steady vacuum signal, then the Sniper seems to be a decent fit, if you go that direction.

Just a few thoughts,

edited to correct error

 

[Bill Blue]

The simplicity of installing the Sniper is alluring. So the price. At first glance, it seems pretty pricey, until you consider the package, which includes wide band. About the only extra needed is a proper fuel supply. And the price is not a whole lot more than some carbs. The lure of a faked out CD is strong, but it is more of a Science Fair project. I'm sure that either would beat the pants off of our carb. If we are able to get decent (25mpg) mileage, we'll probably live with what we have.

Bill

 

[Barry]

Bill,

For a suggestion a bit off the wall, why don't you consider converting your CD carb to be a TBI with a single injector. Then you could drive it with MegaSquirt. If you pull the vacuum piston and fuel bowl parts, you would have a larger 1.5 inch throttle bore and a lot of empty space in the carb body to refill. Think it's been done by someone, as well.

The Sniper is probably rated about 350 CFM @ 2 inches Hg. to support 175 HP.

If you rerate that airflow to the four barrel restriction level of 1.5 inch Hg., then it would only be considered to be about a 210 CFM unit. The Rootes 1725 at 6000 RPM at 100% would need about 185 CFM. Since the fuel metering is controlled electronically by fuel pressure and not different gradients of atmospheric pressure, and your engine maintains a healthy steady vacuum signal, then the Sniper seems to be a decent fit, if you go that direction.

Just a few thoughts,

Don,

Single-barrel and two-barrel carbs were historically flow-rated at 3" Hg. vacuum versus 1.5" Hg. vacuum for four-barrel carbs. If the flow rating for the Sniper EFI Autolite 1100 is 350 CFM @ 3" Hg. vacuum (probably a pretty good estimate), then the 1.5" Hg. flow rating should be about 250 CFM.

The relevant question is the actual manifold vacuum at peak power and WOT for the fastback Alpine engine with the factory manifold and a reasonably low-restriction "throttle body." I suspect that the factory manifold would result in something appreciably greater than 1.5" Hg. manifold vacuum no matter what throttle body is used.

Theoretical and actual vacuum and CFM numbers aside, I agree that the Sniper EFI Autolite 1100 appears to be a good match for the fastback 1725 engine package. Run it in closed-loop mode and enjoy the benefits of modern technology. A conventional vacuum canister distributor would work, but I would be sorely tempted to take advantage of the ignition timing control capability.

Sequential port fuel injection is currently the ultimate (neither easy nor cheap) solution for old engines, but short of that, the Holley Sniper TBI package(s) are hard to beat.

 

[husky drvr]

Single-barrel and two-barrel carbs were historically flow-rated at 3" Hg. vacuum versus 1.5" Hg. vacuum for four-barrel carbs. If the flow rating for the Sniper EFI Autolite 1100 is 350 CFM @ 3" Hg. vacuum (probably a pretty good estimate), then the 1.5" Hg. flow rating should be about 250 CFM.

Thanks Barry,

Was between two projects, got in a hurry, and didn't do the "double check and verify" step I used to hear about at work.

Think I got it corrected.