Need help working out bugs before I decide to rebuild (?)

Well, without full info, here gos.

Assuming your engine is all original with those heads and 4v intake...

Its a '68-'69 with a factory rating of 10.25 compression ratio.

So if your running 87 octane with that timing youll detonate that engine to death.

Even hi-test is pushing it with that much advance at 1900.

Try going to 6deg initial and see if it quiets down any.

And you souldnt be all in till around 2500/2800 at the earliest.

I would go with an HEI if for no other reason than parts avalibility.

Most part-store helpers have never even seen a points dist.

 

The head numbers are right on the top of the head and should be easy to see. there Should be a 3-4 digit date code on the left end (when facing the exhaust side) and a 7-8 digit casting number on the opposite end. if the motor is sludged its probably hidden by the sludge.
:TU:


As far as the ignition, HEI is the only way to go. It will definately increase the engine's HP, and dont forget to get hei plugs and gap for hei (about 60 thousands) DO NOT use the stock coil wire on an hei , its a resistance wire suppling only 5-6 volts, which will negate any hei power gain, so run a new wire to the hei. You will not be sorry with an HEI , its worth every penny.
:Smarty:

As far as carbs go, I probably am in the minority, but for what its worth, I use a edlebrock thunder series- Its an awesome carb, my GS 455 really gets it all to the wheels with this carb and its inexpensive and easy to set/maintain, but you will need an adapter plate for it. I tried using the rochesters for years and they work great when they work, but they are prone to a lot of age related problems. After spending $$$ on a prof rebuild on a rocky and it still idled terrible and still had had choke and secondary problems, I gave up on them and now use an Edlebrock and I have never looked back. The Edlebrock Thunder series 800CFM unit I use now is almost 10 years old now and has never needed ANYTHING. It just contines to work without any headaches. It Starts up fast and the choke works perfect and it never bogs or stumbles, so Im a believer. After years of rochester problems I surrendered to Edlebrock. they are truely the best for the $.:3gears:

 

I found the head casting #'s a few days ago. Numbers are in an earlier post.

When I have some daylight I'm going to make some changes and take notes after test driving. I have new advance weights and springs on the way. Hopefully that will slow the advance down. I'm also going to run it without the vacuum advance connected and see how it does.

Definitely seems like the carb is a matter of opinion and your opinions are welcomed. I'm still on the fence. I need to see if the shop found me a rear float bowl for the holley and then I'll need to go through it again since I know it wasn't right before. The edelbrock I have on the shelf is a 1406 electric choke which I may try but it's missing several small parts.

Anyone ran one of the summit racing $200 carbs?

I've always ran the HEI dizzy's on my chevy's but really want to give this one a chance before I give up on it. I'll try to find the dizzy #.

Also, I know the wiring harness is in poor shape. I haven't really had the car long enough to know if it's charging properly, but I did have to charge yesterday. And I haven't done any troubleshooting there since I'm trying to focus elsewhere. If the alternator is not charging properly can it affect the operation of the coil/distributor? I'm sure the battery was charged during my last test drive when I had all the pinging, but thought I'd ask.

---------- Post added at 06:50 PM ---------- Previous post was at 06:47 PM ----------

Still on the fence with the electronic dizzy conversion, I'm sure it will make maintenance easier but again I'm trying to make my current set up work if possible.

 

Good read. I went to test the coil but my multimeter is shot. Distributor # is 1111334.

---------- Post added at 08:11 PM ---------- Previous post was at 08:08 PM ----------

It's looking like this motor may be from a 69 GS.

 

http://www.summitracing.com/parts/sum-m08600vs/overview/

http://www.summitracing.com/parts/sum-m08750vs/overview/

Are you talking about these?

If so, I sorta have experience with them...

Ive had the older Holley version and if I had to pick a favorite carb, that would be it.

The carb was developed by Holley to fix the old Holley problems.

They took all the traditional Holley tuning parts but didnt have the fuel-leaks/dry-seals troubles.

But they just didnt sell.

People still wanted the old 4150/4160 carbs.

So Holley sold the design to Summit.

I cant speak for the Summit version other than its supposed to be a direct copy.

I wont guarantee any carb will solve all your problems, that would be silly at best and reckless at worst.

But I will say that if the Summit carbs are still as good as the Holleys, they are fantastic:Brow:


The last one I ran was on my '69 Olds 98 with a 455.
On a 4700lb car I had it tuned so well I was getting 22-25mpg and I beat on it:3gears:
A friend bought it and gave me the carb back and put a part-store Q-jet on it ''so it would be right'', it dropped the mpg to 12-15:laugh:

 

Yeah, thats the one. If I cant get my holley sorted out I may go this route. Only bad thing ive read is casting flash inside.

 

I havent had one of of the Summit carbs apart yet so I dont know.

Its a real shame Holley stopped making them.

 

Ill do some but dyno testing soon. I think ill start by adjusting the timing with the stock springs and weights and driving it. If I don't make any progress ill swap the new weights and springs and see what happens. Ive read the timing thread several times and it sinks in a little more each read. I do get it though.

 

I would only add that you need to remember, if your engine is what the evidence looks like, a '69 GS 350 (RP code BTW)...

With Larrys excellent timing advice, your going to have to run high-octane fuel.

It is factory rated at 10.25-1 comp. and that will detonate like crazy unless you retard the timing quite a bit.

I dont advise that mind you, just something you need to keep in mind.

I say time it like Larry says and run premium:3gears:

 

Great advice. My springs and weights came in today. I probably won't get around to it until tomorrow evening or friday. Thanks for all the help and I'll post results.

 

Before I get to turning wrenches tomorrow I was thinking............

My plugs are gapped at .040. Should I put them at .030 as per the manual (if I remember correctly)?

Should I run premium fuel to eliminate pinging from fuel (previous owners fuel is still in it) before I dig in to the timing and carb?

I just don't want to be chasing my tail. :laugh:

 

If you stick with points go 30-35, if you switch to HEI go to 40-45.

Youll have to run premium if that engine is a Hi-Comp engine.

If you try and run low grade fuel it dosnt matter what you do to the carb, youll have pinging.

To much pinging and youll kill the engine.

So yes, run premium.

 

If the fuel is more than a couple of monthes old it will be stale and could be contributing to your problem.

 

I got my Holley back yesterday and still had an issue. So I put an Edelbrock 1406 on there and it seemed ok last night, just at idle, no driving.

Today I checked the dwell and points and they were spot on.

I regapped my plugs to .030 as per the manual

Started checking timing again and things started going south. I'm going to go back and read the timing thread again! :af: I now have very bad "dieseling" after shut down, which it's never done til today.

What do ya think?

I still have plans to put super unleaded, 93, in it later today.

 

Also make sure you run cold heat-range plugs.

Hot plugs+cheep/old gas+hi-compression=dieselingou:

Retard the timing first thing.

Start retarded and work your way advanced.






And not that kind of retard:bla:

 

I'm running Autolite 26, the equivalent of a A/C Delco R45TS.

Since this may be a high comp motor, the initial according to the chassis manual is tdc. So I installed the lightest springs in my kit, set the timing at tdc-0- and was trying to see the advance. Seemed to be advancing way too much with the lightest springs.

---------- Post added at 03:11 PM ---------- Previous post was at 02:56 PM ----------

Got the dieseling taken care of. Carb related. Now back to the timing and a test drive, hopefully.