5.0+030 SBFord. Windsor jr. iron heads ...9.5:1 CR.....Edlebrock Performer RPM manifold.....Re-curved Duraspark distributor 36* total advance all in by2000RPM. MSD ignition box....Delta custom ground roller cam 230/236* duration at 050.....LSA 108* (advanced 6*).....480-ish Lift... T-5 tranny in an off topic (lightweight )car..... Still have the old 3.00:1 peg-leg (one-tire-on-fire) Ford 8 in.. The issue is, when I am creeping along in this slow beach traffic,usually in 1st or 2nd gear the engine seems to load up a little and then the car starts surging/porpoising along. It keeps getting worse and worse until I kick in the clutch and slightly clean it out.....then its better for a while. I would think this is pretty hard on the universal joints and eventually gets kind of annoying. Is it "life-with-a-big-one"(roller) or something I can do to calm it down a little. Any RPM above idle and its great....just the creep along. Thanx 6sally6
I have it happen to me occasionally with a couple of O/T trucks that are stock and real close to stock, so while the cam might be aggravating it, I wouldnt think the cam is the whole problem. Good Luck
When I worked in a parts store years ago I had a bunch of wantabe hot rodders come in to order cams. It seems like about 9 out of 10 just had a stock engine and wanted me to order them "something that has a good rump-rump" When asked what else they had done to the engine as far as pistons, heads etc. I always got the same answer--- nothing. I guess now days they get their "rump-rump' from amps, speakers and fart cans on the exhaust.
Eddy 600cfm carb, so no power valve. Vacuum........can't remember........ but it seems pretty high for whats in the engine. I wanna say 12-14 " at 600RPM idle. I tuned on the carb some by putting softer step up springs and played with the metering rods to get it so it doesn't stink (too bad) when idling in garage. 6sally6
If you put in stiffer springs you went the wrong way. The idea is to keep the metering rods in the jets longer.
While I have more cubes (388) & it's a Chevy , my cam is similar,(232-234°-490 lift ,108°) comp. Is a point higher , 2x4 450 holleys on an Edelbrock street tunnel , Muncie , 355 gear , 28" tall tires , in traffic , under 1500 rpm it will turn into a bucking bronco , it runs so good everywhere else I just drive around it . That's what the clutch is for ! Fwiw , when I had less cam , cubes , compression & carbs ,it did the same thing under 1000 rpm . Part of it is the cam , part is that the car is very light 1800#. You can chase it changing IAB & Idle jets , to me it ain't worth it .
Sally - Not...I repeat...NOT a power valve problem (unless it's leaking)..! You guys need to learn how they work... He's talking idle, or just off of idle rpm's..."I am creeping along in this slow beach traffic" gang..! Again, incorrect..! Learn your equipment. The Carter-Edelbrock carburetors DO...have a power valve system. Ever seen the metering rods ? Ever seen the big aluminum piston that they attach to ? Vacuum actuated, JUST like the Holley power valve. Under low vacuum, the piston lifts, which lifts the metering rods, more fuel enters, JUST like exposing the two windows on a Holley power valve under low vacuum. Wow...just wow. All this knowledge just passed by some. I see it as a combination of rear gear and carburetor adjustment. The cam is not that "big". You've just got a mix-mash of parts that only "sorta" / barely work together well. Except the gear ratio, that's just NOT part of this combination, or it shouldn't be..! I question the 6° of cam advance also. You actually had valve-piston clearance to go that far ? WHY...did you go that far ? What is your dynamic compression ratio ? You know as it shows up on a compression test gauge... Properly (to the engine) adjusting the carburetor will help some. Maybe loosening the valve lash (try .002", then .003", see if things smooth out a little) may help. Mike
What is your 1st gear and rear? With a bigger cam I like the 1st gear x the rear to be close to 10. Mine is a 9.6 or so and does something similar in 1st only. My LSA is 110* so it idles fairly well going slow. Lunati recommended a 700 CFM carb, so that's what I have. I have to read the plugs and probably will jet the primaries down.
If this bucking is occuring below about 1500 rpm changing main jets will have no or very insignificant effect . Your still running on the idle jets with a " little" accelerator fuel thrown in( dependent on how steady your foot is) when the throttle blades are nearly closed....
UR right!...I put softer springs not stiffer ones so the metering rods would not bounce up & down. 6sally6
Never thought about it but.......the metering rods/springs IS a vacuum control method just like a Holley power valve. Advanced it 6* for a couple reasons: One...it was ground "straight-up" unlike most shelf cams that have advance already in it. It was a successful attempt to pick up a little more bottom end with such a tight/narrow LSA. It seemed to have worked because it has A LOT of scoot from 1500RPM up to my "butthole-pinching-range" of 5500/6000 RPM! I checked with a solid lifter AND clay to insure no P/V interference. TWO...just to see if I could do it (degreeing a cam and indexing it with an adjustable cam gear) Don't know what my dynamic CR is. The static CR is 9.5(something/something). I know my 'combination' is not totally ideal...too big a cam and too tall a gear. I do know its the fastest/quickest SBF I've ever put together!! Plus...it sounds totally 'bad-ass' running it thru open headers. That's all I ever wanted From the above posts it looks like the bucking is just part of the fun of driving a souped-up Ford. I have lived with it for the last 5 or so years soooooo..... 6sally6
Apply some brake with your left foot to load engine and feed some throttle with the right foot to maintain speed..I have a 289 +.030 with 242° @ .050 and my method keeps the bucking at bay if it should want to start..
Unless you are running high rpm a lot you have too much carb! Ya could probably be get away with a 390 Holley and be fine. Or put 4.56:1 gears in it and stay off the idle jets which are likely to fat anyway. More fuel isint better.
This bucking sounds like an accelerator pump problem..... Did you check for wear on the pump arm????..... I could be wrong...
How about this thought. Your engine is "loping", which means it is actually surging and lagging as it "lopes". Right? As it surges, it propels the car. When it lags, the car propels the engine because of the straight drive tranny. Once that sequence starts, usually it just keeps getting worse until you press in the clutch. If you have an automatic transmission, you likely wouldn't have that problem, even with the cam. That's my 2 cent thought. I have a friend who has a Malibu wagon that does the same thing. He started with a carburetor and then put Edelbrock EFI on it trying to resolve the problem. After driving it, I told him what I thought. Now, he's putting a 700R4 in it.
,.500 is pretty high for a flat tappet cam , I've seen .700+ for rollers in 350-400 cube engines , the Lope is more a product of duration and event timing than lift AFAIK
Ran a 850 cfm carb on a 306 ford,with way more cam than you have, in a falcon with 4.86 gear and 5k stall no problems. Shifts at 8k.
Well.......FORGET THAT!! On second thought........it ain't that bad. Didn't want a roller with big lift numbers because of the added wear on the springs and such. Its a street machine...not a full on race engine. I told the cam dude I wanted it to idle just-a-tad rougher than a 365/327 shivel-lay motor. He nailed it perfect. Sounds like I got "cam surge"! 6sally6
Bigger is not always better or the best way to go for a carb. Someone said to lower the CFM . This will help . Your engine can probably handle 700 CFM , but is it the best for your type of driving , No . My experience with Edelbrock carbs is they are always rich . Take a look at your plugs and decide what is happening . I always say the vacuum advance is your friend on the street . Determine if it is working and correctly connected , as in full or part vacuum . Cam and Gear are not your issues . I run a larger cam than you with auto trans no one issue . You have a tuning issue , that will drive you nuts until you find it .
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