Project Steph's 1978 Honda Civic 1200

[Thor]

Of course the practicality of fitting the smaller dell'Ortos is that a pair of 32dhlb's and manifold fit without any mods or alterations to any other engine component, the fuel pump and distributor can stay stock.
The 32dhlb came off a Lancia Fulvia 1600 in their day, an engine renowned for its high rpm as it was a boxer configuration, so its max flow rate suits our engines in sane levels of tune, using standard gear ratios and final drives.
I bought my set brand new in 1977 and have never regretted the purchase. they have been used on daily drivers and will be on the road again soon. The music of the induction is seductive and mellifluous, they need fitting for this reason alone, creating a sound like a Lotus twin-camshaft on Webers. Beautiful.

[Thor]

Deleted - double post - CFT again. Sorry.

[Steph]

Yes, I can't wait to hear what they sound like, especially with the trumpets fitted. I'll probably leave the vent open permanently so I can hear them better. It doubled the 'volume' when I used to do it with the EN4 twin-Keihin intake fitted. It sort of works like one of those exhaust cutouts, but on the intake side.

Now, my Christmas list is as follows:

2-post Car Hoist - what a wonderful tool to have in the garage, and Aussie Car Hoists have an absolute cracker for sale at the moment.

I bought my MIG welder from these guys (Dad and Son), and they're good people to deal with.

This one has 3-piece arms (all 4 arms!), and they're well reinforced. It's definitely well designed, in my opinion that is.

oh yeah, it has the lowest height arms at 71.2mm, so no problems with the super low Civic.

[Don]

I found some very interesting numbers on carburetor and their CFM ratings today. It seems Dellorto carburetor have higher CFM ratings than their Weber counterparts, which would explain why the 36mm Dellorto don't seem to run much better than the 40mm Webers do on the 1200.

Source: CB Performance 1991 catalog- no flow specs or venturi sizes
I assume these numbers are @28" H2O per venturi

Dell'Orto 48mm DRLA 388.5cfm
Weber 48mm IDA 372.1cfm
Dell'Orto 45mm DRLA 329.3cfm
Weber 44mm IDF 292.3cfm
Dell'Orto 40mm DRLA 266.4cfm
Weber 40mm IDF 212.8cfm
Dell'Orto 36mm 205.8cfm

I would assume a 32mm Dellorto would have a rating of ~150cfm working from this table, giving a 25% reduction over the Dellorto 36s and Weber 40s,

and that fitting 32mm Dellortos would net the same flow rates as fitting a 36mm Weber, if one existed.

The carburetor listed above are down draft models, not side drafts. Carburetors are typically tested at a much lower vacuum than cylinder heads. The CFM required with manifolds with a shared plenum is much different than an Individual runner setup. Even the single side draft manifolds for the EB pair two cylinders per venturi and have small shared plenum areas too. Comparing an intake system based on its flow rate alone and not its design might not be the best practice. The best way to know what a particular intake system flows or doesn't is to test it. I built my own flow bench a long time ago and it was an education in itself. There should be a flow bench close to you if you're in a decent sized city. I sold my flow bench and now just rent time on another if needed. The adapters are the part you will have to do yourself. Its not hard to make them, most are just plastic and can be machined in a few hours time.

[Steph]

I agree Don, those numbers are pretty soft. I just had a light bulb go off when I noticed the imbalance between flow rates (assuming they had the same venturis?), and it made me think that could be why the larger 35mm DHLBs have always been reported to run like a dog on the 1200, except by Pete (Thor) of course, who seems to have great success with them (a daily driver, no less!). I know the dual Webers have never been reported to work well on the 1200s (over carbed), and if the numbers in the table I posted previously are anything to go by, they sort of explain why the larger DHLBs have 'never' been much chop either.

All my information is based on posts I've read here on the board ( I have zero 1st hand experience), and the only reports of success with the bigger DHLB (other than Pete's) was on an engine that was reported to have custom Wiseco 74mm pistons, 1300 crank, and supposedly made a couple of horses shy of a 100 on the dyno (98hp from memory). The guy's name was Brendan and claimed he had built 2 or 3 of them here in Australia from memory. Apart from that, I can't recall a single success story relating to the larger DHLBs. I've seen a couple fitted in archived posts here, but nothing about how they actually ran.

Interestingly, the DHLB32s were only fitted to the Lancia Fulvia 1100 and 1200cc models while the DHLB35s were fitted to the larger Lancia Fulvia ranging up to 1600cc. The DHLB32s were also fitted to the Fiat 500.

[Thor]

DHLA and DHLB are 2 different models.
They are dimensionally completely different.
Mine are 32 DHLBs.

[Don]

There seems to be some false rumors floating around about the 35mm Delorto DHLB's, they are not problem carburetors at all when set up properly. While I don't doubt that some members couldn't make their cars act right, the reason is not the 35mm DHLB.
PJ had some problems at first on the old board. The previous owner had taken cut on the venturis in a lathe. I suggested he try to put the stock sized venturis back and the cars didn't have a problem after that. He even got a 2nd setup for his wife's Civic. There were a lot of people who got the manifold from Eurocarb remake in the early 2000's. Some went with the 32mm because they were dirt cheap from CB performance. The reason they were cheap is everybody wanted the 35's instead. PJ and I got a few email from Oscar Jackson in around 2000. I think I saved the email. He wanted to release some new old parts, but the board back then was almost as tight then as it is now. So he faded away and nothing got made. I have to dig for the email but his words were that the 35mm side drafts were his favorite by far. He did sell the 35mm kit in his catalog during the 70s and 80s. Finally there is AT Engineering They did not offer a 32mm kit either only the 35mm. Here is a scan from their 1987 catalog. If anyone has a close up of the AT or Jackson throttle linkage let me know I am interested in looking.

[Steph]

Cool, except Eurocarb didn't reproduce anything at all, they bought them from the original supplier in New Zealand, who when I last contacted them (the NZ supplier that is), said they still had the original castings (the same ones they claimed they used to supply Eurocarb and Honda NZ). A few years back I contacted Eurocarb directly (and afterwards another member here emailed them to confirm my information), I cut and pasted the offical response here somewhere, where they unequivocally stated that they had never reproduced them and had always bought theirs from the original (OEM) supplier in New Zealand. I suggest other with any interest contact Eurocarb direct

Interestingly, the last time I got an email from the New Zealand foundry that has the original OEM patterns from the 1970s, they said they'd be happy to cast more, but only in lots of three. From memory they were NZ$330 a piece.

[Oldie]

Mine are 32 DHLBs.

Same here.Originally had tried some used 35 DHLB but could not free up some of the adj screws so i replace them with some 32's.Could not see any visiable difference between the two if my memory serves me correctly.
I also would like to see the throttle arrangement.My throttle linkage is somewhat crude but effective as is the one for the choke.All using the un moded OEM cables.

[Thor]

Steph's is the linkage to look at.
It's in this post somewhere in the last couple of months.
This post really does need chaptering or reducing now as it is getting very unwieldy, sadly.
Maybe locking off and re-started as part 2?