I'm sorry. I hate seeing 20 threads all asking the same thing, but I have to add to the confusion, stocking up on parts for the off season... So, I would really appreciate some input on a cam selection for my car. Here are the details:

1975 L48 4 speed, 57,000 miles
No AC, stock rear end, stock tranny.

The parts I have at my disposal, either already had them, came on the car, or have just bought are:

Holley 600 carb
Edelbrock Performer EPS 2701 intake
Edelbrock Performer 60909 heads (I was told not to go over .515 lift with these)
Crane 1.5 roller rockers
Long tube headers with dual pipe
MSD ignition

Car is a weekend toy, not a track rat, just something I enjoy with my 5 year old and I want him to learn about fast, loud, manual shifting fun...

I'm not really sure what CR I will end up with, as the increase with 64cc chambers may be countered somewhat by the aluminum heads.

So? Any thoughts? Please don't say replace the heads with AFR or something with better flow, these Eddys are as good as free to me, I don't really want to get into big dollar heads on this motor. I am receptive to off the shelf, as well as custom stuff, just not into spending huge dollars on a cam by the time I get it to Canada. That's why I've ruled out converting to a hydraulic roller...

Fire away!
Thanks in advance!

 

I will suggest a Lunati Voodoo part #10120702LK.

 

Do you have one? It seems from the reviews on Summit like it gets used on automatics and pretty stock motors. There is another Lunati with slightly higher lift that is appealing as well. Right now it's the only suggestion I have though... Thanks!

 

Looking at those heads the intake flow looks pretty decent with lowish flowing exhaust ports.
If you divide the exhaust by the intake you can get the percent of intake to exhaust flow. On these heads it's in the low 60's, %62 at .500, %64 at .400 etc. A good percentage of intake to exhaust is considered %70 or better.
http://www.edelbrock.com/automotive/...ormer-sb.shtml

Given those numbers it's going to want a cam with a decent split on the intake vs exhaust duration.
something like this.
https://www.summitracing.com/parts/c...make/chevrolet
However I'm am not a big fan of the extreme line of flat tappet cams due to the seemingly large occurance of a wiped lobe down the road.
This cam by Isky offers a split and I don't see many complaints about Isky cams.
https://www.summitracing.com/parts/i...make/chevrolet
Note that the operating range is 2000 to 6000 RPM. And that it recommends at least a 9.0:1 Cr and a 3.23 rear diff ratio.

I believe a cam like this may suit your needs pretty well, split is a bit low still but overlap is still reasonable at 44*
https://www.summitracing.com/parts/c...make/chevrolet

If you want to give up a bit more bottom and add a higher stall torque converter you could step up to this with 52* of overlap. May be too big for your CR though.
https://www.summitracing.com/parts/l...make/chevrolet


The lift on these cams is based on a 1.5 RR so if you wanted to get it higher you could add 1.6 RR to your build.

I'm a fan of the 108 LSA. But you don't get the split duration so there is a power sacrifice above 4500 rpm with lower flowing exhaust ports and a loss of idle quality.
Something like this is similar to what I use now only mine is a roller cam with more lift and I run 9.9 CR.
https://www.summitracing.com/parts/i...make/chevrolet

Nope I stand corrected I did find what might work in this case in a 108 LSA and a split duration.
https://www.summitracing.com/parts/c...make/chevrolet
This one has 48* of overlap.
It is a comp cam though. Sooo....It might be ok. I just don't have enough experience with flat tappets to say for sure. Do some google searches and see what you can find, maybe some have used one for one or more of these cams and can give feedback.

It's all a trade off. To much duration and too much overlap and you loose bottom end power and idle quality. Too little and you loose RPM and top end power but gain idle quality.


Your CR with the stock pistons in the cylinder .025" at TDC (stock) with 64cc heads will be 9.02:1 if you use a felpro .015 shim gasket. You want that gasket to reduce your quench as much as possible down to the range of .040". Use 17cc's for your piston volume.
This calculator can help you determine this as well as you DCR. DCR is an indicator of cylinder pressure and low rpm torque. Higher is going to be higher torque. For aluminum heads the recommendation is usually 8.5 DCR and with those pistons maybe below 8.2 might a good idea.
https://www.jeepstrokers.com/forum/calculator/

 

With those heads and the low I/E ratio you need to give the exhaust port time as has been pointed out. Not an issue when cammed correctly:

.510/.490
221/234
109 LSA

Designed for the E-brock heads from 350-370 CID.

 

I get a little confused talking about the stall on my 4 speed manual. Is that like adjusting the power band on my MX bikes? I kid! I kid!

Ok... Ok... Seriously that's some really good tech, I appreciate all the work and thought you put into it. It completely makes sense, and explains why those heads weren't exactly flying off shelves at those prices. Almost a mystery why anybody would buy them at all actually!

I really like the Isky, and it might be a coin toss to the Lunati.

Straub, you listed some good specs, but I'm not sure if you meant to link to an actual cam and forgot? I opened it on a couple computers to see if I missed a link somehow.

I don't think I can go to a 1.6 rocker, I'm stuck with the 1.5s I already have. And as far as using the thin gasket, I was told when I got the heads to use a Fel Pro 7733 PT-2 which is .039 compressed. Does that make sense? I'm giving up compression there aren't I?

Sorry for all the questions, but I have another. I need longer push rods don't I? Plus .010 or something to accommodate for a thicker head base?

Thanks again for the solid tech guys, I'm trying to digest it.

 

Oops sorry about that. Got caught up in the cam and all.

Head gasket can be what you want. a .039" compressed with a .025" piston in the hole would be bad for detonation prevention and you loose compression. A .039 gasket would be for a block that is getting zero decked. If that is the case then yes that would be an appropriate gasket.
The felpro 1094 is what I use. .015" thickness.

Push rods will have to be determined during mock up with a head on, tester spring, and an adjustable push rod. You adjust the length until minimum sweep across the valve stem is achieved.
Scott at Straub tech has a you tube video to determine push rod length.

Straub knows cams. The specs he sited are probably his design not an off the shelf cam.

 

I ran those heads when I built the top end on the L48, they dont flow great, hardly at all for that matter, but I had a tight budget, was off work for a leg surgery and on short term disability so funds were low. I ran the comp xe262h( i think a cam with a tighter lsa of say 106 would have made it run better, either a custom cam or lunatis biggest cam for stock compression would be a better choice) 1.6 roller tip rockers, comp 1 piece +.100" push rods ( if nether the head or the block have been milled this will be super close), a crap action plus intake for clearnece that I port matched, morro so drop base air cleaner , Holley 600 V.S. and Hooker comp long tubes with 2.5" duals and Flowmasters and a Mr. Gasket curve kit, it made 260 at the rear wheels and 295 ft-lbs at the tire as well, I had about $1600ish into the hole top end, in hind site I'd go with with .015" steel shims to raise the compression even more and get what little quench it will have into the .040" range as the pistons set .025" in the hole. I don't think the msd ignition is needed, i ran the sttock unit and am still running it on my shp 400" and that money could go toward other parts, so unless you already have it, your running points or your igniton is shot. I also think that edelbrock says the heads are good to ..550" lift, but research it on their site, more compression and a better cam would have helped loads, probably made more power too, Straub is right if the cam is ground to match the heads it will work best. If your budget allows, go with a set if 3.55 to 3.7 rear gears, it will complete the driving experience. Good luck.

 

#1 get rid of that fire bomb, you call an Air Breather, ... dead serious !
that is a major fire hazard, fiberglass and gasoline and open flame equal a corvette burnt to the ground.

 

Like that one straub listed makes sense streetable and would still be lots of fun with that 4 spd...and of course sound good
Nice ride

 

Thanks again for the input, I appreciate it all. I looked at Straubs website and the prices and tech are really good, I'm leaning that way. I have a custom Jay Miller in a roadrace Mustang and I'm really impressed with the custom cam thing. Just for Straub putting that link to the free Youtube tech video I think he deserves the business. The issue always ends up getting stuff over the border. If it was easy to get stuff to Canada as it is to the US I'd be ecstatic.

Sucks to hear the heads don't really flow well, they cost me almost nothing and are loaded ready to go from a really great guy trying to help. I was trying to get Vortec heads but the guys here are looking for almost a thousand bucks for rebuilt sets. The ignition is the same deal, I'm not sure I'll use it. Came with blaster and wires etc, but why fix what isn't broken? It sure does look perty though...

Yes, that thing..... It was on it when I bought it, and checked the partsvboxes that came with the car and I see he forgot to give me the stock air cleaner. Some Googling says the stocker may not fit with that intake and carb, which might explain that being there. I have another option or 2, including a Roush Yates CF drop down cleaner box I may try. I was not aware that filter setup was dangerous though. Seems like a really solid lawsuit in these litigious times! Lol... guess I'll double down the insurance at Haggertys? Kidding....

Does anybody know what my rear gear "should" be? I'll get around to jacking it up and counting, but I can't find a simple answer on the interwebz. Looks like maybe 3:36 or something? Maybe?

And does anybody know, on a scale of 1 to 10, how hard it would be for a 5 year old to swap my rear gears?

 

I'm not %100 sure as it's a four speed and who knows what got changed by the previous owner but I'm guessing 3.08 to 1 it being an L48. Yea the don't flow well, but there are a lot worse heads out there. 260 at the rear tire would land me high 13's to low 14's alot quicker than the mid 15's it turned from the factory with the 180 horse smog motor that came with it. It will pin you and the son (killer photo by the way) in the seats and keep him grinding from ear to ear. If you cam it right and use an intake that works better than the one I used, i could see 280 rwhp from it, the 1.6 rockers made an imprivement. If you are pulling the engine, might I suggest new pistons an rings to get the compression up to 10 to 1. Horsepower TV built a 383 using those heads that made 450 hp with a hydraulic flat tappet camshaft. I also think that the rpm intake would be a better intake selection for your engine. The performer is a good intake,but figure that most cams you'd put in that work well with the heads are going to be in the 6k rpm range and unless mistaken the performer is a 5.5k intake and probably makes peak at 5200 rpm.

 

Don't get me started. The day that motor comes out will be the last day it sees that car under my ownership. That car wants at least a stroked 400, maybe a BB. It would be cheaper to just buy somebody elses built motor than do any more to mine, so I'm drawing the line at the cam. Great idea, but once it's out, it's going into a wrapper in case somebody wants the #'s matching block in another hundred years.

But I can't get the thought of a hydraulic cam out of my head now! Wonder what that costs to convert... To the Google machine!

 

Increase your budget and go with a retro HR cam. It'll caost about $800 more depending upon the quality of parts used.

Check out pricing at JB's Power and performance parts.com if its not practical to get parts from the US. I've bought from these vendors over the past few years and wouldn't hesitate to do so again.

 

performer head was a just a good replacement sbc head, at the time they came out the old iron heads were getting harder to find that werent just plain worn out
They arent expensive and certainly outperform the old stuff plus a good 40 lbs weight savings. Just a budget option really.

http://www.jegs.com/i/Edelbrock/350/60909/10002/-1