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[johnhensleigh2007]

I'm a college student, and I got my first car (1964 TR4) when I was 14. I have managed to return the car to running condition (sort of), but lately I have noticed a certain amount of hesitation, especially when I'm cruising at 55mph and want to boost it to 70mph or so. Slow acceleration is not a problem, only "snap acceleration".

I've done some maintenence on the carbs, so I may have screwed something up there. There are also one or two spark plugs that are consistently oily... (piston rings?)

Any ideas?

[kleykamp]

John,
Sounds like the carbs to me. Out of sinc and probably too rich in the fuel mixture. This would account for the "wet" plugs too. Too much fuel in the mixture will "float" the oil in the cylinders. Also, could be problem with the timing advance in the vacuum line. I'm no expert, but would recommend you start from scratch on setting the carbs, if you have a carb sinc tool. If you don't, I would get it to someone who does. Setting the air flow by ear is iffy. I would also check the vacuum advance connections. Hope this helps. Joe

[metalbender]

what carbs do you have

[johnhensleigh2007]

I have the dual Zenith-Stromberg 175CD carbs... one thing I could be is the air filters... the car was pretty far gone when I got it, and the air filters were shot, so I replace them with washable foam filters...so maybe they're not letting enough air in. Thanks for the help guys, keep it coming.

[Blake Discher]

What oil are you using in the dashpots?  I was using Marvel's Mystery Oil, acceleration at tip in was poor.  I changed to a Castrol 20-50W and couldn't believe what a difference it made.  Be sure to remove all the old oil before putting the new in.  Worth a try... could be a cheap fix.   

[JeffS]

Keep in mind that the ignition system could be letting you down too.  If you're using the original distributor, the advance springs are 44 years old and I guarantee they're stretched out.  That means your igniton timing may be set right at idle, but could be off by 10 degrees or more above that.  Likely, most of your distributor's cetrifugal advance is used up before idle speed due to the weak springs, leaving you with less advance for high speed driving, which is what you're describing.  Try advancing your timing to 15 BTDC at idle and feel the improvement.  If it helps, have your distributor rebuilt and recurved and it will feel like a new car!
www.advanceddistributors.com

[Darrell]

Hi,
Just thought I would add some words of wisdom to this sudject that I have learned over the years (28) of tinkering with various Triumphs (11 Owned, all running).  "Most Carburator problems are Electrical".
Cheers,
Darrell

[herald948]

I agree with Darrell! However, with the Z-S carburetors, symptoms similar to yours can be caused by pinholes or tears in the carburetor diaphragms. For the very short-term (i.e., "emergency"), one can use a bit of plastic electrical tape to patch a tear, but you'd then want to install new diaphragms ASAP.

[johnhensleigh2007]

Okay, I took some advice from all of you. I put some 20-50W in the carbs, made corrections to the vacuum lines, put TR4-rated air filters on. I bought the springs for the distributor, but haven't replaced them yet. I thought the car idled a heck of a lot better, but for whatever reason, it would flood the engine when just sitting turned off. The hesitation was still there, and I'm pretty sure two of my spark plugs quit working about halfway through the 5 mile cruise I took... this is really frustrating.

Any more suggestions? Y'all have been really helpful so far.

[none]

Since the car has been parked for a while it is hard to tell. I would do some testing and try to get more information.
A compression test (wet and dry) and a check of the rocker movement would be a good place to start. And adjust the valves while you are there.
A fuel pressure test and a check of the pump volume would be good.
If these tests give good results you can continue to the dizzy and carbs with more confidence.
Jeff provides fast, reasonable, expert, and excellent service when repairing a dizzy. Many have testified to this including myself. For the money it is one of the smartest things I have done for my car. Yours probably needs help anyway.
At this point you have some time and not a lot of dollars involved.
And that leaves the carbs. What you are describing is often a diafragm. Cheap and easy. If not the problem there is also Jeff at Paltech.
Best of luck,

[Tommal]

One other thing you might check is your fuel filter. If the car sat for a long time you could have had sediment or rust in the tank that is flushing through. I had similar hesitation that I noticed in certain RPM ranges after extended downtime.