500 holley a bit smokey on idle

[Anonymous]

I took the 350 Holley off and put the 500 on my 250 2V. It is a reco one and the settings are all correct. The engine only has 1500 mile on it and is in good nick but on idle with the new 500 it seems a bit smokey on the exhaust. I didnt notice this with the 350. Anyone know if I should or how I should fix this?

 

[Anlushac11]

8)

Make sure the secondary is closed. Other than that it sounds like it needs to be rejetted. Sounds like its running to rich.

Also Racer Walsh a company that specializes in 2.3L 4 cylinders used to sell the 500cfm 2 bbl but they stated that you had to use a kit on the 500cfm 2bbl because on 4 cylinders and 6 cylinders the idle circuit and enrichment curcuit caused the cars to run too rich.

If your car is not hopped up enough to use the extra fuel and airflow you may need to "detune" the carb.

 

[Anonymous]

I seem to remmember someone in a previous post saying that you have to sleave the Idle restrictor jest 16 thou. Or something to that effect. I spoke to a mechanic who told me 500s have no idle restrictor. What do they mean.
I doupt the 500 is too much for the engine which has been "hoped" up with mild cam ect. Economy has stayed the same so far as I tell and it seems to burn clean the rest of the time. Just on Idle which I have set at 1000 rpm.

 

[xctasy]

Easy one first. As long as you have no sucking wounds from the swap over (leaks through rtv or wrongly torqued or warped gaskets and baseplates, the normall maladies with all Holley carbs) then the smoking should stop. Some particulates got in the system? There are cleaners avaliable, but go easy with them.

Second item relating to idle jets. According to Pinto engine tuners in the 1970's, the 500 cfm #2300 Holley with a 4412 number was cleaner emissions wise than the 2V 32/36 DGAS and Holley-Weber staged carbs. They could give the SOHC Ford engine over 170 hp, and still remain streetable. All to do with the richer Weber emulsion tubes and fuel staging on the emission cyles. The 16 thou idle circuit was recommended for the four cylinder 2000 cc hop-ups because the ~21 thou (was it?) restrictor was for a 350- 402 small block with 17 inches of water vacuum at idle.

Some where between the stock size and the 16 thou is the ticket. And closer to the stock size because a stock cammed 250 2V will have okay vaccum.

Aussie7Mains and I discussed the issue with non-staged Holleys (350 and 500) being suseptable to poor low speed running if the cam phasing was too much, or the signal was too small in the carb to survive. Holleys have less of a venturi than Autolites, Rochester 2jETS and 2CG's, or Bendix-Stromberg WW 2-bbl carbs. Sometimes, this causes a fuel stand off situation, and this causes the problem. When it happens, a 2 inch spacer can help, but that means bonnet modes in an area were there isn't a lot of space anyway.

 

[Anonymous]

Thanks for the info. when I bought the Carb from the reconditioner he warned me that I may have this problem. He didnt seem overly concerned unless I was going to let it idle for a long while and often. Im still wondering if I should try and fix it so that it doesnt.
Funny thing about all this is that I have kept the engine the same except for porting the exhaust on the head with the new addition of the 500. In changing from the dual stromberg carb to the reco 350 holley there was no noticeable difference in the fuel economy. At the time the reconditioner told me he had just sold a 500 holley for a standard 250 alloy crossflow Falcon. He said this made a enormous difference in the power ("it went off its brain" were the exact words). I chose not to take his advise because of fuel consumtion worries with the 500 on my 250 2V. He did say it would use more fuel.
I have done some accurate comparisons and on the open road since then and the 500 uses no more than the old strongberg or the 350 Holley. Mind you the figures are 21mpg 13 litres per 100 ks I can get 23 if Im very lucky at 90 to 100 kph with a four speed manual and a (2.72 diff?) My cam is supposed to make the car use less than in standard form which is (21 to 24 mpg cruising) (8 or 9 mpg racing).
I remmember on one of your posts you said the weber on the crossflow can do up to 29 mpg. Big difference must be the better crossflow head in conjuction with the weber carby as well.
Thanks again for the info.

 

[Anonymous]

Finally discovered what all this smoke at idle is caused by. Nothing to do with the new addition of the 500 Holley. It was the head porting I had done. I forgot to give the machinist the rubber cups that seal the guides on the exhaust valves. I called him about this and he said that I only needed them on the inlet and not having them on the exhaust would make no difference at all. He explained the reasons why.
Wrong, wrong, wrong 130$ latter I found out you do need them on the exhaust guides. No smoke now not even a hint. Apparently prior to this if it was left running long enough it would fill the whole workshop with thick smoke.
While I had this rectified they said it was also running a bit rich so I jetted the Carb down a bit. I was pleased to find that it gave a big increase in fuel economy. I Posted the findings on Aussie sixes.