1G Connecting rod differences 6-bolt vs 7-bolt?

[blowinsmoke95]

Okay guys, I need a straight forward answer. I bought a 90 Laser and the guy I bought it off of put one 7 bolt rod on a 6 bolt crank with 3 other 6 bolt rods. Can there be any consequences caused by this?

 

[booostedGSX]

That can't be good. If I'm not mistaken, rods come in a set that are all balanced and weighed to spec. Using a different rod could cause some bad stuff to happen I'm willing to bet, but as to what could happen I cannot say.

 

[pneumo]

Yes, the 7 bolt rods are lighter and weaker. The 7 bolt rod bearings are narrower, too.
No matter how you look at it that's a hacked motor just asking for trouble.

 

[blowinsmoke95]

So, when I buy bearings, I need 3 6 bolt and one 7 bolt or will 4 bearing for a six bolt work? Also, can this cause rod knock??

I guess what I'm trying to ask is, are the rod journals different sized?

I just want this car to last for like a month of easy driving until I can get my dd up and running again. I would like to just put a set of rod bearings in it.

It sucks having 2 no good cars sitting in your driveway.

 

[pneumo]

Your best bet is to use all 4 rod bearings. The journal diameter is the same, the width is different. Yes, it could cause rod knock. Does it have rod knock now? If not, I'd just use thick oil and drive gently until you can rebuild it the right way.

 

[blowinsmoke95]

yes it does have SLIGHT... and i mean slight rod knock as of right now... i just want a temporary fix for now...

 

[Rockbmx1]

I would higly suggest getting another 6 bolt rod to replace the 7 bolt rod.

 

[mitch86]

I would definitely change out the 7 bolt rod asap. It is lighter than the other three and will cause vibration because the crank wont be balanced properly and this could easily break stuff....Bad idea!! Plus the potential of the entire assembly is now limited by the weakness of the 7 bolt rod.

 

[FunkDocta]

Just to be on the safe side get the other rods checked and see if they reusable if not pick up 4 6 bolt rods. I started to develop rod knock yesterday and plan on check if the other rods are reusable.

 

[blowinsmoke95]

Where do I get rods checked? So in other word it would be best to get a brand new set? Can the wrist pins be reused?

Also, how prone is the 6 bolt crank to getting messed up from bad bearings? I mean should I try to piece this back together or find another 6 bolt short block? The head on this car is brand new (rebuilt/re-manufactured) and the body is clean as a pin (for a 90).

I just want a reliable boosted 4g. I'm not too concerned with power or how fast it is right now. I just want it to be quick and reliable.

 

[DSMtsi23]

Change out those 7 bolt rods and put 6 bolt ones in there.

 

[pneumo]

Where do I get rods checked? So in other word it would be best to get a brand new set? Can the wrist pins be reused?

Also, how prone is the 6 bolt crank to getting messed up from bad bearings? I mean should I try to piece this back together or find another 6 bolt short block? The head on this car is brand new (rebuilt/re-manufactured) and the body is clean as a pin (for a 90).

I just want a reliable boosted 4g. I'm not too concerned with power or how fast it is right now. I just want it to be quick and reliable.

Yes, the crank can get scored from spinning a rod bearing. The trick is that you don't know the condition of the crank right now, so it's difficult to make a decision since we lack that info. If you have the funds I'd recommend finding a good crank and block and start rebuilding it. It takes some time to rebuild a block, so drive the car as-is until the new block is ready. If the old shortblock turns out to be re-useable you can either keep it as a spare or sell it to help fund the build of the other block.

 

[RedEyeBanDiT]

Change out those 7 bolt rods and put 6 bolt ones in there.

easier said than done