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Nice long run at speed

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vping

vping

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I took the GT on th parkway doing between 60 & 70 tonight for about an hour. Ran like a top. Very responsive from 60 to 70 if I get on it. Little shake @ 70 I have to figure out. While at a steady run the engine feels like it's pulsing a bit like it's loosing a hair of power for 2 seconds and then the power is back on 2 seconds. Very minor but something that I can feel. Lastly, she back fires 2-3 time while downshifting going on to an exit ramp. Other than that, handles extremely well at speed and whipping around the exit ramp. Nice!
 
Shake at speed is probably tires not true...pulsing could be spark plug wires.
 
It's shake in the steering wheel so I assume it's the front. I wonder if I should try swaping a front tire for a rear to see if it goes away.

Plug wires. Hmm. Brandy new spanking but can't rule them out. Wonder if they are getting a good contact with the pins into the cap.
 
swapping the tires might be an easy check, but I've gotten steering wheel shake even from an out-of-round rear tire before... best way is to take the car to a tire shop that can do wire wheels (motorcycle shops come to mind) and let them balance and check the wheels for proper runout and roundness.
 
Side to side.
I would have to guess popping. It does not go ka-pow but more of a pop-papop-papop. It happen when I am a little higher revs and downshift to hit the turn. Also does it a little if I am wating at a light & give it gas and let it go back to idle but on a smaller scale not as loud.
 
side-to-side would indicate the wires need trueing up. The "popping" is coming from the exhaust? On over-run? IIRC, "reports" from the exhaust usually suggests an over-rich condition, popping from the carbs is an indicator of a lean setting.
 
IIRC?

I thought I had an over rich condition but it has been tough to tweak. If I lean it out it wants to stall and as I adjust the the idle to bring it back up it runs a bit rough.

Another symptom I noticed this morning was if I come to a stop and don't downshift - I just come to a stop & take it out of gear - RPMS drop and she almost stalls. then it comes back on and idles fine.

What should I do as a starting point in setting the carbs? I remember somewhere that some started leaning it all the way up and back out a certain number of flats and start from there. Does this ring a bell and how many flats?

The shake might be part rack related. I just wrote in someones steering rack post that I have rattle going over bumps but am not sure how to diagnose the rack or column.
 
Vping have you rebuilt the carbs and checked for air leaks at the shafts. I forget, in fact I forget what kind of carbs you have. You, I think, have several things wrong, nothing major, just a bit wrong or worn.
 
Shimmy: Sounds to me like wire wheels need service or tires are wearing improperly. Raise the front end and spin the wheels. Look at the lip of the rim and see if it wobbles. Look at the tire sidewall and make sure it runs straight, or at least stays in line with the wobbly wheel. Look at the tread and make sure it does the same, and that the tread does not move differently than the sidewall.

Popping sound: Completely normal. An actual backfire is bad. But a mild popping sound under deceleration is normal for hese engines. Listen to a race engine when they decelerate against the engine. You'll hear some REAL popping noises! Consider it pat of the charm of an old car without a whatchamacalit valve.

Carb issue: Have you checked the oil in the dashpots lately? Does it only happen when the engine is hot? If so, try a thicker oil. I normally use the SU Dashpot Oil that Moss sells but many people use the same 20W-50 oil that is in their engine. ATF fluid works also which I believe is around 30W but I personally wouldn't go this thick unless you're in a relaly hot climate.

Good luck and keep us posted!
 
The wires were blasted & repainted, new tyres installed and blanaced 200 mi ago. The place I took it too could not check or true them up. I asked in the club and nobody had a recommendation as to where to get them trued.

Good point on the carb oil. It is filled with 20-50 and I have not checked it in about 150 miles so I should.

As for carb leaks... I did not rebiuld the carbs just took them apart and gave them a good cleaning. Checking for leaks is with the wd40 test right? How's that done again?

Popping was not a major worry. I can live with it an it actually is a bit cool.
 
Spray the fluid with engine running where the throtle rods come out the side of the carb. If engine changes speed, air leak. Same for gaskets holding carbs to manifold or manifold to engine.
 
Will check later with WD but all gaskets from air cleaner to block are new.
 
How about all the ones between the carb and heat sheld and heat sheald to intake.

Just because they are new does not mean they are sealed, but prob are.
 
I knew I'd get slack for that!!

Yes all new gaskets & yet you have a point that they could be leaking but maybe unlikely.
 
If you have steel wheels, you might loosen the lug nuts and carefully retorque them . I had the same problem and that was the solution.
 
[ QUOTE ]
Popping was not a major worry. I can live with it an it actually is a bit cool.

[/ QUOTE ]

YAY!!! You've dialed it in to a point I'd say you've got no worries. And the decel "popping" lends character. Sleeping dogs and all that. Have some FUN!!!
 
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