Hot Rod Forum : Hotrodders Bulletin Board - Reply to Topic -- Hot Rod Forum

Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Electrical> Rebuilding found 68' GTO Timing Problems
User Name
lost password?   |   register now

Thread: Rebuilding found 68' GTO Timing Problems Reply to Thread
Send Trackbacks to (Separate multiple URLs with spaces) :

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Please select your insurance company (Optional)


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Additional Options
Miscellaneous Options

Topic Review (Newest First)
09-19-2013 03:31 PM
GMCTRUCKS I don't remember if my 70 GTO had a soliniod metal cover on it to keep the heat off it but if you removed it put it back on or get one for it.

Whats the word on the car??
08-20-2012 11:24 AM
Pontiac timing

With the cap off, try turning the rotor in a counter clockwise direction. Assuming it turns, when you release it it should snap back, indicating that the advance is not locked or frozen it is not. If it has very low resistance, someone may have put very light springs in the advance. This would cause it to have full advance at idle. Without having the vacuum advance connected, advance the timing to 30 degrees. If this solves the problem, the distributor needs to be serviced. This is the same advice that Mr. Wizard gave me
08-17-2012 10:55 PM
Originally Posted by BRNFND GTO View Post
... After it is running for a 10-20 mins and we shut it off. we sometimes lose the starter, like no power to the starter what so ever...
Originally Posted by EOD Guy View Post
My guess is starter soak, very common on GM starters, but before I went got a new starter, I'd make sure all my cable connections were clean and tight, if that doesn't fix it ...... probably a new starter is in order....... could be the solenoid or the bendix, but nowdays it's easier just to buy the whole thing with a life-time warrenty.
In addition to EOD Guy's suggestions:

I can't see from the photos -- does it have headers, or OEM cast-iron exhaust manifolds? Headers are notorious for exacerbating the heat-soak problem. Some kind of heat shield between the exhaust and the starter can be helpful. I also used extra large battery cables that I made from 1-gauge welding cable.

The negative terminal should be wired directly to the engine (there should be a stud on the cylinder head for it.) A separate ground strap connects the engine to the body sheet-metal.
08-16-2012 08:48 PM
tuske427 Beautiful car! It's my favorite year GTO. I'm pretty confident that once you get past these issues you're facing and get it running right you won't look back at Chevy. You'll be quite happy with the torque from that 400.
08-16-2012 04:17 AM
EOD Guy Dude, before you go rebuilding the entire engine..... do a compression test, and check the starter!
08-15-2012 01:28 PM
freecontact The best way is to strip the motor and do the rings and bearings with a piston clean.Then do the valve grind on the heads and replace all gaskets.Looks like you may have had a few over-heating problems.A compression test is used to find a blown head gasket or valve leaks.And replace all the frost plugs.A cam grind or replacement while its apart is good,as well as new lifters.You don't need the hi-perf stuff for that size motor...just a quick little clean-up build with cheap standard replacements should do....and just look after the daily runner until you can big spend on the blown jet engine .
08-15-2012 06:50 AM
re: starter

I have found that sometimes there is oil between the starter housing and the block (thus, no ground). To be sure, drop the starter enough to wipe those surfaces till they are clean. Brake cleaner or carb cleaner. I go the extra step and take the bolts out (1 at a time so you don't have to drop the starter) and clean the threads on the bolt and in the bolt holes. It's sounds elementary, but it's happened to me on more than one occasion. To me, that's reason enough to give it a try. If it doesn't change or fix the problem, then you've eliminated one more possibility.
08-15-2012 06:21 AM

that car is a gem. the hidden headlights make it look really nice and increase the value greatly. HANG ON TO IT!

forgive me if i'm covering old ground. no time to read the entire post... make sure that coil is good. my lawn tractor began backfiring and i replaced the coil which stopped the problem. make sure the distributer cap is not cracked. do a compression test.
08-15-2012 05:34 AM

I played with alot of 389 and 400 Pontiacs in my earlier years. The problems you are describing usually showed up just before the timing chain slipped on the cam gear and it would not run at all. Pontiac liked to put a nylon coated cam gear in these engines to reduce noise. By coated I mean the teeth were mostly nylon. Or plastic, whatever you want to call it. When they got some age or wear on them the nylon started to break off in chunks. Resulting in timing issues. No power. Running on after the key was shut off. Running hot. Unable to keep it in time. If this turns out to be your problem I suggest a full metal gear set and the issue will never come up again.
08-07-2012 04:05 AM
EOD Guy My guess is starter soak, very common on GM starters, but before I went got a new starter, I'd make sure all my cable connections were clean and tight, if that doesn't fix it ...... probably a new starter is in order....... could be the solenoid or the bendix, but nowdays it's easier just to buy the whole thing with a life-time warrenty.
08-06-2012 08:57 PM
BRNFND GTO we did alot of work today. We cleaned all of the spark plugs and re gapped them. we adjusted the idle down so we could time it at a lower idle. we timed the motor to 12 and it is running pretty good. It is no longer backfiring and we leaned out the carb so it wont run so rich. We have one major problem now. After it is running for a 10-20 mins and we shut it off. we sometimes lose the starter, like no power to the starter what so ever. Does anyone know what this could be?

thanks for all your guys help!!!
08-06-2012 07:08 PM
EOD Guy You can rotate the oil pump shaft with a screw driver, but to be honest, I've never had to....... a simple lift, twist, drop of the dizzy body, then jiggle the rotor....kinda all at the same time...... don't know why..... it works for me every time....... but if you can't get the feel of it, the pump shaft rotates very easy with a screwdriver. When I rebuild an engine I always prime the oil galleys by using a cut off screwdriver and a drill, before I drop in the dizzy.
08-06-2012 04:36 PM
BRNFND GTO how would i go about aligning the distributor if it only drops in in 2 spots in the oil pump shaft. Meaning the flathead screw like rod that fits in the notch in the bottom of the distributor only drops the distributor in in 2 positions. How do i rotate the distributor gear until it is perfectly alligned ie one tooth at a time, if the dizzy will only drop in those two spots. Our problems seems to be that the oil pump shaft wont allow us to drop the dizzy pointing towards the #1 plug.
08-06-2012 03:38 PM
EOD Guy I wouldn't recommend advancing the spark plugs by one....... at TDC the rotor is in the right spot or it's not..... if it's not, re-index the dizzy until it's in the correct spot. If it runs smooth with the advanced timing etc..... doubt it's a flat camshaft.

You need to verify the rotor is at the number one position at TDC on the compression stroke. (see the diagram above) if it's not pull the dizzy out far enough to advane the gear one tooth at a time , drop back in, recheck rotor position, untill it's in the right position.

Verify you have the correct firing order.....18436572 counterclockwise.... looking from the front bumper at the dizzy (unless a 307 which is clockwise)

Verify you have 12v at the coil (dizzy if HEI) while cranking...."I" terminal from starter is the eaisest way to acomplish this
08-06-2012 03:21 PM
Mr. T pay attention to what EOD Guy told you and give us compression reading first.
This thread has more than 15 replies. Click here to review the whole thread.

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

All times are GMT -6. The time now is 02:13 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.