Twin SU's and Belt Drive 4g32

[mattys]

Hi Guys,

Purchased a set of Twin SU's and manifold for the lancer around 10months ago. Finally the other day i fitted them up!! Just wanted to clear up the myths of the belt drive 32 and the twins. Some said that the twins wouldn't fit as the fuel pump would get in the way. This is NOT the case. The only mod i had to do was to file the rocker cover around 3mm so that the thermostat housing wouldn't hit. The standard pump also runs the su's fine.

The engine has certainly been transformed!! Can't believe the power increase... its awesome.

I Have had one drama with the cooling system however. The temp sender doesn't seem to be registering the correct temp when running. It seems once i stop the motor and leave it for a few mins, then turn the car back on it jumps up to around the operating temp but then slowly returns to 40-50 deg. The temp gauge / sender are VDO aftermarket set and were working fine with the standard manifold (registering 85-90 when running).

The car doesn't seem to be overheating and there appears to be plenty of flow once warm in thru the radiator cap hole.

Any ideas guys??

was maybe thinking the sensor isn't protruding enough into the manifold??

Cheers,

Matt.

[shuggy]

im thinking thermostat is dead maybe? hot water gettign caught around the sensor and then slowly dissapates as engine runs as it starts flowing through the sensor again??

try taking out the thermostat

or have you checked all the wiring? is it a seperate earth wire or does it use the manifold as its earth? if it uses the manifold then you will get strange results if its a different material or if there is any other current in contact with the manifold or carby...

[kodos]

Thats good to know, nice work. Although i would just use an elec fuel pump anyway but hey, good tip
Instead of attacking the rocker cover, would a different angle thermo housing fixed the clearance issues?

[tandanus]

Are these real SUs or Japanese copies?
And yeah, earth the manifold and rocker cover rear bolt (my instrument lights started to work when I earthed that bolt :? ).
T.

[mattys]

Hey guys,

Cheers for the advise!

1. the thermostat is all good as it was working in my previous manifold... but i'll take it out and see what happens.

2. Not sure if the rocker cover or manifold are earthed so i'll give that a go. I suspect that this is probably the drama. Which bolt should i earth off on the manifold??

3. As for the clearance issues.. maybe a different angle thermo housing would work. I just used the standard chain 42 housing which shoots off at 45deg. I also had the north/south belt 42 housing but didn't try that.. maybe that would have solved the problem.. however the whole manifold seemed to fit up alot closer to the head than the standard manifold. Was fairly easy to file and the rocker cover already had a 2cm production notch there anyway. I just extended it to around 6-7cm.

4. What advantages would an electric fuel pump have over the standard rocker pump?? I have an electric pump but its one of the noisy ones.

5. I think perhaps the carbs are copies they say Asian on the side. What differences will i find with these??

I'll post some pics soon.

Cheers,

Matt

[boyracer]

.
Pictures would be good, don't have Jap SU carbs so am interested, what
linkages did you use? did the carbs come off a 4g32?
.
.

[tandanus]

They are probably AISAN HF40Ds. I run these on my Saturn. The difference between these and genuine SUs is that parts for these are made on unobtainium . With some work you can adapt them to take SU parts (needles, jets), but since they were made for the 4G32 you probably wont have to
T.

[davetrees]

There's probably no particular advantage going to an electric fuel pump - other than they don't leak oil ! The stock mechanical pump (in good condition) will provide all the fuel you need.

If you do go the electric pump route though, make sure it's a low pressure one .... anything more than ~5psi fuel pressure is too much for SU-type carbs (3-4psi is ideal).

[mattys]

Hey Guys,

Finally got around to sorting the heating issues.

The issue was the manifold hose connection. Had the manifold water jacket connection plumbed to the outlet from the head. I did this as it had the same pipe diameter connection. This was not working as it didn't seem to have the right amount of pressure or flow. Now i have it plumbed to the outlet from the rear heater hose. Works well now. Wasn't a thermostat or earthing issue.

After investigation the carbs are aisan 40s like tandanus said (found one of your previous posts). Standard linkages etc. will post so,e pics soon! So yeah good to have a factory mod in the lancer!!

Think i may have to refit the pressure reg i had on the stardard carby. The belt drive 32 pump outputs too much psi i think. After a decent run, left to sit for a few hours, then run again it seems to have flood a bit.

In the process of tuning them now.. will let you know how i go!!

Cheers,

Matt

[city hunter]

I'd love to see a picture of this setup. I didnt know they even made a su manifold. Any chance you could use datsun 510 sss su's?

[davetrees]

Think i may have to refit the pressure reg i had on the stardard carby. The belt drive 32 pump outputs too much psi i think. After a decent run, left to sit for a few hours, then run again it seems to have flood a bit.

You shouldn't need a fuel pressure regulator with a mechanical pump, on either the stock carb or the Aisans.

I doubt excess fuel pressure is the root of the problem ... sounds more like fuel metering problem in the carb somewhere ?

The fuel pump pressure will be the same whether the car has been running, sitting, or whatever.

With SU-type carbs, it is critical that the float level in the fuel bowl is set correctly, and also that the needle & seat are in good condition (and that there is no gunk in the fuel bowl ... that will make the needle/seat stick in no time & cause it to flood).

[davetrees]

I'd love to see a picture of this setup. I didnt know they even made a su manifold. Any chance you could use datsun 510 sss su's?

They aren't SUs .... and neither are the ones from Datsuns (they are Hitachis).

Whether the Aisans & Hitachis (or genuine SUs, for that matter) are interchangeable will depend on the diameter & shape of the inlet throat (Datsun 510/610 Hitachis are 38mm, from memory ?)

Don't forget that unless there is no slop at all in the throttle shafts (therefore allowing un-metered air into the system), you'll be forever chasing your tail trying to get them properly balanced or idling worth a damn .... expect to have to get them rebushed if they haven't been fully reconditioned already.

[shuggy]

Think i may have to refit the pressure reg i had on the stardard carby. The belt drive 32 pump outputs too much psi i think. After a decent run, left to sit for a few hours, then run again it seems to have flood a bit.

i got same problem, check your float level, my float leven doesnt change coz my needle valve it fuked and my float level is always super high

[81GL]

Think i may have to refit the pressure reg i had on the stardard carby. The belt drive 32 pump outputs too much psi i think. After a decent run, left to sit for a few hours, then run again it seems to have flood a bit

Is there a plastic spacer in between the pump & head?