Engine: 140 1778cc B18: Distributor Modification

[Dylan144GT]

Hi All!

I've always been aware of 99% of engine mods but today I had a vision! DISTRIBUTOR MODIFICATION! Its managed to slip under the radar! I'm not very clued up on it and its caught my attention.

Please can someone explain the complexities behind it and to what extent they go. I have a stock B18 engine in a 1967 142. I don't know what the distributor model is but will be checking tonight and I'll post it tomorrow. She runs a single SU carb. I find her very flat in high range rpm and I was wondering if I could make this bearable by a few mods to the distributor. It doesn't have a vacuum advance unit.

Thanks

[DaveTrees]

Originally Posted by Dylan144GT

I have a stock B18 engine in a 1967 142. I don't know what the distributor model is but will be checking tonight and I'll post it tomorrow. She runs a single SU carb. I find her very flat in high range rpm ....

Dylan

What sort of rpm range are you talking ? If it's a stock B18A (low compression head, single SU and "A" cam) I would probably expect it to be "flat" at high rpm ! They really don't make much top end power, or rev all that freely.

I suspect that re-curving the distributor would only be playing at the margins.

IMHO, you would be far better off going to the twin SU + "C" cam setup from a B18B/B20B.

Potentially better would be the "D" cam from a B20E, but I am not sure whether you would get the best out of it with the small valve B18 head ?

Have a look at the attached ....

cheers

Dave

[Dylan144GT]

Dave

Thanks for the reply! Funnily enough, I was going through my 140 volvo manual and looked at the compression ratio of the B18B engine and noticed it was very different from the B18A engine; 10.5:1 rather than the 8.7:1. Then you replied to my thread. Nice little coincidence!

Do you know what the part number is of the B18B head is because I want to see if I can get hold of one. I suppose if I'm going to change the head I might as well change the cam. I think I'll go for the C cam because I did just replace my B20B with this B18A as to get better fuel economy and I'd hate to make those hours spent doing the engine swop pointless! BUT she is horribly under powered at the top end when used to the B20B. I think its from about 3500 that she gets lazy. Granted I am still in the process of setting the carb but I suspect that this wouldn't make much of a difference. She runns very nicely at low rpm. Was actually quite surprised a how little the difference was considering the 200 cc difference and the single carb.

As a matter of interest, do you know whether it is possible to run twin Strombergs on the B18? I have a set on my B20 which I've been told won't work on the B18 but this puzzles me a bit and can't see why it won't work if twin SU's do work.

Dylan

[DaveTrees]

Originally Posted by Dylan144GT

Do you know what the part number is of the B18B head is because I want to see if I can get hold of one.

Various parts manuals available at :

http://volvoamazonpictures.se/docume...in_page_en.htm

and

http://www.gcp.se/svenska/kataloger/nav45896?type=sc

Basically, any twin-carb B18 from a P1800, 120 or early 140 series will have that head. I don't think the heads have a part number stamped on them though ? You would probably have to measure the height of the head ... I have the measurements somewhere ... I'll see if I can find them !

If you can't find a B18B head, you could always just put the cam into it & put the twin carbs back on ? Sounds to me like you would have been better off sticking with the original B20B motor !

do you know whether it is possible to run twin Strombergs on the B18? I have a set on my B20 which I've been told won't work on the B18 but this puzzles me a bit and can't see why it won't work if twin SU's do work.

No reason why they shouldn't work .... the manifolds are the same, and whether the cars came with Strombergs or SUs was very much related to the market they were sold in (most Australian delivered B20-engined cars, for example, came with Strombergs ... mine have been replaced with SUs on the same manifold). You will probably have to put different needles in them to suit the B18 though.

[Snowman]

Interesting thread this.

Can't help but think that any fuel economy gain will be marginal with the B18, it's going to have to work harder than the B20 whatever the respective state of tune. In standard A trim, neither the B18 or B20 are going to break 50bhp at the rear wheels and there's a lot of weight to move around.

I kicked off with a 'flat' B20A in my 140 which would produce anything between 25 and 32mpg with a four speed box. That engine seemed incapable of revving beyond 4000 on a single strom. Now running a properly played with B20 and overdrive, twin SU's etc and on a run, will still do 30mpg. Drive it hard though and 16-17 is more accurate. It's all down to how hard you make the motor work and the weight of that right foot!

Good luck with it Dylan and remember the old saying, 'time spent in reconnaissance is seldom wasted'

[Dylan144GT]

Snowman! I like your quote! Thanks for the input guys. Ran the chassis number of the car against the achives and found that my car is not in original condition! Rusted yes, but not mechanically! Turns out this is a B18B motor and it should have had the M41 greabox! Most dissapointed about the gearbox! Oh well, more fun to be had! As for the engine, thats if this engine is the original, it must have had a manifold and carb swop at some point. I must check it with the liscencing records! Is it true that the Strombergs and the SU's are interchangable on the same manifold? If so, my mechanic/source has been lying to me! Little ****! Definately gonna try putting the Strombergs onto the B18. Another reason I didn't stick to the B20 was that its very tired! Timing gears are gone and the compression test says new rings are in order soon. And probably big end bearings too!

Concerning the Dunlop GT Wheel poll, I've attached a pic of the wheel for those that don't know what it looks like.

Dylan

[DaveTrees]

Dylan

Here are the head heights for the various B18 versions :

B18A (1) 1962-1964, head height 88.0 mm, compr. 8,5 : 1
B18A (2) 1965-1968, head height 88.0 mm, compr. 8,7 : 1

B18B (1) 1961-1963, head height 87.0 mm, compr. 9,5 : 1
B18B (2) 1964-1966, head height 86.2 mm, compr. 10,0 : 1
B18B (3) 1967-1968, head height 86.2 mm, compr. 10,0 : 1

B18D (1) 1961-1963, head height 88.0 mm, compr. 8,5 : 1
B18D (2) 1964-1966, head height 88.0 mm, compr. 8,7 : 1
B18D (3) 1967-19.., head height 88.0 mm, compr. 8,7 : 1

The slight differences in CR between versions of the same engine type are, I think due to different head gasket thicknesses.

If you can give me the full engine number, I can tell you whether it's a B18B or not (assuming the head & block are still an original pair)

Is it true that the Strombergs and the SU's are interchangable on the same manifold?

As I posted above - definitely yes .... I have done it. Mounting bolt pattern between carb flange & manifold is exactly the same, although there are minor differences in the carb linkage. Have a look at a workshop manual - it will probably show both setups.

Note - Not sure about the on the B18B-equipped cars with 2 individual aircleaners, but on the B20s the twincarb airbox is not the same between Stromberg & SU equipped cars - the aircleaner mounting bolt holes are in slightly different positions. Very easily adapted from one to the other though (my SU-equipped car runs a Stromberg airbox at the moment ... temporarily as I have a set of these to put on it www.su-filters.com

Dave

[Dylan144GT]

Hi Dave

Sorry this has taken so long. I presume the head is the original head. Is there any way of checking? The engine number is 1968 37 2569 B18. Below the engine number is LGB and below that is 419330.

Where do you coss reference the engine number? Just for fiture reference.

Dylan

[DaveTrees]

Originally Posted by Dylan144GT

Hi Dave

Sorry this has taken so long. I presume the head is the original head. Is there any way of checking? The engine number is 1968 37 2569 B18. Below the engine number is LGB and below that is 419330.

Where do you coss reference the engine number? Just for future reference.

Dylan

That doesn't look like an engine number to me ....

The engine number on B18/B20 motors is on the LHS of the block, below the spark plugs. It is partially cast/partially stamped into the side of the block.

It will start with something like "4968" or similar cast into the block, followed by a flat machined area with more numbers on it. If you can give me the full series of numbers, I can tell you what year & configuration etc the engine is. They are all listed in the Volvo Parts Manual - I'll see if I can find the web link to it again (but I have a copy here anyway.)

Heads are a bit more problematic, as they don't have part numbers anywhere visible on them.

Also - what is the full chassis number etc of your car ? It should be stamped inside the RH front door pillar. That will tell you what engine & transmission in the car should be.

cheers

Dave

[Dylan144GT]

Sorry Dave, my bad. I did take the engine number from where you said. The engine number was wrong in that the beginning 1 should be a 4. ie Volvo 4968 37 2596 B18 is the full line of script on the top of the engine block under the spark plugs. I dunno if you saw any other faults in my previous number but just double checked this one.

Thanks for the help.

Dylan