302 windsor, runs like a pig

[simon]

Started my engine again today. With the benefit of coolant and a cobbled together exhaust system, I could run it for more than ten seconds! The problem is it runs like a pig. I had it running a little bit above tickover, but its as if its only running on six cylinders! However when I turned down the tickover it smoothed out and ran like a peach!!!! It got up to operating temperature and when i tried to rev it slightly, it revved very roughly (but settled back to a smooth tickover) I've slackened off the distributor and moved it slightly either way (as I'm revving it) but it doesnt seem to make any difference.
I'm a bit confused. Could it be a mixture thing? If so, where do I adjust it on the Holley? (it's a 4160 - 600cfm)
Thanks
Simon

[robert]

Did you check the float levels. If it won't rev properly, it might be over fuelling as it is drawing down more air.

The mixture adjusters are two small screws, one each side of the throttle body, the float levels are on the top of the float chambers. It is a screww with a retaining nut.

Robert
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[mikey]

Can you desribe running like a pig a little bit more. If you describe all the symptoms we may be able to help. I agree that if it is running rough its likely to be a fuel problem if you are getting a healthy spark at all cylinders. In addition to above are you getting black exhast fumes. The floats on Holley carbs can stick if left in position for a long period causing too much fuel delivery. Also have you set the float levels ie fuel level with bottom of site plug whilst running (initially set level with pump running and engine stationary if you have an electric pump. Another classic with Holley especially if second hand even with new gaskets is the mating face between the metering block and main body can warp slightly. This leads to fuel being drawn past the gasket giving an over rich mixture. It is a common problem in recon carbs where the mating faces have not been checked for flattness or where the bowl bolts have been overtightened. Way to check is take off the metering block or blocks and check with a straight-edge.

Are you sure you installed the distibutor correctly so that it was firing on the correct cylinder. By the way is it a Chevy. If so turn engine over until No 1 intake valve closes and contine until you meet approx 5 deg BTDC. At this point your rotor should be pointing towards the No1 terminal in the distributor cap with the vacuum unit pointing somewhere in the direction of the offside headlight or front of the offside wing. If it is way out take of the front timing chain cover and see if you got the mark on the crank sprocket and cam sprocket lined up. They should be lin line with No 1 piston at TDC. You can get these 180 deg out and the engine I believe will still run but not smoothly.

More chance that it is a tuning problem so if you describe the symptoms more accurately we may be able to focus in a bit more.

I prepared this before I saw the second post. Sounds to me more like the timing problem now if you are getting a spark at all cylinders. With engine at tickover or cranking, use a spare spark plug and test each lead by placing plug nose against earth and observing for spark just to check you are firing on all 8.
Mike.

Mike.

[simon]

Thanks Robert and mikey, I may have sussed it though. I did a bit of thinking today (on a 500 mile round trip to Devon) and had a look at the carb when I got in. I noticed that the vacuum secondaries were wedged in the open position (my own bloody silly fault) Its a bit late to try it now, so I'll crank it up in the morning and let you know if its any better.
Thanks again
Simon

[mikey]

I am delighted it was that simple. Does this mean you will be bringing it to Stoneleigh.
I think wilf wants everybody to check over the chicks he's inviting to his party.
Mike.

and just when you thought it was safe to go back in the water
If that was a question Wilf - no, I did have a mum and Dad.

[simon]

Sorry guys, If you see my other post you will see i got a bit confused about primaries and secondaries. Its still running badly. It ticks over very smoothly and quietly, and is running on all eight cylinders. When I open the throttle, it hesitates and chugs but does not significantly rev (guessing 1000 - 1500 rpm)I have set the float levels as described and have tried to tweak the mixture but all to no avail. I'm hoping that it's not a mechanical problem. I'm getting a good slug of petrol down the barrels when I open the throttle and it wants to go, but it seems like it just can't.
simon