318 cam and heads help

-
M

mopar_persson

Body Bag
Joined
Nov 13, 2010
Messages
77
Reaction score
0
Location
weikum
hi i have just changed the camshaft in my 318 engine to a Hughes Engines HMC1326AL-9+5 Whiplash Series. the heads are 318 (302) heads and the heads have been ported. I have also replaced all the valve springs and Retainers from a pair of trashed 360 heads (596).

and i have a big problem with the 302 heads, 2 rockerarms have been junk after this, and 2 valevs have broke, they have gone off at the ground of the Valve locks??
it is only on the exhaust valves and exhaust rockerarms.
the push rod have ram right through the rocker arm.

I use the original rockerarms.

it is broken at various times. and the engine run really good befor the breakdown.

the enigen is a stock 1988-318

http://www.hughesengines.com/Index/...V2hpcGxhc2ggTXVzY2xlIENhciBDYW1z&partid=25113
 
Too much lift for stock 318 head. Retainers are hitting valve guides, they need to be cut down.
 
okey but on Hughes Engines webb site they saying that they will work with the original heads ?

from the webb site= No machine work, leave the heads on, raises cylinder pressure. Ground on true .904" cam lobes. This gives you max area under the curve. Has low lift to clear guides.
 
Skip what Hughes says.

No machine work, as long as you bench grind .030 off the retainers lock bore...lol

That's the only thing that makes sense for what happened. And thunk about it...the exh lobe is taller and over .500 advertised. Just mock it up and turn the crank by hand , once at full lift, if you don't feel or hea it hit, then just compress the valve at rocker a bit more and see how much clearence there is, you need about .100 to piston.
 
Ok you have a new cam and used springs off a 360? Buy new springs to match your cam.You can use the old or weaker springs to break in the cam.Then once the cam is broke in replaced the old springs with new springs matched to your cam.
 
Trust but verify. "No machine work needed" unless there IS machine work needed. I would double check valve retainer to guide clearance at full lift. If the guides have been replaced they could be taller than the originals. Also,check the guide to stem clearance, if the valves are too tight in the guides they will stick when the get hot, such as at full throttle.

Since you are breaking rockers and valve tips, I suspect the problem is guide interference. If the valves were hitting the pistons the heads would be getting bent.

If the valve springs are factory 360 springs, you ARE probably experiencing valve float at fairly low RPM with that much lift. Valve float, and minimal retainer-to-guide clearance could cause the problems you are having.
 
You must log in or register to reply here.
-

Back
Top