Hi All:

New here. I have been reading quite a few posts about carbs and modifications. Lars' and other posts have convinced me to keep my quadrajet.

Here is the current configuration:

1975, L-48, unmodified (been in the family since 1979), TH400, 99,500miles.

I am adding dual exhaust from Corvette Central using the stock exhaust manifolds flaring into a 2 1/2 system, no cats, magnaflow mufflers.

During this modification, I have started the never ending tinkering process. After I pulled off the manifolds and refinished them, I am changing spark plugs, wires, and adding the MDS Ignition Coil (part #8225).

For looks and to track down an oil leak, I took off the valve covers and refinished them. I would like to remove the intake manifold and here is my question:

Do I refinish the manifold and put it back on or do I replace it with an aluminum manifold? I can afford the $200 or so for a new intake, but there is nothing wrong with my existing one. I will keep my Q-jet and want to make sure I have clearance on the hood. What do you guys recommend? I like not spending the extra money, but if it is coming off to clean it up, I wouldn't mind the extra power either (the reason I am putting on the dual exhaust).

Any advice is greatly appreciated.

 

Factory aluminum from an 80? or so. Wouldn't hurt to shed a few pounds.

 

Put it all back stock.

 

Put a edelbrock performer intake on 2101

 

your oe would be fine, the factory aluminum new would be ok, used , they're probably not good boat anchors if they've ever been overheated, I've run the edelbrock before I converted to F.I. it worked fine also. with a 75 , that long in the family, and un modified, I'd stay stock, you wont see any real extra power with just a manifold change, but you will with the opened up exhaust and may want to richen your carb.....just a bit

 

Yes. That will fit fine. You won't have to modify your cowl induction system. Also an aluminum manifold will heat up in the morning quite a bit quicker than an iron one.
I have been running an Edelbrock 2101 (on my '74) for a while. I think it improved the power some. A bit more midrange torque, perhaps. From Jegs or Summit, they are pretty cheap.

 

If I were doing a dual plane I'd probably go with the over the counter aluminum offering from GM - the same intake they put on the ZZ4.

10185063

 

Since you are still using the factory cylinder heads on your engine, there would be little benefit to be gained from swapping your intake manifold with a "better" component. The heads must be able to pass the increased flow of the intake manifold. And since your present heads and manifold were designed to be used together, changing the intake, by itself, seems a waste of money, IMO.

Clean up the stock manifold and reinstall it. The entire engine will appreciate the increased ability for it to breathe, as you have opened up the exhaust system...presently the "bottleneck" in your drivetrain.

If you decide later to modify the engine for more HP, you should change the cylinder heads, cam, and intake manifold so they will all be relatively well matched as a set. Even then, there is no need to change the Q-jet carb. There are almost NO 350 cu. in. engines that can actually require more air/fuel flow than the Q-Jet can supply. And, it is self-regulating. The most you would have to do with a MAJOR rebuild of your present engine block would be to optimize primary jets/rods and secondary rods as a result of the increased flow capacity of that more modified engine.

Clean it...paint it (with paint capable of handling more than 500*F, if you are still using your heat riser system to heat the carb)...and reinstall it with good quality gaskets and Permatex Black RTV sealant (per gasket maker instructions).

 

7T1 is correct in all advise above - follow that and you'll be in good shape. If you're wanting a little more power and throttle response, go through the carb and set it up per the "Quickie Performance Setup" section of my Q-Jet paper, and then set your timing curve up as outlined in my timing papers (all available via e-mail request). This will get your Vette running very strong, and you can make it look good by doing the cleanup you're wanting to do.

...and be very hesitant to take serious advise from people who can't spell the names of the parts they're recommending...

Lars
V8FastCars@msn.com

 

Good advice for life in general.

 

sorry about the spelling i just hit the wrong keys at least i had the right part number

 

Thanks for all the input. I'll stay with the current intake until I do a major rebuild (which will take place when I have the money to throw at it or the original motor decides to call it a day; whichever comes first). I have Lars' papers--thanks Lars--now I have to educate myself on vacuum advance and timing, which I know NOTHING about.

I have removed the A.I.R. system since the duals don't have a fitting aft of the collector like the old system did. The heat riser retaining clip fell apart in my hand so I think I will wire it open. The EGR has been disconnected for years. I have kept all of that equipment in case I ever want to put it back again, but it is not required here in Georgia. I am aware that I will experience nominal performance gain, but is there any compensation required in the q-jet based upon these changes? I am aware that I will have to reconfigure the carb for the duals.

R,
David

 

When you get finished with your 'modifications', send an e-mail to Lars [V8FastCars@msn.com]. Supply him with the info on your car, engine, exhaust, transmission, and your carb's part number. Then ask him to advise you of the correct primary rods/jets, secondary rods/cam/hanger, and any other modifications that he would recommend for your carb. And, if you don't feel confident in your ability to rebuild the carb, ask him for his price and timing to do it for you.

 

Or just order a 750 Holley, bolt it on and drive around town eating ice cream.

 

You can pickup used 2101 intakes all day long ebay and craig's list for 50 bucks, if you really want an aluminum intake. It'll remove a little weight from the front of the car, and maybe add a few horsepower, but chances are it won't be anything noticeable. You could paint the intake with high-temp aluminum paint, if you wanted to, nothing wrong with that if you just like the look of an aluminum intake. I have used Rust-oleum 7716 heat resistant silver, and I like it. It looks an awful lot like freshly bead blasted aluminum, and is advertised as being heat resistant up to 1200* F. I've never used it on an intake manifold, but I don't see why it wouldn't work just fine, if you can keep gasoline off of it.


Keep the shiny side up!
Scott

 

Is the Performer intake a knockoff of the original Lt-1 intake? Now that I'm not taking this vette to the track have been thinking of swapping the Torker out and putting the original back on.

 

Yes. Edelbrock used the Chevy LT-1 intake as the pattern for making the Performer.

 

Thanks lars i didnt know that about the intake learn something new everyday

 

http://www.drclassic.com/catalog/Cam...50073-110.html

It does look an awful lot like an older Performer, doesn't it?

http://www.ebay.com/itm/edelbrock-pe...70905882740%26


Keep the shiny side up!
Scott