intake and carb

[johnrem46]

I have a 1977 and want to change the stock intake and carb. I was looking at the edelbrock 3701 intake with EGR and the 1400 carb with electric choke and EGR. Is there an advantage to having the EGR??
I do not have to worry about emission test.
What else would I need to complete this installation?
Should I go without EGR?

I do not have the stock air cleaner I have a chrome air cleaner.

 

[Vettehead Mikey]

That's a lot of money spent for no gain in power. Why bother?

 

[johnrem46]

just looking the dress up the engine and I need a carburator anyway.. john

 

[Vette79]

As Mikey said, you'll gain no performance but it can be removed.

 

[Hib Halverson]

It's important to note that neither "Vettehead Mikey" nor "Vette79" present reasons why they believe that they do about the manifold change much less any real test data to back up their contention that such a change will not affect performance.

Admittedly, the change from the stock intake manifold to the Edelbrock Performer will not result in a significant performance gain. The change will have only modest impact at best, but on an engine in good condition with a properly calibrated carburetor, the manifold will make an improvement.

As for the Edelbrock AFB four-barrel, it also would only make a modest change by itself but there is a problem with Edelbrock AFBs on Corvette in some situations and that's poor control of fuel slosh in the float bowls causing inconsistent air/fuel ratios. From a performance and drvieability standpoint, you are better with the Quadrajet on your engine, now, but with the common performance tuning one does to the QJ. The Quadrajet is a significantly better carburetor design that was the Carter AFB which the Edelbrock is based upon. That's why GM stopped using the AFB in the mid-60s and switched to their own Quadrajet design in the first place.

Now....if you really want to make some power, as long as the rest of the engine is in good condition, in addition to the Performer manifold, go for Edelbrock's Performer camshaft, add a set of headers, a pair of Flowmaster mufflers and appropriate carb and ignition tuning to go with those mods and you'll be looking at a substantial improvement over stock.

 

[Vette79]

Now....if you really want to make some power, as long as the rest of the engine is in good condition, in addition to the Performer manifold, go for Edelbrock's Performer camshaft, add a set of headers, a pair of Flowmaster mufflers and appropriate carb and ignition tuning to go with those mods and you'll be looking at a substantial improvement over stock.

HIB, if you suggest going this far, you might as well look at were the power is really located and that is at the heads. Although, it does not appear he wants to do a top-end rebuild. In order to take full advantage of an upgraded cam, intake manifold and headers (dual exhaust) you should consider a new pair of heads. Any performance gains or losses by removing or retaining the EGR is not noticeable IMHO. Nor would be just an Intake Manifold. A DYNO would produce the minimal statistical benefits.
As mentioned, stick with the QJet. If your looking to get involved and do a little something, go for it! Only way to learn. And we are all here to help you and provide input if we can.

 

[Vettehead Mikey]

It's important to note that neither "Vettehead Mikey" nor "Vette79" present reasons why they believe that they do about the manifold change much less any real test data to back up their contention that such a change will not affect performance.

Ahhh, nor have you..............otfl

 

[Tom Bryant]

John,
Let me toss in my 2 cents worth. Since you are "just looking to dress up the engine and I need a carburator anyway." I'll only opine on the carb and intake.

Do you need an EGR and is there any performance advantage to using one?

Absolutely not unless you need it for emission inspection. You didn't say why you need a new carb but if it's idling and running rough that EGR could be sticking open a little and causing much of your problems. It is strickly an emission device and there is no performance advantage in using it.

As for the carb, the Q-Jet is the best choice for all of the reasons stated by Hib. What you may need more than a new carb is a professional rebuild. Q-jets are easy to tune once you take the time to get to know one. The small primaries give you that instant off idle response and mpg that is hard to achieve with other carbs.

As for the intake, these things have been tested to death over the years. One test I recall on a basically stock 350 showed the stock iron intake out performing the Performer up to 3000-3500 rpm (only marginally and with a stock cam) then the Performer was better on up to 5000 rpm. Both intakes fell off dramatically after 3500. This would tell you that for most of your driving the stock intake and Q-jet would be the best combo.

Then they swapped on the Performer RPM Q-jet and found that it made more hp and torque above 3500 all the way to 5000 plus, not falling off near as much as the other 2 intakes even on the stock engine. What suprised them was that the RPM didn't give up anything below the 3500 mark down to just off idle. The conclusion was that the RPM was the way to go even on an otherwise stock engine. Plus if you further modify the engine later on you won't have to change the intake again.

I don't know how much hood room you have on your car but my choice would be the Performer RPM 7104 Q-Jet manifold and either a properly rebuilt stock Q-Jet or a custom version from someone like Jet Performance. Check out Jets's Stage 1 (Summit# JET-35001) or the lower priced Summit rebuild (Summit# SUM-210212). There are also other sources and maybe even someone local to you that is well respected if you ask around.

The Q-Jet may not have the flash of the shiney Edelbrock but it will be much nicer to live with when the hood is closed and you are cruising down the road.

Tom

 

[Hib Halverson]

As for the suggestion above that the power is really in the heads, I'm not sure with what perspective the remarmk was made. If you mean that you can simply replace the OE heads with a set of AFR big port aluminum heads and see 20hp more than you'd get with the aforementioned bolt ons, I disagree.

If you mean that adding a set of either properly ported, polished stock heads with slightly larger valves and multiangle seats/faces to the combination of carb, intake, cam and headers, will make an additional contribution to performance I agree.

In short, for a street high-performance engine using a production lower end, there is no one mod which is going to make a large difference other than maybe installing nitrous oxide injection. But, there is a combination of modifcations, which taken as a package cah make a significant performance increase.

In short, the right combination of cam, cylinder head, intake, carb and exhaust could add 75 lbs/ft torque and 50-65 hp to the existing short block.

That said, if I had to choose between cam plus bolts ons and heads, I'd do the cam and bolt-ons first then save up and buy the heads. If you put the heads on first, you won't be able to use much of the heads' potential until you free-up the intake and exhaust and let more air into the engine.

 

[GerryLP]

It is all conjecture and seat of the pants feelings without a reasonable test base. You can now take your car to your local dyno (or drag track)and measure the power output of the original engine as it stands (lets face it...it does not really matter what your engine puts out..what matters is whether it crossed the finish line faster than before). After the changes, get it on the dyno again or return to the track. Only then you will really KNOW , and more importantly, measure the improvement or loss of performance (it can go either way) on your engine.

It is unreasonable to expect a whole new "beast" engine as a direct result of minor equipment changes. Nevertheless, improved performance could be gained! Similarly, it is unreasonable to act as if it is not worth the effort to make modest gains of 10 or 20 horsepower on minor improvements. Assuming an example of $500 dollars in an intake and carburetor, then a 20 horsepower gain would have cost approximately $25 dollars per horsepower gain. This is not a bad return-on-investment for a small project like this.

The key is to know and approach the problem from a logical perspective and at least assure validity to whatever results are obtained at the end of the test.

 

[petes74ttop]

Fastest Vette On The planet!

johnrem46, if you have a chrome air cleaner thats cool. You don't have to have everything stock, if it makes you happy do it! If you don't like the looks of your manifold just pull it off and paint it! If you want an aluminum manifold then go for it.
A Q-Jet is a very good carb and you can either rebuild it yourself or have it done by a pro for less than the cost of a replacement. Point is none of us will ever have the fastest Vette on the block. I did a ground up restoration on my 74 and put in a replacement stock engine with the stock manifold, sure it would post some "slow" times at the track, but over the last 8 years it has never let me down and has turned out to be just what I hoped for, a dependable daily driver.
Vette79 your car looks terrific and so does mine, and to me that's the point. The C-3's are the best looking Vettes ever made. If you get to the finish line a few seconds before me, that's OK.
I just can't see spending $500.00 to gain 10 or 20 HP. Realy how much faster can you go with 20 more HP?
PG.

 

[GerryLP]

One fact is that the pursuit of horsepower is never satisfied. Even Z06 owners look to add more power in their Vettes....wait for that post from a future 2009 ZR1 owner asking how to make the ZR1 engine make more power. :eyerole

Mid to late model C3 owners have always pursuit power adders to their Vette, for the General (in response to the government) equipped these Vettes with enough power to push them along the freeway. We have a power complex...:L

 

[Vette79]

Pete, your Vette looks great also. Thanks for the compliment. I suppose the real questions are "What is John trying to accomplish now and for the long term?" Does John have any plans at all to continue with adding to this project with a cam upgrade, cylinder heads or exhaust? If he truely is just wanting to learn and enhance the appearance of his car then the above mentioned mods would be nice. Removing the EGR can be done if he wants as long as there are no concerns for emissions tests. Performance increase would be minimal and up to him if it would be money well spent. I do totally understand what Hib and Gerry are saying. I have to tell you that now that I have done my top-end rebuild, all I want is more power as Gerry mentioned. It's addictive.

 

[GerryLP]

Running 14.600's at 5,000 feet of altitude in the 1/4 mile, I knew that I had reached the engine's potential (about 225 RWHP), but that's at this altitude, so it would only have better slip times at sea level.

(Oops, I had forgotten that I had not finished this post :ugh:eyerole)

My point was that getting the Vette down the track at 14.6 seconds was sufficient for me; however, it was so, for I realized that I would not have the resources to get down to 13 seconds, and then I asked myself whether that would be sufficient, and then I realized that the pursuit of power is never enough, so it was hard in getting used to letting go of this pursuit, but the bottom line is that I glad that I whined myself from this "fever". . .:L

 

[johnrem46]

Thanks for all the suggestions and Ideas.. I am not looking to have the fastest car on the block. I want to have a good driver and something that looks good when the hood is up. I thinks everyone has agreed that keeping the original carb is a good thing. I will have it rebuilt and get a new intake manifold to mount it on. Thanks for all your help. Does anyone know what color blue the 1977 engine is?? It seems to be darker that the blue they used on teh 6 cly.
John

 

[Vette79]

John, my vette originally had a QJet that did not have an electric choke. You can have one installed or purchase a newer QJet that has been rebuilt that has an electric choke. I purchased a professionally rebuilt 1980 QJet with an electric choke. You'll obviously have to improvise for the 12v from the fuse block. Make sure you only get 12v when the ignition is in the start position. Anotherwords, not when the engine is off and the key removed. A full top-end rebuild will yield some additional TQ and HP. Before you get to deep into it though, definitely consider a crate motor replacement. Weigh the pros and cons and what your really after. I wish now I would of spent the extra money and went with a crate motor.