young olds

just got my new 355 to the point where I can drive that car. Right now I'm running a Holley 600, believe it's called side float this is my first Holley and I just call these ones small holleys. Anyways it was on my first 350 and so I just swapped it over on to the current one. The new engine had a lean surge so I bumped the jets up and it went away. Only difference from old to new is .030 over and more compression. The engine is 355, Holley street dom, cam, 9:1 comp and I'm running stock manifolds 2.5" exhaust off the manifold and splits to dual 2.25 out the back. Current carb 68 primary jets, started with 66, no metering block in the back and vacuum secondary. I have a 650 double pumper and a 780 vacuum secondary available to me as well. I'm running 14 base timing and manifold vacuum for advance, I have an hei recurve kit but idk if it's complete.

oldcutlass

Make sure your not using the resistance wire and have full battery voltage to the HEI. You will probably also need to connect the bypass wire from the starter during cranking.

Skip the recurve kit to start and set your total timing without vacuum advance to 34-36 degrees BTDC @ 2800-3000 rpm. Then run your rpm up to 4500 and make sure its not advancing anymore. Then note your curb idle timing for future reference. It will be somewhere around 18-21. Then connect your vacuum advance to ported and limit it to 10 which will give you around 46 total advance. You can experiment using manifold vacuum later. Set your spark plug gap to 45 and use a quality set of 8mm spiral wound wires..

Adjust your carb a/f mixture screws for the highest vacuum or rpm attained while keeping both the same amount of turns out from all the way closed.

young olds

I don't have an adjustable vacuum advance unless stock ones are. I can borrow my dads dial back timing light to set total advance, though I haven't been successful doing that alone. It has some msd streetfire plugs but I cut one too short and it bothers me so I'll probably buy a set of plain Jane 8mm wires.

Intragration

There is a rod coming out of the vacuum advance solenoid that moves the base inside the distributor to vary advance. You can make a restrictor with a small piece of aluminum to prevent the rod from making its full travel. Just screw one end of your homemade restrictor down with the solenoid screw, and make a tab on the other end to limit the rod travel.

young olds

Messed with it a bit today, one of my wires is short and only let me advance it so much so I bought new wires but have not installed them. Hooked my vacuum advance to ported and I increased my jet size again. When I had the vacuum gauge hooked up to set the a/f screws I noticed there wasn't much vacuum, I got it up to 8 but it idles a bit erratic and varies between 7-8 and about 20rpm. Also during the test drive at a steady throttle I could hear the engine note changing kinda like when it was lean but I don't think i feel a surge.

oldcutlass

What are your timing settings?

young olds

I got 18 degrees at idle but I didn't check my total because I use the timing light to check Rpm so it's hard to check timing and be at 3000 rpm. I have a buddy over today so if I mess with the car I'll check

oldcutlass

disconnect your vacuum advance until you can verify settings.

young olds

I put the new wires on so I can advance it more if needed, have not checked my total timing yet though. Wondering if my vacuum at idle should be that low, my cam only has 224 duration.

oldcutlass

Your vacuum is very low. Normal engine vacuum should be around 17-20. The 224 duration does not tell us anything, do you have a pn?

young olds

dont you lose vacuum when you have high duration?

young olds

Hoping to finally check my total timing today. I have been driving the car a bit and I noticed I can hear the exhaust note change while at a steady speed, similar to when it was surging but I went up to 70's for primary jets and I don't feel a surge and now it smells a tad rich.

cutlassefi

That's the problem with older Holleys, not enough tunability for the street.
Imo sell all the carbs you have and buy a 750 Quick Fuel Slayer. Almost infinite tuning, and not expensive.

young olds

you dont think a 750 will be to big? this is mainly a street car, it will see the strip but id rather have drivability then to squeeze every bit of power out.

cutlassefi

750 will be fine but I'd also rather see you use a Performer RPM instead of the Street Dominator.

wr1970

I agree with you on the intake Mark. Not sure about the 750 cfm carb as he may not have enough engine to take advantage of the 750.JMO

cutlassefi

I base it on the fact that I did a very mild 380 with stock heads and small roller cam. It had an RPM on it and a 750 Slayer and was pulling almost 2" of vacuum by the end of the pull. The 750 would be fine.

Seff

How does that engine compare to mine? I have the same except a 800 CFM Q-jet.

wr1970

World of difference in a 380 ci with a roller cam verses a 355 with who knows what cam he didn't say unless i missed it.This is a good thread with good info. Mark don't take this reply wrong as you may be right on the 750 carb.JMO

young olds

I thought single planes didn't need as much carb as a dial plane since one piston pulls from the whole car vs half on a dual plane

young olds

Cam is 224 dur @ .050 and .517 lift single pattern.

cutlassefi

Roller cam on its own means nothing.
A mild cam is a mild cam no matter what style. And if the heads only flow so much then all the more reason for the cam to not be an issue.
The 380 made 325 measured, probably about 360 corrected. Hp is hp so the carb demands will be similar.

coppercutlass

Fwiw I was running a box stock holley 750 3310 and it ran awesome., slightly rich at idle but its no big thing . My carb decided to start leaking the night before I hit the track but a good friend let me borrow an 830 or 850 cfm carb I wanna say. I though it was gonna be wayyyy too much for my 355 and holy hell does it get up and go now. I thought it was good before but was wrong. Track testing will soon tell what's what. My set up is a 10 to 1 355 with a lunati vood cam 522\539 233\241 , rpm intake , I'm running 14 degrees initial total is 34 in by 3200 rpm , 3000 stall and 3.73 gears backed by a th350 .

coppercutlass

Btw i got a pm about how im saying to run an 800 + cfm carb which im not . I should have been more specific and agree that a 750 will work specially if its a vac, secondaries. I was simply posting my experience with the 750 on my small block and how i thought it was perfect but it needed more from what i have experienced so far. This proving if my combo which has more cam more compression needs more than 800 cfm i think a 750 will be fine. The slayer series is the best bang for the buck out there imho. I got my 750 for free but if i had to buy a new one it would have been the slayer.

young olds

My car is a manual with 4.10 gears if that matters. I have the 650 double pumper, single plane and single exhaust for a reason so those will not change. I just want optimum performance as it sits until I finish what I'm after. Btw I just put the 650 on tonight but it's time to play with the baby so I didn't run it much just made sure it started and didn't leak.

young olds

finally checked and reset my total timing, i have 35 in at 3000 and 23 base. also got my dad to tune my carb and the car feels a lot better and at 180 temp the starter still cranks the engine.

young olds

Since I put the 650 on it seems like my engine warms up faster than before curious if it could possibly be related? Also when I put it on I went with 68 jets, my cruise surge seems to be back curious if it could be timing related after setting my total timing or if I should increase the main jets?

young olds

Had my carb off and found that the secondaries were closed enough to not allow any of the transfer slot to be exposed. I adjusted it so it was and my idle greatly improved and I had 12-13 vacuum vs the 6-7 I had before. But I opened them too much and had the primaries closed all the way and the idle was still kinda high so I made a bracket so I can adjust the secondaries from the top side. Since I've had this carb on there I've been able to set the idle so it'll idle by itself but as soon as I drive it it won't anymore.

Octania

Does it want to either idle way too high or else if set lower, loses vacuum, stumbles, and dies?

young olds

No I can set it at 800 give or take and it'll be fine but as soon as I drive it it won't idle by itself anymore

young olds

idk if any of this will help but ill throw it out there. i can get it to idle at a good rpm, vacuum and decently smooth after adjusting idle screw and idle mixture screws. as soon as i drive it, sometimes just rev it in neutral, it wont dile anymore unless i pump the gas constantly. i can still drive if i keep the rpms up. also after adjusting it to idle it does smell rich, and did once notice that i could rev it and it wouldnt idle anymore then rev it again and it would be fine again. im going to try a demon 750 dp my dad just took of his bbc nova to see what it does with another carb. though now that im thinking about it i do not recall the 600 holley doing this

young olds

Do they offer a carb with tuneability like this but no choke horn and mechanical secondary? annular boosters would be great too. If the 750 demon works well I'm going to look into a new carb.

young olds

ive been running the 750 demon for a little while now and its been pretty nice. i took my dad for a ride and he said he thought my surge was from a misfire so i ran the engine tonight after it got dark and the front two plugs on each side of the engine are arcing on the outside. i was expecting the wires to be arcing on the valve covers or each other but ive never seen this before. any ideas?

jpc647

the 750 isn't too large?

wr1970

New wires? If not change them.

young olds

The 750 seems ok as far as size, same jetting as the 650 and if I lost any throttle response it wasn't much. I put dialectric grease in the boots, extra in the offending ones, and pushed the boots down more and yes these are new wires. I did another night time test and didn't see any arcing. Also on the surging front I unplugged my vacuum advance and it seemed to go away so I'm going to limit my vacuum advance to 10 degrees as was advised earlier

young olds

I am going to try the 650 again after I clean it out really well

jpc647

Okay. Was just wondering. I have an edelbrock 1405 600cfm carb, as do many other stockish guys on here, and mine runs a bit rich sometimes. To me, the 750 on a 355 is overkill. But I'm still learning.

young olds

Mine isn't stock, I wouldn't say stockish either, though I wouldnt say it was "built". I did have a 600 Holley on for a while but I do believe it was too small for my engine

jpc647

I understand what you're saying. I don't know what cam you have, or heads, etc. Just seems a lot of other stockish are at 600/650's, so it'd have thought you'd be there and not at 750.