[The Humbler]

Ok, here are my dilemmas,

70 GTO, 400 engine #13 heads Ra 3 exhaust manifolds mild cam Idk what, 16''- 17 vac at manifold 800 rpm, Hei ignition. Engine & trans have less than 2k miles since rebuild 10 yrs ago.

So I am going through the bugs my brother left in the car for years,

I got the car from my him after sitting 10ish years

I rebuilt the 600 holley (which is gone now) had it running pretty good but had alot of pinging, I tried to time it out with no avail & still keep it running well.

I rebuilt a Quadrajet # 17056274 800 cfm, with Cliffs book, Parts & help, installed it on the performer intake ( gone now also) just to see how different it would run, ran awesome but still got pinging, played with he timing no change, also new wires & plugs

Fast foreward...

I ripped the pos holley off threw it across the garage, ripped the performer off, threw it not as far )

Installed a stock 068 manifold with exhaust crossovers blocked.

I pulled the distributor out for inspection during this process & I was not happy with the condition of the unit overall, with the theory that 99% of carb issues is timing, Not knowing the age ( was not new) I replaced it with a NEW standard unit from my local reputable parts shop I have been using for 30 yrs. no spring or weight changes, I just wanted to get a baseline setting before I dealt with that. I cannot drive the car as I am waiting for linkages although I probably would not get very far anyway.

The main issues I am having before the swaps & now are when I try to set initial timing at idle the best idle I can get is 20 advanced, dialed back with a digital light, I can not even get it close to 12 let alone 10( only with vac line plugged) when I re connect it drops back to 20 & idling like sheet, Same with both distributors, although the timing mark on the new unit is steady as a rock the old unit was jumping all over the place.I put the unit in exactly where the old one was at first, same sheet, so i figured it might have been off a tooth.. went a tooth either way wouldn't start. I have confirmed the harmonic balancer mark is accurate by putting the #1 piston at tdc than I aligned the rotor AGAIN.

After screwin with the distributor I can get it to idle still at 20 and stinky stinky exhaust.
if I shut the motor off I can't get it to restart, it will sneeze up through the carb & unless I re adjust the dist and start all over it will not start.
I went through the carb again all looks good there
I can not find any vacuum leaks or any obvious issues, I have been out of the scene for 20+ years but I do have good mechanical abilities, I JUST CANT GET IT!!

Any insight or advise is greatly appreciated.

Thank You

[Sun Tuned]

Now that some things have been changed any distributor you install, and especially any that are remanned from a parts house will likely need to be recurved or recalibrated to your combo.

That and proper installation are tantamount to a good end result.

20 degrees initial is too much, and surely the reason for the high hydrocarbons ( stinging watery eyes).

[Half-Inch Stud]

Rotor-cap phasing has been my peeve. so you may want to cut a window in a spare cap at CYL 6, pop it on and point the timing light on it to see how well the rotor tags the CYL 6 post at idle thru 3600 rpm.

then you will know how well (and where) the spark is helping or hurting.

Time for 34 deg full ADV at 3200 RPM ( no vacuum). Typically need firm springs in the HEI to achieve a ping-free off -idle throttle response.

[dmac]

Set the timing first and then adjust for the best idle you can get at the timing you need- maybe anywhere from 9-15*. Use your vacuum gauge, going back and forth between idle mixture and throttle adj to get best vacuum at idle RPM in drive with brake on. Then, to avoid a lean condition, turn both idle screws back out 1/8 to 1/4 turn. Then check timing at higher RPM to verify mechanical advance is working right.
You may have to compromise both idle timing and mechanical advance until you can reset the curve in the distributor. After reconnecting vacuum advance, reset the idle RPM if necessary..


Also, in 1970, premium gas was 104 octane. If you are still at original compression, and your heads haven't been milled, 93 octane is cutting it close, worse if the heads were ever milled.

[The Humbler]

Sun Tuned..
Distributor was a new unit I understand the curve will need to be re calibrated for my engine application & I have RE checked the install way too many times and I am sure it is installed correctly.

The old dist springs were so loose the weights would move just spinning the shaft by hand.

dmac..
Heads were not milled as far as I know. I can not get timing even close to 9-15, without it running like crap

[steve25]

What is the cranking compression on this motor when checked hot!

[The Humbler]

Steve, I will check that today. I am going back to go fight the issue again in a bit.

[Gary H]

Sounds to me like you've got issues with the new carb. Have you looked at the spark plugs? I would bet that they are black from too much gas. Check the plugs, if they're too dark, replace. Get it cranked again and look for gas dripping down the carb bores. That's a pretty mild cam. You shouldn't have to have a lot of timing in it for it to idle fine. I would say 12-14 would work. What kind of vacuum are you getting now at idle? Keep us informed on what you find.

[The Humbler]

no dripping from nozzles
plugs look good but have been wet from gas from over cranking i would guess
15-17 in at idle 800 rpm

going to throw the Holley back on & see what happens

[geeteeohguy]

My opinion is that the main issue is too much compression. I haven't been able to run 72cc iron heads on a 400 in 30 years out here in CA on 91-92 octane. 72cc heads need 100+ octane, or you will ping. Put some race gas in it and I'll bet it'll run much better. That, and like the gentlemen said, you want less initial (spec. is 6--9 degrees) and about 35-38 total timing.

[Gary H]

Long shot but, does the timing chain have multible keyways so you can advance or retard the camshaft? I've had 2 or 3 cars in my shop over the years that had the timing chain installed wrong because of a mix-up on which timing marks to line up. It caused the camshaft to be retarded and caused poor idle and power.

[Blued and Painted]

Has the balancer slipped. Pull plug 1 or 6. By hand, bring the piston all the way up to TDC checked with some kind of probe. Then look at the balancer mark and timing cover. Should be less than 2 degrees off the pointer.

[mchell]

Are you saying that you can't adjust the timing to what you want? ...or is your problem that it won't idle with anything less than 20 initial?

[Pontirag]

what was wrong witht the holley?

what to get rid of it? pm me

[The Humbler]

Well I didn't get too far yesterday, as you all probably know the Holley will not fit the factory manifold with out an adapter.

I tried to fire it up again first thing with out changing anything.... NG (

I pulled the quadrajet off & the intake was very wet with fuel, I took it apart again to check it out. Everything looked good inside but the gaskets were soaked with fuel. Cliff repaired the well plugs on the carb, they are probably fine but I will check them this morning w some soap & water.

I will respond to posts individually to keep it easy to follow.

[The Humbler]

Originally Posted by steve25

What is the cranking compression on this motor when checked hot!

I did not get there yet, forgot my gauge home, I will post results when I get it back together .

[The Humbler]

Gary,
From the pictures I have when I changed the timing cover it looks like there are at least 2 keyways on the crank, probably 3 here is a pic,


I would think that if there are 3 keyways it would be in 120* increments.
I asked my brother if the cam was advanced when assembled & he does not believe so. ( & I don't remember either, )But his memory on what was done to it has not been the best
maybe the pic will help. The cam timing mark is visible but the crank mark is not. I did not bring the piston up before I tore it apart & this is the best pic I have of it

[The Humbler]

Blued

I checked the balancer earlier in the week all checks out fine there

[shaker455]

Lets see a pic of this dist you bought with the cap & rotor off.

Are you in NY?

How did you wire the HEI?

I see you had issues in another of your post.

[The Humbler]

GTOGUY

So whats a guy to do with the 72cc heads??
I can't run race fuel all the time, I did run super in it with some octane booster in it but I can't say for sure it helped immensely I had my daughter in the car so i couldn't beat on it too much,

This would be a problem to address after I get it running & recurved I guess

My other brother has a '67 w 670 heads on his engine, I don't know if he is doing anything special (we don't talk much) I guess I will have to call him for easter...