alright i have a 68 430 bored.030 the only change its got composte head gaskets other wise the basic is stock so i am thinking its got about 10.1 comp.I am going to be putting a new cam witch specs at 235/249 @.050 and .506/.491 in/ex on a 107,also will be putting a sp1 intake on.Its already got headers gears and converter.do you guys think this is to muck for the 430.
A good "rule of thumb" for carb sizing is to multiply the CID by two. An 850cfm carb will be fine on a strong running 430CID engine. I know, I know, most "calculators" will compute about 660cfm for the 430 as listed, or even less. One must keep in mind with most of these engines, is that we are NOT feeding them with tennis ball size intake ports and huge free flowing single plane intake manifolds. Most intakes only flow about 89-92 percent of the port right to start with. Large cid engines fed by small to moderate size runners quickly see a small carburetor as a restrictor plate. They may also see small intakes as a restriction in the system. Several years ago we tested half a dozen intakes at the track on my old 455 engine making 514hp. Among them were the Torker I, Torker II, Tomahawk, Holley Street Dominator, my own "modified" iron intake, Performer RPM and the Performer. I'll spare you guys the long/detailed results of the testing, however, we had to abort testing with the Performer intake. It lacked enough runner volume to effectively feed the 455 engine. Installing it induced a "stumble/bog" on the starting line, and it "surged" heavily going down the track at high rpm's. It as removed, the iron intake put back in place, and everything was fine......Cliff
OOOK, I am going to agitate some here,,,, I built a 69 engine that started as a 430 and was punched out to 442.... good hot cam ,,,, 12to 1 compression,,, stage 2 set up,,,, I ran a nascar holley 950 cfm 3barrell on it with a offy 360 manifold.... it ran strong.... and could have taken more carb.... personally I think that it could have taken a 1050 cfm 3 barrel easily.... They are still available and are vastly overlooked by most guys.... most guys get all goggle eyed over the dominators and dont know that there is 2 carbs out there that will just bolt on like a 4160 or 4150 , use the same air cleaners that they do, the same linkage, ect and flows 950 and 1050 cfms.... I have 3 of these, a 950 and two 1050s.... that I picked up recently off ebay.... the holley number is 3150/3160.... they use the same repair parts/kit as the 4150/4160 with exception of the secondary diaphragm .... there is a outfit in Fla that rebuilds the secondary diaphragms.... Just some ideas.....
Yep, those old Holley's are NICE carbs. I LOVE the ones with the nozzles for secondary fuel supply tubes vs removable boosters, kind of reminds me of a Quadrajet! I have a friend that hoards those things. I'm surprised that you outbid him on Ebay, he must have been on vacation. Anyhow, I've done enough dyno and track testing at this point to figure out one thing, there is VERY LITTLE difference in ET or MPH with carburetors, provided they are correctly calibrated for the application. They simply have to be big enough, and dialed in pretty close. I've ran 750's, 800', 825's, 850's and 950's at the track on back to back runs on many occassions. We may see a few hundreds quicker short times, a MPH or two on top end, and a few hundreths deviation in ET. I've done this sort of testing on engines in the 450hp to 600hp range. Did some dyno testing about two years ago, 505cid, it made around 620hp/640tq. A Victor/Dominator made 2hp/4ft lbs more power than a Torker II with a 1" spacer and 1977 Pontiac Quadrajet! The engine was broken in on the Victor/Dominator simply because the owner wanted to see it's full potential. He was going to use the T-II and Q-jet on it since it was going to see a lot of street driving. I was expecting 15-20hp loss going to the much smaller intake and carb, on such a large engine. You just never know with these things?.....Cliff
Cliff, in a round about way You are saying what I have said for years.... most mods dont boost hp and torque that much... with the exception of huffers and nitrous.... what they do is to make any given engine get what it is going to get quicker.... that is reaching peak power in say 2 full seconds or 6 seconds.....:Brow: :Brow:
Exactly. Couple of years ago I took on the job of testing all of the intake manifolds at the track that would fit under my hood, back to back testing. The "baseline" testing was done with the "ported" iron intake pictured above. The testing for each intake went like this. We would show up with the iron intake, make one run to heat everything up, the at least 2 more runs, then swap the intakes. The intake swapped on was ran 1-2 more runs and left in place. Next outing, 1 warm up pass, at least two more runs, then swap back to the iron intake. The intakes tested included the Torker I, Torker II, Holley Street Dominator, Performer, Tomahawk (aftermarker ported version of the HSD). Side note: I even tested the RPM at a later date after some engine upgrades, but couldn't accurately compare the numbers due to the changes. The RPM intake shows a very slight advantage to the ported iron intake. I also had to run a differnent air cleaner set-up, as the factory "Shaker" will NOT work with the 1 1/4" taller RPM intake, so the testing was somewhat flawed in that area as well. Anyhow, I went on to extend the testing some and added spacers to a couple of the aftermarket intakes after the initial testing was completed. When the smoke cleared and the dust settled, the factor iron intake was the winner in ET. Yep, it outran all the other intakes. The fastest intake tested was the Tomahawk with a 1" spacer. It ran a solid 2 mph faster than the iron intake, but still ran .02 seconds slower in ET as it gave up .09 seconds in 60' times. Yep, the POS iron intake everyone tosses to the side outran all of the aftermarket intakes. Magazines HATE that sort of stuff. At that time my engine was making 494hp, about 570tq, and the car ran in the 11.64-11.80 range, depending on DA. We also did some carburetor testing, and put our 1977 Pontiac q-jet up against a Demon 850 and Holley 4781-2 850DP carb (both custom tuned). The q-jet outran both carburetors on my iron intake by a solid .02 seconds and .30 mph faster. This testing was actually witnessed and documented by HPP magazine, as we did the testing at a magazine sponsered "shoot-out" where they rented the track and you could make as many runs as you wanted to. Consider this when you look at my test results, 468cid, 10.48 to 1 compression, aftermarket aluminum 268cfm heads, Crower RAIV clone camshaft, 3500 flash stall converter (locked up just about solid above the stall speed), 3.42 gears, 28" tall DOT tires, 3740lbs race weight. I see folks stuffing all sorts of shiney aftermarket intakes on street cars that make a LOT less HP, leave at a much lower rpm, less gear, and push more weight. Few if any of them run quicker, but at least the parts look cool when you pop the hood at a local cruise and tell stories of 10 second runs on your last dragstrip outing! Seriously, I have found again and again, that these sort of parts are worth very little if any ET and MPH over well tuned factory parts. If you find yourself picking WAY up someplace, more than likely one of the parts you replaced was deficient someplace. Distributors (off topic but important) are by far and above the WORST place to spend money in efforts to run faster. The best billet locked out advance bug zapper will not run any quicker than a stock points distributor, and in many cases will run slower, as the points actually provide a natural spark retard at high rpm's. Again, this assumes that the points distributor was in perfect shape, and working correctly. This doesn't mean to avoid aftermarket parts. I love MSD stuff for racing, it's well made and easy to install rev limiters, etc. I still don't use one in my car, since it is daily driven, I use a factory HEI, and carry every single part for it in the tool box. On the dyno back to back against an MSD billet unit, it was just about dead even everyplace, with a very slight edge to the HEI, but negligible. I simply don't like to walk, so I avoid aftermarket parts that I don't have a host of extra parts for. My current engine is up near 600hp, low 11's in full street trim, so we will repeat some of the testing next season, to see at what point we start to run quicker with aftermarket intakes, etc. Certainly there is a "cross-over" point someplace, but I can say for certain, at 500hp the iron intake does a fine job, and the best part is the look you get in staging lanes when someone wonders over to take a gander at the q-jet sitting on top of it......PRICELESS!.....Cliff
Cliff, thanks for the detailed info on your testing but I have a few additional questions. By "ported" iron intake, to what extent was it ported? Naturally, we all want the most power but I have to wonder how the stock intake holds up against just a port matched iron intake, or would it have to completely professionally ported to produce the results you achieved? And how much difference is there between the two? Also, how much does this cost to completely port a stock intake in comparison to buying an aftermarket intake, like a B4B? Weight savings are obvious between iron and aluminum, but from a cost standpoint is there much of a difference between and professionally ported iron than an aftermarket aluminum? I also can't help but wonder if an aftermarket intake can be ported a little to achieve better results than 'out of the box". Has anyone ever tried this? Sorry for the long post but I have one more question :grin: Is there any particular year stock intake that would be better than others?
I attached a couple of pics of my iron intake, and a ported P4B-QJ intake. The iron intake is modified under the carb in the plenum to the apprx size/shape of the Performer RPM intake. I also added extra material for a Holley carb flange. The divider was narrowed, but left intact except for a small amount removed between the secondaries. The runners are stock, just cleaned up, casting flash and bolt bosses removed, etc. The port openings are matched to a stock Felpro blue gasket. I dyno tested the iron intake back to back against an Edelbrock RPM and it was worth 6hp. I also dyno's a ported reproduction 455 HO intake, and it was down 10hp from the iron intake (swallower plenum area). Considering the engineers/designers are working from a clean slate, it clearly shows how good the factory intakes really are.:TU: The runners are excellent, as is the design. Opening it up under the carb helps some, but gives it no advantage whatsoever over a Performer or Performer RPM....Cliff
Cliff, Sounds like you've done lots of testing there and with some interesting results. The only thing here is that some people ,even though you said it, may be missing the fact that you are talking PONTIAC intakes. Now not to say that some of the intake info isn't relevant but the factory cast iron Pontiac intake you are talking about is a good bit better(and from what I read one of the best factory intakes) than the cast Buick intake right off the bat just on carb flange height alone which gives the air a better shot at the intake valve. The Buick is in Death Valley compared to it. Buick only had one basic 400/430/455 intake style from 1967 until 1976. We won't even get to the fact that the Pontiacs are "air gap" type so that helps them out. I'm just getting to the fact that changing the factory Buick intake out will have a greater effect than it will on the Pontiac just by design alone, not that the Buick can't be made to perform. I won't argue about your point of using the wrong type of intake on the wrong car or way overcarbed street/strip cars. Lots of big carbs on mild engines for little or no gain or worse, poor throttle response. Pretty much the Buicks are very limited in the intake selection department. We have factory, Performer, B4B, SP1, and SPX unless you want to use adapters. I wish Edelbrock would've come out with a Performer RPM Air Gap intake for the Buick instead of the heads. Getting back to the 430 question. I'd go with 800-850 size just so you can have some throttle response. With that single plane and what appears to be a Comp Thumpr cam with over 30 degrees of overlap I'd make sure you have at least 3500 stall. That's going to have some lope at idle. I'd say 9.5:1 compression at best. The factory head gasket was .020" steel and yours is .040". Buick always overstated the compression ratio to make up for cheap sob's that tried to run the cars on low octane.
Correct, we are talking about a Pontiac intake. I've also tested SBC intakes, BBC intakes, Old's intakes, etc. Don't be fooled by the "flat" intakes, they are still capable of great performance. Look at a few of the FAST class racers who must run them, and leave on tiny bias ply tires, not to mention Stock Eliminator cars. When I was testing intakes, the power curve the iron intake produces is quite "boring" in comparison to any of the single plane intakes. This is a very important point. There is no "rush" of power anyplace. Installing a Torker I, Torker II or Street Dominator IMMEDIATLEY fools the driver of the vehicle into thinking it is much faster. There provide a strong "rush" of power from apprx 3500rpm's to the shift point. In contrast, the iron and RPM intakes produce a "locomotive" type power curve, pulling very had clear across the rpm range. No "rush" of power anyplace. Anyone who drove my car back to back with the iron and any single plane intake would easily bet an entire weeks pay the single plane intakes will run quicker. The iron and RPM intakes run quicker in 60', and thru the mid-range, producing a better timeslip every single time I've tested them. They typically give up 1-2 MPH over a single plane intake. What is important to convey here, is that my testing is done with a 3740lb street driven vehicle, with a 3500 flash stall converter (locked nearly solid above that rpm), 3.42 gears and 28" tall DOT tires. My engine has 11 to 1 static compression, 290cfm heads, and .630 lift roller cam, 455 cid. I see folks dumping "stock" intakes all the time on 350 engines with 8 to 1 compression, pushing vehicles over 4000lbs with 2.73 gears and a stock converter.....and they think they have just made a performance IMPROVEMENT!ou: ......Cliff
Ok, lots of great information here. I have a `74 455, which, no offense to some of you, is an ugly manifold so I plan to replace it along with the build and I would really like to save some weight in the process. So, which dual plane aluminum intake is the better (I'm not concerned about air cleaner fit), Performer or B4B? How much weight difference is there between a stock `70-`71 style iron intake and the aluminum one? Should I just look for an earlier iron intake?
You can figure on a slight HP edge for the B4B. The only problem using the older "nicer" intake without EGR and AIR passages is all the holes in the heads will have to be plugged including the 2 big ones for the heat x-over. The current B4B or a Performer will cover them no problem. I'd block the big heat x-over pasages anyway to keep the intake cooler. Maybe drill a 1/4" hole in one if you drive in colder climates. Big weight difference just not sure on exact number.
I don't care about the horsepower. Just don't want to have to get out the cherry picker just to change the manifold. :laugh:
Or pay off your chiropractor's BMW from leaning over your car with a huge lump of cast iron !!!!!!!! Look for a B4B. What you may lose in HP will be a wash with the weight savings of aluminum. Just my two cents.... Go with the 800. Or, if you want the flash, buy the 750 Dominator......
The B4B is good for .10-.15 ET ....but you must richen the jetting to get it. Back in the day people would bolt them on and be dissappointed. They ran lean stock so even more lean with B4B. Stagger jetting helps too...at least with the old B4B's. Don't know if they corrected the flow any on the new B4B.
