Outer Limits 4x4 Board

I have a 308 on straight gas and when you plant the throttle it revs fine up until about 1700 rpm then just Sits there fluttering and hesitating. It's an impco gas system. Timing is set at 6*btdc.

Could it be bad gas? It has been sitting for about 6months now and only just fired it up.

More likely the valve seats have dried out do you run additive with the gas.

How is the fuel mix, it may be leaning out which will cause hesitation.

We've only just got the engine started after a 6month cab swap. Before the rollover it ran fine but with no additives I dont think. It has a valve on top of the air filter which can be turned to 5 settings. I had a play with it to see if it turned, and it does. has been returned to the original middle position.

How would I do an upper head lube job with gas? obviously cant mix it with petrol!

Flashlube thingy

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sounds like the diaghram in the mixer, possibly full of oil if its been over.i,d also run a bit more advance than that around 10-12deg,i try and get about 32 deg total.also check that the mixer is shut, dependig on which imco you have they had a cable operated mechanism to open the mixer when running on petrol but the high speed wont work withit open on gas.

Im not so savvy on gas systems which is a bit of a bummer... How do I check the diaphram is working correctly? It may well be full of oil from the rollover.

I dont think there are any cables to the mixer.

Other note, the hesitation starts just after the second butterfly opens. i.e. It revs really nicely up until the second throat opens... May be a clue

Air/vaccum leak.
Dodgy diaphram.

does it hav a vacuum hose on top of the mixer. what model imcp is it it should have a model number on the mixer.

I dont think it has a vac hose on top of the mixer, but i'll double check. Also check model of mixer too.

Cheers