Hi Everyone,

I recently installed a new timing set in my 86 F-150, EFI engine. I changed the water pump too. I used a Cloyes Double Roller set, and set the cam timing to +4deg.

Anyway, I now have a pulsating vibration at upper rpms (above 3000) that gets worse the higher it revs. I changed the harmonic balancer, and the problem is still there. What the heck could this be? I didn't change the belts, but they are fine, and this engine never vibrated like this before.

Advancing the cam timing shouldn't do this, should it?

Ryan.

 

maybe bad wires, cap,plugs and rotor. but are you sure about the timing set

 

I think your valve timing could be too advanced. Most people don't advance the time unless it was retard from the factory (ie only one i know like that is the 460), or if you put in a different cam, and even then, most aftermarket cams are pre-keyed to 4 degrees advanced.

 

uh all ford v8 after 197? were retarded by four degrees in the factory timing set. by advancing it 4 degrees the cam timing is now over eight degrees off. sound like you got a case of bad cam timing to me. check it with a vacuum gauge, i am sure you vacuum will be all over the place. run only the factory timing set with a factory ford cam, otherwise you are looking for trouble..

 

I imagine a cloyes set would did dead on time in the middle unlike the ford right?

 

the aftermarket sets are set at -4', 0' , +4'. the factory set is -4' . it is really a bad idea to try to change the cam timing on any cam. if you try to advance an erson cam that has 4' retard built into it, you will run into a whole heap of troble. cam timing should be set up as the manufacture has stated. that means if you are going to run an aftermarket cam, you need to degree it in. the cloyes set in this application should be set at -4'. chances are the problems with vibration are actually misfires happening at high rpms . Kurt

 

Damn, your right. If it was originally -4, now its +8. Definitely too much. I wish I found this forum before I changed the timing set.

This still has the factory cam. Would zero work?

I will have to pull it off this weekend and change it. Yeah, its probably so far advanced in the upper RPMs, its trying to run backwards.

I know how you feel about setting it back to -4, but you would think setting the cloyes timing set at zero, it would work? +4 isnt too much over stock, but 8 is definitely a problem.

Has anyone here ever tried a stock cam with an aftermarket timing set installed at 0? (+4 from stock)

Ryan.

 

i have run the timing at zero. the only problem i found was that the manifold vacuum has a tendency to be a little low. you will lose about 2-3" at sea level thats ok, but here at 5500' that is about 6 inchs loss to alltitude and 3 inch loss to cam timing. a loss of 9 " can cause power valve problems in both the holley as well at the motorcraft carb. in the edelbrock you will need to change the metering step up springs. you will notice quite a bid improvement in the bottom end though... Kurt

 

This engine is EFI, so my idle quality probably wont be affected.

I think I will try it at zero, and see what happens. It could only be better than what it is now!

Thanks

Ryan.

 

I just replaced my stock timing set on a 1980 351M with an

 

...Don't know why that happened, I didn't hit enter..... Anyway, I replaced the stock set with an Edelbrock set at 0 and left the stock cam in. Vaccuum actually increased from 17 to 21" and it runs fine with definate improvement in throttle response and power. I don't know if it was due to my old timing set being worn out or going from -4 stock to 0. This engine has 120K miles on it.

 

i have a mellings cam and i have a stock cloyse double roller chain. if i get a new another one can i set it a 0 or +4. mine is carbureted. how do you degree a cam anyway. can somebody find a good link that i can follow.

 

jdon chances are the loose timing chain was really screwing the manifold vacuum up, so installing a new set at any position will help out greatly..
f100guy, is your mellings cam a stock one or a performance? a performance mellings sets up at 0'. a stock ford cam sets up on -4'.
as for degreeing in the cam i will check it out and see what i can find. it does require some special tools like a degree wheel and dial indicator. i set them up all the time in my shop but as for teying to explain it, well thats another story... Kurt

 

ok guys found the web page. this is the reason i run isky cam. th technical support and quality is always there. i have been a happy retailer for them for several years now. have instaled or sold over 100 cams and never had one failure. enough with the sales pitch here is the link.... http://www.iskycams.com/techinfo_index.html
hope this helps, its kinda long but you will soon realize the importance of degree'ing a cam... Kurt

 

it is a mellings performance cam in a 302 straight up now with stock timing set. i lopes pretty hard and mellings said this cam is supposed to be 1 step over stock. an rv cam. i don't have power at idle if this is an rv cam why don't i. so i think they sent me the expensive cam in the wrong box. so i guess i need to buy an aftermarket timing set and put it on 0. what would happen if i set it to +4. hopefully when i get it degreed with the timing set to 0 it will give more off idle power.