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Asked by Nov 19, 2013 at 11:05 AM about the 1975 Chevrolet Vega

Question type: General

Hey there,

I am in the process of maybe buying a 75 Cosworth Vega.  I want to make sure it is a numbers matching car.  From doing some research, I am getting some conflicting information.  My understanding is that the vin number on the drivers side dash, should also match the vin plate (silver) riveted under the hood on the cowel?

Also, my understanding is that the block should also have a stamped number on it, but some info says it does not match the vin, and other info says it does????

Does any of this correlat with the number on the dash?  The vehicle I am looking at is #490. The car still has the previous owners Neveda plates.  Any info you can give me would be appreciated.

Mike

3 Answers

11,425

The Vegas had motors that were designed to last about 50K miles then have them replaced. If you have a high mileage car, then you may not have an original factory motor. The piston walls were steel, but the aluminum engine warped so much, the piston walls also warped and could not be sleeved, thus a throw away motor. Good news, they don't make them anymore. Fun to drive, looked good in their time, but a nightmare to maintain. As for all the vin numbers matching, check on line. I think from the factory all vin numbers started out the same.

235

Please go to http://www.cosworthvega.com to see info on the Cosworth Vega. You can also ask questions to Cosworth Vega owners at Yahoo Groups: http://groups.yahoo.com/neo/groups/cosworthvegas/info The stamped numbers on the Cosworth Vega cam carrier, head, block, do not usually reflect in the car number (the dash plaque), but should all be the same for that engine. The stock Cosworth block was very similar to the regular Vega (140 cu in), aluminum block & cylinders. The cylinders were almost impervious to wear - UNLESS - coolant got into them. Then they got trashed. The 140 problems were not part of the Cosworth 122 problems. The early Vegas had a small cooling system and no return (overflow) so when they'd heat and spit out coolant it went on the ground and eventually was running on low coolant and overheated. Therefore blowing the head gasket - aluminum block and cast iron head didn't help matters. GM installed recovery tanks and coolant level sensors at no charge, but the damage was already done - both to the engine and the reputation. The Cosworth Vega had a larger cooling system and by the time of its production had a recovery system (like all cars do now). But, with its aluminum cylinder walls, if they sat with old/ineffective coolant for periods of time they'd get the cylinder walls messed up too. Cared for properly they'd run for a very long time. Many have been rebuilt and sleeved at this point, but many still have the aluminum cylinder walls. I have a high mileage Cosworth Vega (over 90K) and it is still running with no problems, block has never been opened. Since the process of boring and honing the aluminum block is so complicated and required special tools and knowledge, sleeving became the norm for rebuilding. Now, the sleeves are becoming hard to find. But there is a builder that specializes in Cosworth Vega rebuilds, from stock to wild. That was more info than you asked about the VIN. But the VIN is unique to the Cosworth, there is a U (seventh character from right) in it that separates it from regular Vegas. It was option ZO9 on the assembly line. If I can be of more help let me know.

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11,425

My dad worked for the factory the built head plainers and engine boring machines. It did take a skilled machinist to operate the machines. The big problem with the normal Vega motor was the cylinder walls warping due to uncontrollable over heating. The Cosworth Vega motors were built with a lot of specialty parts, includ9ing the heads and cam. They were near bullet proof, but not their little brother. My brother-in-law owned three of those little cars, and they drove him to drinking every time he saw one.

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