pretty much what @Darter6 did to mine before he sold it to me
Installing a 4bbl on a 273 advice
- Thread starter MassDart
- Start date
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I shouild have mentioned that the car has dual exhausts from the heads back, and I suspect it may have 3.23 gr as the car has a 7 1/4 SureGrip and launches better than I would think with a normal 2.74.
I'll be happy if there's a marginal performance increase as I'm still planning on doing the Isky E4 cam in the Spring. I just didn't want it to run worse than the 2bbl in the interim.
Thanks again!
I'll be happy if there's a marginal performance increase as I'm still planning on doing the Isky E4 cam in the Spring. I just didn't want it to run worse than the 2bbl in the interim.
Thanks again!
Man go for it, quit over thinking it. No guts no glory!
pishta
I know I'm right....
@318willrun , wire back that 2nd carbs secondary air door and see if it helps any. If you check out the 1965ish Hot Rod article they did on the 273-8 that had dual AFB's...they did that for some reason. (im thinking it never opened enough otherwise)
A 500 Edelbrock is a great carb for a small street engine. I have run them on several cars up to 451 CID (street for you racers) Even my Hemi 472 (ok I used 2 of them) loved the 500.
Kursplat's car I installed a 600(because it's what I had) with the Edelbrock 318/360 performer that has the small ports.
A small cfm has great throttle response on the street as AJ/FormS has pointed out.
So many over carb on street driven carbs. Hell I have 1 800 AVS on my 472 Hemi now and it's all I need on the street.
Kursplat's car I installed a 600(because it's what I had) with the Edelbrock 318/360 performer that has the small ports.
A small cfm has great throttle response on the street as AJ/FormS has pointed out.
So many over carb on street driven carbs. Hell I have 1 800 AVS on my 472 Hemi now and it's all I need on the street.
Well, that would be like putting a screw in the slot on a holley vacuum secondary to make it open mechanically. You'd get a massive bog because of no accelerator pump on the secondary's
pishta
I know I'm right....
Huh? There is no pump on the secondary of a Carter when those open either, nor a Holley VS. Its just a suggestion from an old Hot Rod article that I can't find at the moment. Perhaps it was set up as a progressive linkage.
FWIW, I've got an old Edelbrock D4B for my 273. Just like the LD4B, but with 273/318 size ports!
CdnValiant
1969 451-S
I put an Edelbrock manifold and 600cfm 4 bbl for a 318 on my 1964 273. The intake manifold to head bolt holes on the early 273 are at a different angle than the later 273's, 318, 340 motors. I had the modify the manifold to bolt it to my early 273.
I did some porting on the heads and added a mild hydraulic lifter cam of about 205 duration at .050 and 2 1/2 inch dual exhaust. My motor was an original 2 bbl motor and I believe it would have benefited from higher compression and at some point, I would like to try a 500 cfm carb, but for a small V8 runs pretty well.
I did some porting on the heads and added a mild hydraulic lifter cam of about 205 duration at .050 and 2 1/2 inch dual exhaust. My motor was an original 2 bbl motor and I believe it would have benefited from higher compression and at some point, I would like to try a 500 cfm carb, but for a small V8 runs pretty well.
Swinger 340
Well-Known Member
What a crude set-up for this 273, 65'. Dual quads, with stock exhaust manifolds!!! Remembering the NASCAR set up. Single 4 bbl on the 426 Hemi's in their NASCAR's and duel carbs on the production cars. I heard it was a way to slow the Hemi down. Of course, extra add-ons would make a difference. It's all in the complete package.
Bret Tschacher
Well-Known Member
A 500 is perfect for a 273. It's been a long time since I saw a LD340 so I can't say how closely the intake ports line up with the heads on a 273 which is a pretty small port. I didn't see where anyone mentioned that issue. With that, I advise checking with gaskets to be sure the mismatch is not going to be an issue. My last experience with a small block was my 318 which I ported and used a Thermoquad & intake from a 340 on. At that time I wasn't all that knowledged on what it took to make a quad work like magic. That came after I had graduated to BB's. So to make my point. My 318 heads looked like 340 heads with port matching work done. I later decided to switch to the smaller AVS 625 that was stock after the AFB's evolved. I used a factory iron 273 4BBl single plane low profile and took out the center of plenum, 4 holes and installed a 1 inch riser. Throttle response instantaneous compared to the thermo Q which wasn't bad until you floored it and hit the secondaries hard. Now, that I am smarter on thermo's I could have most likely fixed that, but who sees them anymore. They were not compatible with Ethanol mixed fuels which was why MOPAR used Qjets in the last years of that tech. The seals didn't last and they don't like sitting dry, among other things. Anyway, The LD is going to have larger ports than the 273 heads and unless you grind on the heads to match the ports there will be a sharp shoulder at the head that will interfere with flow and cause loss of performance potential !!!! It can affect throttle response. It is better to have a larger head port and smaller intake port. Personally at this point, I became a firm believer in the spread bore theme, I never had much success with any Holley spread bore, but Qjets and TQ's, I could make them work great, the small primaries worked awesome on everything for the street and the massive secondaries and high CFM just got it done for everything else when they were set up right. I would even try a TQ or Qjet on a 273 if I had the parts to build one now, but why when you can build a 410 now with stock looking parts and not spend much more than for the little motors. It doesn't make a lot of sense if you're building for performance. Mileage isn't going to make a lot of diff. if you drive sanely most of the time. Unless you plan on racing in stock class, which we all know is pretty much history now. I always wanted a supercharged car and the only way I could have that was to buy a blown up Pontiac 3.8 in a 2000 Bonnie and restore it. I love the 25 MPG or better most of the time and performance is fair, but IT'S JUST NOT WHAT ANY OF MY MOPARS were and bodies are just too hard to find anymore. I would part with my Bonnie in a heartbeat for a nice buildable Dart sport or Duster or any other style for that matter. I wouldn't even care if all the parts weren't there, I have other cars and stuff to drive until I get my Dream car running. I've had A's B's and E's and loved em all. Even had a 65 New Yorker for awhile which was replaced with a 72 Imperial Labaron 2 door. What a BEAST with a 440. Most BE U TE FULL car I ever been around !!!!!!!! In 45 years, I haven't seen another one like that one. Please tell me where I can find one of those, preferably Gold metal flake. Has to be a 2 door vinyl top. That front grill and those hind away head lights with wrap around chrome bumper. I want to put in a narrowed 60 rear and tubs for the most massive wheels and tires out there. Build a 572 Hemi with aluminum heads with twin dryers and install an overdrive auto built diesel tough. Add a Mega Squirt IFE and throw in a healthy doss of fast gas just for ***** and giggles. If I can't have this, I will have to settle for my 540 Cheby Aluminum head project which I already have most of what I need and find something to put that in. It's all up for sale or trade for nice MOPAR Hint coming 1972 Imperial Labaron 2 door, that hood by itself is like owning half of southern Florida and there for sure room under there to hide my dream engine. I can just see other peoples faces when it gets opened up for show and tell time. Yeah I still know this a supposed to be an A body only site but hell, A is the first letter of the alphabet and A would be a proper label for this project, a passing grade !!! Lets here anyone argue that point. After all you have A for all the under hood space, A for all the interior space, A for sure for those Montana sized doors and an A for all that real estate in that stadium size trunk. And those cars weren't all that heavy for their size either. Oh well, seeing as how only 2322 were produced in that style, it's not like I have a high chance of ever owning another one of those. Again, if I only knew then what I know now.
The OP said he is using a LD4B, which is a 273/318 port exit sized manifold. They’re supposed to be one of the best small port manifolds that has ever been made. The Weiand Stealth is a nearly direct copy, but has been reported to have inconsistent casting quality.
Nope. D4B's had the odd 64 and 65 bolt angle with 273 sized ports. The LD4B's had the 66 and newer style 273-360 bolt angle and the smaller 273 ports. (which also includes the 318 size ports) The LD340 is a little different runner design with the 340 (and 360) sized ports.
Wow, I stand corrected (and it's about time)!
I've been a Mopar guy since my teens in the mid '70's. I've never had an LD4B, but they have been legendary since I can remember...
I have had that D4B on a 318 in a '64 Valient that I drove for over a decade and although it was pretty normal to be asked about it, I was never corrected when I explained as above, what I believed to be true.
My apologies to all I may have misled over the years! I bought my D4B for cheap at a swap meet long ago, and I'm pretty sure the seller is the one who told me that story.
As for the manifold bolt angle, being aluminum, you can see the the bolt threads had just cut their own path a bit to correct their angle. I never thought too much about it even though it's been on and off the 318 many times.
Actually, I think this is good news, if I'm not mistaken, D4Bs essentially are LD4Bs with an easily correctable bolt angle!
Also good to know about the LD340...I always wondered if there was a difference, or if it was just a slang expression for LD4B.
Now I'm a little less of a dumb- a** than before this thread. Thanks for the schoolin'!
You're fine. We are here to teach and learn to advance the hobby.
Plymouth 65
I'll be in the shop
Anyone know where to get the beveled washers for the 1965 D4B intake installation on the 273? 65'
Just know if you put the intake and carburetor on now, it's all coming back off when you do the camshaft in the spring. Go for it. It'll run good.
Thinking ahead. Or common sense.
You have to make your own.
Or look it up on a thread or two here.
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