Pinto Misfire & temperatures

Not logged in [Login - Register]

LocostBuilders » Forum » Engine & Transmission » Pinto Misfire & temperatures

Water Pumps at MachineMart.co.uk

Printable Version | Subscribe | Add to Favourites

davidimurray

Contributor

Posts 813
Registered 25/1/10
Location South Wales
Member Is Offline

Photo Archive Go!

Building: Haynes Roadster

posted on 2/9/11 at 07:26 PM

Pinto Misfire & temperatures

Hello

I'm hoping I can pick up some tips from the vast knowledge base on the forum. I have two queries -

I've got my Pinto running now. It's an 1800 fitted with ZX6R carbs - jets are standard, needles are 1 below middle groove and idle screws are 3 turns out. This is all running with a Megajolt - timing has been set and checked and the map I have is one of the 'standard' base maps doing the rounds.

When the car is sat idling (it currently idles at about 1050 RPM) every 10/20 seconds I get a pop from the exhaust. You can hear it on this video here at 15 and 35 seconds - http://www.youtube.com/watch?v=6JVmMO2R4WY

If you watch the video further, when I raise the revs at about 40s second up until 48 seconds you can hear quite a few pops but they don't seem consistent. In the rest of the video I raise the revs further and the pops seems to decrease but there are lots coming off the throttle.

Has anyone got any suggestions on what could be causing this? An initial though I had could be air leaks into the exhaust?

Second question is about temperatures. Let the car get up to full temp. I've got a digidash and that shows that the engine fan comes on at about 105C and turns off at 98C. The fan switch is rated at about 75C so I am guessing this is just a function of the position of the fan switch against the temp sensor in the head. Does this seem like a normal sort of operating temp for a Pinto? If I hold the engine at 3500rpm for a few minutes, with the fan on the temperature sits happily at 101C so it would seem that the cooling system works.

Thanks in advance for your help.

Cheers

Dave

jacko

Contributor

Posts 7029
Registered 1/1/04
Location Hull
Member Is Offline

Photo Archive Go!

Building: MK -INDY 2 LT ON zx9r bike carbs Now sold

posted on 2/9/11 at 08:20 PM

Check you don't have a leak in the exhaust pipe it could be sucking air in to cause the popping
When you come of the throttle the popping seams to happen a lot when using bike carbs [ may be running to rich ]
you need a rolling road to set it up right
Jacko

snapper

Contributor

Posts 5241
Registered 18/12/05
Location Chelmsford
Member Is Offline

Photo Archive Go!

Building: Robin Hood series 3 + new project old Fury

posted on 3/9/11 at 05:43 AM

I second the running rich theory, probably more to with the idle circuit and the progression holes than the main needle.
Temp is way to high for a Pinto, they should ideally run in the 80's not easy to achieve in a 7'n.
I fitted a thermostat that opens at 82 degrees and this helped enormously, a bit of creative ducting to force more air through the rad and I propped the rear of the bonnet 1/2" to help the hot air out.
Also fitted an oil cooler.
Have a spare 13 row, take off and oil stat if your interested.

I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)

davidimurray

Contributor

Posts 813
Registered 25/1/10
Location South Wales
Member Is Offline

Photo Archive Go!

Building: Haynes Roadster

posted on 4/9/11 at 09:55 AM

Hello everyone

Had another play yesterday and made a discovery - I am an idiot :p

It seems while playing with the idle screws I had been turning them the wrong way and leaning out the mix rather than richening it up :eek:

Reset the carbs yesterday and it now runs a lot lot better although it still has the odd pop and bang on the overrun but that is probably an air leak. A wideband lambda is on the shopping list for tuning. I popped a CO meter up the can and at idle I was getting 1.5% CO.

For purely educational purposes I checked my shift lights were working as well - http://www.youtube.com/watch?v=SBZ497TwyII

On the temperature front I've been through the cooling system again and rebled it all and the engine now sits happily at 89C with the fan cutting in and out so it looks like I must have had an air lock somewhere.

Thanks for all the advice guys. I've whipped the exhaust off at the moment topolish it and wrap the headers in the engine bay so when I get it back on I will report how things are going.

Cheers

Dave

LocostBuilders » Forum » Engine & Transmission » Pinto Misfire & temperatures

All content © 2001-16 LocostBuilders. Reproduction prohibited
Opinions expressed in public posts are those of the author and do not necessarily represent
the views of other users or any member of the LocostBuilders team.
Running XMB 1.8 Partagium [© 2002 XMB Group] on Apache under CentOS Linux
Founded, built and operated by ChrisW.