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Carburettors on B20 Fuel Injected Engine[ALL/1998] posted by Earl Huff on
Monday, 29 September 1997, at 1:55 p.m.
I just discovered that my B 18 engine is beyond rebuilding. I'd like to replace it with a B20. Can I use my SU carbs and manifold on a fuel injected B 20 engine. If so, what modifications are necessary?
Re: Carburettors on B20 Fuel Injected Engine[ALL/1998] posted by Brian T. on
Monday, 29 September 1997, at 7:24 p.m.
On the B20, you'll need to buy the plugs to fill the injector holes in the B20 head. Just put the SU carbs on and it should be fine, or you may need to put richer jets in them. I think IPD can help you with the correct jets if they're needed. ---Brian
Re: Carburettors on B20 Fuel Injected Engine[ALL/1998] posted by Jarrod on
Monday, 29 September 1997, at 7:58 p.m.
I've seen it done. The exhaust/intake manifold mount right up no problem. People will tell you different in some quarters but they are wrong.
The injector holes can be filled with 3/8" frost plugs coated with that copper silicone goop. See Plugging the Holes thread.
As for the jets. Give IPD a try but I think Swedish Classics has them (see my Parts Resource Page.
While you have the manifold off, I have heard it is worthwhile to port and polish the manifold. A cheaper way around this is to remove the intake portion of the manifold sandwhich from the carbed B18. THEN, you use the intake portion with the exhaust manifold from the FI system. WHY? Motorheads will tell you that the FI exhaust is less restrictive than the carbed variety. I drove a 140 done this way (jets to boot) and it really smoked. I tell ya it had far more horsepower than any other early Volvo I have driven.
Oh yeah, you'll have to plug that funky preheating deal that comes off the head on the top left. I just looped it back into the engine for a quick fix. Someone told me the merits of aluminum cutting. You can cut a custom part very easily with a band saw, fine tune it with a file and seal it with gasket compund.
I have an extra set of SUs if you want them for parts. Got a lot of other stuff too. Want a headliner for a 140? How 'bout a known-to-be-working alternator? A similar starter? Chrome for a 140? It's all going cheap.
I need to get rid of this stuff.
Anyway, good luck on your swap. The B20 FIs with carbs are really great. Many will tell you this.
Later,
-jarrod
Re: Carburettors on B20 Fuel Injected Engine[ALL/1998] posted by Jim McDonald on
Monday, 29 September 1997, at 9:38 p.m.
Re: exhaust manifold
As far as I can tell, the interior of the carb and injected exhaust manifols are the same. There's a lot more metal in the carb version, though, so it isn't as subject to cracking as the F.I. part.
Re: Carburettors on B20 Fuel Injected Engine[ALL/1998] posted by justin on
Tuesday, 30 September 1997, at 11:51 a.m.
I have considered this conversion on my FI B20 as well. But My question is: Is the FI part you refer to, presumably the intake manifold, prone to cracking as you imply? If so, what are the areas I need to inspect?
Re: Carburettors on B20 Fuel Injected Engine[ALL/1998] posted by Jim McDonald on
Tuesday, 30 September 1997, at 12:25 p.m.
No, it's the exhaust manifold that's fragile. Usually the "arms" try to fall off after extended use. I've had a couple welded several times, but eventually they oxidize to the point where they can't be welded. I've never even cracked a cut-down carb version[from the later one-piece intake and exhaust].
Re: Carburettors on B20 Fuel Injected Engine[ALL/1998] posted by justin on
Friday, 3 October 1997, at 11:12 a.m.
OK, just to be sure, the intake manifold is replaced with a carbed model? The FI exhaust manifold is left in place, although it is more prone to cracking than the carbed model? Just want to have all the facts for when my FI system goes south. Thank you.
Re: Carburettors on B20 Fuel Injected Engine[ALL/1998] posted by Jon K. Evju on
Friday, 3 October 1997, at 10:25 p.m.
I've been following the list of advice you've gotten, since I once did the same thing myself. You're right on. The Intake manifold has to be changed to get the carburators to bolt on. You can (and ought to) keep your current exhaust manifold if your donor car has split intake/exhaust ('61-'66). If it has a one piece intake/exhaust ('67 and newer) manifold, then you have to either split the two apart with suitable tools as has been done and was suggested, or you need to replace the exhaust manifold as well, which may result in some loss of performance. (I don't remember the years that the differrent kinds came for sure, but I think what I have above is correct ?).
Now, I don't recall seeing this mentioned, but I think you need to replace the fuel pump with one that's designed for carburated engines, either the mechanical kind from the donor car (reliable) or an electrical one (some are reliable, some are not).
Also, I think I saw someone explain how to get the correct jet sizes. I never did. It worked fine for two years of my daily 2x45 mi commute (ave 18-20 mpg) and my wife's 7 day 60 mi rural paper route (ave 16-18 mpg), even @ -36F, until the day the head gasket blew and the clutch wire broke. It could easily be that it would have been faster or more economical with the right jets; I was just happy it ran.
If it is the newer style FI that you have (like on a '75 240), you won't have to buy plugs to seal the injector holes. Quarters are the right size... I had 4 "tails".
Re: Carburettors on B20 Fuel Injected Engine[ALL/1998] posted by Brian T. on
Saturday, 4 October 1997, at 12:31 p.m.
The problem with the pre-'67 exhaust manifolds is that they have a single header pipe. '67 and up are dual pipes. It makes a difference in performance. I wanted a dual pipe for my '65 and got an exhaust manifold off a '72 142E. I don't think any of the injected cars have joined int/exh manifolds since "preheating" is not required. If you do have a joined set of manifolds, though, you can still cut them with a hacksaw. I did it to my wife's '67 when I put a Weber on it and it's no big deal. ---Brian