ZR 1, 2 bolt or 4 bolt ?

[Larry McIntosh]

Since I am still looking for my perfect ZR1 one of my questions are:
When did they start using four bolt main bolts on the engine?
Why did they start with two bolt mains, and why did they change?

When I was young and we wanted a full performace engine in our Corvettes we always would go with the higher performace engine, which as far as I knew was a steel crank, and four bolt mains. My 66 350 horse 327 had four bold mains. I replaced that engine with a 1970 350 cubic LT 1 engine had the four bolt mains, also my 1978 L 82 had four bold mains.

Thanks for any input. Larry

 

[Aurora40]

4-bolts started for 1993. They went with a 2-bolt because it is a ladder frame, and is more than enough with 2 bolts. The 4-bolts were extra security I guess.

 

[Wegone]

Lots of good info. here...

http://www.zr1netregistry.com/

Good luck with your hunt..

 

[rkreigh]

Since I am still looking for my perfect ZR1 one of my questions are:
When did they start using four bolt main bolts on the engine?
Why did they start with two bolt mains, and why did they change?

When I was young and we wanted a full performace engine in our Corvettes we always would go with the higher performace engine, which as far as I knew was a steel crank, and four bolt mains. My 66 350 horse 327 had four bold mains. I replaced that engine with a 1970 350 cubic LT 1 engine had the four bolt mains, also my 1978 L 82 had four bold mains.

Thanks for any input. Larry

the 4 bolt engines started in 93 when ALL of the 93-95 engines were built. the 4 bolt design is only about 5% stronger and the 2 bolt engines are plenty strong. the "ladder" style bottom end of these engines is totally different from a normal chevy with main caps. keep in mind a 2 bolt block set the endurance record. that being said, I'm partial to the 95 zr-1 as alot of other small "quality control" items were addressed and they tend to run just a bit tighter. expect to pay quite a bit more for the 93 - 95 cars. the real bargains are the 90 and 91s which run very well.

 

[SPANISHVETTS]

For ½ the difference in the price of a 90 to 93-5 you can blueprint the LT-5, add a set of headers, do a port & polish job and end up with an unbreakable 460 HP beast. Having said that there were other refinements to the late ZR-1s that improved the overall car so buying newer could be better.
I went for a 90 because it was the best Z I could find for the money and I am putting the car away for a few years. It will get collectors plates the next time it has a full registration.

 

[Larry McIntosh]

Thanks for the info on the ZR-1 engines. I would sure like to see one taken apart to see the difference. I have been with covettes since they came out in 1953, of course I was only 17. We sure had fun with all of the 50's and 60's. I am looking forward to getting a good ZR-1, and and showing that old guys still have fun in a fast car.

 

[ZR1 MK]

There is a great article with pictures in the latest ZR1NetRegisrty newsletter by Marc Haibeck showing and comparing the two.