Team Camaro Tech banner

1 - 14 of 14 Posts

·
Premium Member
Joined
·
522 Posts
Discussion Starter #1
Last fall I finally installed my new engine. It seems to like a lot of timing and idles in neutral at about 11-1200. Any lower and when I put her in gear it stalls. It runs great at anything over 12-1300 rpm. Throttle response is instant. I have the Edelbrock Performer rpm flat tappet hydraulic cam, 64cc heads, timing chain, air gap mainfold, fuel pump, summit 1.5 roller rockers, Holley 650 vaccum secondary carb with electric choke, special length pushrods as recommended by Edelbrock, 2400 stall converter, 200r4 trans, headers, hi perf cap, coil etc.
Compression is 9.75 to 1. The cam is listed at 1500-6500 so maybe I'll never get the lower idle without a manual trans. The throttle idle screw is almost all the way out. If I set it to 18 or so initial timing I can get it down to 8-900 at idle but it dies when I put it in gear. Up around 20-25 it idles at 11-1200 and 8-900 in gear but hits 40-45 at 3000 rpm which worries me. I looked for vaccum leaks and if I put my hands loosely over the carb she will stumble and die. I have a CD ignition that I have yet to install, but I like to make changes one at a time. I checked top dead center before the heads where installed with a dial indicator at zero when the pointer also read zero. Is the high idle what I have to deal with since I have an auto trans and this combo, is my convertor too tight, or do I have a carb issue I need to explore? This is my first performance engine build and any help is appreciated. Off idle on up it runs great, and I know a larger carb would help power, but I had the same idle issues with a 750 double pumper and the economy was in the toilet, although power was better. I mainly want to cruise with some fully throttle bumps here and there and maybe a pass or two at the strip in time. Plugs, wires are good, everything on the engine is new, no leaks, and she runs 170-180 water temp, 40-50 psi oil when driving and trans 180-200 when warmed up.
Thanks in advance guys, this site is well worth the $20 a year to be a member.
 

·
Registered
Joined
·
936 Posts
Sounds like a similar set up and problem I had. Here's what solved my problem...........

I sold everything and bought a Harley :D

Just kidding!

For me, the paper thin carb gaskets that sandwich the TV linkage adapter base plate between the intake and carb did not give a good seal so I replaced them with some slightly thicker ones and problems were solved. See this post. http://www.camaros.net/forums/showthread.php?t=139514
 

·
Registered
Joined
·
94 Posts
Assuming this is a small-block (judging by heads, carb, rockers), and without knowing cam spec's other than it pulls from 1500-6500, i'd say that something MIGHT be amiss. But not necessarily. Cam spec's are gonna be the key to determining if this is an abnormally high-idle. My lil 327 in my streetcar has to idle at 11-1200 to stay clear and at anything lower it will load-up and try to die (due to carb and cam combo). My race car idles at 1600 for the same reason.

If the cam is not radical and the carb is appropriate then 11-1200 is high in my opinion. Might be that the carb is letting it load up (run rich) at idle and not allowing you to obtain a friendly idle with your auto trans. Timing plays an equally important role in this as well, however, it sounds as though you are in the ballpark there.

Carb is where I'd start looking, but take my input for what it's worth.
 

·
Registered
Joined
·
8,303 Posts
How are you adjusting idle speed (you said anything lower than 1100 it stalls), and does the engine respond (speed up and slow down) when you are turning the idle mixture screws in and out? Did you check how much of the idle slots are exposed when the primary blades are "closed"?

Even though the cam is listed as making best power 1500-6500 RPM, I don't see anything in the cam specs to indicate that it would want to idle so high.

#7102

ENGINE: CHEVY 283-400 V8
RPM RANGE: 1500-6500

Duration at 0.006" Lift: Intake: 308° Exhaust: 318°
Duration at 0.050" Lift: Intake: 234° Exhaust: 244°
Lift at Cam: Intake: 0.325" Exhaust: 0.340"
Lift at Valve: Intake: 0.488" Exhaust: 0.510"
Timing at 0.050" lift: Open Close
Intake: 10° BTDC 44° ABDC
Exhaust: 59° BBDC 5° ATDC
Centerlines: Lobe Separation - 112° Intake Centerline - 107°



Have you checked your manifold vacuum at idle? Is it fairly steady or all over the place? When you say you have "looked" for vacuum leaks, have you tried doing tests other than visual?

What type of distributor are you running, and does it have vacuum advance? If it has vacuum advance, where do you have it connected (to a port seeing full manifold vacuum, or to a port on the carb with metered vacuum)??

How is it running generally? Does it smell rich at idle? How do the plugs look after it has idled a while?

When it idles at 1100 unloaded, what does it drop to when you pull it into gear?

There are a lot of little things to check, because there are a few things that could be going on to make it need more revs to idle.
 

·
Premium Member
Joined
·
522 Posts
Discussion Starter #5
Thanks guys, here's the answers to your questions.
It does have a thin gasket, I'll try that. It's a .040 350 all machine work fresh and done by a pro. I first adjusted the mixture screws for best idle and vaccum, that was last year & I want to say 12" and steady but I will re-check. I have not checked the idle slots as this carb idled fine on the old motor (milder cam, 882 heads, performer manifold) But I will check. HEI distributor from White Performance with vaccum advance to full vaccum port. Adds about 15 deg. when connected. (is that too much?) Except for idle she runs great at about 900 in gear. I will also pull the plugs and look but she doesn't smell rich.
Thanks again I have some work to do & I've made notes So I'll report back.:thumbsup:
 

·
Retired
Joined
·
26,617 Posts
Sounds like your idle mixture screws are too far in and your idle screw has the throttle too far open. Warm the engine up then shut it off and close the idle mixture screws just till they seat (don't try to tighten them) then open each 1.5 turns and fire the engine back up and use the idle screw to bring the idle back down to 800 rpm. Now see if you can drop it in gear... Make sure the choke is open and that you're off the fast idle.
 

·
Registered
Joined
·
2,292 Posts
Ignition timing first before you move to the carb.
Your 18* initial is fine if the advance weights are at rest.If the advance springs are light enough..you may be setting initial with some mechanical advance.
For testing and initial timing..use heavy advance springs to ensure the weights are not moving outward and set initial at the lowest rpm you can maintain.
Move to the carb next..get comfortable there..then back to the dizzy for more tweaking and then back to the carb.
 

·
Moderator
Joined
·
19,801 Posts
So... it will idle lower but stalls when put into gear, correct ?

I think Dennis is onto it. :yes:
 

·
Premium Member
Joined
·
522 Posts
Discussion Starter #9
Big thumbs up to camsdad aka kurt, put a new thicker gasket on and she idles at 900 and 800 in gear. Sounds like a muscle car should at idle:thumbsup: THANKS GUYS. IF YOUR NOT A MEMBER PAY THE $20 AND SIGN UP:beers:
 

·
Premium Member
Joined
·
522 Posts
Discussion Starter #11
I'll try that after work. I checked out your link. Nice blaster, for that matter nice everything. You obviously have some skills! :thumbsup: I used the POR15 engine paint. Marine clean, metal etch, POR 15 and then their Chevy orange. They say it will last forever. DSCF1882.jpg
 

·
Registered
Joined
·
936 Posts
LOL!
Naah...
I'm a bit anal, and somewhat a perfectionist. I have learned alot from our brothers and sisters here.
Team Camaro is a fantastic site for us 1st Gen Camaro enthusiasts.

Like so many others here I want to do the best I possibly can. Money is somewhat tight so rather than contracting the restoration out to someone, I have bought many tools and equipment pieces for my project and tool chest Argh, Argh, Arhh.
Only real problem I have is finding time to work on my ride.
Currently i am at 6.9 years into the project.:(
 

·
Registered
Joined
·
5,277 Posts
My Holley 650 and Edelbrock RPM Performer intake didn't play well together. With a thin gasket the accellerator pump lever was hitting the #1 runner and creating a vacuum leak along the front of the carb. I installed a thicker gasket and no more interferance, plus a lot of driveability problems went away.
 
1 - 14 of 14 Posts
Top