to weber or not to weber...that is the question

[Gatorac]

Originally Posted by mtpockets

Here are a couple of pics of my build in progress. I bought at Keith Craft 408w. The motor made 511 hp and 550 torque. Should be ready for test and tune in the next 7-10 days. I can post how the Webers are jetted if needed.

What did you do about the power brakes? If you got a manifold with vacuum ports for the brakes, where did you get it?

Thanks a pile.

[mtpockets]

Vacuum pump, Stainless Steel Brakes, 28146 , Summit Racing

I'm also running a custom center pull linkage.

[Great Asp]

Scode, what part of the country are you located in?

I found in St. Louis that the Barometric pressure was the problem keeping the webers running. In the morning they ran great, but in the afternoon not as well. Not hard to tune though.

If you are going to use webers, do not go big on the cam as stated above. I thought Comp cams has grinds for weber set-ups which will help if available.

E

[mtpockets]

Here are the jets used. Again, this is one of Keith Crafts "Econo" 408w crate motors. I asked him to make a recommendation of whether is "Standard" or "Econo" would work better with the Webers. He recommended the Econo with a different cam. I bought the complete Weber set up from a fellow Hot Rodder here in the Houston area. He had a 408w built and had ordered the carbs to fit that motor. Weber setup had never been used.

Jets:
37mm chokes, 160 mains, 200 air correctors, 60 idles, 120 holders, 55 by passes, and F7 emulsion tubes.

Linkage:
The linkage is custom and was designed by Chuck Kendall (AKA Traindriver) on CC. I installed the throttle cable and hooked up all the linkage tonight. Very nice setup. Installed two springs on the linkage (pass tech inspection) and a spring return on the pedal (just because).

Cam:
Off the KC build sheet: Item#: 35-426-8 Comp Cam. Cam specs: 555/576 288/294 236/242 @ /.050

[jmimac351]

Originally Posted by Gatorac

What did you do about the power brakes? If you got a manifold with vacuum ports for the brakes, where did you get it?

Thanks a pile.

Jim, I'm getting ready to put my Webers on. The vacuum pump is a good idea. I've also seen "Traindriver" plumb copper tubing on the underside of the intake to link together each of the ports. A lot more involved. I'd just opt for the pump.

Jim

[traindriver]

GatorAC,

I have a linkage plate for a 351W IDA setup available..someone had ordered it and changed their mind.

The under the manifold method for power brakes is not that hard, i used 1/4" copper tube with compression fittings, tapped into all 8 runners. The only part that was not off the shelf was the feed thru at the back wall of the mainfold. I had to drill out the NPT to AN6 fitting and solder in a piece of copper tube to connect with the tubing network. No big deal.

I autocross my car on occasion, and have never felt any lack of boost in the brakes.

Chuck

[traindriver]

I just put a couple of pics in my gallery of the plumbing arrangement

Chuck

[Gatorac]

That looks pretty straigh forward. Thanks for posting the pics.

[mtpockets]

The new arrival in the Houston Cobra Club is up and running. Now, I need to tune the carbs a bit more. Today it spit and popped a bit at startup idle, when it warmed up it stopped. Then on the road it stumbled a bit at 3500, give it just a bit more throttle and it takes off. Still taking it real easy, only 65 miles on it today. The brakes are working well with the vacuum pump. I mounted it lower driver side frame to the left of the radiator. Clean and out of sight.

[JCoop]

Most excellent!
Bravo!

[ENTDOC]

Pierce manifolds sells the needed post that attaches to the manifold to mount the bellcrank to for 12 dollars, looks stock and takes 10 minutes to put on

[madmaxx]

mtpockets,

Your engine looks incredible. I am glad to see you have it on the road. Be safe!!

[mtpockets]

Ok, I'm going to try a few more changes and then I'll find a pro in the Houston area. Spitting and popping still. Turned the idle mixture screw out 3/4 turn and changed from 60 idle jets to 70. Cleaned it up nicely. Put the stack screen on and spit and popped. Took the screens off and ran better. Tonight i got in and it spit and backfired all night. DAMN, I didnt do anything. Me and a buddy have been reading the tech stuff and will try a few more things this weekend.

If anyone has experienced similar situation let me know what to try next. The stack screens will restrict the air flow. What needs to be changed to overcome that? I don't want to run without any air filtration, just doesn't sound right. Am I nuts??? I haven't lost interest in the Webers, trust me, when you get into the throttle, it slams you back in the seat and flies. Big difference from my 306 (375 hp) to the 408 (511 hp).

Well, more test and tune this weekend and probably the 500 mile checkup and oil change. I'll keep everyone posted.

[ENTDOC]

40 venturies

['65 Cobra]

Originally Posted by ENTDOC

Pierce manifolds sells the needed post that attaches to the manifold to mount the bellcrank to for 12 dollars, looks stock and takes 10 minutes to put on

Do you have the part #?

[RedBarchetta]

Originally Posted by mtpockets

Here are the jets used. Again, this is one of Keith Crafts "Econo" 408w crate motors.
Jets:
37mm chokes, 160 mains, 200 air correctors, 60 idles, 120 holders, 55 by passes, and F7 emulsion tubes.

Cam:
Off the KC build sheet: Item#: 35-426-8 Comp Cam.
Cam specs: 555/576 288/294 236/242 @ /.050

These cam specs got me curious.

My 392" stroke RDI w/Comp Cam dual-pattern hydraulic roller specs at
.540/.540 lift, 240/246 dur @.050, 110 lobe centers. Compression is 9.7:1 with Victor Jr. heads.

I was always under the impression that I had too much cam for Webers. Mine has 4 degrees more duration (i.e. more overlap, which Webers don't like a lot of), but measurably less lift (.015/.036).

Any thoughts on this from the gurus? I'm not in the market for a different induction set-up...just trying to get educated at the moment.

Thanks,

-Dean