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1979 3.0 Rebuild with CIS Guidance

Rebuilding a 1979 3.0 with CIS and need some guidance. It will be going in a 1977 narrow body hot rod that will be lightened for the street. I don't plan on tracking the car and want a strong, reliable engine. I like torque and want a street friendly engine that doesn't require me to rev to redline to have fun. I want it to pull strong and induce some smiles.

Plan to upgrade to SSI and performance exhaust and I am trying to determine what else to do with the engine during the rebuild. I have read the article Extracting Power from CIS by Steve at Rennsport.

Is increasing the compression from 8.5:1 to 9.5:1 and using the 964 profile camshaft the right approach to meet my goals? What impact will this have on reliability and longevity? What is the downside of this approach? Other recommendations that balance benefit and cost?

Thanks for the help!

Old 06-11-2017, 08:46 AM
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Subscribed, embarking on a similar path, but in a lightweight 914.
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Old 06-11-2017, 11:24 AM
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3.0 Build

You are starting with a good base 3.0, and it sounds like you are on the right track as far as modifications go.

As I'm sure you know, the early ('78-'79) U.S. Or ROW 3.0's have a higher flow fuel distributor and large ports that flow well. Upping the CR or a Max Moritz P&C swap is a documented way to provide a nice power boost. MM P&C's are spendy (and near impossible to source in good used condition), but if you are buying a higher CR set anyway it might be worth it.

964 cams have a good reputation in a a 3.0/3.1, but I have spoke to one person who has a bit of trouble with a smooth idle and strong low end (upper end no issues) with 964 cams. Ask your engine builder about other cam possibilities. Most people seem to have no idle issues and a decent low end with 964 cams, but also a nice upper rpm boost.

SSI's and a good performance exhaust add a nice performance boost (and increased longevity).

Since you already mentioned "adding lightness," you might consider a 915 re-gear to make the most of your new build with a bit of mechanical advantage.

I would discuss your performance objectives with a reputable engine builder and see what he/she would suggest. With a careful build and proper maintenance, I don't see a reliability issue - it should last a very long time.

Search 3.0 performance, this has been discussed in detail before.

Last edited by G450X; 06-15-2017 at 07:51 AM..
Old 06-14-2017, 10:20 PM
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If your replacing pistons to up the compression ratio, might as well go the next step and up displacement to 3.2L as well. That's where you'll get the dollop of torque you're after. If you can source used 3.2 cylinders, you can have them bored out and plated to 98mm and buy 98mm 9.5:1 compression JE pistons. EBS was buying up used 3.2 cylinders to do this and providing them already done, so you might want to check with them. It's a cheaper route than buying new.
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Old 06-15-2017, 08:40 AM
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Quote:
Originally Posted by Josh D View Post
If your replacing pistons to up the compression ratio, might as well go the next step and up displacement to 3.2L as well. That's where you'll get the dollop of torque you're after. If you can source used 3.2 cylinders, you can have them bored out and plated to 98mm and buy 98mm 9.5:1 compression JE pistons. EBS was buying up used 3.2 cylinders to do this and providing them already done, so you might want to check with them. It's a cheaper route than buying new.
Unless you have a good "hook," Mahle Max Moritz 98mm P&C's are around $5k...
Old 06-15-2017, 01:40 PM
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Unless you have a good "hook," Mahle Max Moritz 98mm P&C's are around $5k...
I'm into a set for half that. Bought the MM pistons from a Pelican for $500 a few years ago. Bought a set of used 3.2 P&C's for $500 here as well. Sent to EBS and had the cylinders bored and plated for $950. Sealed Power rings were $250.

They're sitting on the shelf in the garage waiting until I get around to doing the top end.

Some luck being at the right place at the right time? Perhaps. But the seller of the pistons had them listed for weeks at $700 and nobody bit. I struck a deal at $500.
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Old 06-15-2017, 08:27 PM
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Quote:
Originally Posted by Josh D View Post
I'm into a set for half that. Bought the MM pistons from a Pelican for $500 a few years ago. Bought a set of used 3.2 P&C's for $500 here as well. Sent to EBS and had the cylinders bored and plated for $950. Sealed Power rings were $250.

They're sitting on the shelf in the garage waiting until I get around to doing the top end.

Some luck being at the right place at the right time? Perhaps. But the seller of the pistons had them listed for weeks at $700 and nobody bit. I struck a deal at $500.
Yes, if one is patient (timing is critical sometimes), deals are still out there. I took a chance on a used MM set several years ago when prices were a bit lower ($1200) and jumped on them. Mahle has a reputation for quality and longevity in their choice of alloys and outstanding machine tolerances, so I have hope they will still be in spec when I send them to EBS for inspection and to re-ring.

Unfortunately, according to EBS, Mahle 1.2/1.2/3.0 rings are hard to come by and they use total seal rings - I suspect they will work fine. They commented that the forged pistons (if they have not been in valve contact) rarely have issues, but that at higher mileages the cylinders could slightly oval and need re-plating.

EBS Reps also commented that they often work up several sets of 98mm 3.0 P&C at a time since the new MM sets are so expensive ($5k+ and hard to source at that price). If I recall correctly, their made up sets are less than half that price.

If one is not in a hurry, it is rewarding to pick up parts here and there to save a bit of coin and to spread out future rebuild costs. Good Luck on the 3.0 build.
Old 06-16-2017, 07:07 AM
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Thanks everyone for the great guidance and suggestions. I like the idea of the 3.2 upgrade and will be looking at options from EBS and of course Pelican.

Regarding cam, is the 964 the right approach for either the 3.0 or 3.2 build? As G450X mentioned, he has heard at least one mixed review. Is there a better option based upon my goals?

Old 06-16-2017, 07:33 AM
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