Overboring Stock 2.0 liners VS NEW Complete set up.

[Benjamin]

I will keep It simple as I am posing the question to those with experience

1978 2.0l Spider
Set up for Spica (conversion to 40DOCE in future)

Stock liners have rust, but machine shop has recommended a minimum overbore will take care of rust. Thus Oversized pistons? JE wants $100 (aprox per)

OR

Just order complete (pistons, rings, liners) set up from supplier and call it a day?


It seems that any route is $800 just a question as to who gets the $.

Purpose: Full engine rebuild for street use during summer 1 day a week.
Also for personal enrichment, I want to build this engine.

Any opinions or experience..
Thanks

Benjamin

[d.albe72]

Hallo,
new liners and pistons kits are a guarantee for machining precision, but JE pistons have for sure a more modern rings package. Alfa pistons have old fashioned heavy iron rings, while JE ones use torsional steel ones, with much better sealing performance, expecially when revving hard. Be sure your machinist know really well his work, liners have to be perfectly cylindrical!. My experience with forged pistons for street use is that you can keep piston gap within stock pistons limits (3 thou). Pistons supplier often reccommend larger gap (usually 4 thou) because of reducing seizing risks when breaking-in is rough, like in competition engines. But this lead to uncomfortably noisy pistons slapping.
I made a 2000 gt this way with CPS pistons and worked great, even wen revved to 7000.

hope this helps

Alberto

[Greg Gordon]

This one isn't even close in my book. Go with the JE's. Most good machine shops can machine the liners at least as well as Alfa did. We have JEs with .010" overbored liners in our supercharged Nord 2.0. Couldn't be happier with them.

Greg Gordon,
Silicone Hose Kits

[d.albe72]

Quote:

Originally Posted by Greg Gordon Most good machine shops can machine the liners at least as well as Alfa did. Greg Gordon, Silicone Hose Kits

[Gordon Raymond]

As you mention, either solution is reasonable. From an engine builders perspective, the advantages of forged JE pistons should be considered. With JE's (ordered for example, from Paul Spruell (800) 552 Alfa) you have a supplier that is familiar with the tremendous number of options available. These pistons can be ordered and machined for about any application imaginable. They can be cut for any style of rings, even gapless if you wish. They are available in any reasonable bore size you wish, with any compression ratio (NO head milling!), and several styles of wrist pins and retainers. They can be further lightened for specific applications, or left as manufactured for long term durability. They can have the valve cutouts deepened or increased in size as well for variations in valve size or cam timing and lift. The quality forged pistons available today are a good investment.
Liners that have been reworked also have many advantages over new. First and foremost, they have been age and heat seasoned, by many heat-up-and-cool-down cycles. They are less likely to fail in use than new, IF PROPERLY PREPARED. They may be cut for oversize pistons and will finish up with a better ring seating surface than new liners. Most race engine builders prefer "seasoned" liners to new. As mentioned in other posts, machining used liners is a job for a specialist. There are several techniques, but honing them oversize leaves the liner with the least internal stress. When cut for maximum bore, they do get pretty thin at the lower flange that seats in the block. Machining stress is not good in this area! If only cut a mm or so this is not a serious concern, but motorcycle shops that bore or hone thin liners are a better idea than those that will be using a boring bar on an old American V8! Again, contact Paul Spruell for machining options. My machinist uses a Sunnen hone for all this type of work and ends up with dimensionally perfect bores with excellent micro-finish that seats rings quickly. Paul may offer a like option.
As you can see, by my discussion, the only time I use new P&L sets is for the customer that wants them, or for one reason or another, there is no other option. This is just my opinion. I hope it helps.

[Benjamin]

Thanks for the great advice,

I will follow up as advised.

Sounds like the machinist's advice is holding true.
I will follow up to encourage others with this good advice..

Along with the tapped oil plugs in the crank shaft.

Best regards,
Benjamin

[60sRacer]

If you want a good reliability mod for a high performance engine, drill new oil passages for the intermediate bearings. Stock, these bearings feed thru the crank. Several threads here describe how to drill feed lines from the main oil gallery on the side of the block.

Robert