If you replace the exhaust manifold with a header the intake manifold will run cooler and there will be a bit of a stumble,(poorer atomization) some worse than others. You can tune out the stumble but in the proccess you will lose some mileage. If you just drive it the way it is without "tuning" I would think that driving "around" the stumble would lower your MPG too. Just something to think about.

By paul (24.81.146.102) on Friday, May 20, 2005 - 02:05 am:

The CVCC heads already run kinda lean with the stratafied charge and such. Polishing the ports is about all that can be done on the head. You might want to think about increaseing the flow velocity with a header.

By Tracy (Rx7speed) (172.158.26.63) on Thursday, May 19, 2005 - 10:50 pm:

I have a 76 accord (ef1) but thankfully I live in caldwell and in canyon county there is no emissions testing here.


and I wouldn't mind making a little more power here but the goal for me isn't really make the car faster but more efficient.
it's just between me and my friends all the cars we have owned it's lets make faster faster faster so what if I only get 10mpg.
figured this would be a good car to try the opposite with and to get good gas mileage though with a catch try not to sacrafise power doing so and if anything help them both out

part of what I'm wanting to do here with the heads.
want to try to take a set of heads and make them flow more efficient.
and don't really want to go to a non-cvcc head unless I will get better gas mileage in the proccess. also part of why I didn't buy a webber yet is I don't know how they would do for gas mileage vs the cvcc system

By username (68.116.93.157) on Thursday, May 19, 2005 - 08:11 pm:

The 8valve is the same as the CVCC but without the auxiliary chambers and ports, they were sold in canada and are still available in wrecking yards, and several of the people here have been able to get them. It does require a different carb, but the intake manifold will fit, the auxiliary ports just deadend. I think that the engine was the 76-78 canadian accords(1600) and 79-82(1751, EL), I can't remember the 1600 designation right now(brain fade), someone here will know though. Idaho should not be a problem, you are closer to Canada than I am, in CA. and it is not too difficult to have parts mailed. I have a friend in Boise who used to have an '80 wagon and was able to find parts for that readily. You might also have trouble getting it to pass the state smog test, depending on what red van you take it to... if you have to smog it. What year and engine are you working with?

By Tracy (Rx7speed) (172.134.167.161) on Tuesday, May 17, 2005 - 01:54 am:

what 8 valve head are you refering to? which motor I guess would be the best question? and is it a cvcc head? I'm not really wanting to switch carbs or anything as such though I'm assuming since you said the intake will fit I'm going to guess it's cvcc also

and I'm not in canada so I don't know what my chances are of comming up with that head would be.

any other ideas for a local head for the states as I am in southwest idaho

By username (68.116.93.157) on Monday, May 16, 2005 - 10:20 pm:

the 8valve Canadian head is the best way to go on that engine. the intake will fit, the exhaust will not. the 80 civic cvcc exhaust manifold will fit if you are not able to get one with the head, or if you are not in Canada... There are people on the board that will help get the pieces that you need, unfortunately I am in CA and have to search for all the pieces that I need too. I have a non-CVCC head from an old engine that I used to run, my experience is that it will give you the best performance base for that engine.(the 8valve head responds very well to porting!)

By Tracy (Rx7speed) (172.155.232.167) on Monday, May 16, 2005 - 09:39 pm:

not really wanting to open the ports up. if anything I want to try to remove the least amount of metal possible.
I know the old v8 heads that I have seen had a nice little piece sticking out where the valve guide was and the bowl area near the the valve was usually full of casting mess
I know on those heads usually it helps out quite a bit to cut down that valve guide boss inside the head and remove some of the casting crap and smooth the bowl area out all this without opening up the port really at all just getting rid of things that are sitting right in the way of the air flow.

usually it gives quite a decent gain of flow with minimal port metal removed... 2cc or so
but it's that aux port that throws me off and I don't want to screw that up


might give it a shot though and see what I can come up

so let me ask this then. I have a ef1. without changing the motor what would be a good head to use as a replacement that is direct bolt in head to the same intake manifold/exhuast and block or is the ef1 head the best I'm going to get without changing the block?

By username (68.116.93.157) on Monday, May 16, 2005 - 08:23 pm:

past experience has shown that the CVCC head will not respond to porting too well. It relys on velocity through the head, open up the ports and you start to run into trouble with the aux chamber... it can get as bad as blowing the fire out under transitional throttle. Removal of the exhaaust inserts has been done, with "some" results. I tried that once, no improvement to report, but have had others tell me that they could feel improvement when done along with opening up the exhuast manifold. (cutting the baffle out)If you have the time, or a spare head, try it out, the worst thing you will get is experience.

By Tracy (Rx7speed) (172.168.23.66) on Monday, May 16, 2005 - 01:15 am:

with most heads I know you cna port them out a little and gain some performance and if done right can do it without hurting fuel economy or low end power. guess more like smoothing out the ports rather then just hogging them out larger

on the cvcc head how much can be gained by doing this?
it seems with the two intake ports one might throw things off a little doing such.


what I'm wondering though is on the head itself are there any weak spots in flow like near the valve guide or the bowl area where honda didn't do the greatest job and made things a little too restrictive.

can this be done on the cvcc without messing up the cvcc part of the system? and how much of an impact would it make for fuel economy and power?

again not talking really making the ports bigger just smoothing out the flow areas getting rid of the restrictions