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Engine upgrades



Well, I finally decided to quit goofing off and do something productive. So, I installed a cam and manifold today. Since we are talking about a '75 L-48, I went kind of low key, with a Edelbrock Performer Plus cam and a Performer intake manifold. At some point in the future (next couple of years) I'll yank the whole thing and try to make some serious ponies . . . but, until then . . .

Side note: I am 44 years old and have been doing this stuff forever, first with my father and then on my own, for about 35 of my years. After untold numbers of rebuilds, upgrades, etc., it is still a BIG thrill to hear that puppy fire up for the first time. This one fired on the third or fourth revolution.

"I love it when a plan comes together" . . . Hannibal Smith

It's late, so I've quit for the evening. I did not have the proper grommets for the fresh air tube and the PCV (I installed new valve covers also), so tomorrow, I get to go shopping again! Can't wait to check out the improvements with a little foot in the carb . . .
Glad to hear it went together smoothly!

If you can, would you mind taking us through the steps you are now going to follow to make sure that your carb and distributor are both tuned in to the new improvements?

So many people get to where you are now, then feel like they are making less hsp than the stock engine because the spark and fuel is off. Sounds like with your years of experience that you are going to get it right.

I also think you made a great choice with that combo as a starting platform. It should really perform well.
Thanks guys. Chris, in regards to your question, the distributor has already been recurved. I had that done when I installed the new ignition system.

The next step will be the carb. I have been pretty adamant in the past that it's hard to beat a Q-jet for everyday driving. They can be a pain in the neck to set up, but once they are there, they really do perform pretty darn well. Unfortunately, I don't have the equipment (or the experience) to properly set up the carb. However, the good news is that there is a guy down the street from my office that can and will tweak in the fuel system. He will run it on a dyno . . . hmmm . . . may have him recheck that advance curve while he's crawing around in there . . .

A side note: so far so good. There is already a noticeable difference, especially in throttle response off idle. I am very pleased.
Speaking of Q-Jets Ron, do you guys remember this being on sale at eBay?

_ken :eek

I did not see that. So, what cha gonna put it on? So far, I am having to keep everything smog legal on mine. Bummer . . . anyone got a pre-'73 for sale?
This is the same setup as I have on my rebuilt '75 - great improvement !:grinshot . I don't know if there is a lot to gain from the new intake manifold over stock - but it sure is a lot lighter !!
Well, I finally got everything dialed in and was able to take a nice little cruise. I was not expecting nearly as much as I got. Performance off the line seems to be comparable. Not surprising, considering that I am running a 3.08:1 ring and pinion. Couple that with the tall first gear of a TH 400 and you can't expect much off the line from a relatively anemic smogger engine.

The real payoff seems to be two fold. The first obvious difference is the lack of 'bog' when you get hard into the secondaries. With the stock setup, WOT would produce a bad bog or hesitation that took some time for the engine to catch up. The lower the RPM, the more pronounced this was. With the new setup, this problem is non-existent. When you hit the throttle hard, it just lights up, no hesitation, no bog.

That leads to the second payoff. Acceleration from around 15 MPH to 70 or so is awesome! Was it worth it? You bet. This'll do until they change the &*#^&* smog laws here in CA, so that I can yank that big hunk o' iron out of there and make some real HP.
Part #'s please!

Hey rpounds,
Would like to know the part numbers of the Edelbrock cam and manifold you dropped in your L-48.

I'm running a smogger in California like youself, and what you've done has inspired me to beef up my baby as well...and still pass the semi-annual smog check.

I'm assuming you replaced the rods and lifters, but did you do any head work as well -- rocker arms, springs?

What about a new timing chain? How many miles did your bottom end have on it?

Just trying to paint a complete picture.

'76 in resto

Howdy to a fellow Southern Californian . . . our mistake was acquiring post '73 vettes . . .

Anyhow, to answer your question, the intake is an Edlebrock Performer #3701. This specific model will be important to you because it retains the EGR - which you will need here in the Golden State.

The cam is the Performer Plus, part #2102. I am also running Crane roller rockers. I replaced the timing gears and chain with a double roller at the same time. A little word of advice . . . I would never re-use a timing chain or gears. I have also re-curved the timing advance so that it gets full advance a low RPM.

Call me a tinkerer, but after doing all of this, I'm thinking about going back in a replacing the heads with aftermarket aluminum heads. It appears that the Edelbrock heads are a pretty decent bargain and with the 64cc combustion chambers, should yield a noticeable difference.

Hope this info helps. There is another thread that is a couple of weeks old called 'Lumpy L-48'. If you want a little more aggresive cam, you might check out the cam recommendations there, especially a couple that Ganey posted. According to the manufacturer, they are 50 state legal. However, check on the Internet with the C.A.R.B. to make sure that these are approved for your year and engine. You can look at a listing of the Executive Orders to determine legal compatibility.

Underhood inspection

Hey Ron, mucho gracias for the fast reply,

Just one more question...the Fed smog sniffers usually do an underhood inspection and will fail any car that has had it's engine visually modified or tampered with. How did you get past the underhood inspectionwith the Edelbrock intake manifold?

You didn't paint it Chevy orange or something sneaky like that?

I remember fondly back in the days before Smog Check when I would cruise around in my NovaSS back in High School. Back then, we'd proudly announce that our motors were "stock" with a smile on our face and fingers crossed behind our backs...just before taking starting line.

Visual modification is not a problem as long as the parts used are CARB certified. Pretty much any grease monkey that does a smog test, will immediately recognize an Edelbrock Performer as a legal switch.
I have a 76 vette. I laugh at the book time for the 1/4 mile on these cars. I have seen high 15's or low 16s. Anyone will tell you the stock ones are running 19's + =( I did a few upgrades myself too. Roller Rocker arms, dual quads, full race cam, 2500 stall speed, 700R4 Trans, and hooker headers/sidepipes. Still need to curve the distributor. With this setup I was able to run a pathetic 15.80 @ 87.9mph feeling a restriction... Ran open headers the other day, 1 run, 14.89 @ 95.8mph. So, if you have the hooker headers/sidepipes, they are killing us. Changing mine to spiral inserts. Monday, I am installing a set of Pro Action Heads =) I ended up going with the 67cc set. Hell, our heads are the worst and most smogged up heads they made. Put any other set on from an older block, you will pick up 30 more hp, plus 1 full point of compression. These Pro Action heads will add 30 hp above those, and another 40+hp since I had them opened up =) Will be close to 100 hp difference =) Should drop me into 13's =) Thinking about swapping out 3.08 with 3.70 also. hmm... low 13's is sounding pretty nice for not investing alot =)
Interesting. It's pretty amazing the amount of ET you picked up by uncorking that thing!!

What size are the dual quads you are running?

I'm getting ready to swap out the heads. I'm looking at the AFR 195's. According to DD2000, this is the second best head for my combo, but the best that is CARB certified.

If you have the flow numbers for the Pro Actions, I would be interested in taking a look. If nothing else, let me know how the swap goes and what you gained.

fasterthanu, sounds like the bug has bit LOL

Hey Ron let me know how it turns out with those heads from AFR. I ordered a brochure and have looked over them. What I really like is the CNC porting they do. I think it will provide more consistent flow for each runner. I think for the price they are not to bad.

Hey Frank!! Good to hear from you. According to DD2000, the AFRs kick b**t out of pretty much everything else. I was a little surprised that the low end torque will not suffer from the somewhat large intake ports. 195 CCs is kinda big for low end torque. I guess we'll see what happens. I'll let everyone know if and when I finally get around to buying a set.

Hey Ron,

What are you running for an ignition setup? I have a '78 L-48 in San Diego and am also looking to get more "legal" power out of her. I am looking at the edelbrock 3701 Manifold and the 3702 Cam, And am also thinking about the 1903 Carb. Would the carb be worth doing, or am I wasting my time and money compared to the Q-Jet I already have? Thanks!!


I'm running an MSD ignition setup. I have the 'brains' hidden inside one of the side vents. It really can't be seen from inside the engine compartment. I don't know if it is strictly legal, but I haven't had a problem with it.

I'm running an Edelbrock manifold with the stock Q-jet. I don't have any personal experience with the Edelbrock carbs. I've heard good and bad. Some people love 'em, some people hate 'em. I've been running Q-jets since I was a kid, so I know them pretty well. That kind of makes me partial to them, although I have run Holleys also. My very humble opinion is that q-jets, when properly tuned, are one of the better street carbs. But again, you'll get as many opinions as there are members on this board.

I'm not real impressed with the power of the Edelbrock Performer cam. Again, my humble opinion. There are a bunch of CARB certified cams out there. Crane has a pretty extensive selection in their XE series that are legal for your application. Cam selection depends so much on so many variables, that it is really best to consult with the cam manufacturer in order to get a good match. They will want to know things like head flow, gear ratio, transmission (stick or auto and if auto, which auto), torque converter stall speed, type of driving you do, etc. We all like that rumpity rump of a fairly aggressive cam, but it is really, really easy to go too big with a camshaft and then be disappointed with the performance and/or driveability of the car. This is especially true if you run stock heads. If I could only spend money in one area of an engine, it would be in the heads. They are the source of the greatest power increases. If you are running stock heads, they are probably 882 castings, which do not flow well and coupled with flat top pistons and a 76cc combustion chamber, yields pretty low compression.

And then, with all the fancy CARB legal stuff we can hang on our engines, the State of California, in their infinite wisdom, has not seen fit to allow us to run headers on our catylitic converter equipped cars, so we choke all of our cool speed stuff to death with stock exhaust manifolds . . .

Anyhow, take a look at www.compcams.com especially at their CARB legal stuff.

And then look at Trick Flow, AFR, World Products cylinder heads. You can get pretty good legal power out of these.


Oops . . . I meant Comp, not Crane . . .
Yeah Ron I am still around here.

Hey whats DD2000?

Yeah those heads seem to be pretty damn good for the cost. They don't even compare to edelbrock/holley aluminum heads for price and flow.

Hey you aren't going to believe this, your exactly 22 yrs older than I am and I do mean exactly. Our B-days are on the same day! And get this so is my stepmoms. She's 10 yrs older than me, go figure.

I am taking a graduate course in combustion and a whole week was spent just on vehicle emissions. This is what I have learned. The EGR system is to reduce NOX and the catalytic converter is to remove CO and hydrocarbons. Heres the best part, the catalytic converter increases the NOX output by 5-8%. Mother nature doesn't give it to you that easy:L

What is it that you guys can't pass, the actual emissions or the visual inspection? Hate to brag but emissions are a joke over here. Nothing that an extra $20 bucks can't fix and I have never had a visual inspection at least they didn't check.

I agree with you on that Quadraject carb. I have faith in them you just have to tune it right. Just like the whole engine. When tuned properly you can get some pretty good gains. I don't have a garage to work in and I don't want to stink up my room with the smell of gas so I can't really tinker with my quadrajet at the moment. But I am pretty hyped to find out what the big deal is!

Hey whats DD2000?


DD2000 is Desktop Dyno 2000 software for engine power prediction. Reports are that is if fairly close for calculating gross flywheel horsepower and torque as long as the inputs are accurate. If nothing else, it seems to give you a really good baseline for comparing components. Besides, it's a lot of fun to play with!! The software is cheap - I think I spent 40 bucks for it off of E-bay.

Hey you aren't going to believe this, your exactly 22 yrs older than I am and I do mean exactly.

Okay, okay . . . you don't gotta rub it in!! :L

What is it that you guys can't pass, the actual emissions or the visual inspection?

It's actually the visual. Headers with the air injection ports would be fine, except that there is no way to hook up the heat riser and the EFE (the do-hickey that actuates the heat riser). You can find someone to do a questionable smog check. But it is #1 - a hassle and #2 kind of uncomfortable for me as I'm not a big fan of participating in anything on the shady side. That's just a personal flaw, my conscience is too big!!

Ah, September 5th . . . a red letter day in history!! Good to hear from you.


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