how to restrict

jordanatkins305 · #1 (**permalink**) 10-02-2003, 08:54 AM

i've just built my first FE 390. the old one had an oil pressure problem which i've heard is common. someone told me that i can put restrictors in the heads but i haven't seen any for sale. Can you make them? I read on one of the posts here that someones engine would diesel because the heads would get hotter than they are supposed too because of the restrictors not allowing sufficient flow of oil to cool.Is there a way to restrict without this problem or not. i just want this engine to run a long time without worrying about oil pressure. Thanks in advance for any help.

ed cougar · #2 (**permalink**) 10-02-2003, 06:34 PM

Below 1 rocker stand on each head is the oil feeder to the rocker shaft, this is where to restrict the oil there are several ways to do it the most common being with a small puck drilled out to .090 then pressed or just tapped in with a small hammer, I had mine drilled and tapped during the head rebuild so i could use screw in restrictors. As far as the deiseling goes, in my opinion if the oil restriction caused heat build up enough to cause deiseling then the valve train is toast. I think thats a false statement. Anyhow no problems with mine and would do it again for sure and highly recomend it.

Eljaro · #3 (**permalink**) 10-04-2003, 05:27 PM

It was in my thread (Dieseling 427) where I mentioned that the oil restrictor was preventing enough oil to reach the heads for cooling.
No, this did not cause dieseling (the culprit was advanced timing because of incompatibility of MSD electronic ignition and some electronic timing lights)
But I did surely get a cooler running engine without the restrictors in place.
SFfiredog in the DOVE HEADS VS. EDELBROCK FOR 390 BUILD post mentions THIS:On street engines I normally do not restrict the oil to the rocker arms. Street engines idle a lot. Race engines don't. The extra oil in the top end keeps the valvetrain well oiled at idle speeds and keeps the valvesprings cool.
I took the restrictors out of my heads and the engine runs cooler, the oil pressure remained the same.

ed cougar · #4 (**permalink**) 10-04-2003, 07:10 PM

You are exactly right, key word (idle) When you run steep gears say 3.91's and 4 speed the R's are usually up above 3000 most of the time, I've gone to the dragstrip and shifted at 6000 RPM's 4 runs 20mins. apart. I think without the oil restricters the oil pump would have come dangerously close to cavitating. On the flip side there's FE's out there with well over 100,000 miles on them and still going but they seldomly see anything over 3500 RPM.