041 heads max rpm ?

[eduardocastrejon]

hi,

Please help me with this:

I'm only wondering the max rpm with 041 heads

tired of my idf webers, I recently bought a cb competition FI, Tired of red that my 34 venturis is a restriction, now I have 48 body throttles. I'm happy !
sadly I can't installed the new toy until next month (business travel.

But I'm dreaming about it !

now, I supose that my limitation are the heads

my engine:

2110cc 82 x 90.5
041 heads 40 x 35.5 ported - cb heads
125 cam - 1.1 rockers
48 body throttles cb fi competition
cb magnaspark dis, mallory 685 cdi
nos sportsman fogger
1 5/8 header


with carbs the engine have a lot of torque, I supose that i will lost bottom end torque.
with carbs the engine dont like to rev over 5500 rpm, I believe that I will obtain 1000 rpm more ?

what is your opinion ?

[Sam]

You should be able to rev much higher than that, I would suspect you may have a valve float issue or a tuning issue, the 125 usually makes power well past 6000 RPM with 40x35 heads.  Putting bigger carbs or TB's won't solve your problem here.

Another possiblity is that your cam is one of the miss marked engle cams floating around. I hear there is some 110's that were stamped 125. That has been verified by engle on another forum. You may want to check the cam.

[wayne harron]

I am running a 2110cc 76x94, Engle 120 with 1.25 rockers, dual 44 idf's, Mofoco 042's with 40x35.5, and dual springs, and it will pull your teeth out all the way to 6000 to 6500 with no problems. Getting ready to switch over to 48 ida's. Until I get my 2332cc finished in which I am not 100% sure of what cam I am going to go with, but with the way my 120 performs I am leaning in that direction. Maybe something just a little bigger. Did I mention that it's in a full bodied street sedan.

[eduardocastrejon]

thanks for your answer

my cam is a scat c45 that is similar to 125

the pair weber was rebuilt by mark harney (great person), and I finish my setup with 200 140 55 50.
the engine can rev more than 6000 rpm but I dont feel more power that I feel at 5500

I dont use it a lot the car, then I will convert to drag configuration.

everybody says that is wise to stay with venturis smaller than intake valves, and with 34 venturis I had a lot of torque, great combo for street.

now with no venturis and 48 real  body throttle I supose that I will  lost torque. and I supose that I will obtain a few ponies .

I will change my r&p from 3.88 to 4.37

what about ? if I change  my 1.1 rocker to 1.4 ?

[Ohio Tom (DdK)]

I don't think adding more lift will help. The 125 cam should only use 1.25 ratio max. Don't go more than that.
My guess is one of 2 things.
1. valve float. your springs are shot.
2. the "ported" heads are not so ported.
Tell us more about the port job on your heads, and everything you know about them.

[wayne harron]

I am with Tom on this one, I don't think adding more lift is the answer. When I purchased my engle cam they (Engle) suggested not using anything more than 1.25 rockers because of the ramp angles on the cam. If I am not mistaken Scat has about the same angles on their's. I would get the springs checked to make sure they are not giving up or all together shot, and definitely find out more about the port job on the heads.

[wayne harron]

Also, I would definitely not change my ring and pinion to a 4.37 it's no where near as strong as the 3.88 and you will see a dramatic difference in rpm's way to high especially on a street car. Mine had a 4.37 in it but I was not making enough power to really use the 3.88, I went to a 4.12 and left the 4th gear stock except for welding it up. I could not be happier, close ratio 1st, 2nd, 3rd, and stock 4th, it pulls hard through the 1/8th and it runs along good at highway speeds. Even running the 1/4 it still pulls good until I shift into 4th and it seems like it is just cruising still pulling just not as hard.

[68turbofastback]

The 34mm venturies are not the problem, it is not jetted correct or the valve springs are bad like the others posted. You wont lose the torque with the big throttle bodies. I have used CB comp fuel injection for 10 years or longer.

[eduardocastrejon]

I bought this heads about 20 years ago to cbperformance, I never used until now.  the heads came ported, I don't have a photo but the intake runners are big and I don't believe than can be ported more, came for 90.5, I only did the modification to acept dual springs.

I will install the fI and feel what happened.

Do I need to took out from the car the engine to can drill and tapped the temp sensor ?

[wayne harron]

I would definitely pull the engine to drill and tap for the sensor. It will make it a lot easier to do. Unless you have removable fenders. But looking at the pictures don't you already have the heads off?

[eduardocastrejon]

[speed7]

Hi ,
I have a a 1776cc engine with 041 40x35.5 heads , prepared by Steve's Heads here in Belgium , 1.1 Rockers , Webcam 119 duallobe cam (as I use it on the street as well as on the Strip) with 48 IDA Webers. I  use Berg dual springs , <chro-mo pushrods and lightened flywheel . Important is that all the mobile gear has been dynamically balanced .
I have a Rev restrictor on my MSD which is set at 7200 rpm , because the engine is really pulling even from 5000 till 7000 rpm ! On the street I rarely pass over 6000 rpm , but the engine is more than willing ...

[Ohio Tom (DdK)]

Some of your photos show heads with only single valve springs.
You most definalty need dual valve springs. Preferably, a set of really good ones like CB's VW-650 springs.

[eduardocastrejon]

the heads came with single springs

 soft springs was used to measure the lenght of the adjustable pushrod easily.

I installed cb performance dual springs with  chromoly pushrods

[Ohio Tom (DdK)]

OK.

Also, I forgot to mention in my last response.
I see lots of room for improvement to the ports and chambers in those heads.
They look very near stock in appearance.
I see lots of work that could be done to the intake ports to make them both larger and straighter.
And, the chambers could use some cleanup work as well. I see ridges where the aluminum meets the valve seats. These ridges will affect flow.

I recommend either sending those heads out for port and chamber work.
Or, doing it yourself.
Or, buying a set of better heads.

[eduardocastrejon]

Thanks Tom

yes, I want another pair of heads and pistons, probably wedge ports and 94 forged pistons  to can run more nitrous

[eduardocastrejon]

[eduardocastrejon]

Intake port is bigger than stock, exhaust port too but not to much

I have 1 5/8 exhaust manifold, can I opened to that size ?