BBC thoughts

General engine tech -- Drag Racing to Circle Track

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prairiehotrodder
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Re: BBC thoughts

Post by prairiehotrodder » Sat Aug 26, 2017 11:41 am

2 q-jets with 2 cables and 2 gas pedals side by side. Drive on one untill i want to race then step on them both at the same time. Be like a double barrel shotgun with 2 triggers!
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Re: BBC thoughts

Post by F-BIRD'88 » Sat Aug 26, 2017 4:52 pm

I never thought about it like that.. Thats brilliant..! I almost spit my coffee when I read that... Ha A...

You got to do it now.... :shock: :twisted:

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Re: BBC thoughts

Post by F-BIRD'88 » Sat Aug 26, 2017 5:05 pm

How is this: You got a lever on the console that grabs the other carb cable
so when you rug it, you can give'er "Two Scoops o' Raisins" :twisted: 8)
Image

Your kid will love that!!!....

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Re: BBC thoughts

Post by F-BIRD'88 » Sat Aug 26, 2017 8:32 pm

Another way to make your own custom Qjet or AFB metering rods "range of sizes" to help you
dial in the carbs for a 2x4 situation is to use brass (brazing rod). Preheat the metering rod tip and dip the end in brazing flux, The add the brass (brazing rod) with a acetelyne torch.
File down the brassed tip diameter size as needed. Now you have a set of rods to adjust the jetting.
2 sets of 4 each of different secondary metering rods should cover it.

For the range of rod hangers make up a lil hanger stand jig that sits on the work bench.
Sit the rod hanger on the jig and measure the distance of the rod finger holes to the bench.
Bend the fingers of the hangers to get different heights ... say +.030" +.050" +.075" +.100" etc as required.
2 sets of 4 different hangers will do the 2 Q jet carbs.

Again on the 2x4 2 Qjets the WOT full power power AFR "jetting" adjustment will be all about the 4 secondary rods and 2 rod hangers and air door tension setup of the 2 carbs.

At WOT the 4 primaries are essentially just along for the ride.

Idle and driving- part throttle "cruising" is all about the primary rods, pri jets, primary metering rod step up spring and APT adjustments of the primary side of the 2 carbs. You will have square even oriented "4 corner idle" when the 2 Q jets are mounted back to back on the 2x4 adapter.

When at idle and when idling "in gear" (auto trans) you ideally want the primary metering rods of the carbs to stay down in the primary jets "lean" at idle. The tension and free length of the primary power piston step up spring controls this... With the big racey cam and low manifold vacuum at idle you want a spring with lighter weaker spring tension than oem stock...
There are different vacuum rated tensions AC Delco GM part# springs for this tuning...
Or you can find your own suitable springs that fit the Qjet.
Last edited by F-BIRD'88 on Sat Aug 26, 2017 8:48 pm, edited 1 time in total.

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Re: BBC thoughts

Post by pamotorman » Sat Aug 26, 2017 8:47 pm

I made my custom Q jet secondary rods by machining a flat on the tip. you can do the math to see how much flat you need to reduce the area to what you want

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Re: BBC thoughts

Post by F-BIRD'88 » Sat Aug 26, 2017 9:01 pm

I found a Weiand one as well but not having any luck on it either

If it is the one from Welland/Port Colborne with the 2x 750 DP holleys on Kijiji,
I know that guy. He was telling me about that BBC Weiand tunnel ram he has for sale here.

It is a bit over priced.... but.....whatever....

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Re: BBC thoughts

Post by prairiehotrodder » Sat Aug 26, 2017 9:25 pm

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Re: BBC thoughts

Post by MadBill » Sat Aug 26, 2017 9:25 pm

For hanger adjustment, I just start with a lean one, say a 'K' or higher, and shim the hanger up as needed...
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

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Re: BBC thoughts

Post by prairiehotrodder » Thu Aug 31, 2017 12:07 am

Weiand tunnel ram inbound. Probably gonna stick with a pair of 750 holley double pumpers. It would be nice to buy a set from AED or another builder that would hopefully get them close to the correct calibration out of the box. I also want to get this Lunati cam out of my motor. It was just a fun , cheap test piece. I'm leaning towards the Erson cam i posted a few posts back. Lots of stuff to do this winter.
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Re: BBC thoughts

Post by prairiehotrodder » Wed Sep 06, 2017 1:56 pm

Weiand tunnel ram showed up today. Looks to have some porting done to it. The upper plenum port openings were brought to point. Appears to be in great condition. The ports roofs where they meet the head were also worked on a bit. I bought a pair of 1/2" plastic carb spacers to go on top to isolate the carbs from the heat a little. I've considered my new plan of attack for this winter. I did buy the Erson cam i listed a few posts back. I'm wondering if pulling my heads and having them milled is worthwhile to gain some compression. According to AFR every .006 is one CC and they start at 121. I could chop .024 to lose 4 cc's. That would take me from 9.99 Cr to 10.29. Might be worth some power. Might also be a big hassle. What do you think?
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Re: BBC thoughts

Post by bigjoe1 » Wed Sep 06, 2017 2:59 pm

Do NOT waste your money on the milling-- You will NEVER notice the difference




JOE SHERMAN RACING

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Re: BBC thoughts

Post by mark_follweiler » Wed Sep 06, 2017 3:19 pm

3/10s of a point will not get you anywhere....except a lighter wallet.

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Re: BBC thoughts

Post by prairiehotrodder » Wed Sep 06, 2017 6:10 pm

thanks thats what i wanted to know.
brian
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Re: BBC thoughts

Post by vortecpro » Wed Sep 06, 2017 6:14 pm

prairiehotrodder wrote:thanks thats what i wanted to know.
brian
Whats your altitude?
Racing a NA NHRA stocker should be mandatory before any posting.

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Re: BBC thoughts

Post by prairiehotrodder » Wed Sep 06, 2017 6:26 pm

1500 feet with notoriosly bad air.
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