Anyone have a good setup to take a stock 72 351C 4V up to around 400HP? I'm looking for carb, intake, cam etc.. suggestions. Want to build a street motor that will be some fun to play with.

 

>Anyone have a good setup to take a stock 72 351C 4V up to
>around 400HP? I'm looking for carb, intake, cam etc..
>suggestions. Want to build a street motor that will be some
>fun to play with.

Assuming this is a US engine, you have either a CJ (9:1) or a 4V (10.7:1) with open chamber heads. If it is a CJ (like mine), the first suggestion is to drop some Aussie heads on it - raising compression to 10.7:1. If you already have a 4V and 10.7:1 (and I am assuming this is a US engine) then you have the open chambers and are likely having difficulty finding fuel to allow you to run without knocking. If so - again, the Aussie heads would help here too. Though the compression would stay the same, the closed chambers (if polished) would allow you to run on 92/93 octane pump gas with no knocking. The heads should be cleaned up (machined) a bit - typical stuff.

Next - get a dual plane intake such as the Edelbrock Performer, mated with a carb of at least 600 CFM (I would go 750 CFM), a K&N air filter, a moderate cam offering low-end torque, a straight-up timing chain, electronic ignition, a set of small tube headers, h-pipe, and dual free-flowing exhaust. Depending on cam, and on extent of head work you would be up to 330 to 350 HP at this point (more if you have a manual transmission).

To push it much further (more cam, high-rise intake, higher compression) will get you closer to your goal of 400 but will make it less 'streetable'.

 

>Assuming this is a US engine, you have either a CJ (9:1) or
>a 4V (10.7:1) with open chamber heads. If it is a CJ (like
>mine), the first suggestion is to drop some Aussie heads on
>it - raising compression to 10.7:1.

----> Open chamber heads do not give 10.7:1 compression... but closed chamber 4v's do, depending on what piston you use; remember, open chamber is low compression and closed chamber is high compression. Aussie closed chamber heads actually have a smaller combustion chamber than 4v closed chamber units, so 10.8+ would be more like it. But remember, they also have the smaller 2v ports and valves, which will not be able to yield 400hp without severe modification.

>If you already have a
>4V and 10.7:1 (and I am assuming this is a US engine) then
>you have the open chambers and are likely having difficulty
>finding fuel to allow you to run without knocking. If so -
>again, the Aussie heads would help here too. Though the
>compression would stay the same, the closed chambers (if
>polished) would allow you to run on 92/93 octane pump gas
>with no knocking. The heads should be cleaned up (machined)
>a bit - typical stuff.

-----> If you have 10.7:1 compression, you have closed chamber heads, either 2v or 4v. No open chamber head will yield 10.7 compression with stock pistons. And of course, both being closed chambered, 4v quench or aussie heads both give a quench effect.

>
>Next - get a dual plane intake such as the Edelbrock
>Performer, mated with a carb of at least 600 CFM (I would go
>750 CFM), a K&N air filter, a moderate cam offering low-end
>torque, a straight-up timing chain, electronic ignition, a
>set of small tube headers, h-pipe, and dual free-flowing
>exhaust. Depending on cam, and on extent of head work you
>would be up to 330 to 350 HP at this point (more if you have
>a manual transmission).

-----> All good for a conservative street engine with 2v heads, but if you want 400 hp you'll need to look at using 4v heads, large tube headers, single plane intake and 750+cfm carb, with a cam in the range 3000-6500 rpm. Ford Aus released a 4v 11:1 compression 351C in 71 which made around 380hp with stock 4v closed chamber heads, and that was with a dual plane intake, 780cfm holley, HM headers, aggressive cam and careful blueprinting for reliability at higher rpms. Needless to say, such an engine would require the use of a high-stall torque convertor if mated to an automatic transmission.
You can in fact order a 'Phase III spec' cam from cam suppliers in Australia. This was the most aggressive cam to ever come in a factory 351c.

 

I don't want to sound stupid but how can I tell the difference between the open and closed chmber heads? What do I look for?

This is definately a US motor.

 

>
>-----> If you have 10.7:1 compression, you have closed
>chamber heads, either 2v or 4v. No open chamber head will
>yield 10.7 compression with stock pistons. And of course,
>both being closed chambered, 4v quench or aussie heads both
>give a quench effect.
>

So - in 1972, since they had the 351-CJ with 4v heads at 9:1 and they had the 351-4V with 4v heads at 10.7:1 they must have been shipping both open and closed chamber 4V heads? I thought they were all open chamber by 1972, and got to the 10.7:1 by using domed pistons. I guess that would not be too plausible given the octane that would be required. Got me there.

>
>-----> All good for a conservative street engine with 2v
>heads, but if you want 400 hp you'll need to look at using
>4v heads, large tube headers, single plane intake and
>750+cfm carb, with a cam in the range 3000-6500 rpm...
>...the use of a high-stall torque convertor if mated to an
>automatic transmission.

It sounds like to get to 400, he would be making the engine less 'streetable' (power at higher RPM than typical for the street), at least for a daily driver. Perhaps if he wants a daily driver (not sure if he does) it would be better to start with a 400, 429, or 460 since they would yield 400 HP with less effort...

 

[updated:LAST EDITED ON 25-Apr-02 AT 06:39 AM (EST)]>So - in 1972, since they had the 351-CJ with 4v heads at 9:1
>and they had the 351-4V with 4v heads at 10.7:1 they must
>have been shipping both open and closed chamber 4V heads? I
>thought they were all open chamber by 1972, and got to the
>10.7:1 by using domed pistons. I guess that would not be
>too plausible given the octane that would be required. Got
>me there.
>

-----> Basically, open chamber heads will ping with even a moderate increase in comression (milling, pistons etc), and you will not be able to run 10.7:1 pistons with them without very high octane fuel.

>It sounds like to get to 400, he would be making the engine
>less 'streetable' (power at higher RPM than typical for the
>street), at least for a daily driver. Perhaps if he wants a
>daily driver (not sure if he does) it would be better to
>start with a 400, 429, or 460 since they would yield 400 HP
>with less effort...


To some extent, yes. He might be able to get 400 with 2v heads but will need to get them modified properly.

Oh, and with regards to the question about open or closed chamber head identification, the part number on the head will tell you, but cant be checked without taking the heads off, which would in itself let you see what tye they are. Hmm... basically, if it wont run on 87 octane fuel you have closed chamber heads. Not sure how else to find out without ripping them off.

 

The motor is apart, but I don't know how to tell the difference.

 

>The motor is apart, but I don't know how to tell the
>difference.

AHA! Find the casting numbers on the intake side of the head, should be D2??-???? or something like that. Post it here, and someone should be able to tell you. Or - just look at the combustion chamber. If it is round then you have open chamber, if it is more of an oval then you have closed chamber. This link takes you to a picture of some closed chamber (Aussie in this case) heads:

http://www.powerheads.com/351c.html

 

to tell the diff, open chambers are round bowls, close have about 1/3rd of the bowl filled in.

 

ok 400 hp from a 351

4v heads, closed chambered are better
2v aussie heads, port as much as you can, install 4v valves - this is a fallback setup
a high cr, @11:1 max
a single plane intake - wieand excelerator, holly strip dominator
750cfm carb
large headers - 1 3/4 - 2 inch
a good cam @ .550-.580 lift with 225-245 duration @.050


this should get you close to 400hp

 

HERE ARE THE ENGINE SPECS FOR MY 351C, DESK TOP DYNO CALCULATED 458 HP AT 6500RPM AND 413 FOOT POUNDS OF TORQUE AT 500O RPM, USED AIR FLOW FIGURES FOR STOCK 4V HEADS FROM "WALDENS".

STOCK CLOSED CHAMBER 4V HEADS 62CC
FORGED FLAT TOP PISTONS
WITH 30 THOU DECK HEIGHT THIS GAVE 9.9:1 COMPRESSION
EDELBROCK TORQUER SINGLE PLAIN INTAKE MANIFOLD
750 CFM DOUBLE PUMPER ANNULAR DISCHARGE HOLLEY
CAMSHAFT: SOLID 263 DEG. DURATION AT 0.050 INTAKE
273 DEG. DURATION AT 0.050 EXHAUST
0.578" LIFT INTAKE
0.595" LIFT EXHAUST
108 DEGREE LOBE CENTRE.
ROLLER ROCKERS
STAINLESS VALVES STANDARD SIZE
4MA CRANK
STANDARD RODS
FULLY BALANCED
1.75" EXTRACTORS.

ENGINE WAS IN A 3500 POUND AUSSIE XT GT 4 SPEED, RAN 8.00 ON 1/8 MILE.
WITH 8" TYRES. WILL GET MORE HP WITH LOWER DECK HEIGHT, ZERO DECK HEIGHT IS BEST FOR CONTROLLING DETONATION, BUT WILL INCREASE COMPRESSION RATIO, HOWEVER DIDNT HAVE PROBLEM WITH DETONATION USING 95 OCTANE FUEL AND 38 DEGREES TOTAL TIMING. THIS COMBINATION WAS OK ON STREET, COULD IMPROVE DRIVABILTY WITH LESS RADICAL CAM AND STILL HAVE 400 HP.

 

One of the better ways to get that kind of power is to stroke the engine. Scat make 3.85" and 4.00" cranks with Cleveland journals, but I don't know what will clear that block. The cranks list at $499. Check with Silvolite for pistons. You may not end up with 400hp, but you will end up with 400 ft/lbs of torque

 

[updated:LAST EDITED ON 01-May-02 AT 00:39 AM (EST)]ok if you go with the build i like.


10.5 cr with a 650cfm and stock headers
383hp @6000/ 374# @4500

10.5 cr with a 750cfm and large tube headers
469hp @6500 / 438# @5000

11 cr with a 650cfm and stock headers
392hp @6000/ 381# @4500

11 cr with a 750cfm and large tube headers
479hp @6500 / 444# @5000


now if anyone wants to know, i made my own flow table with posted flow rates for the 4v cleveland head. i will send that file if you need.

 

ok i have a ?....wahts the difference between 4V and 2V....adnd waht does 2 barrel heads and 4 barrel heads mean...its probably something small and stupid but i dont get it at all...thanks weezel

 

>ok i have a ?....wahts the difference between 4V and
>2V....adnd waht does 2 barrel heads and 4 barrel heads
>mean...its probably something small and stupid but i dont
>get it at all...thanks weezel

In the US, the Cleveland heads were either 4V or 2V - named for whether they were mated with a 2V or 4V carb. The 4V heads have larger ports (too large for most street applications) and large valves. The 4V heads are great for high-revving HP, but the large ports hurt low-end torque due to low port velocity. The 4V heads were available in open or closed/quench chamber. The quench chamber raises compression but allows higher compression without detonation (to a point).

The US 2V heads had the smaller valves and ports, and have the higher port velocity that is good for low-end torque. All US 2V heads were open chamber, so they don't support higher compression very well (I would not go higher than 9.5:1 on pump gas).

The Aussie heads have the 2V port size and valve size, but with closed chamber. For street performance, this is ideal. Even better if you increase valve size and massage them a bit. Specifically, polishing the chambers is a good idea to control detonation.