well, i just yanked my half worn out cammed 350 and put a built 355 in its place. it is a 4 bolt 30 over 350 with steel crank and rods, with KB 11:1 domes. it has world sportsmanII heads on it with a solid lifter lunati cam.

the cam specs out at:

.507 lift on intake side and .519 on the exhaust side
249 duration on intake and 259 duration on the exhaust (@.050 lift)

its grind number is SPA2-295

i have a weiand stealth manifold for hood clearance reasons.

i dont know if i should re-jet my 600 edelbrock or find another carb. i can get my hands on a holly 650 dual feed double pump, but was told the vacuum secondaries probably wouldnt work right on a standard shift car. so if anybody has good insight on what would work better for me, it would be very much appreciated.

 

double pump holleys don't have vacuum secondaries. You want a 750 double pumper ideally. This will have mechanical secondaries.

 

well i tried that 650DP holly i was talking about. and my ignorance has been shown to holly carbs, as i didnt even know the DP carbs were all mechanical. reguardless, i've tried 3 now, and had no luck with them. they have to be good carbs or half of the motor world woudlnt praise them, but for me, they just hate me i suppose. i've got a few grand into this engine and clutch already, so i'm just going to buy a NEW carb, a 750 edelbrock. they've never tried to burn my car to the ground yet. just wondering if a cam that large will be hard to tune a carb to or not? i bought the engine built, but it just seems like it is a bit on the extreme side.

 

skip the edeljunk and buy a holley and pay to have it tuned if you're not willing to learn how to tune it.

 

i have already tried the holly route multiple times now and it never has ended well.
i will NOT buy a holly. yes, i understand they perform better than a edelbrock. this car gets driven, once the edels are set, they are set, they dont loose tune like the holly's seem to do, the bowls dont start to leak after time like the hollys do, the floats don't come out of adustment like hollys do, you dont have to drain the bowls and make a mess of your engine to do ANY carb adjustment with an edelbrock. so i loose 10 or 20 HP or whatever to not run a holly carb in trade of a more reliable carb, completely fine with me.

so as far as "edeljunk".....i wouldnt knock any parts on somebody elses car they've spent tons of time and money on, so if nobody knows how to dink with an edelbrock, then i suppose i will eventually figure it out, unless there is a better reason than "they perfrom just a tad bit better than an edelbrock" to use a holly.

 

Hmmm, I've been running a Holley since 2001, and not once has it ever "lost" its tune.

I must be doing something wrong. . .

 

Vacuum secondaries work just fine on a stick-shifted car, they are just a bit slow to perform if you lift off the throttle between shifts. They snap the secondaries shut pretty quick when you lift off the throttle but won't open them again nearly as fast. That is probably the reason you've been given that advice.

Now, if you're like me and you stay wide open between shifts, you avoid this problem! I learned how to do this on all shifts (including the tricky 2-3 shift). Now it's obviously dangerous if you miss a shift and over-rev, but it can be done.

That being said, If I was building that engine from scratch it would certainly have a bigger carb on it than a little 600 and it would also be a double-pumper. I generally have little use for Holley DP carbs, but in this case it's called for. When you set your phaser to "kill" on a combo like you've got..... well, there is a reason Holley double pumpers were invented. That's the reason.

 

Mine never fall out of adjustment or have settings move. Must be one of those internet myths. I am free to knock your parts because you obviously built a combo to perform well otherwise you wouldn't have chosen a cam that is for racing instead of a cam for a daily driver. You want to choke your engine with a carb for a motorhome go right ahead. You asked for advice I gave it to you, if you want to be stubborn about it then why ask for advice? I've done tons of combos for people and they all have picked up ET and mph with letting me tune them. Obviously they come to me for honest advice. You're making the wrong decision and that's up to you.

 

What you want is a Holley 750HP, vacuum secondary. The problem with Holley carbs is some people and start tuning then right away. You need to dtermine what size power valve is needed for the car it is on, there are instructions online at Holley on how to do this. All you need is a vacuum gauge and a working tach! Once the right power valve is in them, tuning them is quite easy, again instructions online!
I have been running Holley's for a very long time, they never need constant adjusting, usually ignition or other problems and people start turning screws on the carb, don't be afraid of them because of somebody;s used piece of crap did not work well. Go buy a new one, size the pv and tune it, you'll be surprised...LOL

 

a 750 DP is too big for a 355 on the street, yes it can be made to work but a 650 will be way better. I would say to go with a 650 DP it will be PERFECT, I just put one on mine and it blows the bigger carb out of the water.

I would buy the holley and if you have any trouble with it I can give suggestions on how to tune it for you. If not the edelbrock is still a good carb, THEY CERTAINLY AREN'T JUNK. I would jet your 600 edelbrock to the 1605 specifications (70x47, .100, 5" IIRC) and go from there. But you would be best off with a 650 double pumper. If your dead set on edelbrocks I would look at a 650 AVS also.

Don't even bother with vacuum secondaries.

 

noooo that's not what a stick shifted car wants at all in a performance application. Go buy a book on holley carbs and it'll explain everything you need to know about why your comment is off.

Edelbrock carbs were not accepted back in the day when they were called carter carbs. A 750 is no where near "too big" on a motor with a huge cam that will make some decent power. Your feeling on the bigger carb being slow is based on dyno readings with a drop in HP and TQ or seat of the pants due to a tuning issue? Sounds to me like you should have jetted the bigger carb by reading plugs or a wideband and it would have picked up power across the board.

 

a .507 lift cam is huge to you? what world do you live in? A 750 would only help him by a few HP on the very top end and would hurt the lower end, use more gas and be less streetable. If he is going to be drag racing, then it would be fine, but for the street it is overkill, a 650 WILL be better.

The bigger carb was dialed in, I am no fool at tuning carburetors. Carter carb's weren't accepted back in the day? You might want to go back to 1962 and look at a 327 and see whats on top of it. I'm sick of the edelbrock/carter bashing, for cost and ease of tuning they can't be beat, and they work very well on the street. For preformance a holley double pumper is hard to beat, and is my recommendation.

 

not the lift the duration + it's a solid lifter cam. I could care less about the lift. A 650 will choke the motor, and if you can't get a 750 to sip on gas then you didn't lean out the primaries. Look over his combo again, this isn't a grocery getter motor, and your agenda to push a motorhome carb is kinda out there since it's obviously a performance build. The air flapper secondaries are going to make the motor not as responsive either from gearshift to gearshift. As for ease of tuning, I didn't know a 5/16" wrench to pull the bowls during intial tuning was that bad.

 

Ok well I am wrong bout the vacuum secondaries, but that motor could use a 750 IMO, as far as what type, get a Holley, iy is a better performance carb. He's running good heads, high comp and a decent cam.

 

Vacuum secondaries tend to both open and close slowly. Not a good situation with a manual transmission, especially a T5 - you let off the throttle as you push the clutch in, RPMs flash because the secondaries are still closing, as you let the clutch out in the next gear you shock the transmission with the high RPMs. If you're "speed shifting", it's not as much as an issue because you're keeping the throttle open anyway - but T5's don't take very kindly to speed shifting.

If you are traction limited and need to control power out of the hole, you can use vacuum secondary tuning to hold the power down until the car gets moving. The best way to do that is with a Quick Fuel Technology adjustable secondary housing, which meters the vacuum signal rather than the spring rate. You then will have all of the high-RPM flow you need while not over-powering your traction off the line.

Having said all that, 99% of the time, a mechanical secondary double pumper is the best choice with a manual transmission.

 

i do appreciate the replys now and advice, dont get me wrong, but for 3 days, all i got was 2 replys basically bashing the edelbrocks and holly is the only way. i've always ran edelbrocks and had great luck with them. to be fair, the hollys i've tried have not been new, but borrowed from what seemed to be good running cars, then again i've never had a new edelbrock either.

i most deffinately know the 600 is way on the small side, which is why i asked if it was worthwhile to try and jet it bigger, or if a bigger carb was a must, which it now seems more than obvious. i do have a 725 "cheater" (???) holly, as it was put to me to try out. my friends dad down the road is in love with DP hollys and i'm letting him throw it on my car and see if it'll run halfway decent, if it does not, he' going to put a 650DP he rebuilt last fall, an ended up buying a new one. i really hope one of these two hollys work well, honestly, as putting this motor together has busted the cashfunds to nothing and its now slow season at the shop so its slow to come again. but if i have to save for a little bit and buy a new carb, i just dont know if i'm comfortable spending 400 or 500 bucks on a new holly, that i'm completely unfamiliar with, and generally just had bad luck out of, when i can go buy a bigger edelbrock new and have enough knowlege of those to get it pretty close. working at 9 bucks an hour, a 500 dollar wrong choice is a big deal is all i'm saying.

 

You can't jet a small carb "bigger" once the proper a/f ratio is found that is it. The throttle bore sizes dictate how much airflow you're going to get out of it. I gave my advice as this is the best choice, there are thousands of used holley 750 double pumpers laying around that are in good shape. As long as you buy one that is clean inside and out then the going rate is 150-200 for one. Pull off the bowls in front of the person and look at the insides of them and the metering block holes, if there is sediment then pass on them.

 

Most negative recommendations come from a lack of understanding of operation and therefore inappropriate tuning/adjustments/repair. Q-jets are huge victims of this. Holleys are close behind.

In this case, though, it's fundamental design that drives my recommendation. The Edelbrock Performer and q-jet share a secondary air valve design, which, although different in execution, in function produces an opening delay with every WOT shift. If you can live with that, and you are comfortable with the Performer carb, more power to you. A vacuum secondary carb, though, is a different animal, and I wouldn't recommend anyone with a T5 run one.

 

everyone with there own opinions. i run a 600cfm edlebrock carb and no problems there. Edlebrock is good and so is holly just different preference choose what you want and go with it.

 

i've one more holly to try and i'm confident in this one atleast. finally a 750DP holly. a guy that used to be a painter at the shop i work at bought it or his Grand Prix but it wasnt quite big enough. might have seen him on that show "trucks" when they did project HRT, he was the guy named brian botger they flew in to paint that truck. he says he'll sell it for 200 bucks and he has the reciept that it cost a bit over 600 bucks. so i'll give that a go this weekend and hope all goes well...