Yep
Best 4bbl
- Thread starter nodemon
- Start date
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dano
Evil Handy Man
Since you have an open chambered head on one side and a closed chambered head on the other I'd say get a pair of matching heads. I still go back to wait on the Speed Master Black Friday sale and pick up a set of heads. Closed chambers, decent street ports, and lighter.
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j par
Well-hung Member
So I'm pretty known out here for not getting on the Internet and saying buy this and buy that..
Here's my point you get a new carburetor and you slapped on and pretty much don't have a prayer of it running correctly but you drive it and see what it does so you know what to do with it. If you're like me or like you probably haven't AF gauge.. and like my customer that I'm working on is 750 today. It's rich in the primary and the secondary not by a whole lot but it is rich. We ordered one set of metering rods one set of primary Jets and one set of regular Holly jets for the secondary....
In my case I have two 625 Street demons and they're not even using 625 metering rods or jets.. kind of a mixture of 750 and 625 stuff... And since I have two carburetors that would have meant ordering two 625 and two 750 kits... In the end I bought probably enough stuff to build up to one kit to get them correct.. and it took more than a dozen tries and probably weeks worth the research it's been a couple years now.. I actually drilled 9/16 holes in both sides of my secondaries.. a trick I learned from online research where the only known Street demon dual-quad application was ever written about... A lot of what I learned about tuning dual carburetors was from the Edelbrock site and what they actually put in there dual quad setup...
Apparently you've done like me a side by side comparison of the step up Springs and found that the Holly Street demon Springs and the Edelbrock Springs have the same coloring pattern except the Holly uses a I can't remember if it was a six or the seven greenspring Factory but the Edelbrock offers the other one. I think I'm using the pink edelbrocks and the orange edelbrocks in mine.. also I changed the squirters for a larger pump shot and those are holly... I'm definitely don't come in a kit...
I'll report back later today on how the $20 my customer spent on the next step down for his jetting worked whether I was wrong or right... That will be a straightforward application where mine is terribly unique... Also really wouldn't recommend dual quad Street demons for most as they don't have an infinite amount of metering rods and primary Jets like edelbrocks do... I have about 12 different available metering rods and primary Jets where Edelbrock has hundreds...
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I used an a/f gauge on the 750 (early on with my vans 410) and my sons 78 Magnum (360 w/625 carb) The gauge made tuning each circuit sooooo easy (I suck at doing plug readings anyways 
) And with the van engine right next to me I could watch the metering rod Pistons rise and drop with varying throttle loads so that made spring selection even easier, I could watch the gauge, the pistons and feel how it ran all at the same time. Anyway, they are easy to tune that’s for sure 
) And with the van engine right next to me I could watch the metering rod Pistons rise and drop with varying throttle loads so that made spring selection even easier, I could watch the gauge, the pistons and feel how it ran all at the same time. Anyway, they are easy to tune that’s for sure
j par
Well-hung Member
I'm not great at reading plugs but I've got a good idea. My AF cage isn't 100% happy but my plugs are pretty happy...I used an a/f gauge on the 750 (early on with my vans 410) and my sons 78 Magnum (360 w/625 carb) The gauge made tuning each circuit sooooo easy (I suck at doing plug readings anyways
And most of all I'm happy because it runs really well lol..
And when I change those primary squirters around that made quite the difference.. I had a unique situation under heavy throttle with what was explained to me as "standoff".. we're at speed when I would really punch it you could see the gas crawling over the top of the carburetor and out... Again I wouldn't recommend these carbs for a dual quad application there were no less than a nightmare to get correct.. but again once correct I've been enjoying them.. and also I will report back this evening as I'm going to work here in just a little bit and we're going to take a swing at those leaner rods and jets and the 400 Pontiac...
Keep an eye on these 302 closed chamber heads when they come back in stock again.
They were in stock for over a year now, see they got bought up. Hopefully they do the next run pretty soon. Was like 2 heads 500 bucks shipped to your door, no cores.
Great product and machine work, 1 year guarantee too.
Just need to port match the heads to your LD4B intake port shapes. Then bolt them on.
Like the way I just port matched these 360 heads for 360 application.
302, 646, 714 heads all the same.
'86 - '91 dodge (pickups) 318s
Mock up with LD4B intake
They were in stock for over a year now, see they got bought up. Hopefully they do the next run pretty soon. Was like 2 heads 500 bucks shipped to your door, no cores.
Great product and machine work, 1 year guarantee too.
Just need to port match the heads to your LD4B intake port shapes. Then bolt them on.
Like the way I just port matched these 360 heads for 360 application.
302, 646, 714 heads all the same.
'86 - '91 dodge (pickups) 318s
Mock up with LD4B intake
j par
Well-hung Member
I used an a/f gauge on the 750 (early on with my vans 410) and my sons 78 Magnum (360 w/625 carb) The gauge made tuning each circuit sooooo easy (I suck at doing plug readings anyways
As I stated before my customer with his Pontiac 400 reported that it was dying around left hand corners and pretty much Rich all over... That's according to his dual AF gauges. So metering rods and primary judge had not came in but I was able to set the floats at their correct height and we took a small swing at the secondaries that didn't come in ..
I took it for a test drive and we did a little air blade adjustment and we were able to get it to idle at what we wanted and you reported no more stalling around corners and full throttle acceleration had picked up.. at the end of the day the primary Jets and metering rods came in and I had coached him through putting it back together so he's going to switch those out and see if he can't get it a little leaner at cruise and full throttle...
I spend most of my day dressing up this 327 to get ready to break it in on the engine stand. Just a bunch of parts we used to break in Chevy engines at his place... This is a 65 327 block that will go into a 65 Chevelle. .
SS Lancer
Well-Known Member
For your situation smaller the better , wish we were closer I would loan u a
[ 390-500-600 cfm ] carbs to try out .
I wish I was closer too.. You have carbs for sale..or just loan..?
SS Lancer
Well-Known Member
Sorry just for current projects
SS Lancer
Well-Known Member
Plenty of them with members
Just put out an
( APB ) and one will show up !!!
I bought a 390 Holley from Roy in FL a few months back for backup on my Powerwagon Ambulance with ( RV/TOWING) cam never gets over 3500 rpm.
U are building a modest build which want turn high rpm so lean on ( LESS ) CFM it will complement your build.
Just put out an
( APB ) and one will show up !!!
I bought a 390 Holley from Roy in FL a few months back for backup on my Powerwagon Ambulance with ( RV/TOWING) cam never gets over 3500 rpm.
U are building a modest build which want turn high rpm so lean on ( LESS ) CFM it will complement your build.
pishta
I know I'm right....
same.....
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