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WELDING QUESTION

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S1 Elan Kurt. Appley
Akron, Ia., USA   USA
That is slick, Paul. Course you don't have to contend with the steering shaft and pedal arrangement on the intake side of the engine like us. Whats the drive ratio? 1300cc would require 650cc per rev to feed with no boost so if you are running 1 to 1 you would need a pretty low initial compression.

Kurt.

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Yankeedriver Avatar
Yankeedriver Platinum AdvertiserAdvertiser Joel Young
Albuquerque, NM, USA   USA
In reply to # 3696305 by humbucker Hi Joel.

Are you the guy doing the blow through supercharger?

Making a jig and clamping every thing is the ultimate way to ensure everything stays aligned.

You should still tack the four corners of the flat bar and when cool, remove from jig, turn over and tack weld the other four corners. Check that everything is still in line then weld about 1" and turn over. Weld another inch then turn over etc. This should help prevent distortion of the tubes and spread the heat more evenly.

Cheers, Paul.

PS here's my supercharger set-up - draw through Toyota SC14 (1400cc) supercharger fed by one 2"SU. I didn't bother with a serpentine belt. Just made the charger pulley to suit an A section vee belt with a spring loaded belt tensioner.

Paul,

Very cool! I considered a dual V-belt, combo serpentine and V-belt, but settled on a single 5-rib belt as best for this setup. I've worked with Smoothflow Pulleys to produce an A-series specific, 5-rib 6061 aluminum water pump pulley that came out great, and shortly will have the bespoke matching crank pulleys in-hand.

Yup, I'm the DIY blow-through Spridget guy. This bracket is to put the alternator a touch more outboard and aft, to avoid people having to grind its front mounting ear and/or the corresponding water pump lug.

Cool, thanks for the suggestions on avoiding burn-through on the tubes!

If I end up making the second bracket design, obviously I'd just be welding around the circumference of each end. But I gather I'd still tack first at both ends, then finish the beads. Also, with the second design, I suppose I could simply slip the 5/16" bolts or hardwood dowels through the tubes and bracket ends to align them before starting to weld.

Joel


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humbucker Silver Member Paul Whitworth
Toronto, NSW, Australia   AUS
In reply to # 3696489 by S1 Elan That is slick, Paul. Course you don't have to contend with the steering shaft and pedal arrangement on the intake side of the engine like us. Whats the drive ratio? 1300cc would require 650cc per rev to feed with no boost so if you are running 1 to 1 you would need a pretty low initial compression.

Kurt.
Hello Kurt.

My car is an 1845cc MGB (I only jumped on this thread to help out with the welding question.)

The ratio is about 1:1.1 (crank to supercharger) which is good because the supercharger isn't working too hard to provide enough volume to the engine.

Max boost is 7psi at 6000 rpm and at highway speeds the supercharger is in vacuum, not boost, which is also good for the charger and fuel economy. Of course if you plant your foot it is boosting to 7psi immediately.

I haven't calculated the compression ratio but the engine is an 18GB high compression unit originally 8.8:1. Could be more now as it's bored +0.040 and the head has been ground.

Running about 12deg before TDC static (plus vac advance and centrifugal advance). Does not run hot or ping (as yet - dynotune next week)

The intake runner after the carb gets ice cold with the volume of fuel and air running through it!

Cheers!

S1 Elan Kurt. Appley
Akron, Ia., USA   USA
I know the no boost at cruise is common now days but never looked into how that is activated. What switches the intake to no boost? Throttle position sensor???

Thanks
Kurt.

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Yankeedriver Platinum AdvertiserAdvertiser Joel Young
Albuquerque, NM, USA   USA
In reply to # 3697410 by S1 Elan I know the no boost at cruise is common now days but never looked into how that is activated. What switches the intake to no boost? Throttle position sensor???

Thanks
Kurt.

Kurt,

We might switch this over to the DIY supercharger thread - https://www.mgexp.com/phorum/read.php?3,3418377,3696180,page=34#msg-3696180 - but two things:

First, no boost is merely the result of not dipping into the throttle; and

Second, in my configuration--as in many draw-through setups--there is a bypass valve that senses vacuum. Mine uses a stock Mini Cooper S bypass valve, pictured here. It effectively lets the throttle body (or carb) draw directly from the air filter rather than from the blower (and intercooler, in my application).

Joel



Edited 2 time(s). Last edit at 2018-03-14 08:36 PM by Yankeedriver.


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humbucker Avatar
humbucker Silver Member Paul Whitworth
Toronto, NSW, Australia   AUS
In reply to # 3697434 by Yankeedriver
In reply to # 3697410 by S1 Elan I know the no boost at cruise is common now days but never looked into how that is activated. What switches the intake to no boost? Throttle position sensor???

Thanks
Kurt.

Kurt,

We might switch this over to the DIY supercharger thread - https://www.mgexp.com/phorum/read.php?3,3418377,3696180,page=34#msg-3696180 - but two things:

First, no boost is merely the result of not dipping into the throttle; and

Second, in my configuration--as in many draw-through setups--there is a bypass valve that senses vacuum. Mine uses a stock Mini Cooper S bypass valve, pictured here. It effectively lets the throttle body (or carb) draw directly from the air filter rather than from the blower (and intercooler, in my application).

Joel

Hi Kurt and Joel,

I do not have a bypass valve on my setup. Just a very large supercharger (1400cc) that is not turning much faster than the engine. At 110 km/hr (62 mph) the gauge is showing vacuum and I have the throttle pressed down about 1/4". This is because of the high flow volume of the 2" SU which of course is far greater than the 1 3/4" SUs on the Moss kit which has an Eaton M45? which has a capacity of about 740cc which is why the ratio to the crank is much higher than mine at 1:1.1 (7 psi boost).

The Eaton has to spin much faster to feed the engine so it's a good idea if they have a bypass or electric clutch and bypass even better.

ps - I also have a 5-speed Toyota box so overdrive 5th helps keep the revs down at highway speeds.

Cheers.



Edited 3 time(s). Last edit at 2018-03-15 02:09 AM by humbucker.

S1 Elan Kurt. Appley
Akron, Ia., USA   USA
I see, so in Joel's set up the bypass is just vacuum actuated from the large vacuum created after the throttle plate closes.

Kurt

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Yankeedriver Platinum AdvertiserAdvertiser Joel Young
Albuquerque, NM, USA   USA
In reply to # 3697636 by S1 Elan I see, so in Joel's set up the bypass is just vacuum actuated from the large vacuum created after the throttle plate closes.

Kurt

Bingo. I like it because it's an elegantly simple system, easily serviced (the diaphragm is detachable as on a distributor), etc.

Joel



Edited 1 time(s). Last edit at 2018-03-15 09:34 AM by Yankeedriver.


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Yankeedriver Platinum AdvertiserAdvertiser Joel Young
Albuquerque, NM, USA   USA
So, back to the welding issue...

The new rig arrives today, purportedly out for delivery. I'm dropping the ancient unit I've been borrowing back at the neighbor's before work this morning. Oh, duh, I'll need to buy a bottle of gas on the way home, too.

Wife and dog will be driving back from Okie City Saturday, so I'm hoping to have some quiet time to get used to the new, more powerful setup. I may get some practice welding thin to thick steel by turning my Harbor Freight dual-level task cart into a combo welding-and-tool caddy. I think the new welder may just squeeze into the lower shelf, so I'd just have to add an affair to hold the bottle and hoses. Hey! Maybe my Loni Anderson trash can would be big enough around to hold the bottle!

Joel


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humbucker Avatar
humbucker Silver Member Paul Whitworth
Toronto, NSW, Australia   AUS
In reply to # 3697653 by Yankeedriver So, back to the welding issue...

The new rig arrives today, purportedly out for delivery. I'm dropping the ancient unit I've been borrowing back at the neighbor's before work this morning. Oh, duh, I'll need to buy a bottle of gas on the way home, too.

Wife and dog will be driving back from Okie City Saturday, so I'm hoping to have some quiet time to get used to the new, more powerful setup. I may get some practice welding thin to thick steel by turning my Harbor Freight dual-level task cart into a combo welding-and-tool caddy. I think the new welder may just squeeze into the lower shelf, so I'd just have to add an affair to hold the bottle and hoses. Hey! Maybe my Loni Anderson trash can would be big enough around to hold the bottle!

Joel

Oh, NO! Why is Loni on a trash can....

Yankeedriver Avatar
Yankeedriver Platinum AdvertiserAdvertiser Joel Young
Albuquerque, NM, USA   USA
In reply to # 3698115 by humbucker
In reply to # 3697653 by Yankeedriver So, back to the welding issue... I may get some practice welding thin to thick steel by turning my Harbor Freight dual-level task cart into a combo welding-and-tool caddy. I think the new welder may just squeeze into the lower shelf, so I'd just have to add an affair to hold the bottle and hoses. Hey! Maybe my Loni Anderson trash can would be big enough around to hold the bottle!

Joel

Oh, NO! Why is Loni on a trash can....

Yeah, isn't that a gas? A classmate of mine many years back found that in a garage sale, and she said I HAD to have it in my shop. Guess Loni needed a house payment, or something... here's the flip side, where she's changed outfits.

Decided to just buy a Harbor Freight cart, which I upgraded with better front casters. It's pretty stable, actually, and the new Hobart j-u-s-t slips into the top shelf with the bolt heads toward the inside. I'm just doing 120V flux core stuff today to get ready to do the supercharger & alternator mount stuff, which will have to wait for next weekend. Couldn't get to the city before Trigas closed for the weekend.

Mark (Bugeye turbo project) recommended a Miller or Lincoln, but this was cheaper with similar features, and is still all U.S. made. Five-year warranty, plus will run an aluminum spool gun that reviews say actually works. So, thought I'd give it a shot. Also, has a handle and weighs ~75 lbs. so doubles as exercise equipment.

Joel


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S1 Elan Kurt. Appley
Akron, Ia., USA   USA
Hobart is a good name or at least used to be.

Kurt.

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Yankeedriver Platinum AdvertiserAdvertiser Joel Young
Albuquerque, NM, USA   USA
In reply to # 3698926 by S1 Elan Hobart is a good name or at least used to be.

Kurt.

Cool, thanks for the reassurance on the purchase. It's going to take a few weekends to develop technique for welds good enough for a Creative Spridgets product, but it seems like a good machine. I got good penetration welding 3/16" plate to 3/8" thick rebar, and rebar to rebar, even using the 120V option (since the 240V cord won't get here until Monday).

I expect that I will enjoy argon/CO2 better than flux core. I don't much like the flux core splatter, and I understand that the welds are more consistent with a good gas shield.

Joel


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