I'm pulling my engine to get rid of all the oil leaks. It runs well and the performance is only a little less than I'd like. I'm an older guy and am not looking for a ton of power. I'd like to be able to spin the tires from a stop.,

I'm using an Edelbrock performer intake with the stock Quadrajet, have full dual exhaust (2") using factory manifolds. Engine has ~90K on it.

I know the heads suck, and it's a low compression, 2 bolt main, engine. Again, not looking for a whole lot of power.

All that said, is there a cam kit that will work with the stock L48 to make a little more power?

Appreciate any help!

 

Forgot to mention it's an auto (TH 400) and has 3.36 gears.

 

I think putting in a replacement flat tappet cam is risky at best now days. I would go roller, but that means updating valve springs.

something roller around 204/212 duration and .450 lift for your combo would be my choice.

 

*In before the Jebby recipe*

A cam should not be your first step in improving the performance of your L48. With stock manifolds and near stock ignition curve, you're leaving a lot of potential on the table. Upgrade to a set of headers and a proper ignition curve first. See if that gives you the extra "oomph" you want. If you still want some more, there are cam options that will work.

Going with a flat tappet cam these days does have SOME risk, but a lot of that can be mitigated with parts selection from a reputable vendor or source and a proven break-in procedure. I just replaced the stock cam in my '80 LFortyGreat with a Summit 1065 (made by Elgin Industries, who makes good stuff), a set of Summit's Z28 springs (springs made by Elgin, locks retainers and keepers made by Trickflow), and a set of Melling flat tappets. The 1065 is a near clone of the old Comp Cams 268H (not the XE268H) with specs of 218*/218* @ .050" .458"/.458" 110+5. Break-in went smooth and I've had no problems. I followed the " @Jebbysan Recipe and Procedure" and had no issues. The resident engine experts will probably chime in on this, but with your gears and TH400, a cam with an @.050" intake duration of 214-218 will probably be the absolute limit you could go and not destroy your drivability.

If you're pulling the engine to reseal it up, it wouldn't be a ton more work to pull the heads and swap to a thinner head gasket to help get your compression ratio out of the crapper, new cam or not.

 

The L48 cam is an emissions cam, really chokes down the engine (194/203 @.050 and .390/.410 lift). With low compression and small valve heads, I agree that a good upgrade would be the Comp HE268. Z0 is correct, sbc like/need headers. The Edelbrock Performer with the above cam and a set of headers will really wake up your engine without affecting driveability - you will need new tires!

 

Also, if you are pulling a SBC with 90K miles, you might as well add rings/bearings and a valve job to the list.

 

And by the time you total all of THAT up (with the previous suggestions), you have spent a lot more than a running 5.3L Gen III or Gen IV junkyard truck engine, which comes with EFI, a roller cam, and twice the HP of a stock L48.

If you want to throw a cam at it, great! But start with timing. It might wake up your car enough if it hadn't been optimized before.

 

I started looking into flat tappet cams and saw all the problems people have had with wiping lobes. I'm not up for that.

I think the timing chain is stretched, which I plan to replace while its out (along with the oil pump). Timing seemed inconsistent. Either way, the engine is partially disassembled for removal so no turning back now.

Would conversion to a roller cam be worthwhile? Link bar lifters or spider hold down? I feel capable of drilling/tapping the holes for the bolts as long as it can be safely done without complete engine disassembly. Being my age, I have fallen down the "while I'm there" rabbit hole more than once and overdone/overspent what I aimed for.

Any comments/suggestions on the roller cam conversion (at a reasonable cost) are eagerly invited.

Thanks for all your comments thus far!

 

Follow my procedure and you won't have any issues. I break in at least four or more flat tappet cams every year......have not had one go flat since the whole "Zincgate" happened in 2005.......do the prep and it will be fine. The internet is chock full of MF'ing experts who will tell you about wiping lobes and roller is the only way.......about 1 in 100 will tell you how to do it right though.......do you think that thousands of flat tappet cams still get sold and all of them wipe out? People love to Bandwagon and shitpost trendy topics that they have zero concept of and this is no exception......
Put the 268H in it as suggested......it works. Use a Cloyes 9-1100 Timing set NOT a cheap "double roller"......
A set of long tube headers and 2.5" exhaust are the perfect compliment to the cam and intake......with these three things and correct tune.....it will feel like someone stuffed another engine in it......it will spin tires from a dead stop......not a rocket....but torquey and quick......

Now I did not invent these engines....and you can do whatever you want. A roller conversion on your engine will cost you well over $1200...you can't "drill and tap" an old block to accept the "spider", you will need link bar lifters.....and is almost an insult to do it without good heads.....But I did come up with a procedure on my own that will damn near guarantee a successful break-in........all about attention to detail.

Jebby

 

Always listen to Jebby he knows these old school engines.
I looked at a roller conversion for my engine about 7 years ago when I was rebuilding my engine. I was looking into it for the increase in power that a roller cam can offer. But as I am overseas, everything costs double to triple what you pay in the States. And even 7 years ago, I just couldn't justify the expense.
I am also of the belief that there are literally millions of these engines all over the globe still running flat tappet cams. And the vast majority of them are running just fine!
Including mine. I had no issues running in my new cam.

 

Jebby, what is your procedure?

 

Purchasing and installing a Roller Cam kit would cost more than the entire engine is worth.

There are virtually hundreds of thousands of Flat Tappets running w/o issues out there in the real world.
Just remember one word: Zinc.

 

Jebby

 

Hey Jebbysan, I appreciate all your knowledge and willingness to share your expertise.

Would this kit work well? https://www.summitracing.com/parts/c...make/chevrolet $493.95 Includes cam lifters, springs, retainers, locks, valve seals and timing set. I purchased a Melling double roller timing set, is it not of high enough quality? I can return it.

Regarding your procedure, couple of questions:

3) Priming the dry lifters so that each lifter plunger is in the right position to open the valve right away. What position do the lifters need to be in, or do you mean just prime the engine and make sure oil is going up the pushrod tubes?

4) The firing order method of valve lash at 1/2 from zero lash. I assume zero lash is found by spinning the pushrod while tightening the rocker arm, and achieved when you feel a light drag, then 1/2 turn tighter. Correct? How do I get it 15* without starting it.

Sorry for the newbie questions. I have done all this before (couple of times) but it's been at least 2 decades. I just don't want to F it up too bad.

Thanks in advance!!

 

Set the lash and prime the engine with the oil primer....this will fill the lifters.

I wiggle the pushrod up and down....spinning it is not a good indicator of zero lash....

To get 15 degrees....mark where the rotor is on the base of the distributor after install on TDC #1.....remove the cap and turn the distributor counterclockwise until you line the mark you made with the edge of the rotor tang....this is 15 degrees + or - a degree or two....enough to start the engine reliably.....and not be grossly retarded or advanced.....
If the header tubes start glowing red at 2000+ RPM....then dial in some advance....have a timing light hooked up and ready.....I even install an remote oil pressure gauge and water temp gauge so I can monitor outside the car....

Jebby

 

I wouldn't buy that Comp kit.....in fact....I believe the same 268 cam is available in the Summit brand for $100 less and they have a 1.250 spring/lock/retainer kit with seals....you need the lighter of the two kits they offer....one has a little less pressure.....
The same Elgin Z/28 spring kit is available through E-Bay, Amazon and others...Alex's parts has them too....same stuff....less dough.
You will need to measure your spring boss to see what seals you need.....if there is not a match...then use Umbrella....they work surpisingly well....some Mercruiser V6/V8 Chevy's use Viton on the intake and umbrella on the exhaust for a little more lubrication in the extreme load environment it is subjected to....
I always cut the boss for Viton seals....so I do not know if a press on positive Viton seal is available for stock guide boss.....you will have to hit the books....
The Melling is fine if it is a "True Roller" and not just a cheap "double roller"....you can tell by the pins.....the true roller has a sleeve over the pin that rotates....
That piece of trash that comes in the Comp kit makes me laugh.....it will have 4 degrees slack in 10k miles.....

Jebby

 

Here’s my shopping list. Look OK?

Summit Racing SUM-1065 - Summit Racing™ Camshafts $149.99

Melling JB-817 - Melling Replacement Hydraulic Lifters (16) $124.32

Summit Racing SUM-174001 - Summit Racing™ Valve Spring and Retainer Kits $104.99

Cloyes Gear 9-1100 - Cloyes Street True Roller Timing Sets $35.99

Fel-Pro 7733SH1 - Fel-Pro Head Gaskets (2) $25.98

Total $441.27 + tax/shipping



I’ll decide on my oil pump later, unless someone has a good suggestion.

Special thanks to Jebbysan for all the expertise and willingness to answer amateurish questions. (I actually have assembled a few engines, but parts selection is not my strong suit).

 

A bad l 48 is like beating a dead horse. You can buy a modern long block with what ever Hp. Like 275 or 300 or 325.

If you want to spin the tires you have to get a quality TQ. NOT some cheap higher stall

 

I had a 75 that I modded.
That L48 really responds to true dual exhaust & headers. That cat was awful that year.
The timing curve helped it a lot also. It will feel like a different engine even with the stock cam.
Then you have made it breathe so much better you seriously need to think about sending the QJet out to Lars for a rejet.
Mine ran very very lean.
And almost no one else left around knows how to rejet QJets like Lars does these days.
That knowledge, and those parts, to mod QJets, is on the brink of being lost forever.

A cam will help a little more, but go with Jebby's suggestion, and keep it very mild, due to your low CR..
His is the biggest I would put in it.
That is a 218 dur on a 110LC. Your stock was a 195dur.
That's big enough for 8.2 CR.

 

Umm...
That is not the 268H cam
It has 218dur @ .o5o but has way too much adv dur at 286 not 268.
It will have too much overlap and be soggy off idle with a stock convertor.


This is the Comp Cam 268H
https://www.summitracing.com/parts/c...make/chevrolet

The 268H was specifically designed for these low CR engines (8.0-9.0) and build TQ & HP without making it so big that the low rpm TQ starts to drop off. They pull great from just a little bit above idle. It has 23 degrees more duration than your stock (195) cam so it pulls higher, and stronger, has nice vacuum, and works well with stock convertors and gears. It is almost as big as the 350-350 cam without the low rpm TQ drop-off. The mild (non-aggressive) lobes have less break-in failures than the more aggressive Extreme Energy versions with much quicker lobes. Those I do not like for their high failure rate.