timing chain? (long)

[87911jon]

Just met with a new mechanic who now works at my friend's shop. He's a seasoned NASA (993 Turbo/ RSR replica) racer and full time Pcar wrench. We are new to each other... Here's the story. I bought a vintage GT3 racecar 3 years ago from a close friend. 1970 914/6. 2.4 liter bumped to a 2.5. 40 webers. Unknown cams, headers. Car sat in a heated warehouse for 4? years before I bought it. 2 years ago last November I did my first/last track weekend with this car. Can ran great. No problems here. I have it historically tagged so I can drive it around from time to time. Maybe 6 months ago after driving it I popped the engine lid to check things out and noticed the float was stuck and so the carbs needed rebuilding. Car ran great besides dumping massive amounts of fuel. Bought the rebuild kits and planned to do it myself. Fast forward 3 months, nothing getting done on my end so I took the car over to my friend's shop where the new, very seasoned mechanic now works. He rebuilt the carbs. Picked the car up and it ran poorly. No power under load. Would rev ok when sitting still. The mechanic said the plug wires, points, rotor ect needed to be replaced, so I replaced them. Ran the same. Dropped it back off to the shop. Last week I had a leak down/compression test done and it yielded excellent/healthy numbers. What's being said now is that there's alot of timing chain noise going on. He saying that the chain is ready to let loose, because it's "that" loose it's throwing the timing way off and therefore causing the engine to run poorly. Thoughts please?

[911pcars]

I would ask him what happened in between the time period mentioned.

"........so I took the car over to my friend's shop where the new, very seasoned mechanic now works. He rebuilt the carbs. Picked the car up and it ran poorly."

I mean the time period between "he rebuilt the carbs" to where you picked the car up. When a shop rebuilds carbs for a customer, they usually run it on the engine to make final adjustments... and it should run better than when you brought it in. If the car doesn't run correctly because of the carbs, they should make it right. If the engine doesn't run well otherwise, the shop should inform you before swiping your credit card. Does that sound reasonable? Evidently, he didn't for some reason. I would ask him the question, then get a second opinion, perhaps from your garage owner friend.... or someone else.

BTW, an engine with strong, healthy compression test numbers should run well unless the fuel or ignition system is not. If the chain is so loose a compression test should have lower numbers to reflect that as well.

When you said this, "The mechanic said the plug wires, points, rotor ect needed to be replaced, so I replaced them.", that tells me he diagnosis by replacing parts - a technique favored by many consumers - not a technique used by someone who should know better. I think he owes you some refund money.

My $.02
Sherwood


Sherwood

[87911jon]

When questioned repeatably about why the engine ran so poorly after the carbs were rebuilt, he said the hydraulic tensioners could loose their pressure from sitting and thus make the chain loose which would/could throw the timing off... I should have gone with my first instinct and done the work myself!