MKIV Engine Problems

[Rob.Hendriks]

Martyn
Working on the KISS principle, you need air (in/out), fuel, compression and spark to make an engine work. So based on this thread thus far:

AIR (inlet) - has the filter been cleaned/replaced. A severely blocked air cleaner can case this type of problem

AIR (exhaust) - many people forget that just as an engine breathes in, it must also breathe out. Is there an exhaust blockage e.g. the catalytic converter. You mention that the CO2 emissions are out, suggesting that the catalytic converter is not functioning properly and you also mention low exhaust temperatures, these combined raise concerns. A "normal" engine exhaust temperature is 400-900C and catalytic converters do not really work well below 250-300C, hence the suggestion to warm it up, an optimum temperature being around 400C

FUEL – supposedly the carb has been setup correctly, but has the fuel inlet pressure been checked (had a similar problem with a friends double pumper). Air/fuel ratio will have a direct effect on exhaust temperatures. Also a 650CFM double pumper is a lot of carb for what is basically a stock 302.

COMPRESSION - you have confirmed is fine

SPARK – would suggest checking the distributor, worn bushes or bearings could cause this issue at higher RPM

Regards
Rob
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