# Tuning question 1965 389



## topfuel67 (Dec 23, 2008)

I have a 65 Tempest with a 389 from a 1965 Catalina. I bought a beat up 4 door that was rusted, that a guy spent $4k rebuilding the 389 to factory specs (even the 2bl carb). It was the smoothest running 389 I have ever seen. All 8 cyl. were at 190 psi. I pulled the motor and droped it in with a NEW Edelbrock RPM cam (.420/.444 lift), RPM manifold, holley 4 bbl and it has the stock distributor with the mallory no points conversion. I've rebuilt the carb and set the floats, and fuel mix the best I could considering where I'm at.

Its still not running good. I have checked my cam position and it is not advanced or retarded. I have the initial timing at about 15-18 degrees. It pings bad. I retard the timing, it won't start. Just to where it will start, it pings. If I advance it further it pings harder and runs rougher.

Any ideas?


----------



## Rukee (Feb 8, 2007)

I`d say check with this thread first and if you have any further questions go ahead and ask.
http://www.gtoforum.com/f50/gto-tuning-setup-tips-13052/
The first thing that comes to mind is the vacuum advanced connected to ported vacuum instead of manifold vacuum.


----------



## jetstang (Nov 5, 2008)

Sounds like the cam was installed incorrectly to me. Check for vac leaks and vac lines left off, PCV and brakes. Pinging is ignition timing. Running crappy, lean or dumping gas is carb and vacuum. Recheck everything you have done. Recheck your firing order and make sure you are timing it on 1 with the vacuum advance disconnected.


----------



## topfuel67 (Dec 23, 2008)

Thanks for the replies. I did pull the front end of the motor off to recheck the cam, its dead on. I have rechecked all hoses and connections. New pcv, no power brakes, new vaccuum advance, all new lines and hoses, new msd coil and so on. 

I read that article. I will try setting up the dist. with those springs. Time to pull the distrubutor apart now. I have no idea how to check that play, hopefully its in the trusty old 65 Pontiac Tempest shop manual.


----------



## jetstang (Nov 5, 2008)

I would replace the dist with a new HEI unit. I have bought 2 new HEI distributors off ebay within the last year for $60 shipped and haven't had a problem in my Lemans and 90 454 SS. Brand new Billet HEI, new coil, cap, ignition module, everything. Cheap bang for the buck replacement for an unknown/troublesome distributor. If I need another distributor again, I will get another one. Easy 1 wire hookup. Also, if you know anyone with a diff carb, try it. New Holleys are great, rebuilt Holleys can be real headaches.


----------



## geeteeohguy (Feb 2, 2008)

I would have changed to a 4bbl intake and left it alone. Basically stock, well assembled Poncho motors with stock intakes, cams, and distributors seem to run better, smoother, and more reliably than "upgraded" ones do. That said, you need to check everything you DID do. To me, it sounds like the distributor is in wrong (off a tooth). How is the firing order? The cam, though verified installed correctly, may be defective. Rare, but it's happened to me. Keyway was mis-cut. Mine ran way retarded, though. You want to run a stock compression 389 with about 4 to 6 degrees base timing (vacuum advance disconnected while checking) and you want to run a good premium fuel, probably with octane boost. Even if it has the 2bbl. heads, your cranking compression indicates that you're running at least 10:1 compression. Make sure you don't have any intake leaks at the manifold runners. Good luck, and keep us posted!
jeff


----------



## topfuel67 (Dec 23, 2008)

I was thinking about one of those hei distributors on ebay. They say for 67 and up motors, but I assume those work on the 65 389s too. 

I've heard of cams being ground bad or even different makes with the same specs not being as powerful. I did get a new Edelbrock cam. I did some research on this a while back and one of the Pontiac magazines did an article on this cam. It got better mpg than stock and made more power. The rpm cam is only has a little more intake lift than the stock cam, but a lot more exhaust lift. The duration is tuned better to these motors and its not lopey at all.

The factory specs on this motor is 10.5:1, figuring the heads were probably milled and the block decked I would bet its at about 10.75-11 (and it has a slightly larger exhaust valve than the gto 389). I am running premium, but no boost. I had a real 65 GTO back in the mid 90s and it ran ok on premium with no boost, but when I got it dyno tuned the guy set it up for higher octane. It still ran better with no octane boost than this motor with no boost.


----------



## geeteeohguy (Feb 2, 2008)

My '65 with 10.75 ran ok on 94 leaded in the '80's and early '90's too. Around here, only 91 unleaded is available: Ping City. I run a booster. If I ever go thru the motor again, I'll install dished pistons. Good luck with it!


----------



## topfuel67 (Dec 23, 2008)

Yep, boost is defitely needed in these motors, but I'm not near running that good. I'm in the L.A. area of So. Ca. I'm pinging hard at low accelaration. I'm leaning towards this distributor not being set up right. The 326 that was in the car that I used the distributor from had a lopey cam. I didn't use the stock distributor because the 326 one had the mallory no points conversion. Unfortunately, I sold that original distributor on ebay (same codes as a gto dist.).


----------



## jetstang (Nov 5, 2008)

Put some 104 race gas in it and see if it runs correctly. You have a bunch of compression, but that doesn't expain it only running in limited timing ranges. You should be able to retard the timing and keep it running without pinging.
New cams have improved efficiency due to engineering, years of research and technology, vastly improving cam technology. New cam designs are better. Voodoo cams are the benchmark for cams, split lift fixes design flaws in the heads.


----------



## topfuel67 (Dec 23, 2008)

I bought a new HEI distributor off ebay. It looks great and it fit perfectly. In reading the set up instructions it explains how to set up the timing curves centrifigual and then with vaccuum. It says to insert a 3/32 allen key into the vaccuum canister and turn it all the way clockwise and then to set the centr. timing and adjust it to where the car doesn't ping with the vaccuum line plugged. Then hook up the vaccuum line and adjust the allen key two turns if it pings and repeat until it stops pinging. 

This could have been the adjustment I needed in the first place since I had replaced the vaccuum canister on my original distributor. I'll try to take it for a test drive tomorrow. I need to trim the new set of spark plug wires to fit the larger cap with different plug fittings first.


----------



## Rukee (Feb 8, 2007)

The adjustable vaccuum module is an aftermarket unit, the original ones did not adjust like that. But it's a nice feature. If it were mine I'd add an MSD unit to the mix as well, that'll wake it right up. :cheers


----------



## topfuel67 (Dec 23, 2008)

Rukee said:


> The adjustable vaccuum module is an aftermarket unit, the original ones did not adjust like that. But it's a nice feature. If it were mine I'd add an MSD unit to the mix as well, that'll wake it right up. :cheers


I was hoping there wouldn't be a stock adjustment that easy that I missed! I've restored and rebuilt enough of these cars to know better.

Anyways, that new HEI unit did the trick. The car idles smooth and has tons of power and the cam isn't near broken in. Just testing it out it ripped the tire with just the lightest throttle. It starts with the slightest turn of the key.


----------



## Rukee (Feb 8, 2007)

:cheers


----------

