Preparing for a Weber 38

[TodB]

I’m contemplating an upgrade from a 32/36 Weber to a Weber 38.

 

My car is a stock ‘75 with a 32/36 (water choke) with a stahl header into an Ansa exhaust. It runs great but I’d like a bit more ummph. The motor has 106k on it and has never been cracked open other than for normal maintenance. I don’t experience a lot of oil usage.  There is very minor blue smoke on start up sometimes (very minor) and I’m told a little blue smoke on decel which I can’t see it out the rear view mirror so it’s not chronic, certainly not something that needs immediate attention. I figure a head refresh is in the future (and maybe lower end) but nothing that has to happen right now. I’m really trying to control scope creep on this project and limit it to just the carb upgrade. 

I also recently added a programmable 123 distributor which made it just run better. 

My plan is to get a canon manifold, port match the intakes and bolt it on. I’ll need the correct throttle rod also. Anything else?

Questions

Stick with the mechanical fuel pump or go electric?
I assume I continue with a water choke?
I’ve done the searching, but can’t seem to find a curve to use. Right now, it’s set up as follows for the 32/36:

700,12
1000,22
3000,42
8000,42

It starts much better, especially cold starts, and it runs like a top. Should I continue to use this curve with the 38?

I’m trying to go into this eyes wide open. Any other suggestions or concerns?

Edited July 13, 2019 by TodB

[Chris_B]

There is absolutely no reason to go with an electric fuel pump. I would say, go with an electric choke, just because it is so much more simple and won't be likely to spring a leak. You will have to determine how to wire the circuit up, but close proximity to the fuse block makes that fairly easy.

[resra]

Tod, I have a very nice manifold that was ported for the 38/38. It is used but pretty clean. Let me know if you want it and I can send photo to you.

[Simeon]

Don’t go with the Canon manifold. Work with what you have and save $$

[TodB]

6 hours ago, Chris_B said:

There is absolutely no reason to go with an electric fuel pump. I would say, go with an electric choke, just because it is so much more simple and won't be likely to spring a leak. You will have to determine how to wire the circuit up, but close proximity to the fuse block makes that fairly easy.

 

Wiring should not be an issue. Any other steps or parts I need to do away the the existing choke plumbing?

[Vicleonardo1]

Have you thought about trying out a Sync-Link. May give you the same results with POSSIBLY some less hassle and expense.

Some have had a wonderful experience and some have had a lot of trouble with jetting etc. 

 

No need for manifold change etc. 

 

My worthless rapidly depreciating 2 Venezuelan cents. 

 

Cheers! 

[jireland2002]

42 degrees of ignition advance???  Have you checked it with a timing light?

[TodB]

1 hour ago, jireland2002 said:

42 degrees of ignition advance???  Have you checked it with a timing light?

When I installed the 123 distributor, I did verify with a light that the timing was 25 degrees at 1400 before I locked it down. I based my curve on what I found in Haynes for my car vintage, from some searching on this site and it seems like my curve is in spec with the dist I removed. I am running a straight mechanical curve with no vacuum advance. Do you have a concern?

[robspeed]

I had a 38/38 on my '69 and slowly grew to hate it.  Very abrupt off idle, and not smooth torque delivery.  IMO way too much carb for a two liter stock engine (they were OE on 2.8 and 3-liter Ford V6es).

[Chris_B]

On 7/13/2019 at 2:08 AM, TodB said:

 

Wiring should not be an issue. Any other steps or parts I need to do away the the existing choke plumbing?

So, if  you are converting from a hot water choke to an electric choke, you will need to set up a bypass for the plumbing to the choke. Meaning, you will have to connect the two water hoses running to the choke housing together to bypass the choke housing.

[rstclark]

+ 1 with VicLeonardo1   It's well worth a try with a sync-link on your 32/36  Especially for a stock motor  A 38/38 is intended for a 6 cylinder It's a lot of carburetor.  Even on a modified motor a 38/38 needs to be jetted leaner  Regarding 42 degrees of total advance. that's way too much.

If you have a 123 tune, put in the Tii curve  with a little vacuum advance and max the total advance at 36 degrees or less around 3500 rpm.  Spend some time reading the lengthy threads on 123's by searching before you burn up your motor 

[TodB]

Thanks for the continued replies, very much appreciated.

 

With regard to my current curve, I did a lot of research which included reading all of the related 123 posts on this site. Over and over again .  The post copy I provide below was what I used to install the dist and build my initial curve. It’s essentially similar to what I found in the Haynes manual (which gives ignition ranges by rpm level). The curve below essentially recommends the lower ranges of Haynes which I took as a safe starting point. I started with it (with no MAP advance), and over time removed the redundant values, and slowly raised the value at 3000 from 38 to 42, the upper 3000 rpm range level from Haynes. I have not added any MAP advance values and don’t intend to. 

 

Im not being defensive or challenging the brain trust here. I thought I had tweaked what was a safe static curve and kept it within spec. I don’t hear any pinging. That said, I will probably reduce the upper limit given the recommendations and concerns. My goal was not to set up this motor within an inch of its life and blow it up. More comments welcome. 

 

With regard to going with a Weber 38 on a stock, late model motor, there seems to be two camps of opinions on this site, those who swear by it as a good upgrade when set up properly and others who say it’s just too much carb. Clearly, The smart move would be to stay with the 32/36, with a modified curve , which runs super well and call it a day. 

 

Not sure what to do. 

 

*****

 

If you are not going to run with the MAP settings (line connected to a fitting on your manifold, not the port on your Weber), you will need to adjust Zinz's Static Map to account for when he is adding advance at different MAP values.  You can use these values to mimic the Blue Book Advance settings for a non-Tii car using the 123 Ignition Distributor and then introduce the MAP advance settings after the car is running using just the Centrifugal settings.

 

RPM Limit 6500

1 - 500, 0.0

2 - 700, 6.0

3 - 1000, 21

4 - 1500, 26

5 - 2000, 31

6 - 2700, 36

7 - 3000, 38

8 - 3500, 42

9 - 6400, 42

10 - 8000, 42

 

Set the car at TDC, the light on the 123 distributor at TDC (turning the distributor until the green light comes on), install the above settings in the program, leave the MAP settings at 0.0, don't connect anything to the port on the distributor, start the car.  Use a timing light to verify 25 degrees of advance (the flywheel ball in the window) at 1400 RPM, you may need to adjust/turn the distributor slightly to see the ball at 1400 RPM.  When this is done, you lock down the distributor...

[rstclark]

Just running mechanical advance is often misunderstood as high performance, which it is if all you do is drag race at full throttle when there is no vacuum.  But that's not how we drive our cars - most of the time. For overall driving there is real value in having vacuum advance that comes in at idle and cruise speeds.I can send you a mechanical curve with MAP settings that I can guarantee you will be happy with. It's on my laptop so I'll look it up and forward it to you in a subsequent post.

 

[TodB]

Many thanks @rstclark. I appreciate your guidance. 

[rstclark]

OKAY  Try this

 

Mechanical

700  6

1500  18

2000  23

2500  28

4000  34

6000  32  ---

MAP

0kp   0

29kp  0

30kp  10

50 kp  10

60kp  2

75kp  0

100kp  0

200kp  0

 

Take the vacuum off the manifold under the carb rather than from the carb. Just be sure the vacuum is from under the carb throttle plate

Static can be set low  like 2-4 degrees because the mechanical and map kick in early

Find a good idle  and go from there.

BTW  I have an electric choke 38/38 (jetted down) on a 9.5 :1 compression motor with a 284 cam etc.  I really like the 38/38 for  good low end torque and great colds and idle.  So I wouldn't talk you out of a 38/38    but  it well worth a try of a Sync Link especially if your 32/36 is running well 

Good luck with this project.

 

Good luck with your project