Since you all helped me out so much last time, I thought that I would start here first.

I put an Edelbrock cam in my 69 351w and replaced the timing set with a cloyles double roller. Anyway I installed the cam straight up and set the distributer to 10 degrees (just like the instructions said).

I buttoned everthing up and went for a drive and it was detonating terribly when the vacum was working. You know - part throttle labor knocking. Full throttle every thing is great untill just before it shifts.

I unhooked the vacum and that helped except that I lost some HP and torque. (I didn't fix it, just helped). I have turned the distributer back and forth and can't find a happy medium between "go fast" and "holy piston batman".

So do I need to recurve the distributer? If so how? I would need "I'll hold your hand" instruction!

Thanks

 

What distributor brand are you running? You also need to check and see if your mech. advance is even coming in. Unplug your vac. advance hose from carb. and plug it and check timing at idle with timing light and slowly apply throttle while watching timing marks. All mech. advance should be in at 3000rpm; record this number. You want your total timing to be no more than 38* - 40* BTDC. Total timing is intial+vacuum+mechanical and make sure your vac. advance hose is routed to a ported outlet on carb above the throttle plates. Check all this and advise us on where you stand.

 

Go here: http://www.fordmuscle.com/archives/2...ng/index.shtml

This is a very good tech article about timing. Read it well until you understand it. It will help you figure out what to do.
Clint

 

Not to start a argument here but on every engine ive ever built, or seen on a dyno, ford and chevy, it made its best HP with the total timing between 32-36 degres, and having it all in b4 or by 3000 RPM should work great. DW

 

Not to start a argument here but on every engine ive ever built, or seen on a dyno, ford and chevy, it made its best HP with the total timing between 32-36 degres, and having it all in b4 or by 3000 RPM should work great. DW

 

Thanks for all of your help on this problem.

I have the stock distributer (single points style) with a pertronix kit that replaces the points.

I bought an advance curve timing light and checked everything out yesterday. My initial timing is 10 degrees (cam installation instructions said 10-14) with total at 36 degrees (cam range 35-38) at about 3000RPM. So all that checks out.

Is it possible that the vacum advance is advancing the timing too much at part throttle? If so is there a Ford ditributer for the 351w that has adjustable vacum advance. I found a Crane adjustable vacum advance unit for $22.00. However, I would have to wait a week before it got here. I also found a Mr. Gasket recurve kit that contained a one set of springs for about $7.00.

Also is it possible that the carb (Edlebrock 600cfm) is leaning out on part throttle? Currently I am running it without vacum advance and it is really sluggish from a dead stop. However, it begins to really come on about 2000-2200 RPM. This falls in line with the centrifugal advances beginning. There is some detonation at about 5200RPM just before the tranny shifts. Which lead me to the carb question.

Thanks again.

 

Back up a sec. how big is your cam? whats your duration @ .050 and gros lift ? DW

 

5200 RPM is probably pushing that 600 cfm carb over the limit. 2 separate problems with the same symptoms and same cure. The part throttle is probably because the fuel curve is too lean and the top end ping is probably because the carb is too small.
Try replacing the carb.

 

All this may be moot if that cam you're using is a "hot", "lumpy" grind intended for wide open 3500 + up running. Too much cam, too bigga carb, two of the biggest mistakes out there for street users. Do your power brakes still work (if so equipped)? If they have mysteriously gotten pale, your duration is too long for street use. eBay is full of "barley used" big cams and big carbs.