308 metal in the oil fuel coming out of spark plug

[geforcevb]

No mate 600 if stuffed, and it was causing black smoke to but not as bad as the 750 I am going to a compressing test this weekend but still worried about the fine metal like you could barely see them but a lot of and wouldn't stick to a magnet but really shine pieces that was in the oil, but not in there after an oil change flush and a re-run of the engine for about 20mins and the engine runs good and revs alright but not chirp. I think the black smoke was I had the mixture screws wound out to far I now have all four screws 1/2 turn out it seems to stop 90% of the black smoke I am going to jet it down a bit like 62 front 68 back and see what happens. As the car is still on stands I cant take it for a run to clean the cob webs out and sitting in the shed for 20 year I suppose something has to give.

 

[geforcevb]

Well compression good change the jets 58 front 62 back and made little different not much to write home about. The plugs are black as, but when I try to advance the dizy to lean it out or adjust the mixture screws a bit she runs like a bitch. She backfiring out of the back when I give it a rev, and up the carb when I go to start it. I brought some new 8.5 spark plug lead from flebay a few months ago and I am pretty sure they are sparking across each other on the dizy as soon as I touch the rubber boots instance spark throw me I think the insulation boots are to thin. I brought a MSD 8589 pro billet dizzy MSD 6420 6al and MSD blaster 3 coil and e98100bk leads from a mate at work pick them up next week let hope this helps.

 

[geforcevb]

update I put a new 650 holley on and runs like a dream I guess the 750 was to big.

 

[profat]

there is a calculation for discerning correct cfm of an engine ......


cubic displacement divided by 2 (ex: 308 =154)

maximum rpm divided by 1728 (ex: 6000 rpm=3.47)

multiply those two figures (ex: 154 x 3.47=534.38 cfm)

Hold on we are not done. You now have to factor in volumetric efficiency. A race engine runs at 85%-90% volumetric efficiency. A normal street car will be 75-80%, depending on what you have done with your heads and exhaust.

Ex: 608.98 x 75%=400.785 cfm

 

[mr j-man]

What cube is the engine? Only hectic 308's and 355's require a 750 cfm carby

 

[Sabbath']

750's are great on a 308 if you want all ypur power to come on like a rocket about 20 seconds and 100m after you mash the throttle.

 

[ari666]

i remember 750 holleys.




nothing like a bit of carby lag.

 

[SL/ENUT]

Only hectic 308's and 355's require a 750 cfm carby

Do you realise the standard Rochester Quadajet is 750 cfm on 308s?

 

[mr j-man]

Do you realise the standard Rochester Quadajet is 750 cfm on 308s?

No I wasnt aware that they were a 750. So the 750 quaddy and a mechanical secondary 750 holley/demon are the same?? Sure the CFM may be the same but 2 completely different carbys

 

[ari666]

Do you realise the standard Rochester Quadajet is 750 cfm on 308s?

730cfm actually.

but that figure is meaningless, since the only flaps that are mechanical are 230cfm and the secondarys never get sucked open far enough to use their full venturies.