Incredible older ad. I love it!!
The performance difference doesn’t seem huge according to that, but like someone else had said-the sound is lovely. With all those trumpets, it’s a breathing dragon ready to spit fire at it’s enemies.
If yer spittin’ fire out the trumpets… you have a mixture problem.
I put dual Weber 42 DCOE’s on my Cosworth Vega back in 1989. I think they run great and are quite trouble free but mine came as a kit already jetted specifically by an expert for the Cosworth Vega engine. I have taken them apart and cleaned a couple of times but have made it a point to never mess with the original jets and internals. Just occasional re-syncing and idle mixture adjustment. They probably would be good on an E too as long as you are sure to get them dialed in properly at the installation. I had a friend who had problems getting Webers set up well on his '68 E but I could not advise him much since I never really had to do an initial Weber set up.
David
68 E-type FHC
Key words, bolded…
Interesting article. I have no clue how much additional horsepower “should” cost. But it seems to me at $525 plus labor on what was then a $5000 car was quite a lot of money. If we assume a somewhat similar car to an E Type today would cost $75,000, that would be about equivalent to a $7500 modification (plus labor, another $1000) today. And I have no idea how much additional power was obtained to make the faster acceleration times. I do not know if we are talking 5 or 50 hp. But it seems to me maybe 20 hp??? This Weber conversion did not include an air filter. From what I have read here on the forum, Jaguar would have gained 16 hp simply by deleting the air filter. That would be much cheaper.
Tom
Or, better yet, simply opening up the filter to reduce the restriction.
Tom, did you see Bob Exlby’s dyno chart above?
99hp & 70lbft of torque increase for the cost of a set of Webers. Pretty good ROI in my opinion. (Although I have to believe there was something wrong with his Strombergs).
Speed costs money, right? So can we agree that it was at least $5k in 1966 money for 1/2 sec off 0-60?
Set of new Webers on Ebay for $2500 from the guy in Saratoga. Could be a bargain IF someone could just figure out what jetting to put in the things!
Makes two of us: I’d be highly doubtful that all Strangleberg cars were that anemic (anaemic, for our Commonwealth brethren!).
I’d want to see those results on a few known, well-tuned ZS cars, before buying a 100-hp increase, on all cars.
Can’t help being from Missouri…
Pretty safe bet they were tuned too rich. You’d be amazed at how many people still think that if you put more fuel in, it’ll go faster.
I’d bet the downstream butterflies weren’t opening up fully. I think I screwed that up once or twice myself. Duh@
Still… its a good day when you find 99hp.
Yes I did, and it is very impressive. But I do not know how to legitimately compare. Hp is not always hp. For instance, the original SU’s were rated at 265. So a 30hp increase. The original ZS were 245, so 50 hp. But were those old ratings comparable to the dyno hp above? Maybe better, maybe worse, I have no idea.
Do you think the guy in the Road & Track article had the jetting correct?
I do not know if these issues are very significant, but an OEM cannot put out a product with these issues. Would solving these issues cut hp? I do not know.
Tom
Alfas has Webers, before the SPICA inezione, and they didn’t pop at all.
Paul, yes and Fiats and probably any other OEM that used Webers. The point is that possibly if the mods on the engine that had the large hp increae would have been in a manner to prevent the pops etc, another words had those mods been made to the acceptability of the general public, would the hp increase still have been that great?
Tom
If the Webers pop, they are not dialed in for your particular engine and setup. Each engine is different, altitude is different, with or without velocity stacks, headers, free flowing exhaust or stock, ignition timing, cams, etc. One size does not fit all. I did not have any popping on my XKE race car even with rather large cams. Webers have many more adjustments available than the SU carbs so you can match to your particular engine. The SU was matched by Jaguar for a stock engine. Start changing things and you will get some popping from the SUs. It is a shame to blame bad running on Webers when they are not properly set up. Ever wonder why Jaguar did not use SUs on the D-type instead of Webers? Could it be because they wanted to go faster and win the race? The SUs are a Constant Depression carb. As such, when a hot cam, large valves, porting or anything that effects the smoothness of the vacuum signal, they do not behave as well. The easy fix is to put up with a 1100 RPM rough idle. The Webers work well with a irratic vacuum signal and since you can tune each cylinder for mixture and flow, it can be made to idle slower and smoother.
Bingo.
And you answered the popping question.
There is one important thing to add in addition to the points that Dick notes in his post "If the Webers pop, they are not dialed in for your particular engine and setup. Each engine is different, altitude is different, with or without velocity stacks, headers, free flowing exhaust or stock, ignition timing, cams, etc. One size does not fit all.
As noted there is a wide range of “tunable” parts for the Weber carbs. In the day manufacturers, Alfa, Aston Martin, Jag, Ferrari would have Weber “create” a carb for the engine. The variable here was the number, diameter and position of the progression holes, the holes that are exposed progressively as the butterflies are opened, that are drilled in the carb body. So a 45 DCOE 9 could have a different progression hole setup than a 45 DCOE 13. The key point here is to my knowledge there is not a comprehensive analysis or published data on the position and diameter or the position of the progression holes for the carb produced for each engine. The later 45 DCOE 152 need another progression hole drilled (to make it 4 holes) so that the new hole sits over the butterfly when the throttle is closed. Given the progression holes are in the idle circuit which operates up to 2500 to 3000 rpm this is where the spitting, popping etc comes from. On an unmodified 152 model carb you need a large idle jet to compensate for insufficient fuel being delivered through the progression holes. Not the best perfomance and lousy fuel consumption results. I can get around 18 to 20 mpg with the Webers cruising. Being noisy, not so much.
So if you you remove the progression hole cap and shining a flashlight into the carb throat from the manifold end the first progression hole is covered by the butterfly then your carbs are a long way to being good to go. If not pm me as I have the specs somewhere for where to drill the hole and the size.
To Dick’s other point about idle, with a Rob Beere full race cam (long duration and high lift) it will idle at 500rpm when cold and “normal” is set to around 700 and probably increases to 800 when it gets really hot.
Good luck and regards
Keith
With reference to the Dyno results (June 26th)
The Strombergs were certainly in pretty poor shape but knowing they were heading in the same general direction as James Love’s (which is where this thread started) I had no real inclination to spend time even looking at them.
The Webers were installed exactly as supplied; the variables being broadly set I believe by the manufacturer for a standard 4.2. The hope I guess is that a Weber dealer will then finish off the job with the final set up on a Dyno.
The Weber numbers on the graph are from my initial Weber session, but after a couple of runs it was clear that the advance curve on the Lucas distributor was way out of spec. As I intended to replace it with a 123 type plus new leads and plug caps we decided to re-schedule when that was done.
After fitting the 123 (No2 setting / static 10 degrees), acceleration felt more progressive and I can live with the occasional ‘phut’ on a light throttle typically between 1500 and 2500 RPM. Plugs indicate it’s running a little rich and idle at 800 RPM is rough-ish so I definitely do need to get around to booking another session. It will be interesting to see if any improvement on what I already considered to be a pretty good result can be made. I will of course publish the result on this forum.
Hi Bob,
If it is just one carb or throat that is giving you the “phut” and you know which one it is, then with a trusty screwdriver open the idle mixture screw a 1/16 of a turn and see if it goes away.If not then try another 1/16th of a turn. This assumes that the carbs are synchonized - two throats /one carb being the issue I would check they are still in synch. Rod linkage is usually set and check but there may be some settling in.
A lot of the tuning advice is based on people with 4 bangers where shutting off the idle screw and then opening until the idle is smoothest is pretty obvious. With a 6 cylinder shutting off the fuel to one cylinder is barely noticeable.
I assume you have the 152 model carbs in which case the “spec” for the idle screws is 2 (2 1/4) to 3 turns off the seat. Having said that the usual assumption is that the settings all 3 carbs (synch and fuel height) and 6 chokes are identical which assume each cylinder has exactly the same characteristics/performance. I have used Colortunes for years (at least 2 are required) so that you can adjust one and then get the next cylinder to be the same as the first. Then move #1 to # 3 rinse and repeat trying to avoid burns on your fingers! What I observed was that the contrary to the “adjust by a 1/4 of a turn” was that the amount of adjustment to go from sort of OK to best was more like a 1/16 or and 1/8 of a turn. So between the Colortunes and the exhaust sound and idle smoothness (assuming the carbs are synchronized to start with) you can get it pretty good.
Regards
Keith
Tempero D-Type