rkk69olds

thought $300 was pricey, but had nothing to compare it to. only place in Wichita Falls, TX that offered it kpe engineering. Now I know better, but live in a small town in WV now so not sure I will have any better options unless I go to Pittsburgh.

Captjim - cam is the 224/234 performer rpm.

Have a Flexalite black magic 3300 cfm electric fan. Like it, but have some shroud work to do as it does not cover the entire radiator.

If I do decide to do some head work I think I may have a clearance problem as I used head studs and do not think the head will clear the ac system on the firewall....anyone have experience with that?

InfoJunkie

I've always like stock class. Had a friend from NY State with a 72' W30 that ran ES/A . 11.85 ET's. That's with a stock spec engine. No porting, Qjet, full body(less back seat). Dave is right tune it to get all you can out.

71 Cutlass

rkk69olds,
Still not sure what your ultimate goal is. If it is a car just for street use and occasional track fun, the 224/234 cam you have (which I told captjim you had waay back in this thread, of course he said I was wrong), is in my opinion fine for the street.

cutlassefi

Yeah but it's slow and on the wrong lobe sep which compromises low to midrange torque.

rkk69-You're making almost nothing below 2500rpm, especially for having over 10.0:1 compression. That tells me the cam may not be the best, either not degreed or just not right for this as I mentioned. Also the fact that you're at almost 14:1 air/fuel in the upper range is by my experience too lean. Need to work on that fuel curve.

captjim

In post #5 of this thread I mentioned that a different cam might make more torque, it seems low for that high a Cr.

rkk69olds, Do you have the cam card? Do you know where the shop installed it?

cutlassefi

Didn't read every post, sorry Jim. but I was enjoying your sparring match

captjim

Mark, just curious, what would you grind for a 355 with that high a Cr, stock heads, to run on premium fuel? Flat, no roller.

cutlassefi

Basically the same as what he has, except 2 differences. I'd use a intake lobe that was just a bit faster and then grind it on a 110 in with at least 4 degrees advance.

We're not sure that his timing is optimized either, that could be another reason for the laziness down low.

MN71W30

I was amazed what a couple of jet size difference can do to an engine. If I recall right, I lost 3 tp 4 mph and almost .5 going from a 71 jet to a 68 on a qjet in a 455. I'd get the fuel ratio right first.

rkk69olds

Cam card is packed in some boxes that are stored somewhere in WV as we are still in the moving process. Car is in temporary non-climate controlled storage and it is amazing how the elements can still get to it. went from a heated garage in dry NW TX to cold and wet WV. valve covers are already oxidizing and it appears as though my ceramic coated headers are rusting....

You are right on the mark with no power down low and you now have me wondering about my cam, but I am by no means an expert on the subject. Going to work on the easy stuff (by easy I mean degree of disassembly) like timing and air fuel.

will not be able to work on the car until end of Jan when I have a garage, but keep the advice coming. I am going to get a 750 to try and if it works I will have a slightly used 670 and 650 avs for sale if anyone is interested. Could not decide on carbs, but can tell you this - the 650 avs is better from a stop,but the holley seems to produce more power.

cutlassefi

Get the jetting right first before you swap carbs. I did a 362 SBO with 9.4:1 and a Lunati 223/231 cam on a 108 with a 670 Holley and Performer. Ran awesome, real snappy and responsive, and it had less compression. Didn't dyno it but the customer was real happy, said it ran great everywhere. Only real difference from yours is cam and tuning.

rkk69olds

I have a jet kit so I can experiment. Any suggestions on where to start as far as jets, pump cams, nozzle and is the 30 cc pump adequate. One big difference between avs and holly is that the holley always seemed to have a bit of stumble from idle.

cutlassefi

A stumble is normally from accelerator pump cam, nozzle or pump itself. Check there first. Then go richer on the main jets, is it better, worse etc. Don't forget the power valve as well.

Without a dyno it'll be seat of the pants trial and error.

captjim

To add to the above, in my experience a stumble is usually lean. I fixed 2 lean stumbles on 355 SBOs by going to the 50cc pump up front. Maybe that and like a 34-36 squirter, but like Mark stated, you will just have to experiment. The good thing about Holley's is that they are infinitely adjustable. The bad thing is........they are infinitely adjustable. Make small changes, one at a time, under the same conditions. First thing, make sure the float level is correct, that can goof things up.

Jharken

Dyno says lean for sure on the secondary side.

Try a 1"inch open spacer.But it will make it even more leaner.

Make sure with a vac secondary you're getting the back barrels open all the way.Paper clip on the rod that goes to the vacuum pod then go for a ride then see how far it moved.Get the spring kit from Holley and play with the different color springs start light as possible then heavier till bog is gone.With that converter it might hole shot better with the vac sec carb.

I have had no problems with the 30cc pump on many 350 olds with that same carb.You're primary plates are open too far and your pulling fuel out of the transfer slots.Make you're transfer slots square use the rear plates to set idle speed. Small screw on botom of carburetor.That cam has a good amount of overlap and will be a pain to tune with the street avenger.750 will be a more bolt on deal for sure.

When you change jetting you will have to start over with shooters and pump cams etc.

Timing curve and total timing should be done before the carb tuning.

I have had good luck with 32-33 total on #5 heads.

My stock bore 350 with #5 heads with just the big valves in 2.07/1.71 no porting did 266hp to the wheels at 5200rpms. This was a measured 9.14cr
with 219/226 108/104 cam My 670 street avenger was dead on fuel curve with 68 primary 76 secondary.And a 37 shooter on the front this is with 3.90 gears and 2800 stall and should be a starting point.
Hope this helps

cutlassefi

I agree with most of it, except the primary side can go more leaner (huh?) just as easily as the secondary side.
All Holleys have a changeable power valve to my knowledge. That means when you install a cam like his you just need to put in a lower number power valve. And for the record that cam is lazy but the fact that it's ground on a 112 vacuum/tuning really shouldn't be an issue with that carb. I've put those carbs on other applications that had much bigger cams, no issue.

And I didn't think the accelerator circuit went thru the main circuit. If is doesn't then a main jet change won't necessarily directly effect your pump changes. Anyone else on this? Thanks.

captjim

I'm kinda with you on that, The combination of squirter/pump/cam will have by far the most effect on the initial shot, jet size very little, if at all.

EDIT,
from here,
http://www.stockcarracing.com/techar...ent/index.html
... Once the arms have moved to depress the diaphragm, fuel is pressure-fed through passages in the metering block. These passages terminate under the squirter. The squirter is held in place by a bolt slightly smaller in diameter than its hole. Fuel then travels through the squirter and is released into the venturi air stream under pressure. This is the way fuel is fed to the engine when the throttle is abruptly opened and there is not enough airflow to pull fuel through the jets. Without the accelerator pump's shot of fuel, the engine will likely backfire through the carb...

Aceshigh

You're not going to get 300hp and 400ft lbs at the wheels.
Maybe the crank, but not the wheels. My '70 350 is putting that out at the crank.
I wish I knew what cam I had so I could tell you......but it made 324ft lbs at the wheels through the auto.

Heads are your biggest limiting factor, Olds heads kinda really suck for air flow.
It's a lesson in futility without major headwork, and even then it doesn't pay off huge to keep it streetable.

At least you dyno'd it though.
Most guys just shoot from the hip with their HP guesstimates from paper combo's.

I wish someone would make an LS style head for the Olds. It would literally sell like hotcakes.

captjim

Google is our friend, from here,
http://www.holley.com/data/Products/...al/R7849-2.pdf
ACCELERATOR PUMP
The accelerator pump system consists of three main components: the pump diaphragm, the pump cam and the pump nozzle. This is the carburetor system that is most responsible for having good, crisp, off-idle throttle response. Its purpose is to inject a certain amount of fuel down the throttle bores when the throttle is opened. By accomplishing this purpose it acts to smooth the transition between the idle and main circuits so that no stumble, hesitation or sluggishness will be evident during this transition phase.
NOTE: The old saying “if a little is good, a lot is better” does not apply to the proper tuning of the accelerator pump. Your car’s performance can be just as bad if it receives too much fuel as if it receives too little fuel.
Two factors affect the accelerator pump’s delivery: First, The amount of fuel that can be delivered by one accelerator pump stroke. This is determined by the pump’s capacity and the profile of the pump cam. Secondly, the period of time that it will take for this pre-determined amount of fuel to be delivered. This is affected by the pump nozzle size.
Pump Nozzle or “Shooter”
A larger pump nozzle will allow this fuel to be delivered much sooner than a smaller pump nozzle. If you need more pump
shot sooner, then a larger pump nozzle size is required. During acceleration tests, if you notice that the car first hesitates and then picks up, it’s a sure bet that the pump nozzle size should be increased. A backfire (lean condition) on acceleration also calls for a step up in pump nozzle size. Conversely, if off-idle acceleration does not feel crisp or clean, then the pump nozzle size may already be too large. In this case a smaller size is required.
Holley accelerator pump nozzles are stamped with a number (Figure 5) which indicates the drilled pump hole size. For example, a pump nozzle stamped “35” is drilled .035". Pump nozzle sizes are available from .025" to .052". Please note that whenever a .040" or larger accelerator pump nozzle is installed the “hollow” pump nozzle screw should also be used. This screw will allow more fuel to flow to the pump nozzle, assuring that the pump nozzle itself will be the limiting restriction in the accelerator pump fuel supply system.
NOTE: When changing the pump nozzle it’s best to jump three sizes. For example, if there is currently an off-line hesitation with #28 (.028”) pump nozzle, try a #31 (.031”) pump nozzle.
Pump Cams
Once a pump nozzle size selection has been made the accelerator pump system can be further tailored with the pump cam. Holley offers an assortment of different pump cams, each with uniquely different lift and duration profiles that are available under Holley P/N 20-12. Switching cams will directly affect the movement of the accelerator pump lever and, subsequently, the amount of fuel available at the pump nozzle. Lay out the pump cams side by side and note the profile differences. This little exercise may help to better explain the differences between the cams and their effect on pump action.
Installing a pump cam is straightforward (Figure 6). It’s a simple matter of loosening one screw, placing the new pump cam next to the throttle lever and tightening it up. There are two and sometimes three holes in each pump cam, numbered 1, 2 and 3. Placing the screw in position #1 activates the accelerator pump a little early, allowing full use of the pump’s capacity. Generally, vehicles which normally run at lower idle speeds (600 or 700 RPM) find this position more useful because they can have a good pump shot available coming right off this relatively low idle. Positions #2 and #3 delay the pump action, relatively speaking. These two cam positions are good for engines that idle around 1000 RPM and above. Repositioning the cam in this way makes allowance for the extra throttle rotation required to maintain the relatively higher idle setting. Pump arm adjustment and clearance should be checked and verified each and every time the pump cam and/or pump cam position is changed

captjim

We kinda all agreed on that, now we are just trying to help him maximize what he has. I believe there is definitely some torque left on the table.

cutlassefi

Thought so, you da man Jim!

380 Racer

X2

tonycpe

OK,just a couple things cause i don't feel like typing
I have a similar build 350 for over 40 years
Been through what your goin through
I haven't run a 650 cfm since 1972, goin on my 3rd 750 cfm
I ran the cam you are using a few years ago . i think i ran 13.30's
2.00 intake and 1.625 ex. valves are W-31 valves , small block
the reason i went to bigger 2.08 and 1.68 big block valves is because they have longer stems which allowed me to use springs that did not bind at higher lift
My motor is being balanced and bored right now and i will give a run down and track times this summer.My last cam was comp xe-294h.
And lastly always listen to what captjim has to say
cause i'd be checkin you dist curve and all his other ideas.

MN71W30

In the case of my 455 after I changed carbs it had a stumble like an accelerator pump but not as severe. I put a 71 455 carb on it and pulled off a leaky 67 98 q-jet. I noticed the stumble right away. In fact I changed acc pump before I started playing with the jets, I thought the carb was bad. I didn't realize the extent of the power loss until I went to the track. The bigger jets eliminated the stumble and greatly increased off idle power when only opening the primarys.