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Discussion Starter · #1 ·
taking a stock 351c 2v and enlarging the valves to that of the 4v 2.19/1.71
how would the engine respond?
yes the 4v has larger ports and a bigger cam profile...

My end will be to use Dan Jones's outline for building a 351c 2v
with a cam, hydraulic roller lifters, roller rockers, Edelbrock intake dual plane.
that is about a $1,000 build... not counting the machine work on the heads
and the new SS valves.
But right now just looking for you input
Best
 

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Bring the comp up to around 10-1 and it'll move right along. Smaller ports will give better TQ at lower/off the line speeds. Bigger valves will let it breathe at higher RPMs. Just make sure there's no airport bump in the exhaust port.
 

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Discussion Starter · #3 ·
Hi Rick, thanks for your input.
As stated, I plan on building the engine out a little, when I had the engine rebuilt
way back in the last century, they installed a "stage 2" cam, what ever that meant
in those days is was like a Torq style cam, I could burn rubber in second gear all day long.
since then the engine has not been in a running car... I fire it up every so often.
But since I had a spare pair of heads, I thought I'd do the valve increase and install
the roller rockers I have, just to see how the engine runs like that..
I will still install a newer 2 profile cam, and roller lifters...
This is the cam spec from Dan Jones,, which was a special made cam
228/232 degree @0.050 lift
(280/284 @ 0.006 ")
0.588/0.588 lift
107 LSA.
68 deg overlap
installed in engine on a 104 centerline.

I am looking at one from Howard cams
Valve Lift Intake:
 .571
Valve Lift Exhaust:
 .577
Duration Intake:
 270
Duration Exhaust:
 278
Duration at 050 Intake:
 217
Duration at 050 Exhaust:
 225
Lobe Separation:
 110
Intake Centerline:
 106
 

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Discussion Starter · #5 ·
really nothing, other then road trips... hell I might just leave it as is.
But looking at options that maybe I should have done years ago
that $1K could go a long way on my 56 Packard...
So I'll probably just upgrade to a 4bbl intake, I have a 4100 carb, rebuilt
and I"ll rebuild the spare pair of heads... with the roller rockers and the larger valves
my friend owns a machine shop.. so the cost is nothing.
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really nothing, other then road trips... hell I might just leave it as is.
But looking at options that maybe I should have done years ago
that $1K could go a long way on my 56 Packard...
So I'll probably just upgrade to a 4bbl intake, I have a 4100 carb, rebuilt
and I"ll rebuild the spare pair of heads... with the roller rockers and the larger valves
my friend owns a machine shop.. so the cost is nothing.
best
Personally, I would drop that cam down to around.510 lift with a 214/224 dur @ .050" lift.
 

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Discussion Starter · #7 ·
thanks for that input Rick... you might be right..
while I was reading yesterday, I realized I have a set of roller rockers with a 1.73
ration... and I don't want to get near 0.600 lift ..
I bought these many years ago, good deal I guess, but like anything not a good
deal if you can't or don't use them..
again thanks
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taking a stock 351c 2v and enlarging the valves to that of the 4v 2.19/1.71
I'd recommend against it. The short side radius is the most important thing on Cleveland heads and too large a valve will hurt it. An intermediate size intake valve 2.08" or 2.1" works best. Keep the 1.65" on the exhaust side as you can flow over 200 CFM with them. The LSA in that cam was a mistake. For a 2V head, I'd recommend something in the 109 to 111 LSA range, 220 degrees or so @ 0.050 (270 degrees seat duration) depending upon the vehicle and other build specifics. For a purely street application, a single pattern cam or something with only a small split will work best. I typically test a shorter rocker ratio on the exhaust side and often see better average power. Since the time we did that series of dyno tests, Dave McLain had a series of Cleveland specific hydraulic roller lobes designed by Steve Ingram which are available through Demos Cams. The Performer RPM Air Gap dual plane is a good choice but in some combinations we find the old Holley Street Dominator 2V single plane works better. If you go with a dual plane, test a hybrid (oval on one side, 2 holes on the other) carb spacer with the oval over the upper plane. Try a 4 hole or HVH tapered spacer on the single plane. You didn't mention headers but you'll need those, along with efficient mufflers. It looks like you're interested in a hydraulic roller version of this build but with 2V heads:

http://www.the351cforum.com/viewtopic.php?f=4&t=656

Mike and Lori love the way that engine works on the street. You can mill the open chamber heads and/or block to bump up the compression but you might also consider a set of Keith Black KB149 domed pistons with the thinner ring pack. I'm not quite following you on the rockers but 1.73:1 is the stock rocker ratio.

Dan Jones
 
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