Members Login
Username 
 
Password 
    Remember Me  
Canadian Poncho Homepage -> Canadian Poncho -> 65-70 Full Size Power Train Tech Forum -> 1970 Pontiac Laurentian - carburetor
Post Info TOPIC: 1970 Pontiac Laurentian - carburetor
laurent


Member

Status: Offline
Posts: 8
Date:
1970 Pontiac Laurentian - carburetor
Permalink  

I have just replaced the motor with a new crate engine from GM -a 350 small block - but car is not running smoothly.  The carb has just been rebuilt but is still rough when  idling.  Should I replace the old carburetor with a new one?



__________________
4SPEED427


A Poncho Legend!

Status: Offline
Posts: 48806
Date:
Permalink  

Wow, I can't believe nobody has chimed in here.

Do you know for sure it's a carb problem?

Have you tried adjusting the idle mixture screws?

__________________

1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles 

1966 Grande Parisienne, 396 1 of 23 factory air cars
4SPEED427


A Poncho Legend!

Status: Offline
Posts: 48806
Date:
Permalink  

Also, have you checked for any vacuum leaks? Is it still the same intake manifold as before the engine swap (carb to intake mismatch?)

__________________

1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles 

1966 Grande Parisienne, 396 1 of 23 factory air cars
jonathanD


Poncho Master!

Status: Offline
Posts: 1769
Date:
Permalink  

my engine would not even fire up soooo  i duck taped all the places i could be having a vacuum leak and there she goes fires right up every time now =0



__________________

1967 parisienne 

 
67custom


Guru

Status: Offline
Posts: 634
Date:
Permalink  

laurent wrote:

I have just replaced the motor with a new crate engine from GM -a 350 small block - but car is not running smoothly.  The carb has just been rebuilt but is still rough when  idling.  Should I replace the old carburetor with a new one?

 Which Engine did you get, the 350 290hp ??



__________________

1967 Beaumont Custom

Canadian Poncho Supporting Member
laurent


Member

Status: Offline
Posts: 8
Date:
Permalink  

yes, I've tried that.  I had a kit put in too.  Since the new kit was installed, I'm now getting lube on the dome.  Never saw that before.



__________________
laurent


Member

Status: Offline
Posts: 8
Date:
Permalink  

I'm still using the same manifold and the same carb (Rochester) but I'm seriously thinking about buying another carb.



__________________
laurent


Member

Status: Offline
Posts: 8
Date:
Permalink  

That's the one - ordered it from GM dealership here.  Got it shipped from GM in Montreal, I believe.



__________________
laurent


Member

Status: Offline
Posts: 8
Date:
Permalink  

I'm taking it to a garage today to have the rear springs replaced.  I'll ask them to check for a vacuum leak.  When I had it running yesterday, someone said they could hear a hissing when I had the hood up and so they thought there was a vacuum leak somewhere too.



__________________
rabbit64cs


Canadian Poncho Superstar!

Status: Offline
Posts: 7176
Date:
Permalink  

are the intake and carb matched? around 67 , the 4 bbl intake had 2 small ports in the front of the intake that were heat risers to warm the base of the carb. IF the carb is not the correct style for that intake, you will get a terrible vacuum leak. simply plug the heat riser ports with a small frost plugs, or tap the 1/4 NPT .

something to check??

sorry ,, read the whole post over,, intake will not be the problem, but is the carb bse gasket the right one ??


__________________

later...rog

AADD supporting member !!
I'm a collector...not a builder!!Located in sunny central Saskatchewan at the lakehead!
Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.
Canadian Poncho Homepage -> Canadian Poncho -> 65-70 Full Size Power Train Tech Forum -> 1970 Pontiac Laurentian - carburetor
Tweet this page Post to Digg Post to Del.icio.us
.
Support Canadian Poncho!
Select Amount:
<
.
.
.