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'69 350 with 670 heads

  
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'69 350 with 670 heads

 
iflytoohigh1 iflytoohigh1
New User | Posts: 5 | Joined: 04/11
Posted: 03/05/12
10:00 PM

Hey all,

I'm looking for some feedback or suggestions.

I have a '69 Custom S with a 350 XS motor.  I put a set of '67 670 heads on it.  I hear a slight ticking when it is idling.

Someone told me this, but I don't know if it is correct or not and looking to get more advice on the situation:
the 670 heads went on a 400 or 428 block with a 4.12" bore.  my 350 block is 3.890".  therefore the valves might hit the cylinders.

Is this correct?  what suggestions?  I'd really like to run the 670 heads but I don't want to bend a push rod or mess up the valves.  

mb68bird mb68bird
Enthusiast | Posts: 468 | Joined: 06/10
Posted: 03/06/12
12:34 PM

Doubt the valves are hitting, you have to have to be lifting the valve 1/2" or more for that to happen. What cam is in there?  

iflytoohigh1 iflytoohigh1
New User | Posts: 5 | Joined: 04/11
Posted: 03/06/12
01:31 PM

it's the stock cam.  

I'm really a noob when it comes to engine building.  I bought the car a few years ago so I could learn more about working on cars.  

So far I have run new brake lines, replaced all the drums and brake hardware, replaced the radiator, refurbished some rally II rims, shocks, all new front suspension, exhaust manifolds & exhaust,  and most recently swapped out the heads/intake/carb.

I have come a long way in what I know about cars, but I still have a lot to learn.

I would think that if the valves were hitting it would be pretty noisy.  the ticking i hear is not that loud. it's about as loud as an ignition coil sparking to the distributor cap or a plug wire.  In fact, i might check that.  maybe that is the ticking?  

idrivejunk idrivejunk
Addict | Posts: 5151 | Joined: 12/09
Posted: 03/06/12
06:36 PM

Run it in total darkness and look for an arc somewhere?

Could be an exhaust manifold leaking, they can make a ticking sound. Look for a black spot at the gaskets somewhere. You can always isolate the noise carefully using a stethoscope or a stick. Like put it on the valve cover and see if the noise is in there. Pontiacs with stock valvetrains have a few things that can get loose under there and tick. Maybe a loose rocker arm nut or a worn part or a rocker stud backing out, all of which would just make the old loose pushrod sound, especially at idle when oil pressure is low. Its not a bad idea to put locking, set-screw type rocker nuts on an old stocker like that, clearances change a lot over the years and with rebuilds.  
idrivejunk

Pontiacman8 Pontiacman8
Moderator | Posts: 5777 | Joined: 02/08
Posted: 03/06/12
06:49 PM

I very much doubt the valves are hitting the cylinder, I have #13 heads with 2.11/1.77 valves and .504 lift and have no clearance issues of such.  
Engine builder,self taught auto body guy.
Horsepower sells engines and torque wins races

Pontiacman8
Pontiacman8
Pontiacman8

iflytoohigh1 iflytoohigh1
New User | Posts: 5 | Joined: 04/11
Posted: 03/06/12
07:54 PM

That's great news to hear guys.  I went out and bought a stethoscope. (always wanted an excuse to get one)  I'll check around to see where that ticking is coming from.  I should also invest in some locker nuts for the rocker arms.  i ended up reusing the old ones and they went on pretty easy, so maybe a rocker arm is loose.  

i'll also check around the exhaust manifolds to see if there is a leak.  thanks for all the great suggestions.  

I'll keep you guys updated on what I find.  

iflytoohigh1 iflytoohigh1
New User | Posts: 5 | Joined: 04/11
Posted: 03/06/12
09:51 PM

so, i was so excited to use my new stethoscope.  before i started her up i moved a couple plug wires away from the ignition coil.  got her started.  i don't hear the ticking.  i put the stethoscope on the valve cover in a few spots but didn't hear anything out of the ordinary.  

maybe it was just sparking?  i'll try again more this weekend.  my wife made me stop because i was gonna wake up the babies.  

Daniel Austin Daniel Austin
New User | Posts: 3 | Joined: 02/14
Posted: 03/16/14
08:12 PM

Icon QuotePontiacman8:
I very much doubt the valves are hitting the cylinder, I have #13 heads with 2.11/1.77 valves and .504 lift and have no clearance issues of such.

I just bought some #62 heads (ported polished, seats, 3 angle, roller rockers) for my 1970 Pontiac 350 and was concerned about valve clearance issues.  Stock bore being 3.875 and #62 valves measuring 3.875 across.  Will they scrape the cylinder walls, do I need to chamfer the tops of my cylinders @intake and exhaust, or bore out.....??????? Confused


1970 Lemans
Edelbrock performer rpm dual plane intake, Holley 700 4bbl, hooker long tubes, 2 1/2" duals, Mallory dist, coil, & box, 480 cam, rebuilt th350 with stage 2 kit, 3.36 posi,  

barneyformula barneyformula
Addict | Posts: 3306 | Joined: 01/07
Posted: 03/17/14
05:01 PM

Many of these 350 blocks were chamfered for the big valves, my 70 Tempest 350 has them. It is a throwback to the 69 350HO which was the only year to have 2.11 and 1.77 valves. Later 350's are only chamfered on the intake side because they only used 2.11 intakes with 1.66 exhausts.  
A little help... 'cause we don't all have to learn the hard way!

Daniel Austin Daniel Austin
New User | Posts: 3 | Joined: 02/14
Posted: 03/17/14
08:26 PM

What if there is no chamfer, will I have to chamfer, also what about cylinder wall clearance......hopefully I will have time to get my heads off soon, and I guess all of my questions will be answered.  Was the 69 ho 350 3.875 bore? That's a little relieving knowing your 70 tempest was chamferd.  

Pontiacman8 Pontiacman8
Moderator | Posts: 5777 | Joined: 02/08
Posted: 03/18/14
07:51 AM

All Pontiac 350 engines had the same bore size from the factory H.O. or not.  
Engine builder,self taught auto body guy.
Horsepower sells engines and torque wins races

Pontiacman8
Pontiacman8
Pontiacman8

Casper77 Casper77
User | Posts: 61 | Joined: 01/14
Posted: 04/01/14
09:35 PM

Back in the day I bought some new valves with a set of 16s on a 69 350, it happens. Don't remember the lift on the cam.  

ROWSLEY ROWSLEY
Guru | Posts: 1016 | Joined: 07/11
Posted: 04/03/14
08:06 PM

the chamfer was for inproved air flow! the head gasket will show you where the chamfer should be on the deck. just don't get into the top ring!!  
76 455/4spd TRANS AM
69 GRAND PRIX 455/5SPD