Just purchased a edelbrock performer kit, 3701 intake, 2102 cam, and 60909 aluminum heads. The guy that is helping me with the install is saying that the ramshorns are going to be to restrictive and I should go with headers. I am trying to stay somewhat original and wanted to keep the ramshorns, also don't headers create more engine compartment heat??. Would there be a problem mating up the cast iron manifolds with the aluminum heads? How much horsepower will be lost sticking with the cast iron manifolds....the kit says it will do about 320 hp and 382 ft lb torque installed on a crate motor with 1 3/4" headers. Thanks.

 

The rams horns will work on your heads. Yes, they are restrictive. You will get far superior scavenging with the headers though, and of course make more power. I guess it comes down to what the car will be used for. If you have changed as much stuff as you say. Well, than keeping the rams horns for originality seems abit silly when you consider the power loss from not using headers. Probably 30-40 horse loss, depending on the cam.
If i were you. I would install the headers, and enjoy the full potential of your aftermarket bolt on's. Just keep all the original parts in a box. You can always convert back to the stock set-up when your done having fun with it. :cheers:

 

A couple things.

First, the ram's horns are good for up to 325HP. You're borderline on that number so headers may, or may not, help you gain much.

Second, if you get ceramic coated headers, they will actually cut down on engine compartment heat.

Third, how original is "somewhat original"? Will you be going with true dual exhaust? If not, there is not much point in installing the headers.

 

I guess what I mean by 'somewhat original' is I want to keep the stock exhaust system, egr, Q-jet carb and all accessories that were originally on the engine. I don't plan on going true dual exhaust, but I do want to get a high flow cat and better flowing mufflers. I am not using the car for any kind of competition, just a weekend and night cruiser. I just want to give it a bit more oompff when I mash the accelerator.


[Modified by Rods77, 10:22 PM 5/11/2002]

 

Rams horns are the best manifolds ever made and unless you are making lots of HP will work fine. As a matter of fact in some cases changing to headers even decreases torque and low end power. Rams horns are acually better than SOME cheapie headers. Headers are noisey, leak, heat the engine compartment, heat soak the starter, burn plug wires, and are a general PIA. Use the ramshorns. :cool:

 

What about installing the stainless tubular exhaust mainifolds from a 81 or newer. They shoould bolt right up to the factory exhaust. What kind if power gain/loss would you get?
I am thinking about these manifolds with true duals on a TPI motor, maybe a little of both worlds?

 

Rod

If you want to keep the manifolds, you can. You need more cam unless you are wanting slightly more than L-48 stock!

What's trans. & ex.? More cam strongly rec.!

:cool:

 

As far as the rams horns go, if you are making 300-350 horses then I would be suprised if not going with headers would cost more than 15-20 horses or so. Headers can definately be a pain in the butt, and are undoubtable less durable - I had Jet Hot headers and they still have rusted a bit in just two years. If it were critical, you could send them out for extrude honing, and increase the flow a bit. Not sure how much that costs, but I think it's similar to the cost of headers. You can also try port matching the manifolds to the head exhaust ports if you use them.

After reading Ganey's post I looked at the specs on the Edelbrock cam and I totally agree with Ganey! That cam is dinky. When I had my stock L-48, I put in a Comp XE256 (212/218@.050, .447/.454 lift). I did a lot of research, and that was a conservative cam choice (I tend to err on the conservative side with cams). I had 3.08s, stock heads, performer intake, holley 650, stock th350 with stock stall. If I did it again I would consider going with a 218/224 Comp XE series - they are good cams with aggressive profiles. I later ran that exact same cam in a Camaro with another 8.5:1 882 head motor. If I were you I would seriously reconsider that camshaft, you can sell it, return it, whatever, and get something at least as large as the XE256. Ask for advice on this forum for a cam matched to your combo, and call a few cam manufacturers (like Comp, Crane, Lunati).

If you run a bigger cam with the manifolds then you can be making more power than running that dinky cam with headers! So you can make up for your loss with manifolds right there.

Rob




[Modified by robzr, 10:04 AM 5/12/2002]

 

One of the most restrictive parts of your set up and what REALLY robs 75-82's of power is that 2-1-2 exhaust Even with a better flowing cat and mufflers. If you want a stock manifold, consider on going with the earlier C2 2 1/2" rams horns and then do yourself a favor. Go with the true duals if you can. The 1974 true duals without cats should bolt right up. You'll get a LOT more bang for the money you spend on performance parts for your engine that way. Otherwise, your exhaust is just going to clog everything up.

That's my $0.02.

 

79MakoL82

If you haven't seen it, here's the proof you may need sometime.
See Why Exhaust is problem for HP on 75-81 http://www.corvettefaq.com/c3/ganeyexhaust.htm

:cheers:

 

I was worried about going with more cam because I need to get the car smogged here. Also I don't want to change from the stock torque converter and did'nt want to loose much vacuum. I am a bit ignorant to all this but have gained quit a bit of knowledge from this forum and talking to people in the know. The dyno results in the add for this setup says everything is matched to work with one another, so I figured this would be a foolproof way of going, that way I could'nt screw it up....much. :crazy: :)

 

As far as emissions goes, I got my 388 with a 224/230 @ .050 hyd roller, AFR 195 heads, 750 cc carb through emissions with no cats (sshhhhh) in Illinois last year - that was on a rolling dyno test. Took a few tries, some tuning (carb & timing), and a little bit of HEET, but I got through. You should have no problems with any of those cams especially if you have a cat.

As far as the dyno matched combo goes - that's just Edelbrock marketing. I think the Performer heads have identical intake/exhaust ports to the Edelbrock Performer RPM heads (I think the difference is the exhaust crossover), and Edelbrocks "dyno matched" cam that goes with those heads is in the 240 @ .050 range. That's big! You are much better off matching a camshaft to YOUR unique and specific needs including car weight, rear gear, tire size, transmission, converter, and driving habits. The people best suited to do this would be the camshaft techs at various companies (Comp, Crane, Lunati, Crower, etc...) and the people on this forum who have run setups identical to yours - so they have actual experience. Remember, the camshaft is the "brain" of your engine, and is really often the single item that can make or break a combo. It's also a real PITA to change out later, so take your time choosing one, and make sure you do it right the first time! I think you should call as many cam techs as you can, get peoples advice here on the forum, and then kind of average out all the recommendations and make an educated decision.

Rob

 

Forget the 2102 cam "matched" to what car? Expect you know there are many Chevy cars, wts., tire dia., etc. A- a heavier car, not Corvette. 2102 is about 1 step over L-48 cam.
Not enough for a CORVETTE. There is no problem matching a cam to your Corvette setup.

Comp 260H & 268H are legal. A very good min. cam would be XE256 for your setup.

 

If you need to pass a "visual" inspection and need to have the SMOG pump and cats connected and don't want to swap anything after passing the SMOG check. Then just use the ramhorns cause the headers really only allow more power at higher RPMs through a non-restrictive exhaust. You will get much better performance out of a Comp Cams XE262H and still have a very smooth idle to pass the SMOG check. I think the 268H may be tricky to fine tune for passing a smog check...it's been done, but it's tricky.

Another point I want to make is that the heads aren't going to do as much as you think if the exhaust is going to stay the same...you might get another 50HP which is excellent, but 350HP with single exhaust through a cat just isn't going to happen without some serious work like a custom exhaust that is 2-1/2" diameter with a high flow cat and muffler. Ricers do this all the time and it gets them some extra HP, the problem is that these systems aren't as popular for V8's...most performance V8's keep the smog equipment around for their visit to the smog station, then it gets pulled off and the straight pipes and glass packs and headers get installed...smog pump removed, EGR blocked off...etc...it's a once every two years ritual. I don't know what the count is on the number of people getting caught and paying fines etc...but I know that as long as the noise is kept down around town, and you only open up WOT in more secluded places then the police aren't going to pursue you for it.

 

If I do get a bigger cam...at what point is to much cam for a stock torque converter...I really don't want to change that out too. I'm trying to stay on a budget because not only am I doing the engine but also replacing the whole from end of the car damaged from a previous accident. I'm doing the engine now because everything is just so easy to get at with the front end off. I really just want to keep it simple....meaning I don't want to have to fiddle with it to pass smog and then have change it back each time, maybe later on when I gain a better understanding how all this stuff works.

 

I just got unequal length headers (1 5/8) made up and it made a world of difference mid range! I have the XE256 with 2101 intake port matched to ported 882 heads & 2.02/1.6 valves. XE 256 is a minimum! At 2500 rpm it gets and boogies. I would like to go to the next cam up.

:cheers:

 

I run a ZZ4 with rams horns. Even with the stock exhaust this thing makes a lot power than the L82. Sure I could make a bit more hp with headers, but been down the header route with leaks and excessive heat. Now that I have to pass an emissions check it's even all the more reason to use the stock manifolds.

Also, there was company that used to sell ported rams horms for stock car racing that required stock manifolds. Not sure what happened to them.

Note that one the 80 to 82 models the exhaust runs under the crossmember, not through it, so it is only 1 hour job to swap to duals if needed. So far only running the two into one system

Dave