Rebuilding a L46 engine that has remained 100% stock sans intake / carb.





Bought as a driver with few drivabilty issue and finally found that the No.1 Intake Cam lobe is wiped. Car actually had decent get up and go for 7.25 cylinders working.

Looking for solid, complete advice on what I can do to keep as original as possible, but make something can be driven for 2-4 hour road trips. I do have 93 in my area as well as excess to few gallons of 100LL.

I would like to stay Flat Tappet if possible due to costs.

I've rebuilt flatheads and one stock 5.7 (TBI motor) before so not new to engine rebuilding but new to Hi- Performance Rebuilding.

I have done alot of research and searching but often there are missing info, or engine is not kept original at all or just replaced.


Thank You guys!

 

Assuming you want to save the block stamping numbers, the .015" thick steel shim head gasket is a must have IMO. They need a coat of copper coat head gasket spray before installation. This will establish a good tight quench that helps prevent detonation.

if the bores can be saved, you will be able to save a LOT on an overhaul. Beg your machinist to measure it carefully for you. Some guys want to rebore EVERYTHING that comes into the shop. A hard stone hone job will show you where the bores are as far as being able to reuse them. Let's hope you can save them.

Don't upgrade the valve springs. Don't use "Z/28" springs. Use base engine springs. Your cam and lifters will thank you.

That's all I got off the top of my head.

 

I am very hesitant to be handing out advice to anyone because I am new to this but responded to this thread because of what I just did to my '69 Fathom Green L-46 with a non-original intake & carb. It also developed a problem with the #2 exhaust lobe but I caught it early when I was doing valve stem seals last December. Maybe this will give you some ideas.

You didn't mention a full rebuild so I don't know exactly what you intend. In my case I did this over the fender - didn't see a need to pull the engine as I did compression tests on it first and each cylinder was healthy. It never burned any oil but was a ping monster so I decided this was a good time to address that. Yes, over the years I spent quite a bit of time tuning it and got virtually all the detonation out of it, it was fun to drive but I had to dial the timing way back and always felt the car could do better.

I pulled the 3927186 heads. The engine was rebuilt around around 1988-90 @ .030 over and they used Sealed Power 7070P pistons that appear to duplicate the original OEM. They are domed and I had to be careful selecting heads and head gaskets. I didn't need an expensive explosive disassembly.

JEGS makes a useful cam degree kit for those of us who won't be doing this very often: Precision Cam Degree Wheel Kit [11 in.] I also picked up a magnetic base and a deck bridge for the dial caliper and checked each cylinder. The block had not been decked when rebuilt and the pistons were already down approximately .030" and I tried a .015 shim. I clayed the pistons and no way that was going to work, no clearance.I probably could have tried a .028 or .030 but frankly I got sick of farting around with it and got a 7733P2 @ .039. I know the quench isn't right but it wasn't before with the same gasket and again, didn't want to take any chances.

I cc'd the old camel humps and they'd been relieved to 68cc. I chose the Edelbrock 5073 @ 70cc as a reasonable replacement and again, I had no clearance worries. I wasn't looking for a horsepower monster and I am not concerned that much with originality, I just wanted a fun cruiser so I picked a mild cam. Also added Patriot H8019-1 headers and HiFlow C2 style side pipes that tuck under the OEM covers. Oh, and I sourced everything I possibly could Made in the USA.

I just broke it in recently and have tuned it sufficiently to drive it but have to get after some details before I can really cruise with it. Nothing exciting just time consuming, small fiddly stuff.

For the few miles I have put on it though my backside dyno tells me I must've done something right, it sounds great and I think I found a few more horses in the barn. I also gave it the full 36 degrees base timing and not a single ping - yet anyway.

This is what I used:

Howards Cams Street Force 2 Hydraulic Flat Tappet Camshaft and lifter Kits CL112571-12

Howards Cams Performance Valve Spring and Retainer Kits 98412-K11

Howards Cams Swedged End Pushrods 95012

Howards Cams Long Slot Rocker Arms 90005

Edelbrock E-Street Cylinder Heads 5073

 

I am hoping a hone job would work as well. The car itself has 62,000 miles on it and I am confident I am first into the motor.

 

If ya must use a flat tappet cam, suggest SOLID Mechanical lifters that ALSO have a "direct-lube" EDM oil-hole thru face of lifter (Not possible w/ hydraulic lifters). If the rest of your valvetrain is up to snuff, it will Not require routine lashing/lifter adjustments. Yes, they make a sound all their own; many find it comforting.

You can build/reimagine it better than L46. Today's piston options allow thinner, metric ringpaks that offer benefit of reduced friction, greater efficiency, lighter reciprocating mass. However, your machinist Must be alive to modern honing protocol required by today's thinner standards.

For Cam/Lifters etc: Highly recommend speaking with Mike Jones of Jones Cam Designs at Denver NC USA. Jones' spring recs trump any here.
http://jonescams.com/

 

Thank you for the reply and detailed info!

I plan on reusing the stock heads. The car overall is pretty original so like to keep it that way.

Honestly if it wasn't as such I would have an easy time making a nice SBC to work with.

 

Apologies. This morning when I responded from my desktop that picture wasn’t there. In fact I couldn’t upload one either. Now that I’m using my phone I see everything. Odd. My fault, I have my home PC a little too restricted.

Good luck with your build!