I started rebuilding my motor today B18C1 GSR to stock specs. Im currently using acl race bearings for both main and rods. My question is when i plastigaged the rods from the timing side to the the clutch side it reads, .0015/.0015/.001/.001 isn't the .001 too tight or out of spec?

the service manual is saying
B18C1 engine:
Standard New: 0.032 - 0.050 mm
(0.0013 0.0020in)
Service Limit: 0.060mm (0.0024in)

am i doing something wrong or reading it wrong? i've plastigaged it more than a few times and coming out with the same numbers.

 

what kind of rods

 

everything is stock

 

green plastigage?

 

yeah, http://www.aircooledtech.com/plastigage/plastigage2.jpg

 

when you put the bearings in, are the dry. no oil on the back

 

yeah dry

 

not sure if it matters, but the crank was micropolished and balanced

 

if anything that will make the crank smaller, leading to more clearance.

Maybe have your machine shop double check for you

tight rod bearing clearance is a no-no

 

got'cha guess ill swing by there tomorrow.

 

I second having a machine shop check clearances.

It is this exact reason why I won't use plasti-gage any longer. Too inconsistent in my opinion.

 

you can always use the acl race x series bearings that will give you more clearence.
you can use one acl race h bearing and one acl race x bearing that will give you a little more clearence.
If you use both x bearing your clearence will be in the .0020 range but if you mix and match it will be in the .0015 range.

 

One thing I have seen, is plastigauge not being used correctly on rod bearing checks. How do you seperate the cap from the rod? If you tap on the nuts or studs it will squish plastigauge if you have it under the cap side bearing. If you put the plastigauge on the rod side you have a better chance of not disturbing the material.

 

i actually had it on the rod cap side and tapped the rod end cap left to right while pulling on the cap end until it came off, ill probably try it on the rod side to see if i get a different reading

 

nice work

 

make sure to use 30weight on the rod bolts

and torque to spec *not more

using other fastener lubes tend to let it glide more = lower torque values..
seen this happen numerous times when using ARP assembly lube

sometimes the figures are so small it doesnt matter..
but in ur case.. that small diff may well matter alot


HTH

 

Is it possible the rod caps got mixed up? Do the numbers stamped on the sides of the cap match up?

 

for checking clearances I would use 50% tq instead of the full value

 

Thats stupid. Clearences change based off torque value. 50% torque on my other block was ok. 100% torque mechanically siezed the crank because the journals were out of round in the block.

If you use 50% torque to check clearences you might as well be slapping a junk engine together for an engine blow show

 

I usually never go full torque either during mock up. I feel it's better to not stretch the fasteners any more times than you have to. I go about 30% less. So far so good here but maybe I just been lucky.

Are you sure your since your mains were that far out that that was the reason the crank seized?
Next build I will measure the bores at different torque specs and observe.

 

Yeah im sure. After I checked the clearances and saw how tight it was I used a telescoping gauge and it was pretty far out. Used a different block and all was good

 

Agree, sort of.

Nothing beats a mic and a detailed build sheet. Plastigage is great for doing a final sanity check and comparing to that build sheet to make sure the numbers are correct.

Wouldn't rely on it as my only measurement though.