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1968 Looks like Engine rebuild

Sarge

Well-known member
Joined
Nov 22, 2002
Messages
333
Location
Folsom, CA
Hey all, my restoration on my Cal Special is on a little hold while the Engine is getting rebuilt. Upon removal of valve covers, they found some dark marks on the valves and valve and spring issues (I'm not technical, so don't ask too much) and wanted to send it out to have the valves, seals and guides replaced. They want to do the hardened seals since they are at it.

Upon further inspection, it appears that the piston skirts are cracked and "broken off" on 6 of the 8 pistons, so he is telling me I should do a rebuild since the engine is out of the car. Car has 146k miles on it, never rebuilt. New pistons, rings, camshaft, not sure what else, will learn more tomorrow when I drive up there.

I am not made of money, but it would make sense to take care of as much as I can afford while the engine is out of the body. Question is: What components would be a good fit? My car is a 302, with Edelbrock 600 CFM carb, Weiand 8011 intake manifold, MSD disti and ignition. C4 Auto Trans, with 3.00 gears (if they are stock, could not swear to it).

I am not looking to make a ton of HP over what is stock, but I have no idea what cam, duration, lift, etc, piston type, valve type etc, etc, etc. Any ideas what would work well with what I have? I am really at the mercy of the engine shop, as I don't know what works with what. I know I haven't given enough info, and what I would probably hear back is "stock", but not sure.

Thanks for listening,
Robert
 

dalorzo_f

Well-known member
Joined
Jan 7, 2006
Messages
1,886
Location
Brisbane Australia
If it is a driver build it back to OEM, or near, specs. Don't get lost in all the "more HP is better" hype as all it does for a street car is add costs... if your tooling around town at 25-45 mph most of the time, who care what the peak HP at 6500 rpm is?

Assuming you are using the stock hydraulic flat tappet just ask them to source a cam similar to OEM (don't ahev specs handy). Mannel's book lists a C3AZ-6250-V, lobe lift .2663/.2657 (intake/exhaust), .368/.381 theoretical valve lift. Duration 266/256 w/30 degree overlap.

Pistons were flat tops with valve reliefs. Shorter skirt than 289, any basic 302 piston will do as long as deck height and valve clearance are checked. Cast is fine, no need to pay for forged, not used on many Mustang engines and the mythology around them is just that. Good stuff, but not needed in most cases.

The stock 302 was rated near 250Hp, so not a fire breathing engine. If you want that, a basic build will get you there. The $ go up as the "more Hp" pieces drive upgrades across the build. More cam lead to new head, leads to ne intake and carb, leads to stronger bottom end. Keep it all in line, build the bottom end for power/durability and the top end to breathe as required and a basic build will run for another 20+ years...

A basic kit like this will do fine, and save you $ over the "bigger/faster" slippery slope... $300 for all that kit is a good deal. I just paid more than that for a FE cam kit... ;-(

You could buy the kit and upgrade to Clevite bearings and Moly rings. A double roller timing set is an upgrade to consider. For a bit more for the upgrades you get a very solid build for a street driver.

http://www.northernautoparts.com/part/ek-ek0443b / ek0445
 

franklinair

Well-known member
Joined
Mar 1, 2007
Messages
4,740
The only suggestion I have is to stay as close to the original stock bore as possible. I cringe when I hear of oversize bore in these small block engines. .030 MAX if you HAVE to have it bored. More than that can/will cause overheat problems due to the thinner walls of the cylinders.
For normal driving, stock is fine, as Richard said.

Neil
 
OP
OP
Sarge

Sarge

Well-known member
Joined
Nov 22, 2002
Messages
333
Location
Folsom, CA
Thanks guys, pretty much in line with what I was thinking. I didn't want to go crazy with building a monster HP car (though that would be fun too!!!! :cheesy:) and then worry about frame, shock towers, tranny, etc.

Appreciate the opinions!
Robert
 

robert campbell

Well-known member
Joined
Apr 10, 2007
Messages
4,321
Hardened valve seats are a waste of money. Unless you are a trailer pulling truck, a motor home, or a large boat. Lack of lead and a toy car is a myth. And they are known for pulling loose and causing problems. Stay stock on the valve seats

You already have a nice intake an manifold and carb. I would recommend hyperkinetic pistons over cast. Better heat dissipation and way longer life. Neil knows these pistons were developed in WW II for the airplane engines. Yup another reason we won the war!!

I would recommend a mild Edelbrock hydraulic flat tappet cam and some Comp Cam roller tip rockers. Same price as the old stock rocker arms and a nice add on.

Sarge, you have it apart. You can do so many things for a very small investment. Time to step up over stock!!! Live a little, go fast, have fun!!!

A little port clean up on the exhaust side and set of shorty headers.... All the better!

Rob
 

somethingspecial

Well-known member
Joined
Aug 13, 2005
Messages
1,795
Neil knows these pistons were developed in WW II for the airplane engines. Yup another reason we won the war!!

Rob

Wow Rob, You learn something new everyday. I wasn't aware one of the reasons we won the war was because Neil knew about hyper what ever pistons used in aircraft. Way to go Neil. LOL Smart Ass Mike
 

robert campbell

Well-known member
Joined
Apr 10, 2007
Messages
4,321
Mike,
Neil's influence spans many decades!!!

They were developed due to extreme temperature changes from sea level to max altitude for our piston engine fighters. They are far superior to cast pistons and are in use in most car engines today. And they cost just a bit more than cast!!

Rob
 

p51

Well-known member
Joined
Aug 2, 2005
Messages
1,025
Location
NorCal
Mike,
Neil's influence spans many decades!!!

They were developed due to extreme temperature changes from sea level to max altitude for our piston engine fighters. They are far superior to cast pistons and are in use in most car engines today. And they cost just a bit more than cast!!

Rob

Rob
I've read that there is one "downside" to hypereutectic pistons. That is, with the addition of more silicon they become stronger but also less malleable (more brittle - see ** below) than normal cast pistons. They are therefore more sensitive to cracking if you get detonation. Any insight on this?
Thanks
James


**From Wikipedia:
"When a material has reached the limit of its strength, it usually has the option of either deformation or fracture. A naturally malleable metal can be made stronger by impeding the mechanisms of plastic deformation (reducing grain size, precipitation hardening, work hardening, etc.), but if this is taken to an extreme, fracture becomes the more likely outcome, and the material can become brittle. Improving material toughness is therefore a balancing act."
 

dalorzo_f

Well-known member
Joined
Jan 7, 2006
Messages
1,886
Location
Brisbane Australia
I don't plan on driving my car at 20,000 ft...! :tongue: :smile:

While some benefit may be gained, it can be the start of the "while I am at it". Engine builders love the "race cars us it, so it has to be better" (more expensive parts, more markup for them as profit, to some extent) Better piston, to stronger rod, to bigger cam, to.....

The kit noted above allows upgrade to SealedPower hypereutectics for about $50. So a minor cost bump, if you stop there!

One would have to ask, if a stock FoMoCo lasts 40+ years in many cases, is an original style cast piston really an issue in a daily driver?
 
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franklinair

Well-known member
Joined
Mar 1, 2007
Messages
4,740
+1
If that 302 went 146K miles, that speaks well of the stock components.
And (even at stock configuration) you'll notice a marked increase in performance due to the gradual deterioration over the years that creeps up on you (worn piston rings, worn valve seats).
I'm not a Hi-Po fan. Stock performance meets my driving requirements (and saves a few $$ in the process. My mods consist of 4BBL carb, electronic ignition, dual exhaust.

Neil
 
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