HS4s

[Gundy]

I'm getting ready to add 2xHS4s to the Sprite.
I was thinking of ordering a Colortune gizmo to
help fine tune the suckers. The carbs have been set up for my 1380cc engine but like any carb I'm sure they will need fine tuning.
14mm set? Does the thing help?
Tips, suggestions appreciated.

 

[Hap Waldrop]

Re: Colortune suggestions

I never use any of the store bought tuning devices, just do it all the old fashion way, ears and eyes. First thing I would do David is pull the dashpots and pistons and record what needles you have, and then take the plunger end of a set of dial calipers and record the jet down form the bridge. At this time you will also be able to check the drop rate of the piston in the dashpots. Use that same oil in the carbs as you run in the engine, like 20/50. The biggest issue you'll have with those carbs on your engine is trying get rid of the off/on throttle bog, very common when using bigger carbs. Also worth noting is how the vacuum is pulled for the dizzy, is it manifold or port off the carb, and is it the same as what you are doing now, if you're not running a vacuum on the dizzy now, be sure to plug any vacuum sources for the dizzy on the HS4s. Now hopefully these are early solid needle, solid butterfly HS4 with no evac tubes, so if they have solid needles #5 would been the stock needle for a MGB, I guessing thecorrect neelde for your engine w/the HS4s is going to be somewhere around #2 or #3, and I would start with the jet about .050 -.060" down form the bridge. This si alot of carbs for even hot rodded street engine, so getting them lean enough will be the challenge. Have new spark plugs on hand, get NGK BP6ES, you can get them at the local parts stores. Hope this helps.

 

[Hairyone]

Re: Colortune suggestions

Yes it will help set the mixture screw, assuming you have the correct needle in the 1st place. An exhaust gas analiser will be better but a lot more money & will only give you some numbers which may or may not be correct depending on the accuracy of the analiser. Where as with a colourtune you can see the colour of the flame. I've used one on my Frogeye & a Mini with good results.

 

[Gundy]

Re: Colortune suggestions

Thanks Hap. The dizzy is an Aldon Yellow with vac advance.
The vac will draw from the same area, base of carb, as the
current HIF6 I'm using. These are "earlier" HS4s.
I have the needle type at the office and I'll post the type later today.
I'll pick up some spare plugs before I start.
I know this is a lot of carb even for a hot rod but with
my improved head, hot cam and header I'm hoping to gain
a couple of horses in the stable.
The HIF6 runs great but the engine sure feels like it could use some more gas on full throttle.
That plus I hate how the single carb LOOKS under the bonnet.
Heck about all I ever do is drive wide open anyway.
I rarely shift below 5K. Around town I like keeping the revs up with gear selection. This engine hates lugging around.
I may regret this but I'm giving it a shot.
You know what they say about a fool and his money.
Again, thanks for your tips. I really trust your opinion
and advice.

 

[John Moore]

Re: Colortune suggestions

I haven't tried a colortune on my sprite, but didn't have good luck with them on my MGB. I don't know if it's the type of fuel we have these days, but I found that with the color tune, when it appeared to be dialed in with "bunson blue", but engine was running lean. I found the "spark plug color" method a bit better but even that can be a bit difficult these days with clean burning fuel. The best method is with a Air/Fuel meter. But I would advise you pick up a unisyn if you don't already have one.

Also, be sure to check out John Twist on youtube tuning SU's. Good stuff.

This one is him tuning HiF's, I think there is also one with HS4's.

https://www.youtube.com/watch?v=ASeMfXfjNpw

 

[Gundy]

Re: Colortune suggestions

Yes it will help set the mixture screw, assuming you have the correct needle in the 1st place. An exhaust gas analiser will be better but a lot more money & will only give you some numbers which may or may not be correct depending on the accuracy of the analiser. Where as with a colourtune you can see the colour of the flame. I've used one on my Frogeye & a Mini with good results.

Thanks! My eyes and ears aren't experienced enough to trust.
I think I'll order one.

 

[losmorob]

Re: Colortune suggestions

I'll sell you one...cheap! Used maybe twice.
PM me.

Edit; I also have a Gunson exhaust analyzer I'd sell as well. See a Moss catalogue for details.

After many years of tuning SU's, I just don't use them.

 

[Gundy]

Woo Pow!

Well, I slapped fat suckers on today. No biggie. A one
:banana: job. I had to remove the steering shaft to get clearance to move the header past the studs. Hour and a half
start to fire.
Fired on first try. Adjustments later this week. Idles lumpy
at about 1100 rpms. Just like the HIF6. I love those lumpy tunes.
Runs like a scalded dawg. Very noticeable power increase.
It does have a sputter at wide open throttle yet at
2/3 throttle it is making more power than with wide open HIF6.
New plugs and adjustments should get her dialed in better.
It's even louder. Good throttle response.
I can't wait to "try" to dial 'em in. Been a long time since I diddled with twin SUs.
Keeping my fingers crossed.
Ohm...bugeye,bugeye,bugeye...Ohm

 

[drooartz]

Re: Woo Pow!

Fantastic, David.

Besides, twin SUs just look right on a LBC.

 

[Gundy]

Re: Woo Pow!

Fantastic, David.

Besides, twin SUs just look right on a LBC.

You know I like taking pics. Sorry about the dirty engine.
Ol girl has taken a few spirited runs the last year.

Fantasic remains to be seen. Sputterin' wide open STINKS.
If I don't get these bubbas settled down and doing their
business. Just saying. No options are off the table.


Funny how you took a car in need and have done so well
and I've taken a perfectly good running one and now it runs like crap. I know the source of my ills. ME.

 

[drooartz]

Re: Woo Pow!

Funny how you took a car in need and have done so well
and I've taken a perfectly good running one and now it runs like crap. I know the source of my ills. ME.

Mine runs as well as it does thanks to other folks.

I'm learning, though, and haven't made too many big mistakes yet.

 

[Nelson]

Re: Woo Pow!

You will like the HS4's if they work anywhere as well as my H4's do. I had some work done at Donald Healey's dealership before I shipped my 62 Sprite to the States. They installed a pair of H4's and their "high efficiency" exhaust system for me. Performance was noticeably enhanced. With no other changes from the original 948 engine my top end went up more than 15 miles per hour. I could do 95 easily but of course I wouldn't try that now.

 

[Gundy]

Re: Woo Pow!

You will like the HS4's if they work anywhere as well as my H4's do. I had some work done at Donald Healey's dealership before I shipped my 62 Sprite to the States. They installed a pair of H4's and their "high efficiency" exhaust system for me. Performance was noticeably enhanced. With no other changes from the original 948 engine my top end went up more than 15 miles per hour. I could do 95 easily but of course I wouldn't try that now.

Wow Nelson! Shipping a 62 across the pond.
That's hardcore!


Thanks for the encouragement.

 

[Gundy]

Re: Woo Pow!

I'm getting there. Some tweaking this afternoon has made a significant improvement. New hotter plugs and more tweaking this weekend.
My needles are AAM by the way.

 

[Gundy]

Re: Woo Pow!

Dialed them big ol suckers in this afternoon.
Holy Cow! Much more power. Idles at 1000 + or -
and no more sputtering at full throttle.
I love these carbs!
Funny thing is I had to enrich the carbs.
The setting that came with the carbs had the flats painted on one facet. Nice touch, btw. Yet I had to go 3 flats more in enrichment to get the wide open sputters to quit.
No off idle stumbles either.
I couldn't be more pleased.
:thumbsup:

Before and after pics.

 

[jlaird]

Re: Woo Pow!

Great.

 

[Nelson]

Re: Woo Pow!

I have a heat shield between my H4's and the manifold. That is how Donald Healey's mechanics installed them on my Sprite. Is there a reason why you don't have one? I think it was a good idea. My original one developed a crack so I made a new one out of heavy sheet metal.

 

[Gundy]

Re: Woo Pow!

I have a heat shield between my H4's and the manifold. That is how Donald Healey's mechanics installed them on my Sprite. Is there a reason why you don't have one? I think it was a good idea. My original one developed a crack so I made a new one out of heavy sheet metal.

I'm using two polished, stainless steel, heat shields.
They do sort of blend in with the other stuff.
The intake is ceramic coated. Look close and you can see
one heat shield in the pic above. Guess it's a kind of
shiny camouflage.
The wife doubted me when I was excited to get the heater tube in green. "Your motor isn't green. Isn't it aluminum or something?" I showed her the sparky side of the A as proof.

 

[JPSmit]

Re: Woo Pow!

sweet!

 

[Gundy]

bad ears

Guess it was all those years of Rock and Roll 'cause
my carbs weren't close to sync'ed by hearing.
I borrowed a unisync and was shocked to see how out of adjustment the carbs were. Not now.


Also borrowed the same friend's colortune. My nose is better than my ears. Yellow at idle and nice blue otherwise.
No further adjustment was needed.
Holds idle at 1100 rpms.
Saturday's mountain run should be fun!