Discussion in 'Small Block Tech' started by partsrparts, Nov 18, 2016.
Finally got to fire the engine and get the 30min cam break in done! sounded real sweet! 75psi oil pressure on start up, varied rpm from 1800-2500 for 30 min. oil pressure down to 65-70 at 2000 rpm after 30 min. 50psi at 1000 rpm. no thermostat and straight water for now, temp was about 185-190 after 30 min. run in garage with 2 window fans blowing through rad. have a very slight fuel line leak to fix, double check timing and adj. idle mixture, install front clip and off to her maiden voyage!
Ok, here's where it's at right now
oil pressure when up to temp, 75psi @ 2500rpm, 60psi @ 1000rpm
should i lower it?
Erratic vacuum, very rapid movement between 11-13 @ 1000rpm, goes up with rpm but keeps the rapid movement between 2 points
idles rough below 1000rpm( but sounds really mean!)
TA dual plane manifold, holley 750 DP, 4 corner idle, idle gets worse about 1/2-3/4 turns out, can't go in enough to see if it will smooth out.
checked manifold gaskets, carb and disconnected and pluged all vacuum fittings and found no leaks
engine has always had this erratic vacuum. when engine was rebuilt the 1st time with stock 4bl intake and Qjet, with DP manifold and Qjet, and with holley, and now with fresh motor, DP and holley.
the V6 even had erratic vacuum.
Yes i have tried 2 different vacuum gauges
What size oil are you running? Your oil choice may be to thick?
Adjusting the oil pressure will just lower or raise the max it will go to before the bypass will open. Using the thinnest oil you can, that will give you at least 15-30 PSI at hot idle will fix it.
The pressures you have would be fine IF it didn't create excessive stress on the front cam bearing that can eventually make it fail. Switch to thinner oil and you will be fine. I think they even make 0w-10 now so you may be able to use that weight if need be?
Another added bonus is that using thinner oil can help to unlock a few HP as well. GL
You also need to drive the car at highway speeds for 15 minutes or so to get the oil as hot as it can get. Just because the coolant is up to temperature does not mean the oil is.
still has the amsoil break in oil in it, engine builder said to run it for 500mi since it's actual break in oil, but i'm going to change it at 100mi. then i will be running the amsoil zinc (ZROD) oil.
ran it around yesterday between 55-65mph for a bit and pressure came down to 50psi. i will wait until i change the oil and put some highway miles on to see what my pressures are and then take it from there. i need to get my idle problem taken care of first
Hi guys, well I have 350mi. on this motor now and I'm trying to get it all dialed in.
1st issue is with the idle mixture, I am running a 750 holley DP with 4 corner idle. The smoothest idle I can get is with the RF,RR and LR at 1 turn out, the LF bottoms out before it reaches it's smoothest point, I run it at 1/4 turn out just so it isn't bottomed out. the transfer slot has the correct amount showing and I adjust the curb idle off the secondary throttle shaft. No matter what I try I can't get it any better.
I've had this issue with this carb even with the old motor. Bought new.
Jetting and such I believe is real close to where it needs to be.
2nd issue, timing mark bounces around, there is about 2 deg. of slack between crank and dist., power timed as per Larry's post last year and timing mark stayed steady, checked it just before I pulled the motor and it was bouncing around just like it does now making me believe it's in the dist. new engine, timing chain, gears, cam, ect.
With yellow springs in dist. initial timing bounces between 12-14, 32 total at 2100rpm
With 1 yellow and 1 silver initial bounces between 10-12, all in at 2600rpm
With both blue springs initial timing is a steady 7deg.
It seems to have a misfire, studder at idle, I've put the timing light on different plug wires and you can see it on all cyls.
HEI dist. from TA, New MSD cap, rotor, coil, plug wires and plugs gapped at .045 and also tried at .060, no change.
3rd issue cooling. I live in a high desert valley at 5800ft. elev. and when i leave the house it's up hill in all directions, on the flats around here and around town temp stays around 180, but pulling the hills at 2500-3000 rpm the temp goes up to 200-215 quickly, but when you flatten out or start down hill it cools off just as quickly, but temp keeps climbing if I'm cruising the mountain roads.
Installed 2yrs ago a new stock replacement radiator
Just installed a TA high flow water pump
TSP "special" 350 high stall converter with cooler mounted on front of rad.( cooling issues with old motor also).
The tune issues only seem to be at idle, off idle this thing flat SH*TS AN GITS!
You don't want any mechanical timing in at idle, so the yellow springs are too light. Use them to set your total timing, and then use stiffer springs so the mechanical timing begins off idle. The 2 blue are probably fine.
Sounds like the radiator just isn't adequate. You probably need a 4 core or 2 core aluminum radiator. Are you using vacuum advance? Your cruise timing should be around 40* including the vacuum advance. 7* idle timing is relatively retarded timing, that will heat the motor up if it is allowed to idle there.
Did you remove resistor wire so you have 12 volts supply to hei?
running the yellow/silver combo right now so initial is 10-12, 32 total at 2600rpm. If I use the blue springs I'm thinking the total will be all in way to high in the rpm's. Yes I'm running off ported vacuum, with the yellow/yellow combo or the yellow/blue combo manifold vac advances timing to much and makes it idle a little rougher. Vac advance is limited to 8deg.
Is there anyway to tighten up the dist.?
Which is better, 4 core or 2 core alum.? and what size tubes?
The car is a 76 Skylark that came with the V6 and HEI dist., I didn't think it had a resister wire, there's 12.3 volts going to the dist. with the key on and not running. I ran a jumper straight off the battery to the dist. and it made no difference.
Tighten the distributor?
NO MORE than 2 core, 1” tubes MINIMUM, 1 1/4” is better.
Put the stiffer springs in to check if the problem goes away .
There's not a tremendous difference that can't be adjusted out by going a few hundred rpm higher for max mechanical advance. It's not like you would have this long flat spot in the rpm range to get past that point.
I meant tighten up the advance weights a little without having to go with heavier springs
More is always better, whats a good brand and are they direct replacement?
Ok I will start changing springs around to get the lightest ones that won't give me advance at idle and see what the RPM's are at total mech. advance.
Yes, put stiffer springs in. Advance can be in by 3000 and you'll be fine. You can buy the Mr. Gasket kit, and mix and match the springs if you need to.
Turn idle mix screws all the way in then out 1/4 turn, back theidle speed all the way off then turn it back in 2.5 turns, pump and it should fire and have a high idle, if it doesn't add another half turn to the speed screw, then once it's up and going back the speed screw off as much as possible without it cutting off, then adjust all screws 1/8 of a turn at a time till the max vac reading is reached, then you will be able to back off the speed screw significantly or I have seen instances where you can back it all the way off
I meant to ask what is a good brand for the radiator and can they be gotten as direct bolt in?
I've tried every possible way to adjust the idle mixture and nothing I do has any effect, I'm almost to the point of drilling small holes in the butterflys to get more air in at an idle
Are your secondarys adjustable, if so crack them open just a little, no vac leaks anywhere correct?
My radiator is a Griffin. I bought it in May of 2000, and it still performs flawlessly. I hesitate to recommend them as I believe their quality has slipped. Be Cool makes a good radiator. I'm sure there are others. You do not have an A body car, so I am not sure what is available for the Skylark/Nova/Apollo type X body cars. You will have to research that. The important thing to remember is that you want NO MORE THAN 2 rows of tubes. Look for tube size of 1" MINIMUM. 1 1/4" is even better. If you see an aluminum radiator that has 3 or 4 rows, keep looking. You may need to have one built.
Not going to re-read the entire thread to catch some details...
Your timing might be jumping around from having too much throttle opening at idle, exposing the timed vacuum port.
You could be either caught up on the fast idle step or simply just need more initial timing.
Have you ran it with 4 more degrees of timing and backed down the idle speed screw?
If that's going on it would explain both jumpy timing and no mixture control.