L-48 Rebuild

[Jake1798]

Okay, I made a post on here a few months back about possibly rebuilding the 350 in my '76 Vette. At the time I was indecisive about whether or not I really wanted to rebuild the engine. But now it turns out that I have coolant leaking into my heads (bare in mind that this engine had a rebuild 4 years ago, at the local NAPA, and only has MAYBE 15,000 miles on it since) so I decided to do another rebuild. From what I understand it wasn't a complete rebuild at NAPA..ie pistons and such were not replaced. I believe they referred to it as a "re-ring" job. I have already began the process of removing the engine so there's no turning back for me at this point.

My questioning comes with the parts to use. It is a daily driver but something like 300HP would still be nice. Can I achieve that kind of power without going the aluminum head route? I'm not too keen on spending $1600 (keep in mind we're talking Canadian dollars) on a pair of aluminum heads. Aside from that I was thinking of going the Edelbrock route..performer series stuff as far as the cam, intake, carb and all of that go.

 

[waterboy1976]

Pick up a nice set of Dart Iron Eagle heads....they come complete at about $800 American dollars.....They're nice heads for the dollar. I have a set on my 350 and am running 10.32:1 compression with 420hp and 440lbs torque...

 

[twamd80driver]

Why not build it to LT-1 specs 350/350. It is very drivable, can be built at affordable cost, and there is published data for tune ups. Just my 2 cents!

 

[Jake1798]

waterboy, I will look into those heads for sure. twamd, what kind of parts are involved in building to LT-1 specs? New crankshaft or anything?

 

[twamd80driver]

What you can do is get the technical specs for a 70 LT-1 from the internet or a book from boarders. I am sure it will be a complete changing of crank, rods, and any part that handle the increased forces. MOST of these parts can come from a normal auto recycler. I would compile a list of required parts, and go shopping! Pull your engine and pickle it! That way you have the original intact for a later date. When it comes time to do my L-82, that is what I will do. I really like the fact of having published tune up data, and performance. I would not want to have to take my car to a mechanic that does not have any refrence numbers. I also know that it will fit, and have durability. We write enough checks for these beasts! If you want, I would help you find the stuff.

 

[problemenko]

Waterboy1976, I too am considering the Dart Iron Eagles. What cam and carb are you using to get to 420HP?

 

[Jack]

64cc iron eagles (or 64cc world sportsman2) heads, edelbrock performer P/N 2101 intake, speedpro P/N H100CP flattop 2VR pistons, speedpro P/N cs1062R hyd flat tap cam (220*/231* .468"/.480") will put you right at 9.7 - 9.8:1 CR and will make a good 350+ hp and motor will be very reliable ... using your freshened carb & distributor.

Smaller "fastburn" combustion chambers with flattops are current technology that provides better flamefront. LT1 does not have modern fastburn chambers & uses domed "popup" pistons ... popups interfere w/ flamefront ... they worked real well but not as well as fastburns & flattops.
JACK:gap

 

[problemenko]

Jack, Thanks for your advice. It's where I want to be for the time being.

 

[waterboy1976]

Waterboy1976, I too am considering the Dart Iron Eagles. What cam and carb are you using to get to 420HP?

edelbrock rpm air gap
mighty demon 650 carb
edelbrock 7102 cam......234/244 dur @ .50 488/510 lift (corrected lift with 1.6 rollers is .544 intake side)
1.6 comp cam roller rockers
dart 180cc runners 64 cc chambers shaved .010
10.32/1 comp
dynoed at 419 hp and 437 lbs toprque

now that cam is very lumpy....it loves 4 to 500 rpm range, my car is a 4 speed manual...if you have an automatic youll want to go to a smaller cam...ie: comps 268x cam is a good one...using a mighty demon carb instead because of my duration......is over .240.......good luck

 

[problemenko]

Many thanks! I'll order up some parts and let you gents know how it goes!

 

[Tom Bryant]

Here is the link to my engine build. It is a lot of reading but it is also very similar to rebuilding an L48 for mild sttreet performance on a budget. All of the proceedures, specs and costs are in the thread. Like you, I didn't want to spend a lot on new heads so mine are ported 76cc stockers. I realize the benefits of the fast burn chamber and many in the aftermarket have went to that design, including Edelbrock, but it wasn't in the budget. Mine is now a flat top hyper piston 9.3:1 with a GM Performance Parts cam (by Crane) and I'd guess it to be an honest 300-325 horse engine.

Here is the link-----------X

Tom