Mystery 2054 with 40 dells

[NJ John]

I’m trying to buy a mild 1915 engine. So, I dug out my 40 dells. Turns out I have two 28mm and two 30mm venturis. I’m going to order two more 30’s. Unless I should go bigger? Also, any jetting suggestions? Thanks
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1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[67rustavenger]

You need to provide more information on the engine spec before, anyone can make a recommendation on the correct vent sizes for your dells.

Why change from the turbo engine to a 1915?
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[NJ John]

The turbo 1600 is broke. I’m so busy, I’m just gonna yank it out for now. But, yeah, I can’t wait to see what’s in this 1915. It’s a good deal, and I hope it actually becomes reality. I haven’t even seen it, yet.
_________________
1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[Rome]

Try to find out what size intake valves that 1915 engine has if the seller has a build sheet or parts receipts. That is among the biggest factors to choose venturi size. Or at least pull down one of the valve covers to check the first 3 digits of the head part number, though of course larger valves could've been fitted to stock heads... Also, what will be your intended upper rpm range? Fast, prolonged highway driving (75+ mph), or high revs for drag racing or road circuit races? 30 mm venturies will cover intake valves from stock 35.5 thru 40 mm and will run fine. Not max power, but run well.

What are the main and idle jets in your 40 Dells now? They might already be suitable for your planned engine.

[NJ John]

I’ll let you guys know when I get it and preform something expository procedures. Can’t wait, actually.
_________________
1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[NJ John]

Got the engine home. This is all I know so far. Full flow, Berg pump cover, light flywheel, solid shafts and these CB heads with dual springs. The only stamp I see.

_________________
1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[NJ John]

The engine also has a sand seal. Now I have to buy a pulley. A quick 10pm measure jobs shows around.430 lift and wait for it….. 74mm stroke!
I don’t see dual springs offered on CB’s stock heads.
_________________
1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[Erik G]

all I'm going to say about ordering vents is get 4 of the same. Don't just order two CB vents and think they will be the same as your original Dell vents. If you have 2 original Dell vents find 2 more originals.
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[mcdragracer]

[NJ John]

Thanks for that info.
_________________
1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[NJ John]

Since I’m probably ordering 4 venturis. Would 34mm be a good choice? Not what came form the factory for dual 40’s? But, empi “D” series come with 34mm.
I don’t want to take this engine apart to learn what’s all inside. Is there anything I could see with a borescope camera? My buddy has one, I can borrow. Kinda curious what rods it has.
_________________
1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[esde]

I would run the smallest vents possible, that don't limit upper rpm. 28's seem to be good to about 100hp, and keep low end driving snappy. 30 if you have doubts or think the engine has more potential. I think 34's are too big and your low end operation will be sloppy. Just because EMPI does something doesn't mean it's a good idea. Actually, usually I would do the opposite of them...
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modok wrote:
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[NJ John]

Thanks. Good information.
Here’s some more pics. The flywheel looks to be maybe a 12lbs?

_________________
1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[oprn]

31mm seem to be a nice match for my 1911cc type 4 engine with stock valves. Great low end, no flat spots in transition and still pulling hard at 5800 RPM.
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Our cars get old, we get old but driving an old VW never gets old!

[Zed999]

My 2020cc type-1 pulled hard off the end of the 6,500rp rev counter with 30 vents in DRLA 40s. 32's just softened the low end, 28's weren't much different to the 30s.

[Rome]

Yes, lightened flywheel. Also dual valve springs, ball-end type valve adjusters (ugh), valve keeper ends not ground for self-locking, solid rocker shafts. Looks like a shim under the rocker arm blocks. Clues of a moderate cam. With the valve cover off, you can test with a magnet if the pushrods are steel or aluminum.

[NJ John]

I’ve had many swivel ball adjuster engines. Never any issues.
_________________
1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[mcdragracer]

I would go with 30 mm on the venturi's, with that engine even if you had a stock cam and no head work you'll be safe to go with that size

[NJ John]

It seems that only 27mm vents are available from CB Performance. Haven’t pulled the trigger, yet.
_________________
1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[NJ John]

I’m guessing these are stock chambers with a clean up cut. Does it look like it’s flycut for compression? 74x94 stock chamber= 9 something to 1?

_________________
1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage