smooth running

[Adambul]

Hi all,

This is only my second post on PH, although i've been surfing this forum for a couple of years, so go easy on me.

I have a 4.2 that runs OK but not great. It is awesome on full chat but a bit lumpy at tickover and hesitates a bit around 1,800 - 2,000 rpm at light/part throttle. It also rattles a lot at low revs, I'm not sure if the noise goes away with revs or just the roar of the engine blocks it out. What I would like to know is can these engines be made, with the right effort tuning and commitment, to run smoother and consequently more pleasurable to drive at lower speeds?
I've started to do some light tuning with the throttles removing slop from the linkages and balancing etc and it will now hold a 900 rpm tick over but its not exactly happy and prefers to run slightly faster. There is definitely a difference between the intakes on one side in airflow as I've bought an airflow never and across one bank the flow goes up and down by quite a bit, between 3-5 m. I'm planning on working my way up starting with the basics such as checking exhaust manifolds for cracks and defective seals against the head, and then moving on to the valve clearances, followed by intlet air leaks. I will then move on to more involved balancing between the banks and possibly the individual chokes if needs be.

Before I get too far involved I thought I'd ask if the running of the engine is normal for what is effectively a race engine and that I,m not chasing something that can not be delivered.
I have heard talk on this forum of people saying that there AJP runs a smooth as a turbine, on the other hand there are plenty of threads about poor running.
I welcome your thoughts/comments.

[waveydavey1000]

Hi Adam, I too have a 4.2 and it runs like a dream! Tickover is very even at 1000 RPM, there is no lumpiness or stuttering throughout the rev range. The only major change I have done to the car is to have it decatted and It runs alot better now it can breathe! It felt as if it was being strangled and "stuffy" before the decatting and it runs and revs much more freely now.
I bought the car in July last year from Hexham Horseless Carriages with it just having a 12k service, new clutch and slave cylinder.

[ukkid35]

Although improvements from remapping are less spectacular with the 4.2 than with the 4.5, you should still consider this option, and speak with Joolz. However make sure you do everything else on your list first, especially tappets and manifold cracks. Also make sure your engine won't spill it guts on the rollers, by refreshing the cooling system and generally addressing fluid leaks.

[Adambul]

Thanks for the advise and its good to hear that they can run smoother. I've already done the exhaust manifolds, no cracks but they were leaking against the heads. I, he now fitted some gaskets as supplied by ACT and they are much better. Tappets next stop!