Project "86 Inline 6 Rebuild"

xmen3

Cadet
Joined
Sep 3, 2006
Messages
22
Took my block with 2 bad holes to the only shop in western Canada that works on inline mercs and was told that it had to get bored 20 over in each hole and new wiseco forged pistons installed. Boring @ $60/hole + 6 pistons not installed =$1400; about $1250 US.
Seems high to me. I usually pay $20-$25 per hole for my automotive stuff and about $40 per piston.
As well, to my eye, 2 holes were not marked at all and 2 only slightly scored. The other 2 appeared to have deeper scoring.
Sure feels like they are trying to run up the bill.
Finally got them to admit that 20 over was only needed in the 2 bad holes but that 15 over was needed in the others.This sounds a little more plausible. They also said that I can supply my own pistons if I like, but they won't bore it until I give them the new pistons so that they can measure them.
Now the 20 over is only available as a 2 ring forged wiseco and the 15 is only available as 2 or 3 ring cast.
So my first question is would there be a problem mixing cast and forged?
This shop says that they have never had a problem with the wiseco's and they recommend the newer 2 ring pistons over the 3.
Now forged 2 ring wiseco's are frowned upon by some of the most respected posters in this forum so I am in a quandry as to what to do.
One poster recommends the old 3 ring cast, but if they are better , why were they discontinued in favour of the 2 keystone ringed pistons?
Just curious as to which piston will withstand the most abuse in case of overheating or predetonation.
I have also read here that forged and cast expand at different rates and need different size clearances.
Is this true?
Some else posted here that the shop shouldn't need to have the pistons, they should just bore it to spec and it should be fine, todays pistons are all spot on.
I know I can find 15's cheap but the 20's are triple the price.
I am wondering if should I splurge on this thing and try to build it for as much power as possible (30 over cast or 40 over forged all around), what else can I do to get the most performance out of it like a 1500 XS.
How much would I gain by doing all this extra work and how much should I expect to pay?
Maybe I should just bore it minimally and go slap it back together on the cheap and not worry about beefing it up?
Would really like to know the ins and outs of the different kinds of pistons first so that I can make a better informed decision.
Thanks in advance.
 

Laddies

Banned
Joined
Sep 10, 2004
Messages
12,218
Re: Project

Re: Project

Price for boring is about right, it takes a dead end boring bar so they alway charge more. If you use WISCO pistions you need to be careful on the tolarances and break in, they will scuff quite easily, We try not to us them on customers engine inless we run the engines in, we had some scuff years back so we only OEM type pistions
 

xmen3

Cadet
Joined
Sep 3, 2006
Messages
22
Re: Project

Re: Project

Thanks Laddies.
Do you know if it is alright to mix forged and cast pistons?
I don't want to bore it out any more than necessary and 2 20's and 4 15's seem to be the answer.
 
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