I know that this topic has been discussed before, but after searching and reading for the last 2 hours I am more confused on what I need as I am new to this stuff. Here is what I have as I just bought the car recently. It is an original 350/350HP that was rebuilt to around 9~9.5:1 to run on 92 octane. I don't know much else about the engine as I can't track down the original builder, but it does appear to have a very mild cam and along with a 750 quad. I want to wake up the motor and it looks like the order is to do headers, exhaust, ignition, cam, intake & carb....correct? I will ask about the cam, heads, intake & carb when I am ready again in about another month for those after I get the headers & exhaust squared away.

Headers...I have headers on the car but have no idea which style I have. The pipes all bend towards the center and then straight down to into a collector with a 90 degree elbow if this is any help. I want to buy the best headers possible for my 350....recommendations welcomed. I am somehat concerned about the 90 degree bend in flow restrictions on my current setup and also curious about more equal length headers (athough I think the current ones are pretty close to equal length) and any fitment issues that I should be aware of. I had a set of custom headers made for my other car and enjoy them very much but were very pricey and know I can buy a proven set for the vette that are ready to install.

Exhaust...I have a shop here in S. Florida that has a full mandrell bending machine that did a great job on my other car. I will be using them to build a custom 2.5" x-pipe system. My question is do all the header systems end at the same point? In other words, if I have the shop build a 2.5" SS system to my current headers and then switch out my headers...will the mounting points match up or should I wait until I get the headers (if new headers needed) ordered. The exhaust shop can do my car this week and I am anxious to drop it off to be worked on.

Thanks...

 

No not all headers will dump in the same location. If you are going to change headers I would wait until you have the ones you are going to run.

 

It is a good idea to get the exhaust squared away first. Doing it this way will allow the exhaust system to support all the other mods that you make.

It sounds like you have block hugger headers now. Long tube 4 into 1 headers will improve the breathing ability of the engine. Dynomax, Hooker and Hedman all make a header to fit C3 Corvettes. Take a look at their websites to find what you need. Keep in mind that you may need to comply with emissions requirements. You will want to wait to get the rest of the exhaust system until after the headers are in place as the connection points are different.

After the headers I would suggest doing some head work. A street port job only costs about $100 and can be worth 20 to 35HP. This and the headers can add up to 50 to 60HP depending on how bad the original systems were. You can find out more about head porting here.

http://www.sa-motorsports.com/diyport.shtm

As far as the ignition goes, it should only need a good re-curve to be more than adequate.

BigBlockk

Later.....

 

If you want Lars' papers for tuning q-jets, send me a PM with your email address and i'll send them to you.

trw

 

I bought Hooker super comp. headers coated inside and out by Jet Hot. I ran 2 1/2 true duals with an h pipe then into flowmasters. I like them very much.

 

I've got Hooker Super Comps on my 79 L82 4 spd. They fit great and do not leak. Pricier than some but worth it.

 

Your exhaust has to go through the crossmember near the gearbox so regardless on what you do with headers the exhaust MUST go through there. So if you get the exhaust done now you will have to do mods in front of but not behind that crossmember.

If you are chasing HP and noise is not a problem then consider side pipes, thats where real exhasut flow is gained

 

thanks for the responses....I went and checked the headers and from everything I can see and find it looks like I do have the "block hugger headers".

My next question is will I see/feel a big difference in going with something like the Hooker Super Comps versus my current setup?

I can't find any pics of the other brands mentioned....do they not have the 90 degree bend that my current setup has?

Between the dynomax, hooker, and hedman....do any preform a lot better than the other or are they all pretty much the same?

Thanks for the tip on the heads...that will be done before x-mas also.

Side exhaust is something I have thought very serious about...but for at least now and the next 3 years I will go with the rear exhaust setup.

 

Headers...something that will be debated here for all eternity...
If you are going to go with longtube headers...the rule of thumb is that if you have a street motor, that isn't going to go above 6000 rpm too much, and has less then 200cc intakes on your head, then 1 5/8" primaries will serve you best. I'm currently running hooker super comps (1 3/4" primaries) on my car with refurbished stock heads but I plan on changing that (I got such a good deal on the headers that I couldn't pass them up). As far as one company performing better then the others, I don't think that there is much of a difference. Equal length vs non-equal length doesn't play much into low compression (under 11 to 1) street motors. I'd go with 4 into 1 longtubes that you can afford, and you should feel a big difference over those little block hugger headers (which I believe flow little better then stock ram horns).

trw

 

 

Running Hooker Super Comps (1 3/4" tubes) w/ceramic coating......very satisfied.

 

My dad was telling me about an article he ran into the other day online that talked about headers, and said that while you can have a little bit of gain with switching out to headers, the real gain for that to be effective was to have a good port & polish on the head. The article went on to say that the stock exhaust manifold was actually rather effective for exhaust flow versus headers, and wouldn't be that big of a gain to switch out to headers immediately.

I'll have to post the link to it tonight when I get home.

 

I had a custom 2 1/2" exhaust installed and went with headman coated headers. Some additional things to watch out for:

1. When working on many of the underside components of the car require that you remove or loosen part of the exhaust (mine is welded in most placed and not very moveable).

2. Keep in mind that some of the aftermarket or modern design heads move the exhaust ports further up\down\outboard, so there can be problems with headers fitting unless you research them.

I think if I had it all to do again I would have purchased the Flow Master Exhaust System, (preformed sections, mandrel bent, mufflers of choice, etc... for less money then what I spent on custom...

Audie

 

I have one last question before I buy what seems to be a popular choice are the Hooker Super Comp. I heard that they hang a little lower than others...is this true? I am planning on lowering the car just a tad by no more than 1". Right now it has a nice stance at factory height with about 1" fender/wheel gap at the top, but I want to tighten up this gap. I heard that I may run into problems running these headers with the car sitting a little lower going over some bumps or inclines. Not that I plan to take the vette off roading...just don't want to have to worry about scrapping them up. Tire height will be close to stock being at 26.7".