tjstarduster

had the same problem in a '65 small block i had several years back plus an off-idle stumble. i was running a holley 770 street avenger. tried everything and nothing seemed to completely cure it. the last thing i tried was a 3.5 power valve and that cured both problems! good luck, tjs

TXSTICK

The vaccum does seem low, (have to stand on the breaks if I need to stop quickly) my 66 power breaks stopped much easier. I had a 327/350 in it with a lot smaller cam than this one. I will have to check the vaccum level and try a diff power valve along with the rejetting.



chuck

Kensmith

Chuck,

Check vacuum lines, those breaks would stop on a dime when I had the car. Especially after adding the stainless braided lines. Something has happened as I did not have to hit the brakes hard at all, ever! You may have lost vacuum somewhere?

Crunch527

For what its worth, I live at 6500ft and had a 383 with AFR 195 heads and a healthy cam (500hp). I ran a 750 Holley and dropped it 4 jet sizes from stock and went to a 4.5 power valve.

It still was rich but I wanted to be careful and not get greedy on the tuning for fear of burning a valve. It still ate gas but it ran really strong And it still wreaked of gas when I pulled into the garage after driving.

I then tried an aftermarket throttle body fuel injection system, Powerjection, and it was complete junk.

sorry for rambling...

Frank

TXSTICK

I bought the Holley Jet assortment Kit yesterday. Not sure if I will need the power valve, but sounds like most go to a 4.5 and get good results.
This car right now is rich at idle and driving down the road. (I don't even want to talk about the smell in the garage after a drive)



Chuck

Kensmith

Chuck,

That smell will get better but never go away. Remember back when you had your 66. No catalytic converter. Makes a big difference. I use to start the 65 and quickly let it roll out of the garage. The wife gave me that idea. Wasn't nice about it either.

65tripleblack

In your first post you stated that the car smelled rich to someone following you while cruising. If your PV is at fault during these conditions then you have a problem. The engine should be developing vacuum far, far in excess of 4.5 in-hg.......more in the vicinity of 15-25 in-hg, depending on cam and axle ratio....while at steady state cruising. If you find that the jets are not more than 2 sizes on the rich side, then you might have a nervous foot while cruising, which will cause excessive operation of the enrichment pump and possibly the PV.

Once you get your primary jets sized properly, be sure to maintain the existing primary/secondary "spread" (some brands are as much as 10 sizes, and others as few as 6), by changing the secondary jets by the same amount. Once this is done, then get the engine to operating temp, get it to STEADY, FLAT cruise on the highway. After cleaning the plugs for at least 5 minutes in this way, then put in the clutch, shut it off and drift over to the shoulder or other safe place. Pull all of the plugs.............the insulators should be tan/white, dry and you should be able to see how the fuel is washing across them by the pattern of discoloration on the insulator porcelain. Photos would be helpful.

TXSTICK

I expect the smell in the garage after pulling the car in.
I have an exhaust fan that I turn on and it clears the smell in about an hour. But I need to get rid of the idle and cruising richness.

Hopefully the new jets and adjusting the carb will take care of it. I will check to see what power valve is in it while I have it apart.
I will also post what jets are currently in it. Then we will know if they changed them when they did the dyno tune.

TXSTICK

It does have a large cam .544/.555 lift. Also the elevation is almost 3000 ft higher here than where is was setup orig.
I don't know what power valve is in it right now, it might still be the stock 6.5. I did notice last time I drove it and had to stop quickly for a light change that I had to stand on the power brakes hard to stop the car.
So I think the vacuum must be low at idle. I will post what I find.

65tripleblack

How does this speak to my prior post which you quoted?

Also, are those valve lifts with 1.5 or 1.6 rockers? That's not excessively high valve lift by today's standards. Post the durations at both J604d and 0.050" lift as well as lobe centers to best define your cam.

TXSTICK

You talked about the vacuum it should have. A 6.5 PV would make it run rich with low vacuum while driving.

It has 411 axle ration.
5sp tranny.

1.6 rockers


Comp Xtreme Energy XR282HR. Specs (int/exh)...
Advertised Duration= 282/288
Duration @ .050= 230/236
Lift (1.6 rockers)= .544/.555
Lobe Separation Angle= 110 degrees

Air Gap intake.

65tripleblack

You don't understand how a PV functions. If you were hypothetically only developing 6.5 in-hg while cruising then something would be very wrong. You should be nowhere near having the PV opening while cruising unless you are climbing a fairly steep hill, or getting into the throttle fairly hard. With that mild cam, you should be cruising at about 18 in-hg. If the trans has an OD 5th gear, then you might be cruising at 20 in-hg. This is not anywhere near your PV's opening vacuum of 6.5 in-hg.

Stay focused with installing the optimal jets, do the spark plug check I suggested when you're finished and fugeddabout the PV.

TXSTICK

I will try the jets first.

TXSTICK

I changed out the jets (Front 72 to 69, rear 75 to 72).
The mixture screws were a little over two turns out.
I seated them and backed them out about 1 1/2 turns.
I started the car and warmed it up. I had to bump up the idle just a little to keep it running. I checked the vacuum and it was at about -12. (I did not check the vacuum before the jet change)
I tweaked the mixer screws out about 1/2 turn. The vacuum was a little better and it ran better at about 1 3/4 turns. Back in 1/4. That is were I left it.
I took the car out for a run, it has a lot more get up and go. It does not smell rich while driving now.
Much better Idle and I never thought it was going to stall like before.
It might of liked having the PV at 5.5, but I left in the 6.5 for now.

427Hotrod

I would look at the whole timing advance curve also. I can't think of anything I'd leave with 12* initial timing in it. Recurving the distributor with 20-25* initial (at least) and limited total advance will really wake it up and clean up the low speed issues.

JIM

Kensmith

I think he is referring to the vacuum 12 in-hg and not vacuum advance. Timing needs to be left alone as it should be fine. The roller cam in this motor is a strong/aggressive street cam which will produce a lower vacuum than an average street cam.

Astrodokk

Do the brakes work better now too? Just curious, because when you said it had low vacuum and you had to "stand" on the brakes, mine does the same thing and I've been told it could be rear rotor runout.
Also, Ken never wanted to race me in that car. Get it working so we can perhaps someday do that!

robert miller

I had the same problems but if the car has ever back fired you may have a bad power valve in it now that is putting gas into the intake also. Check this and get the new ones that will not blow out on you... Robert

64moneypitbutloveit

what oil pan were you running with the 383? Do you have PS? Everything clear ok without any modifications needed to steering?