New Carb

[ellis8500]

What a difference a new carb made on my near-stock Ford 302. Had a Summit 600 CFM which is Holley inside a one piece body. It was just too much for the engine. Never could get the idle down even when throttle plates were closed...still sucking too much mixture through the transfer slots. Plus, the geometry was not quite right for my AOD shift characteristics. Replaced it with a 500 CFM Edelbrock. Worked great right out of the box. Only had to adjust choke and idle speed. Plus, works perfect with the AOD. It was like driving a different car. So the moral here is size your carb for the engine. Bigger is not always better. I'm not knocking the Summit carb. It would be perfect for a bigger engine; was just too big for mine.

 

[benT]

Yeah, we really like the edelbrock carbs. Both dad and I have dual 500's on our '27's and we put a 50o on the 283 in my uncles bucket. Can't go wrong with these on a mild street ride

 

[butch27]

I have the same problem with the 600 Edelbrock on my 302". It IS too much. A lot of people brag about the bigness of their carbs but in truth most do not need the bigger carbs.

 

[choppedtop]

I have the 600 Edelbrock on my stock 350 with a RV cam. I am thinking that I would have been happier with the 500. Seem when I go wot it is just a bit to much, and not burning clean.
Lee

 

[Screaming Metal]

Glad to see the carb is to your liking. Yes, a 390 to a 500 cfm are about perfect for the 302. My Brother had a 302 in a Maverick, he had a fairly mild cam, in it 10:1 pistons, mild porting and portmatching, a edelbrock dual plane with a 500 Holley, C4 with shiftkit and converter and something like 3.55's....he'd pounce on the Chevlles and Novas all day long....hahaha....
about 8% of the time your motor will be idling, 90% between 1500-3000 rpms....

 

[Screaming Metal]

We usually use the 600's and 650's for racing the 302's, depending on the cam, and heads....

 

[ellis8500]

This is cam I have. 1,200 to 4,500 RPM range: Hydraulic Flat Tappet, Advertised Duration 280/290, Lift .449/.473, Ford, 5.0L HO. With the 500 CFM carb the off-idle transition is much smoother than was the 600 CFM. Like they all say, everything has to match. Sometimes we just need to try different things to get the right combo. Or, we can read from here and other places and just listen to the experts and get it done right the first time......which, usually costs fewer $$$$$$.

 

[Keeper]

It took me a bit to dial in my Holley 390 on my 350 (see long thread on my adventures) but once I did, I have been extremely happy with it.

 

[RPM]

We usually use the 600's and 650's for racing the 302's, depending on the cam, and heads....

I believe the 67-69 Z28 with a 302 came with a 780 Holley and lord knows they ran good.

 

[ellis8500]

Here is link to all you want to know about the 69 Z28 302 engine.

http://www.holisticpage.com/camaro/camaros/302.htm

 

[Screaming Metal]

Yea, Ron,

I believe the 67-69 Z28 with a 302 came with a 780 Holley and lord knows they ran good.

its a diff. era now.The 302 Z motors had a really stout cam, had good valvesprings so it could wind up, nice size headers, BUT, where the hanging point is now days, we don't have the street fuel to run the high compression ratios that they did.
They had Real Gasoline, with Real Lead in it....it burned fast, good clean and hot. They didn't have to worry about the timing falling out because of weak fuel....

That little 302 put out some horses, too! Alot of folks would get their Z's, throw on some cheater slicks, have to old slapper bars on the rear springs....put on some old wore out shocks on the front end (before the 90/10 drag shocks), and they'd run in the low 12's maybe even high 11's with a full bodied street car....
Impressive as hell.
Then you had the 350's that had the 750's, the Rats ran the big Holleys. The 396 Loved the 750 dual feed doublepumpers, if it had enough cam under its belt with some good headers, the 780 cfm'ers
Those were the good ole days, reals supercars with real motors making big power....
To run those cars now, you have to keep resetting the timing and run gas additives, etc. Really, the only correct way to run those motors nowadays, is with the EFI systems

 

[Screaming Metal]

Yea, Ron, I believe the 67-69 Z28 with a 302 came with a 780 Holley and lord knows they ran good.

its a diff. era now.The 302 Z motors had a really stout cam, had good valvesprings so it could wind up, nice size headers, BUT, where the hanging point is now days, we don't have the street fuel to run the high compression ratios that they did.
They had Real Gasoline, with Real Lead in it....it burned fast, good clean and hot. They didn't have to worry about the timing falling out because of weak fuel....

That little 302 put out some horses, too! Alot of folks would get their Z's, throw on some cheater slicks, have to old slapper bars on the rear springs....put on some old wore out shocks on the front end (before the 90/10 drag shocks), and they'd run in the low 12's maybe even high 11's with a full bodied street car....
Impressive as hell.
Then you had the 350's that had the 750's, the Rats ran the big Holleys. The 396 Loved the 750 dual feed doublepumpers, if it had enough cam under its belt with some good headers, the 780 cfm'ers
Those were the good ole days, reals supercars with real motors making big power....
To run those cars now, you have to keep resetting the timing and run gas additives, etc. Really, the only correct way to run those motors nowadays, is with the EFI systems

 

[Wild Mango]

IMHO the great thing about a vac secondary Holley is, you can effectively size it to the engine. A 600cfm Holley like the list 1830 will flow about 300CFM through the primaries, and as the rating says, about 600CFM through all four. The vacuum signal from the primaries "tells" the secondaries when to start opening and you can tailor this by changing the springs on top of the secondary diaphragm. The new quick change kits make this a snip. The vacuum signal method of actuating the secondaries is a far more indicative signal of engine demand than a flow flap like in the Edelbrock. If you add a metering block to the secondary that takes screw in jets like the primary, you can jet the secondary same as the primary, another good thing.
Both good carbs, and as posters say, the Edelbrock is a bolt on and pretty close right from the start. The Holley is far more tunable and will get you better results if you have the time, know how, a good vacuum gauge and, of course, the inclination.
You pays your money and takes your choices.

 

[Mike]

Holley and Edelbrock (why don't we just call that a Carter AFB??? ) have their own strengths and weaknesses. I generally tend toward the Holleys, just because I've been inside a couple gajillion of them and have a lot of parts for them. But for someone who sets their timing by ear (@RPM will know which inactive member I am alluding to), not having a vulnerable power valve diaphragm can be a plus. The Carter has a huge advantage that a lot of people never consider, in that there are no gaskets below the fuel level, so there are never any fuel leaks. And whilst most people sneer at them, look at all the incredibly fast Chevy Super Stockers with Quadra-Jets on them.

The bottom line with carbs is to not let the carb be any smarter than you are. Because those devices which so craftily meter fuel to our engines are really dumber than rocks. Without a pressure differential, a carb cannot and will not work.

 

[Screaming Metal]

Yep, Mike Is right! Those supersmall primaries make for really crisp throttle response. Once you get the taper right on your metering rods, and secondary opening rate down, those carbs are killer. Like Mike said, look at the ET's some of the old SS's were running back in the 70's and 80's....
The Holley spreadbores are pretty decent carbs, but I'd run past them and run the QJet every day of the week if I had my way. I had people laugh at me when I had a 8-71 on my old Pontiac Firebird, which ran 2 Qjets....They quit laughing when the ET and MPH came up on the boards though....

 

[jcunning]

I had one of the 68 Z/28s and it was a screamer. 302, 4 speed, 4:56 Posi. Great little car.

 

[Screaming Metal]

, nice size headers,

Well, some came with the streamlined cast iron manifolds that flowed really well, almost as good as headers. But, the thing was if you bought the good Hooker Hedders, with the equal length primarys, THAT REALLY Woke up the 302's! Yea, they were more expensive than the cheaper over the counter headers, but that allowed all the parts in the little 302's motor make ALOT of Horsepower....

 

[RPM]

I had one of the 68 Z/28s and it was a screamer. 302, 4 speed, 4:56 Posi. Great little car.

Then in 70-71 those cars could be bought for a mere $1000.00. Wish I would have bought some and stored them. An original numbers matching car in perfect condition will bring over $100,000 now. A ZL-1 Camaro will bring $600,000, since they only made 69 of them.