Pat Downs posted:

I have found that using longer duration cams with cylinder heads that have high port velocity give the best of both power and driveability...

Thank you, Pat, for taking the time for the detailed explanation. I shortened it only because, being directly above this there's no reason to repeat it. Al 

56widebody posted:

Wow. Such an amazing article and information.  I just spoke w Pat yesterday about trying to get more power out of my motor,  and he sent me in a different direction than I was thinking.  Lol he's such a wealth of Knowledge and a gentleman. Thanks Pat Downs 

Care to share the conversation?

Brian's engine has a CB 2242 cam and 1.25:1 rockers. Anand's has a 2292(FK-10) with 1.4:1. Other than compression ratio and cam, the engines are identical internally. Externally, Anand's has Dell 45 vs. Brian's 44 IDF, and of course exhaust. Brian has 1 5/8" from A-1 I believe. I'm not aware of Anand's exhaust specs.

I know this because Brian came to me and asked for my help building his CB engine kit. He now knows about measuring everything, gapping rings, measuring deck height, shimming cylinders, valve geometry, cutting pushrods, shimming rockers, case assembly, and breaking in lifters. Plus cleaning the case and running a tap through all the threaded holes. It was fun, ummmm, well, at least it's done and hasn't blown up. At least 40 hours of time was spent by me.

I wouldn't.  They're a tad too big, in my opinion (but whaddo I know, right?)

Looking at Anand's spec for his engine (similar to yours), he's running:

"Carbs: 45 Dellorto DRLAs with 38 venturis, .152 Main jets. .70 Idle jets. "

That sounds about perfect, whether Dells or Webers, even though you're both running slightly different cams, plus IIRC, you've got 1-5/8" exhaust tubes coupled to your exhaust valve size.  I would be borderline on whether to go to bigger pipes, but 1-5/8" should be good for most canyon carving and good low-mid torque if you stuck with the 45's.  (Now watch.....  Pat will probably chime in and say, "Sure!  48's would be perfect!")   

What size carbs do you have now?

56widebody posted:

Boy this thread faded quick. Does anyone have an opinion about putting 48's on this setup? I have a couple people telling me its going to be too much. Thanks in advance 

I would up the compression (as Pat D suggested) and, since you already have the 44IDF's, try them. What size venturis do they have? They'll need 38's to get the most out of the carbs. 48's will emphasize top end horsepower a little more, while leaving the lower midrange/bottom end (and throttle response) a wee bit softer (mind you, with a 2332, the size alone will make bucketfuls of bottom end, no matter how high it's made to rev!). I would expect the 2242 (248° @0.050"), being ground on 107° lobe centers, even with 1.25 rockers (which will add 4-5° to the @ 0.050" figure) to be done by 52-5500 rpm so I don't expect 48's to really add much except to extend the top end a tiny bit, but I haven't built hundreds (thousands?) of engines, so take my advice for what it is. What's the compression now? Is it running so you'll have something to compare it to?

Also, Gordon has some good points. Al

56widebody posted:

Boy this thread faded quick. Does anyone have an opinion about putting 48's on this setup? I have a couple people telling me its going to be too much. Thanks in advance 

I see why you're asking. A 2332 is a big engine, and conventional wisdom says that big engines make more power on bigger carbs.

However-- have you seen the ports on Panchitos? They're cute little fellas, and smaller than any ports I've ever put on anything. Pat recommended a very aggressive cam to go with this recipe, because the heads have so much port velocity that they can overcome the sogginess at low RPMs that would come otherwise. 

Personally, I wouldn't color too far outside the lines on this- Pat has gifted us with a baking recipe, not a cooking recipe. When you cook, you can throw in a bit of this and a bit of that, and 9 times out of 10 it comes out adequately. When you bake, you follow the recipe, or you don't get the cake you are after.

Switching to 48s is a big change. I doubt it would help, and it would most likely hurt drivability.

I've been thinking about this engine since Anand brought the details to the table. It's unconventional and completely awesome. 180 hp is nothing to sneeze about. To do it on 40 mm intakes, and tiny little ports is cool enough that I needed to try it.

My heads, cam, and lifters came a couple of weeks ago. I'll have more details as they develop.

Like Stan says, Brian, all or nothing. I'm with Stan 150% on this. Either precisely Pat's formula or ????? you won't know what you'll get. 

Stan: Brian and I put this engine together, well, together. He knows exactly what his ports(and mine) look like. 

I do like what Al is saying, maybe just throw 38 vents in his existing carbs, after we remove the heads for flycutting. It's at 8.8:1 now from what I remember, but I didn't write any numbers down. Not my circus, not my monkeys. I just charged free admission LOL!

Thank you Stan, Sooo I'm trying to bake this cake per chef Pat. Cutting heads and upgrading from 44's to 48's is his receipe.  But a couple people that have been doing this longer than me are hesitant to give their blessing.  So that's why I put this out here. My thoughts are Pat does a decent amount of unconventional things, and 2 it's Pat Downs. Why question it, just trust the man

56widebody posted:

Thank you Stan, Sooo I'm trying to bake this cake per chef Pat. Cutting heads and upgrading from 44's to 48's is his receipe.  But a couple people that have been doing this longer than me are hesitant to give their blessing.  So that's why I put this out here. My thoughts are Pat does a decent amount of unconventional things, and 2 it's Pat Downs. Why question it, just trust the man

If that's his recipe, go for it.

edsnova posted:

I think you're right. I have heard somewhere that Del 45s are closer to Weber 48s than to Weber 44s. Del 40s are more like Weber 44s than Weber 40s. . . . No idea why this would be though.

Because the standard vents are bigger on the Dellorto 45s. Getting bigger vents for the IDF 44s gets them into the same ballpark as the Dellortos.

Bigger throttle plates present their own tuning challenges. Everybody is always worried about "how big" the carbs are, but a smaller carb with a bigger vent is nicer to drive than a great big carb with a small vent. Progression is just easier to control with the smaller throttle plate.

 

56widebody posted:

Also correct me if im wrong.  I thought the specs on Weber 48's were almost the same as Del 45's

Stan Galat posted:
edsnova posted:

I think you're right. I have heard somewhere that Del 45s are closer to Weber 48s than to Weber 44s. Del 40s are more like Weber 44s than Weber 40s. . . . No idea why this would be though.

Because the standard vents are bigger on the Dellorto 45s. Getting bigger vents for the IDF 44s gets them into the same ballpark as the Dellortos.

Bigger throttle plates present their own tuning challenges. Everybody is always worried about "how big" the carbs are, but a smaller carb with a bigger vent is nicer to drive than a great big carb with a small vent. Progression is just easier to control with the smaller throttle plate.

 

^^^What Stan said^^^  Comparing 40, 44/45 or 48mm Webers/Dellortos, when equipped with the same size venturis the carbs will have similar flow and hp #'s. People get all confused because 40 mm IDF's normally come with 28mm vents while the same size Dellortos have 30's or 32's, so of course it's possible to make more power with the Del's out of the box. Same with the 44IDF/45Del- bigger vents in the Del's give people the impression that they'll make more power (and they do), but equip the Webers with the same size vents and and now the carbs have very similar outputs. Both  carburetor series are very similar in design, and yes, the Dellorto has some slightly superior features to the IDF, but probably only a very experienced driver will notice, and only when the car is being driven close to it's limit.

@DannyP wrote- 

 I do like what Al is saying, maybe just throw 38 vents in his existing carbs, after we remove the heads for flycutting. It's at 8.8:1 now from what I remember, but I didn't write any numbers down. Not my circus, not my monkeys. I just charged free admission LOL!

Instead of springing for new carbs right away, try the bigger vents- you may be so thrilled with it that you leave it as is. Even if you down the road put 48's on it you'll have a baseline to compare to- I think I know how it'll turn out, but it'll be interesting to hear what you think!

Brian- how much is Pat suggesting you raise the compression?

ALB posted:

 

56widebody posted:

Also correct me if im wrong.  I thought the specs on Weber 48's were almost the same as Del 45's

Stan Galat posted:
edsnova posted:

I think you're right. I have heard somewhere that Del 45s are closer to Weber 48s than to Weber 44s. Del 40s are more like Weber 44s than Weber 40s. . . . No idea why this would be though.

Because the standard vents are bigger on the Dellorto 45s. Getting bigger vents for the IDF 44s gets them into the same ballpark as the Dellortos.

Bigger throttle plates present their own tuning challenges. Everybody is always worried about "how big" the carbs are, but a smaller carb with a bigger vent is nicer to drive than a great big carb with a small vent. Progression is just easier to control with the smaller throttle plate.

 

^^^What Stan said^^^  Comparing 40, 44/45 or 48mm Webers/Dellortos, when equipped with the same size venturis the carbs will have similar flow and hp #'s. People get all confused because 40 mm IDF's normally come with 28mm vents while the same size Dellortos have 30's or 32's, so of course it's possible to make more power with the Del's out of the box. Same with the 44IDF/45Del- bigger vents in the Del's give people the impression that they'll make more power (and they do), but equip the Webers with the same size vents and and now the carbs have very similar outputs. Both  carburetor series are very similar in design, and yes, the Dellorto has some slightly superior features to the IDF, but probably only a very experienced driver will notice, and only when the car is being driven close to it's limit.

@DannyP wrote- 

 I do like what Al is saying, maybe just throw 38 vents in his existing carbs, after we remove the heads for flycutting. It's at 8.8:1 now from what I remember, but I didn't write any numbers down. Not my circus, not my monkeys. I just charged free admission LOL!

Instead of springing for new carbs right away, try the bigger vents- you may be so thrilled with it that you leave it as is. Even if you down the road put 48's on it you'll have a baseline to compare to- I think I know how it'll turn out, but it'll be interesting to hear what you think!

Brian- how much is Pat suggesting you raise the compression?

The suggestion is 10.1 

10:1 would be right in the ballpark with a 2292 cam, assuming you can keep it cool. Speedsters are notorious for being difficult to cool. If you're confident in your setup (good shroud, extra oil capacity, BIG oil cooler, etc,), then go for it. Otherwise, I'd hang in the mid 9s:1.

See that's the thing. Anand's motor on here has a 2292/1.4 rocker combo. Pat is advising Brian to increase the CR to 10:1 KEEPING the 2242 and 1.25:1 and going to 48IDF.

I'm suggesting to Brian off-line to go the whole hog to the 2292 and all that Anand's motor has. And that increasing the CR without ALL of the Anand recipe isn't going to yield a happy result.

Personal experience says that a Spyder is not easy or better with respect to cooling than a Speedster. They all suck, but at least the Speedster can isolate cool intake and hot cooling exhaust air. The Spyder recirculates that hot air from the bottom of the cylinders right into the fan and carbs, unless steps are taken to stop this. Or you happen to be moving faster than 30mph. Below that, it's a runaway heat-sink that cooks itself.

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Ted*LongFellaKevin - Bay Area
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