The all-new Front Page News Feed is now live   Read the announcement
TRExp

Spitfire & GT6 Forum

Bypass screw help!

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

GriffinNC Dennis D
Greenville, SC, USA   USA
It looks as though the bypass screws for my carb is frozen. I pulled the bypass apart and there is now way to get it to turn. The car had some really bad gas left in it and I believe it has it glued right. As well when I went to adjust it the ear on the top of the screw snapped.

Does anyone know where I can get just the screw? Or does someone have one laying around they don’t need?

On the high note it left the garage under it own power today... couple trips around my driveway only, but it’s a start. The front end sound like a grinder with the wheels cut full over. sad smiley

Thanks

. Hide this ad & support a small business by becoming a Gold Supporting Member

Attachments:
F835F28C-ADFB-4A12-93FA-A8C0BB83AD0F.jpeg    15.6 KB
F835F28C-ADFB-4A12-93FA-A8C0BB83AD0F.jpeg

Was this post helpful or interesting?
Yes No Thank
clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1601029 by GriffinNC It looks as though the bypass screws for my carb is frozen. I pulled the bypass apart and there is now way to get it to turn. The car had some really bad gas left in it and I believe it has it glued right. As well when I went to adjust it the ear on the top of the screw snapped.

Does anyone know where I can get just the screw? Or does someone have one laying around they don’t need?

On the high note it left the garage under it own power today... couple trips around my driveway only, but it’s a start. The front end sound like a grinder with the wheels cut full over. sad smiley

Thanks

Just because you CAN cut the wheels full over doesn't mean you SHOULD.
Those very tight Spitfire turns are best performed on dirt, gravel, or sandy asphalt.

Was this post helpful or interesting?
Yes No Thank
GriffinNC Dennis D
Greenville, SC, USA   USA
In reply to # 1601035 by clshore
In reply to # 1601029 by GriffinNC It looks as though the bypass screws for my carb is frozen. I pulled the bypass apart and there is now way to get it to turn. The car had some really bad gas left in it and I believe it has it glued right. As well when I went to adjust it the ear on the top of the screw snapped.

Does anyone know where I can get just the screw? Or does someone have one laying around they don’t need?

On the high note it left the garage under it own power today... couple trips around my driveway only, but it’s a start. The front end sound like a grinder with the wheels cut full over. sad smiley

Thanks

Just because you CAN cut the wheels full over doesn't mean you SHOULD.
Those very tight Spitfire turns are best performed on dirt, gravel, or sandy asphalt.


Why is that? I know that my suspension is shot in the front, but the grinding noise wan't expected.

. Hide this ad & support a small business by becoming a Gold Supporting Member
Was this post helpful or interesting?
Yes No Thank
Growe58 Avatar
Growe58 Greg Rowe
Hatfield, PA, USA   USA
In a turn, the inner wheel describes a smaller circle which means that it has to turn at a slightly greater angle (apologies if you already know this). The steering is geared in a manner to reflect this. It's called Ackerman geometry.

The Spitfire's steering allows you to make a very tight turn, however at the uttermost angles you lose the Ackerman. So the only way that the turn can be accomplished is with tire scrubbing. As Carter points out, the scrubbing is much less hard on the tires if you have a slippery surface like dirt or gravel.

Was this post helpful or interesting?
Yes No Thank
GriffinNC Dennis D
Greenville, SC, USA   USA
Interesting.

Now I need to find the bypass screw and I can check carb 100% off my list. I think I actually have the dang choke working at the moment

Was this post helpful or interesting?
Yes No Thank
Doug in Vegas Avatar
Doug in Vegas Douglas D
Las Vegas, NV, USA   USA
Most cars have stops on the rack to limit travel.

Adding mags often requires them to prevent the tires from rubbing.

Was this post helpful or interesting?
Yes No Thank
Outfect Avatar
Outfect Dave B
La Sal, UT, USA   USA
1940 Ford N Series Tractors "Henry"
1951 Other Not Listed "SnowMan"
1979 Triumph Spitfire 1500 "White October"
1980 Triumph Spitfire 1500 "Tangerine Dream"
Dennis,

PM for parts.

DaveInUtah

Was this post helpful or interesting?
Yes No Thank
POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
In reply to # 1601058 by GriffinNC Interesting.

Now I need to find the bypass screw and I can check carb 100% off my list. I think I actually have the dang choke working at the moment

I can just drop a whole by-pass in the mail if you wish, screw and all. Don't worry about money. Drop a PM.

I would recommend getting a new diaphragm though. The original is probable not flexible at all. Although I see BPNW is out of stock at the moment, this is what you want. Other venders have them too. - Pete

https://www.bpnorthwest.com/triumph/spitfire/fuel-system/bypass-valve-kit-zenith-stromberg-carbs.html

Was this post helpful or interesting?
Yes No Thank
GriffinNC Dennis D
Greenville, SC, USA   USA
Thanks Pete. I have one on the way already. I put a new diaphragm in when I rebuilt the carb, but i tried now to mess with the screw so I didn't have to adjust it. You don't happen to know what is a good starting point for the screw is? I'm going to try and measure the distance on the old one.... it's frozen in plan anyway and match it and see if that work.

Was this post helpful or interesting?
Yes No Thank
POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
Setting it where the old one was is probably a good bet. What you are after is your normal idle speed. Important to know that turning the screw clockwise will open it sooner and counterclockwise will keep it seated longer.

When you get it all put together. Start the engine and after warm-up observe the idle speed. Turn the screw CW. The idle should rise at some point. Then turn the screw CCW until the idle drops back down to your spec. Blip the throttle. If the RPM hangs at the higher throttle speed turn the screw CCW a half a turn or so. If the idle speed still hangs a bit after blipping the throttle, turn the screw CCW a bit more. When it is right, the idle speed will drop normally after a throttle blip. Note that all the adjustments are made to get the engine to RETURN to a normal idle after purposely being set at the too high idle - Pete.

Was this post helpful or interesting?
Yes No Thank
. Hide this ad & support a small business by becoming a Gold Supporting Member

To add your reply, or post your own questions




Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster