Larry, I need my idle that high or it will kill when I put it in gear! I adjusted the idle down to about 850 in park and looked at my timing. The timing mark jumps all over the place so it is difficult to see the mark! I am using two silver springs. I am pulling the vacuum off of the drivers side small port. I just went out and changed the vacuum to the passenger side, little larger port and I am getting 15-17 lbs of vacuum, the needle fluctuates from 15-17 lbs when at idle.If I rev up the motor a little the vacuum smooths out. I hooked up the vacuum advance to this port. I noticed that the timing mark is very erratic at 850 to 1,300rpms above that the timing mark smooths out. What do you think? Tim
Tim, Is this with the engine at operating temperature? Do you have a HV/HP oil pump? Sometimes the oil pump, can cause spark scatter when it drags on the distributor. You might see this with the engine cold, as the pump is pumping cold thick oil. The other thing is worn distributor bushings that allow the shaft to wobble some. The idle vacuum should be relatively steady with the engine warmed up. Have you ever had the carb gone over? Check for vacuum leaks??
Larry, the engine is at operating temperature when timed and vacuum checked. The carb was a sealed rebuild when I bought it however it was probably sitting on a shelf for a few years before I got it so there is a good chance that the gaskets are dried out. I bought the distributor used. Why would the timing mark become steady with higher rpm's? What is the best way to check for vacuum leaks around the intake and carb? Would it be worth it to change all of the gaskets in the carb? When I check the ported vacuum off of the drivers side port, I have 5lbs at idle, if I move the throttle linkage up a little, not enough to change the idle rpm's the vacuum will jump to 15 lbs. Is this normal? Thanks Tim
The best way to check for vacuum leaks is to put a vacuum gauge on a manifold vacuum source. Then spray some gumout around the carb to manifold gasket. Look for large changes in the vacuum level, when you hit a leak. I doubt you have a manifold leak. I see this engine was built at TSP. Have you contacted JW? What carb and distributor did he use? There shouldn't be any vacuum on the ported side at idle. I suspect that you have the throttle plates open too much at idle. This gives a small amount of ported vacuum, from that drivers side port. when you open the throttle further it climbs. Yes, that is normal. I think you have a combination of carb/distributor problems. Find out what Jim used. Jetting, timing, etc. I know 35* total is where your best power is. The distributor may be worn, and sloppy(advance mechanism)
Question.... What brand distributor are you using? I would like to convert my 67 400 from points to HEI but don't know what year GM distributor will fit. Does anyone out there know?
Sure, an HEI from a 75-76 455 will work. You can buy these rebuilt at your favorite parts store. However this is a much better alternative: www.davessmallbodyheis.com This has been covered many times on this board. Try using the Search function, and inputting "HEI" Be aware you must replace the factory resistance wire so that the HEI receives full battery voltage. BTW, I had my 70 at a cruise at Hempstead Turnpike, and Jerusalem Ave, in Levitown(Old K-Mart Parking Lot). It's there every Tuesday night starting around 5:30 P.M.
Larry, Yes, I know. I live 2 blocks north of the Gulf Station. Don't know if you remember me but we met at Captree a few months ago. I have the Blue 67 GS Conv. and the 67 GS 340. Hope to see you in K-mart next week, weather permitting of course! For the record, I did a search and I must say there are many opinions of the conversion. Since I'm "NOT" thinking of racing this baby I pretty much talked myself out of doing the conversion. I will say, my 340 did run much better with the HEI. Regards, Andy
Tim when the above problem happened to me I had a cam and distributor gear wore out. I had to install a distributor gear oiler and new distributor. It took 2 cams before I got it worked out. I now use a brass dist. gear with no problems. I use a HEI from "DUI" Davis Unified Ignitions curved to 24*@3,000 rpm. It seems to work good for me. 50,000 volts to NGK plugs gaped to .55. Larry helped me alot with my setup. He made the whole timing thing understandable for me. Mike
