zguitar71

OK Tony D, I bought a flapper wheel and so far have the venturies at 37 mm and upped the main from145 to 150 and I like the way it runs. I have not lost any bottom end and it seems to be better now on the low end with response than before. I know it could be wishful thinking but power is available to near 7k but no loss on the lower rpms. Before it was going down after 6500. This is with my butt dyno, so..... Anyway the flapper wheel worked great and I would have never thought of it so thanks for the advice.

OK Tony D, I bought a flapper wheel and so far have the venturies at 37 mm and upped the main from145 to 150 and I like the way it runs. I have not lost any bottom end and it seems to be better now on the low end with response than before. I know it could be wishful thinking but power is available to near 7k but no loss on the lower rpms. Before it was going down after 6500. This is with my butt dyno, so..... Anyway the flapper wheel worked great and I would have never thought of it so thanks for the advice.

Great, thanks for the advice. I will start messing with it and try to figure thing out before winter is here and I have to shut the garage doors for 4 months.

Yea I am still figuring all this out and still have a long way to go as far as education when it comes to high performance motors. When Rebello made the head they also ported the intake to match the carbs and ports on the head and have the right amount of taper ect.... When I talked with them they said that my head work, carbs intake and header are the same that would be used on a stroker that they advertise as 300+ hp. I was told to set the cam on the second hole of the stock sprocket and the timing at 34 and the max hp should be around 7200 and that I should go with a minimum of 36 for the venturies (I also bought the carbs and header from them). So my initial assumption for the venturies being too small was based on a that info.

Ok Tony D, I do have an extra set of venturies so I think the flapper wheel will be in my future. So just a guess here but removing aluminum probably calls for about a 60 grit to start then move to finer grits to smoothe it out a bit. What do you think? JMortensen, are you thinking that the lower duration of the cam could be the reason for not making power to 7200 verses the size of the Venturi? In the end if I increase the Venturi size and the top end still stays the same then I will know its not venturi size.

They do make them in 1mm I increments. http://www.piercemanifolds.com/product_p/72116.370.htm Unfortunately I do not have a lathe or access to one. You suggest .5mm steps, is that because changes in Venturi size are very sensitive? In other words would I be foolish to spend money on the 37s much less the 38s plus the jetting that would accompany them.

When I built the motor in my car I whent with OER 45s with 36mm ventures. I settled with 36 after talking with local people who said that would be almost too big while Rebello (who built the head) said 36 is the minimum I should run. So I took the safe ground. The max power of the motor should be around 7100-7200 rpm, the 36 Venturi starts to run out of steam around 6600. Currently I do not have any problems driving at lower rpms and can open the throttle fully at 2500 in second without stumbles. A 37 would put max power at 6950 and a 38 would be 7350. Would I sacrifice too much on the low end moving to a 37 or 38. Much of what I was told by my local buds was not correct so that Leeds me to believe I can run the lager sizes. Having to roll into the throttle at 2500 as apposed to flooring it is fine with me at lower rpms to gain more on the top end. Any one running big venturies on the street? This is on a 2.8 with a zx 5 speed and a 4.44 diff with a 279/540 lift cam 10.7:1 comp and a ported Rebello head. Thanks for any advice

I have the Rebello hot "b" cam in my L28. If you are looking to have a streetable motor then get this cam. It has plenty of low end torque for the road. The cam has 279 duration and 540 lift for both intake and exhaust. The lobes are asymmetrical and ramp up pretty quick but I do not know the specs on that. Don't be scared of a bigger cam, I think I could have a streetable motor with even cam than I have. I also have 10:75 compression and Leon is correct about the octane. It is not too bad if the temp is 75 or lower but above that I need about 94-95 in order to lay into the throttle below 3500 rpm or so. The compression makes the motor less streetable than the cam in my car.

The idle circuit takes the motor to +- 3k so the richness is not just at idle. I agree that it is a waste of fuel if your worried about mpg; however, the 12.5 is for performance not fuel efficiency. The nature of the dcoe carb is to give the best performance at the 12.5 ratio ( or close to that). They can be tuned to a more efficient ratio but I only run them for the performance aspects not the best mpg.

If it falls in between 12 and 13 your probably good. The guage usually varies quite a bit. Mostly you do not want any lean or rich spots as you go through the rev range or as you progress through the circuits of the carbs. The a/f meters are great for showing problems that you other wise might not realize are there like leaning out at wot or too rich, they really help in the fine tuning. The stickey linkage can be as trying as the jetting. Mine was great for about a year then started doing the same thing yours is. I readjusted everything so it was as free as possible when it was cold so when everything got hot later and all the metal expands there would not be any binding. So far so good but our weather has not started to be very warm yet.....

I'm using 55 f9s for the idle but might need to go to a 50 or 55 f? And get more air vs less fuel I'm just a little too rich. On the top end I have 145 jets and 195 airs with 36 venturies. I have played with so many combos, all with 36 venturies, I'm not sure of the fuel/air ratio but the top end runs great but I run out of air before cam shaft. I can get small variations in power with more fuel vs air and visa versa but no combo gets past 7k before the power falls off, the cam should pull to 7500 and every time I calculate the Venturi size I get 37 as the best option. But then I have to go through the entire jetting ordeal again and right now I need to sort some other issues on the car that I have put off. I'm going to try and get the carbs exactly as I want them by the end of this summer.

With carbs I'm shooting for 12.5:1 and my timming is 18 at idle and 34 by 3000. I ran 36 but that is only with race fuel. I have 10.7:1 compression and I can barley get by with premium on a cool day so I brought it back to 34 and on auto crosses I bump it to 95 octane just to be careful. The dcoes are better with a little richer mix than the optimal 14.5 or so.

I have the borla on the back in the usual muffler spot. I ran it by itself for a while but it was very loud. I loved it with a helmet on but on the streets it was too loud. So I put a small glass pack muffler about 16x4 with a 2.5 opening in the middle probably right under my ass and the volume is still loud but not to the point of complaining neighbors or alerting every cop out there that I'm headed there way. The quality of the sound I think went up because I can hear more of the webers pulling in air. That mixed with the exhaust note sound like an old Aston Martin, I love it.

It seams that either you get the cheap mr gasket or you spend more than your budget for other types. I have the mr g and put a gauge on it and found that on 3 the pressure was around 7.5-8 dead ending in the gauge and around 5 free flowing. I found that I had to set it on 1 for the right pressure. The difference between 1 And 2 was very small then a big jump to 3, go figure. I am about to put the car away for the winter but I plan to spend some cash next spring and on the list is a good fpr. I don't trust the mr g. Pierce manifolds has one for webers that is around $50 I do not know anything about it but you might try it.

I still have the l6 because of limitations by scca rules for autocrossing. I have too much money into the motor now to ever change it. I am also nostalgic wich is part of the reason I autocross in the class I do. Power will always be limited but I am concentrating on weight now instead.

Go with the ITG or other brands of the same type design, if you can and get the tallest that will fit around the carbs. I can fit a 100 mm and just clear the brake MC and strut tower area with a shorter Sanyo/SK manifold and O.E.R. 45mm carbs. The more room to breathe the better so go with the single unit vs individual ones.

I used compressed air through all the holes until nothing blew out then forced water through it and compressed air again and kept doing that until it was clean then let it dry for a couple of days. Then I used 0000 steel wool in the cylinder, it did not leave any scratches on the surface, probably did not need to use it but I did. The cylinder did not have any pits or groves in it, if it had I would have gotten a new one. So far so good, 4 months in and no leaking and it holds pressure.

Well I am in the final stages of tuning my new set up and I'm looking for some advice from any dcoe experts. I am currently too lean on the idle circuit. I started with the OER jets which were 60's and designed like a F13 and it was very lean. I moved to a Weber f9 55 and that richened it up but I am 2.25 turns out (from 2.5) on the mix screws and it misses when I lift on the throttle but not when cruising under light load. I am hesitant to buy the next size up without being sure they are big enough, I cannot keep buying jets and not have them work, too pricey. The OER's are 45mm and the venturis are 36's feeding a ported and polished head with 279/540 cam. I am guessing f9 65's will get me to 1.5 turns on the mix screws and no more missing on the throttle lift. Any opinions out there? Thanks

Vantage, I gotta say thinks for giving so much good advice on this thread. I just change to a zx Distributor on my `71 240 and every problem I had was solved with this thread. I would still be in the garage pulling my hair out without it! Thanks again!

The E-31,88; N-42 are all good heads to use but they will all have to be very worked over to get the kind of power most fp zcars make. The stock bottom end should be built up to in order to handel the revs and change the compression with different shaped pistons in combination with the head chamber shape. You must keep the same crank dimensions and rod lengths and no more than .040 overbore.

O.K. thanks. I had it backwards.

I have a `71 with a 7/8 master cyl that is shot, a new one is $280. If I went with a 15/16 from a zx will the feel of the brakes be too spongy? I am running a stock brake system with steel braided lines and Hawk pads on front and the pedal is firm. I would love to spend $100 less for a zx master but don't want to loose too much feel.

I talked with them today and it seems they do not actually put the carbs together. They tell Peirce Manifolds what the specs are and they put the hole thing together and give it to Rebello then they put the carbs on the manifold I gave them and put the linkage together then ship it to me. Really Rebello should have looked to make sure all was O.K. before it shipped though. WizardBlack you are absolutely right, I should check things like that, I learned something here. Like you say Jon they are good on the phone and they do have good customer service but this was not the only problem I encountered with this order. Every thing is good now but it is a bit of a pain in the a$$.

Now I am stunned. I opened the carbs once again, and I do not know how I missed this before, there are not main jets on all three carbs! They must have forgotten to put them in. I just assumed they were all set up right since they were shipped attached to the manifold and all the linkage was set up. The pilot jets are there (60's) but there are two big screw holes above them with nothing in them, no air jet,emulsion tubes or main jets. I double checked the box every thing was shipped in and they are not there. So no wonder it ran like sh!t, died when I gave it gas and would hardly have enough power to get rolling but amazingly it would rev up to 6k for a split second. Well I guess I'll call Rebello first thing. I will say that they have been very good to deal with so far and very helpful, sometimes people make mistakes. I found the setting for the reluctor too.

I just put together a new motor. I have checked the timing marks over and over again, I have the cam sprocket on the shiny link and tried 1 tooth before and after the shiny link (on the no. 1 position on the cam and on the link). The motor starts and runs on all three positions but obviously on the shiny link it is best. It will barely idle below 1500 or so and when I give it a lot of gas it dies. It will rev up to 6k but I have not tried to go any higher yet. I checked to make sure the carbs are getting enough fuel and not too much pressure. I have adjusted the accel pump but that made no difference. I have not made any adjustments to the carbs other than the base settings to get things started, fuel screws backed off 1.5 turns and all the linkage set evenly and the idle screws evenly set. I tried moving the plug wires one position over but that did not work. I am starting to run out of ideas. Rebello made the head and put the proper jets (tripple 45m OER's) for the motor specs so that should all be correct. I keep thinking it is a timing issue. What am I missing? Please help. Thanks EDIT: O.K. I just realized I removed the reluctor out of the dist. and when I put it back in I did not set the proper distance from the fins on the shaft. Could that be the problem? and does anyone know what the setting should be?