Thread: carb ?

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BTW, just to interject something here. When I got my T running it had a terrible bog if I stomped on it hard off of idle , then it would pick up and rpm ok. I moved the accelerator pump rod one hole closer (to pump more fuel in a little faster) and the problem disappeared immediately. I've seen that before, but never so dramatically.

Don

Carb CFM is an interesting subject to be sure.. Just had a 327 on a dyno and here is what I learned/saw.. First the engine spec. 327 (u knew this) performer intake and Vortex fast burn heads............ With a 750 mounted @ 6000 rpm is was consuming 489 cfm .. HP was 371 . Then a 600 was mounted and again @ 6000 rpm it consumed 467 cfm.. HP 351., Looking at the numbers two things stand out, the engine never consumed all that was available (cfm) and that the larger carb did run better with a 20 point difference in air and HP. So it seems to me that the 600 cfm was not the best carb size. I understand intake charge speed but this sure adds a question mark to the general school of thought, as I see it.

would a 4150 be a double pumper .. if so it`s needs to be tossed anyway

Originally Posted by HOSS429

would a 4150 be a double pumper .. if so it`s needs to be tossed anyway

Yeah, just toss it over here......We don't discard Holleys 'round here

Originally Posted by DennyW

I'm really glad you saw the difference. I was put down pretty good for my calculations on picking a carb. I take the ci x 2. In your case, 327 x 2 = 654. If it's over half, like the 54, I go to the next whole number. So, I would use a 700 + on that motor, with vacuum secondaries, and your in. If you get a chance, maybe not now, but it would be nice to see what the 700 did in comparison.

(Oh wes ? this is an example my friend).

Wish I had that luxury, I sure did find that little test note worthy. The math you have there spits out some good tuning numbers, can not get any easier then that. I will use it........

Originally Posted by DennyW

I'm really glad you saw the difference. I was put down pretty good for my calculations on picking a carb. I take the ci x 2. In your case, 327 x 2 = 654. If it's over half, like the 54, I go to the next whole number. So, I would use a 700 + on that motor, with vacuum secondaries, and your in. If you get a chance, maybe not now, but it would be nice to see what the 700 did in comparison.

(Oh wes ? this is an example my friend).

Denny w I like your carb math . It's COOL and will work for me TANGO

Wrenchinrick,all the info mentioned befor is correct but don't scrap that holley just yet.If you use that carb again start ingine and look into carb,see if fuel is pooring in if soo floats set to high,have also seen things like,needle stick in seat letting in to much fuel,or found things like dirt and thred tape in needle seat.

But try really hard not to wait a year before making that decision.

Read this thred for first time today,had same problem this summer with my car just sharring what i found,some new members may benifit frome it and thats' what CHR is all about right.didn't no threds had an experation date,sorry won't happen again

My bad Denny took it the wrong way,no harm no foul sorry Nitro.Thanx Denny

a liitle late on feedback ran the 600 all summer seems to run clean .pulled the plugs after about 500 miles to inspect.they all looked clean.loaned the 750 to a friend to use on his lemans 400 cubic inch motor that he drag races.he was running an eldelbrock carb and said the holly ran 3/4 of a second faster.he wants to buy it from me but Im not sure im ready to part with it.I may have dejetted the 750 and used it but gas was 4 plus a gallon and thought the 600 might get a little better milage (what was I thinking hotrods arnt about gas milage)

My Question; Would have been what year is the 750 carb.
Do you have a blown power valve, has anyone rejetted it.
Are the floats set right. Is it set or adjusted right.
In cold weather it should run a little richer.
I know alot of people don't like holley's but I have
had good luck with them.
I think Denny is right about the 700 carb, the 600 will
leave the 350 starving for more fuel.
Running to lean is not good either if it starts running
hot you'll know why! Kurt

While my experience is not near as deep as others on this site, I have worked with Holley, Q-Jet and most recently Edelbrock. In the 1970’s I was in the Air Force and it seemed no matter where I was stationed, someone always wanted me to build a motor. The Holley 4150 double pumper was the only carb I ever used on "slightly-to-very modified" 327 Chevy motors. I figured that this one had been around since the late 1950’s and it seemed to perform well with a lot of options. The Z28 302 with the cross ram and two Holly carbs not only looked awesome, but it just flat ran like a scalded goose.

I really like the Q-jet, but don’t know very much about them. I know that they sure sound awesome on a big block when the secondaries come to life.

Most recently, I have used several of the Edelbrock line. They work well and are reasonably priced. One thing that I have found is that they tend to run a bit rich when used on a stock motor. Case in point – my son has a 71 C10 with a fairly stock 350 and an automatic. The previous owner had put in an “RV Cam” (I have no idea what the spec’s are) and a set of Hooker headers. Ryan wanted things to look a bit nicer under the hood (see before and after below) so we opted for a polished manifold, new valve covers and a new 1806, 650 cfm “Thunder” series carb. (Also updated to power brakes - another story.) The stock jetting left us “under whelmed” from idle to about 3000RPM. There was a real rich smell about the exhaust as well. Fortunately, Edelbrock includes a great little book with detailed instructions and in less than an hour, we went from .095 to .092 on jets and changed the metering rods from the stock .068 to .065. The change was remarkable and the mileage significantly improved (2+ MPG).

I guess carbs and cams are kinda like stereo equipment – lots of good ones and with some tuning, they all can be made to perform well. (Anyone remember Crower or Mondello cams? They were the rage in the 60’s in Sothern California where I cut my teeth on small block Chevy motors.)

It really comes to a personal preference as to what one likes, however; the tips on this site are invaluable and I continue to be amazed when I read about someone’s experience and think, “man I wish I had known that last time I was fighting with the same issue!”

Regards All,
Glenn

Wrenchinrick; Here's some calculator's.

http://www.newcelica.org/other/calc.htm

Kurt