Timing chain question.

[Gregs672000]

Cap it as said. So far so good. Check timing, balance the carbs. Lets see what's what... Fingers crossed!!

[newby]

Cap it as said. So far so good. Check timing, balance the carbs. Lets see what's what... Fingers crossed!!

I capped it. Now I am checking the balance, but at idle or 2000 rpm (for mixture balance) putting the uni-syn on the right carb causes the engine to bog down, the ball floats about the same one both but it bogs when I put it on the right so it makes it hard to adjust. Am I doing something wrong?

[jrusso07]

No, that is the problem with unisyn, it restricts air flow.

Suggest you open up the unisyn more. This will allow more air thru the carb and lower were the pea sits in the tube. Try to get the pea to sit in the middle of the scale of the unisyn.

The fact that it only bogs one carb would suggest the carbs are out of balance. The balance screw fixes that. You might give it a 1/2 to 1 full turn up or down depending on which carb is bogging down. Look at the linkage and you will be able to tell which one.

Without looking, I think CW on the balance screw will raise the rpm on the rear carb...you can tell when you see the linkage.

I set the running balance and mixture at about 3000 rpm. This usually gets me a little rich at idle. But I rather have it optimized at running rpm.

[Gregs672000]

Yes, the unisyn as indicated is a "touch, read and off" kind of action. Reducing the restriction will help get a more accurate reading. You may also want to check for any intake leaks, as both carbs should react the same assuming they are balanced. At idle or just above, a rocking motor suggests inbalance; a shakey motor, spit back on the carbs or black plugs likely air/fuel mix in my experience. The more it revs up the less it will rock as any imbalance gets hidden.

Since she is warming up now, I would do a compression test when and if you can. If you have an air compressor I (we) can guide you on doing a leak down test to see if you have bent the valves and are leaking past the valve seats.

Compression test with the engine warm, plugs out, throttle wide open, crank 4-5 times.


Progress!!!

[newby]

Here is a quick video " onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;
It's shows the shaking at idle. I took it for a spin around the block it drove pretty good. The exhaust is kinda stinky but it doesn't have a catalytic converter or anything. Anyway tell me what y'all think

[jrusso07]

Shake isn't so bad, I have seen worse. My U20s idle rough...not that rough but they are far from smooth. Seems to smooth right out as you raise the throttle.

I am confused by what appears to be the rise in rpm when you disabled the rear carb by lifting the piston. Idle should drop running on one carb, not raise but engine should continue to run, roughly but not stall. Seems like front carb is too rich.

[mraitch]

engine/tranny mounts ??

[newby]

engine/tranny mounts ??

They are NOS just put them on...

[newby]

Shake isn't so bad, I have seen worse. My U20s idle rough...not that rough but they are far from smooth. Seems to smooth right out as you raise the throttle.

I am confused by what appears to be the rise in rpm when you disabled the rear carb by lifting the piston. Idle should drop running on one carb, not raise but engine should continue to run, roughly but not stall. Seems like front carb is too rich.

Yeah setting them up is confusing. If I push up on the piston on the carb in the back and it speeds up, what do i adjust?
conversely when i push the pin up on the front carb it stumbles sometimes...
Should i not worry about the shakes?

[Gregs672000]

At work so I can't turn it up, will watch when off. I could not see if the carbs were balanced but I assume they were equal.

IT'S NOT BAD, but I want to hear it. Honestly, (and I really hate saying it and hope I'm wrong) I am a bit worried by the shake IF the carbs are balanced and we have no intake leaks... I need to watch it again and listen. Also, what do the plugs look like? If they are black or were fouled, I wonder if you can put in a clean set... I want to eliminate any possible misfire, though unlikely. I mean, my engine shakes too, but there's something about that shake that says it's not right (yet). It seemed to get better after you reved it up.

Any chance you can do a compression or even better a leak down test? If you have even a small compressor and a compression tester with a hose that threads into the plug hole we can do some leak down testing. What we would do is set the motor so the valves are all closed on that hole, put it in gear, set the brake hard, removed the shrader valve from the compression tester hose, screw that in, attach the compressor, and put a few (30lbs or so) of pressure to that hole and listen for air leaking past the valves (not worried about the rings on this new motor... probably not seated yet). Leaking past the exhaust valve and you will hear it in the tail pipe,; out the intake valve you'll hear it in the carbs; out the valve cover cap and that is rings). You have to check each cylinder and set up each one. On a new motor you should get nothing past the valves... unless they are bent (doh!).

I know you probably don't really want to know, but...

When checking the carbs, it should raise idle slightly then drop almost immediately and run on two. I think no drop means its too rich. Try leaning it (the opposit carb than what you are pushing the pin up on) a 1/4 turn at a time, noting how many turns you do on that one and see what happens. If it doesn't help, go back to where it was and richen it up and see if that does it. Unfortunately, I have not messed with SUs in quite awhile so I defer to the experts...

[newby]

At work so I can't turn it up, will watch when off. I could not see if the carbs were balanced but I assume they were equal.

IT'S NOT BAD, but I want to hear it. Honestly, (and I really hate saying it and hope I'm wrong) I am a bit worried by the shake IF the carbs are balanced and we have no intake leaks... I need to watch it again and listen. Also, what do the plugs look like? If they are black or were fouled, I wonder if you can put in a clean set... I want to eliminate any possible misfire, though unlikely. I mean, my engine shakes too, but there's something about that shake that says it's not right (yet). It seemed to get better after you reved it up.

TO be honest I'm not very confident in my job of balancing and fuel mixture. I think they are balanced but I cant get the car to idle very well at 600 RPM because the carbs get really out of sync and its hard to make the ball rise to the middle so I balanced them at 1000 RPM ( what is the idle supposed to be set to normally, 600?) All this, BTW assuming that my Tach works properly. When i pulled the Plugs out a few days ago to check the gapping they where black so I cleaned them up. I am getting new ones tomorrow.
It does rev up nice and when i drove it around the block there was no backfires or stumbling. I didn't go faster than 35 though because the Police was around and the car isn't fully legal yet.

[jrusso07]

Shake isn't so bad, I have seen worse. My U20s idle rough...not that rough but they are far from smooth. Seems to smooth right out as you raise the throttle.

I am confused by what appears to be the rise in rpm when you disabled the rear carb by lifting the piston. Idle should drop running on one carb, not raise but engine should continue to run, roughly but not stall. Seems like front carb is too rich.

Yeah setting them up is confusing. If I push up on the piston on the carb in the back and it speeds up, what do i adjust?
conversely when i push the pin up on the front carb it stumbles sometimes...
Should i not worry about the shakes?

As Greg said, lean out the front carb. Turn the mixture screw 1/4 turn CCW and then check again. Also, these engines are cold hearted beasts. Make sure you have the engine at operating temp before diddling the carbs.

You are close. Suggest you

1) warm engine to temp by running at at 2000 to 2500 rpms.
2) check ignition timing and dwell. Suggest you get a dwell meter that also reads rpm. Not sure About reading the tach although yours is amazingly steady...that's a good sign.

3) lean out front carb and check balance

To set carbs from scratch. Turn mixture knobs to full CCW then back them off 2.5 turns. Use the little round nub as a reference point.

Start engine set Idle to 800 rpm and balance using unisyn.

Simultaneously turn the two mixture screws CCW 1/4 turn, if idle rises, keep going CCW until you get highest idle, go by it a bit and observe it drops, then go back CW to high idle point. if idle doesn't 't rise up in CCw go CW past the 2.5 turn starting point.

Set throttle adjust screws to get back to 800 or 900 rpm. Use unisyn to balance.

Check mixture by raising piston on each carb. As Greg said idle will rise, then drop but engine should not stall

If stall, enrichen the carb you didn't disable by turning its mixture knob CW. Repeat over and over until you get desired results.

Check balance with unisyn

Next crank up the high idle screw until you get 3500 rpm. Check balance with unisyn. Open unisyn up wide as lots of air moving thru carb now. Adjust balance screw until balanced

Now simultaneously turn mixture screws again until you get highest rpm. Go CW or CCW, 50/50 guess. Find mixture that gives you highest rpm. Check balance.

Back high idle screw off until engine goes back to idle. Check and adjust balance if needed (should not need). Check mixture by repeating the disable each carb procedure again.

If all is good, take it for a ride!

[newby]

Here is a video of me driving it around the block. " onclick="window.open(this.href);return false;
Maybe listening to it might be helpful. I don't have a muffler on it. I have glass packs

[notoptoy]

OK, that was a really short video. How about a once around the car at idle, show the engine, walk to the tail pipe so we can hear that.
Still, congratulations, that first ride has to be amazing!

[newby]

OK, that was a really short video. How about a once around the car at idle, show the engine, walk to the tail pipe so we can hear that.
Still, congratulations, that first ride has to be amazing!

Yeah that's a good idea. I'll do that tomorrow. This is a short video