Carb Spacer and RPMMMMMS

Spanish Dave · Aug 3, 2005

I have a B.G. Speed Demon 650 carb on an Edelbrock RPM air gap manifold with an Edelbrock wood half inch spacer. The thing is that the spacer has a central dividing bar and I am wondering if this is the right one to have ... as the manifold has a piece cut out between the two sides of the plenum ... do I need to junk this spacer, or get an open plenum type ???
Also ... how high should I be able to rev this engine (see sig for details) I have gone to 6000 rpm with the MSD limiter in place, but would like to replace this with a 7000 rpm chip and see what it will do ... any tips or caveats?? I have replaced the stock rod bolts with the best ARP ones and am about to replace the stock damper with a Fluidampr which I have here.

10secgoal · Aug 3, 2005

With the divider, it basically makes the throttle bores in you carb longer, making more vaccum and more low end. Putting a spacer on it makes the motor think it has a bigger intake than it has. The spacer you have makes me thin of a bigger dual plane. It's wood, cut it out and make it open. If you don't like it, buy another. Ahh, the price of experimentation. As for the 7k pill, onlt the track will tell you that by your timeslips. If it likes it, it will go faster. But likely, will sound great, but will be harder on the motor, for no gain.

Jc69Stang · Aug 3, 2005

7000 rpms sounds a bit high to me.

SoCalCruising · Aug 3, 2005

That's a flat tappet cam, right? If the springs are right, I would think that 6500 would be okay. 7K might be pushing it. But, like said above, try and find out. At least you won't be bouncing roller lifters if the springs don't hold up.

brianj5600 · Aug 3, 2005

Edelbrock website has a dyno graph that ends at 6500 and the power is still going up. I say put a 7500 chip in it!

iskwezm · Aug 3, 2005

I dont think 7K rpm is gonna happen.I had the same heads and cam,the valves floated at about 6K rpm,I changed the springs and it would ony get to about 6300 max.

12sec67 · Aug 4, 2005

iskwezm said:
I had the same heads and cam,the valves floated at about 6K rpm,I changed the springs and it would ony get to about 6300 max.

Me too, 6100rpm valve float

10secgoal · Aug 4, 2005

I never did get that. I took those heads to 6500 on a REGULAR basis.

LMan · Aug 4, 2005

brianj5600 said:
Edelbrock website has a dyno graph that ends at 6500 and the power is still going up. I say put a 7500 chip in it!

its not the cam he should worry about...its the other parts of the valvetrain. If you have stock valvesprings in there, you can forget about 7500 RPM.

On a related note, how are your rod bolts?

MustangMatt1966 · Aug 4, 2005

i have almost the same set-up and i agree with everyone else, i dont like to take mine above 6,000.....but again, every engine is a monster of their own, some perform dif than others...

12sec67 · Aug 4, 2005

10secgoal said:
I never did get that. I took those heads to 6500 on a REGULAR basis.

i think your take was off!

J/K.. do you remember that!

sorry guys... inside joke

10secgoal · Aug 4, 2005

I think you mean tach ? Yes I remember.
I guess you could try it, but I would think it is going to take a helluva cam to actually be making power that high.

Spanish Dave · Aug 5, 2005

thanks for all the replies ... I wasn't meaning that I was going to rev the engine to 7000, but just that is the next highest chip for the MSD I have. I can see now that the first thing to hold back the revs would be the valve springs ... next the properties of the cam. I realise all the really high revving setups seem to have cams, intakes etc. that start working at 4000+. I am pretty satisfied with the performance up to now and will probably keep the 6000 limit chip in.
I am going drag racing here next month .... may not sound such a big deal, but there are to my knowledge no actual drag strips here in Spain ... we have to get a section of road closed down, set it up and go racing. I will post some pics after the event if anyone is interested. The only other time I have raced here was 2 months ago ... same sort of set up, but it was ony 1/8 mile (the next one is 1/4 mile). Just goes to show how lucky you are in the States

mudbilly · Aug 5, 2005

real street racing................

yea, i'd be interested to see some pics.........and learning more about the whole concept

what do they do with the onlookers??? are they just standing on the side of the road???

what kinda cars play, old and new??? how many does it draw??? do you get to pick your competition???

etc, etc, etc

brianj5600 · Aug 5, 2005

http://www.edelbrock.com/automotive_new/mc/power_package/pdf/14-15.pdf At the bottom of the second page you will see a dyno chart that is climbing at 6500 with the same parts as your's. If you have decent pistons you won't hurt the motor revving it to 7000 or more, and it WILL make better power.

Spanish Dave · Aug 6, 2005

Here are some pics
http://www.siglostaffords.co.uk/drag4.jpg
http://www.siglostaffords.co.uk/drag5.jpg
http://www.siglostaffords.co.uk/drag6.jpg
The event was organised as part of the American Car Club of Catalunya show and was strictly speaking an exhibition of acceleration tests not racing
Several thousand people came to see the show which had over 200 American cars of all ages from 1940's pickups to 2005 cars. The show was over 3 days and included burnouts, street cruising, do-nuts, racing etc. .... and of course drinking beer
For the racing you filled in details of your car ... HP etc. and the organisers chose who you went up against. My mustang was put against a Corvette ZR1 first time out ... he jumped the light though
A few of the guys on the previous evening had a few private races on the local roads though .... you seem to get away with quite a lot here in Spain. The only thing is though modifying the cars is not legal here as the annual test for the cars is very strict .... i.e. if you have different sized wheels from stock they wont pass it let alone if you change the heads, carb put a blower on etc. I can get away with mine as it is English registered.

iskwezm · Aug 6, 2005

mudbilly said:
yea, i'd be interested to see some pics.........and learning more about the whole concept

etc, etc, etc

me too

Carb Spacer and RPMMMMMS

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