TheSamba.com :: View topic - Type 4 running way too rich after rebuild

Fri Jul 13, 2018 12:58 pm

I've recently rebuilt my Type 4 1800 engine

I fitted a scat c25 cam and good reconditioned pair of dellorto drla 36 carbs set up for a type 4
40 X 34 Valve heads

I've been trying to get the thing to run right for months now it has a massive over fuelling problem and fouls the plugs and i get a fair amount of black smoke

Im running stock push rods with shimmed rocker arms and was wondering if the valve train geometry might be a bit out resulting in the valves opening and shutting at the wrong point ?

I've tested it on two different sets of carbs and it still smokes and runs rich
i have yet to test full pressure but if you crimp the fuel line to reduce the flow i still have the same symptoms

I've tried a couple of different dizzies but still i have the same problems

The bus runs and idles and revs smoothly but eventually starts fouling the plugs and running bad. also i get quite a loud sucking / slightly agressive induction noice through the carbs, It doesn't sound right at about 3000 rpm

So the carb spec is

135 main
180 air correct
33 pump jet
idle jet i think is a 57 but its hart to tell as the numbers are a bit warn on all four.
9164.2 E TUBES

The timing is set at 7.5 at btdc and 28 bdtc at 3000 rpm

I haven't checked the float levels yet but the engine shop that i bought reconditioned carbs from one of the best engine shops hear in the UK who speicalize in type 4 race engines. i know i should have checked the them but i trusted the they were all set and ready to go.

But i will be taking the carbs off this weekend to double check

Im also running a single vac dizzy with electronic ignition with bosch WR8CC plugs and a stock after market fuel pump

Any advice would be greatly appreciated

Peace.

Fri Jul 13, 2018 1:37 pm

¡Bienvenido a la Samba!
A lot is missing here, starting w/ no mention of jetting.
Suggest strip a carb down far enough to read & report on what sizes (main, idle, air correction & emulsion tube) are installed.
Shimming the rocker shaft stands is a useful method to correct rockerarm geometry, but it won't cause " ..... the valves opening and shutting at the wrong point ?" That's the job of a camshaft.

The overheating issue could possibly be a case of improper timing: so can ya tell us where she's set for both static timing & full advance?

Fri Jul 13, 2018 1:39 pm

are the carbs new to the engine also?

Sat Jul 14, 2018 4:40 am

So the carb spec is

135 main
180 air correct
33 pump jet
idle jet i think is a 57 but its hart to tell as the numbers are a bit warn on all four.
9164.2 E TUBES

The timing is set at 7.5 at btdc and 28 bdtc at 3000 rpm

I haven't checked the float levels yet but the engine shop that i bought reconditioned carbs from one of the best engine shops hear in the UK who speicalize in type 4 race engines. i know i should have checked the them but i trusted the they were all set and ready to go.

But i will be taking the carbs off this weekend to double check

Im also running a single vac dizzy with electronic ignition with bosch WR8CC plugs

Peace.

Sat Jul 14, 2018 4:42 am

[email protected] wrote: are the carbs new to the engine also?

Yes the carbs are new to the engine.

Sat Jul 14, 2018 1:59 pm

Probably has "the drip"

Sat Jul 14, 2018 10:48 pm

FeelthySanchez wrote: ¡Bienvenido a la Samba!
A lot is missing here, starting w/ no mention of jetting.
Suggest strip a carb down far enough to read & report on what sizes (main, idle, air correction & emulsion tube) are installed.
Shimming the rocker shaft stands is a useful method to correct rockerarm geometry, but it won't cause " ..... the valves opening and shutting at the wrong point ?" That's the job of a camshaft.

The overheating issue could possibly be a case of improper timing: so can ya tell us where she's set for both static timing & full advance?

So the carb spec is

135 main
180 air correct
33 pump jet
idle jet i think is a 57 but its hart to tell as the numbers are a bit warn on all four.
9164.2 E TUBES

The timing is set at 7.5 at btdc and 28 bdtc at 3000 rpm

I haven't checked the float levels yet but the engine shop that i bought reconditioned carbs from one of the best engine shops hear in the UK who speicalize in type 4 race engines. i know i should have checked them but i trusted the they were all set and ready to go.

But i will be taking the carbs off this weekend to double check

Im also running a single vac dizzy with electronic ignition with bosch WR8CC plugs and a stock after market fuel pump

Sun Jul 15, 2018 9:06 am

as covered in dozens of threads here on Samba, what # which is on the jet is irrelevant. Many have seen the sharp side of drill bits. Check them.

Sun Jul 15, 2018 9:38 am

I would check the pressure from that “stock aftermarket fuel pump” sooner rather than later. It’s easy to do, and a pretty easy fix if you find that it’s the culprit.

Sat Jul 28, 2018 12:09 pm

Thanks for all the advice guys :D