Ford Forums banner

1 - 20 of 21 Posts

·
82XE 351c
Joined
·
628 Posts
Discussion Starter #1
Hey all

need some advise from you guys already running some bigger cubes. What Jet sizes for both the prim and sec and maybe power valves..

specs are;
408c 10.6 comp
268 272 dur 620 620 lift 112lobe
AFD 4V, TFC high plenum intake
C4 only 2400 stall at the moment

Caby is out of the box Proform 750DP....

can you say what you use and your cam specs pls...(c'mon brenx)
just a good ball park to run the motor in..... the proform comes with something like 74 in the prim and 80 something in the sec...

cheers all!!!
 

·
Registered
Joined
·
397 Posts
do you know what your manifold vac is in gear?
Id leave it as is then do a wot run and read the plugs after killing the motor at peak revs, that will tell you straight away which way to go with jetting
 

·
74 XB Fairmont
Joined
·
5,113 Posts
You've got more cam than I do.

I've got 76's in the front and 80's in the rear with a 4.5 powervalve. That's an 830 anular carb. With a 750 you might want 76 in the front and maybe 82's in the rear. Air will flow faster through a 750 than an 830 due to the smaller venturi size.

That 408 will run like a dog with a 2400rpm stall. F246 with 351ci didn't like 3300rpm stall.
 

·
Registered
Joined
·
1,946 Posts
brenx said:
With a 750 you might want 76 in the front and maybe 82's in the rear. Air will flow faster through a 750 than an 830 due to the smaller venturi size.
Remember, you are talking more "volocity" with the 750, not more airflow.
 

·
Registered
Joined
·
1,946 Posts
Dont assume it will need bigger jets to get more fuel. If it has a lot more volocity in the 750 comapred to an 830, it will draw more fuel through the venturi with the same jets. I wouldn't be guessing. I run 77 and 85 in my 351c with the 750 BG and with my 850 BG it needed 82 and 90. Since the 850dp didn't have the volocity with the smaller 357c capicity, it needed bigger jets to stop running lean in the top end as it didn't have the airspeed to draw fuel enough/correctly. And ofcorse it ran rich down low, so this is why it is important to select the correct "airflow" carby for a particular setup.
 

·
74 XB Fairmont
Joined
·
5,113 Posts
xdclevo said:
Dont assume it will need bigger jets to get more fuel. If it has a lot more volocity in the 750 comapred to an 830, it will draw more fuel through the venturi with the same jets. I wouldn't be guessing. I run 77 and 85 in my 351c with the 750 BG and with my 850 BG it needed 82 and 90. Since the 850dp didn't have the volocity with the smaller 357c capicity, it needed bigger jets to stop running lean in the top end as it didn't have the airspeed to draw fuel enough/correctly. And ofcorse it ran rich down low, so this is why it is important to select the correct "airflow" carby for a particular setup.
I'm going by what I ran on my 750carb. It had 76 in the front and 82's in the rear with a 4.5 powervalve.

The 830 was jetted for the 351 and guess what? The jets were perfect for a 393 ;)
 

·
82XE 351c
Joined
·
628 Posts
Discussion Starter #7
its my cousins...
this motor is only new so we wont be holding WOT for a fair while yet....

The story goes, finished build, put around 1,000kms on the clock and then bolted on the proform 750dp which seemed to run fine.
The stall does suck but this thing seems to be able to produce more than enough torque to get it going. The stall is only there until $ allows a bigger one.
complete bare metal XF ute in blood orange and this motor all in 1yr has hit the bank book hard...

anyway, its go a 7lt sump.. was cruzing on the highway and just heading over a slight hill will slight load heard a knock, clearly.
Turned the key straight away, as he did the oil pressure light come on.
(running no pressure psi gauge when it happen)
Towed it home and check sump, had only 4lts left!!

So it got pulled, look all over the bearings, bore and all check fine. Some new bearings went in and it went back together. didn't remove the heads.

so all is finer, but want to make sure the tune is better this time as all it could be was fuel washing? compression test has came back fine...

cheers all
 

·
74 XB Fairmont
Joined
·
5,113 Posts
Worst thing you can do is not load them up. Another bad thing you can do is have it understalled. The stall will be causing overfueling. I'll give an example:

My prior 351 used 72lt's to travel 200-220k's with a 3300rpm stall. Fitted the 5200rpm stall and did the same trip on 35-38lt's of fuel. Tune untouched. Only change was the stall.

Till the new stall covertor goes in. I'd suggest not driving it. Otherwise he'll wash the bores.

Mine had hit max rpm within 2 hours of cam run in. In those 2 hours it had a cooling period and inner springs fitted.
 

·
Registered
Joined
·
330 Posts
Brenx was that 3300 stall with the f246 cam? and the new 5200 stall with the same cam? I have the svo 248/258 596/606 solid and originaly brought a 4200 9" stall through QCES but sold it before i ran it as i needed some bucks and starting my donk was and still is a while off. The Q is do you think this stall is sufficent in a 351/2v/ xy wagon weight 3600 pound's and 3.89 lsd and 26 inch tall tires? Engine should put out around 430-440 at the engine through my TFC manifold 750 Proform, Magnafuel fuel system, MSD 6 Digi Spark and MSD Dizzy, have more specs of engine available. I am looking at a Allfast or TCE converter shortly, I wont use QCES as mates car went slower with one of there converter's and it's put me off a bit. I should open a thread about Stall converter brands perhap's!
AZZA
 

·
74 XB Fairmont
Joined
·
5,113 Posts
azza said:
Brenx was that 3300 stall with the f246 cam? and the new 5200 stall with the same cam? I have the svo 248/258 596/606 solid and originaly brought a 4200 9" stall through QCES but sold it before i ran it as i needed some bucks and starting my donk was and still is a while off. The Q is do you think this stall is sufficent in a 351/2v/ xy wagon weight 3600 pound's and 3.89 lsd and 26 inch tall tires? Engine should put out around 430-440 at the engine through my TFC manifold 750 Proform, Magnafuel fuel system, MSD 6 Digi Spark and MSD Dizzy, have more specs of engine available. I am looking at a Allfast or TCE converter shortly, I wont use QCES as mates car went slower with one of there converter's and it's put me off a bit. I should open a thread about Stall converter brands perhap's!
AZZA
Start a thread and I'll post there.
 

·
82XE 351c
Joined
·
628 Posts
Discussion Starter #11
how does the small stall cause over fueling?

He is only running 3.0 diff gears as well, this would not help that situation...
 

·
74 XB Fairmont
Joined
·
5,113 Posts
carb's trying to fuel for a higher rpm than the engine can do due to stall rpm and diff gears. It's like opening the secondaries @ idle. It just floods before it goes.
 

·
1970 Torino GT 408C
Joined
·
26 Posts
pracy said:
Hey all

need some advise from you guys already running some bigger cubes. What Jet sizes for both the prim and sec and maybe power valves..

specs are;
408c 10.6 comp
268 272 dur 620 620 lift 112lobe
AFD 4V, TFC high plenum intake
C4 only 2400 stall at the moment

I think the 750 is way too small.
 

·
82XE 351c
Joined
·
628 Posts
Discussion Starter #15
i would have thought that as well, but in that case what has caused the oil the dissapear?

the the jetting is ok, the stall or something else must be the problem as what else can it be other than washing of the bores?

mind you if that was happening, i thought we would have seen more damage?....

either way hi lost enough oil to cause a knock! any ideas?
 

·
74 XB Fairmont
Joined
·
5,113 Posts
You are aware that the gudgeon pin on a 408 kit on a 9.2" deckheight block sits in the oil ring land. In english this means oil consumption for a street car. I'm sure someone else on another forum had the same issue and it was related to the type of rings. The rings supplied weren't suitable for the application. Which caused all sorts of grief.
 

·
74 XB Fairmont
Joined
·
5,113 Posts
Here's what the user stated

I have had a huge issue with oil control on a 408 Cleveland. Since learned that the only rings available are super low tension oil rings, not great for the street engine that it is. VPW supplied the kit and are saying that standard tension oil rings are not available for this setup. 1/16,1/16, 3mm oil ring. Can anyone tell me where I can source the rings I need?

Had a lot of oil in the breathers, had to install a puke tank. Then it turned real nasty. After holding at 5800rpm in top gear, 3.0 diff, for about 1 min and then came to a stop, noise developed in engine. Shut it off and towed it home. Pulled it down to find a spun rod bearing. Top of pistons and combustion chambers coated in thick carbon layer, and telltale signs on 2nd ring that it was not coping with oil control. Motor had not done 5000km. Only after this did I realize that the oil rings were of the super low tension variety. It is a pure road car, so standard tension oil rings are vital. Oil ring on the 408 is only 3mm. other than this issue, engine does everything perfect. Tows 2 tonne trailer, aircon, power steer, 2300rpm stall, idles at 550rpm, makes power to 6300rpm. AFD 4V heads, TFC manifold, small custom solid flat tappet by CompCams 236, 242 at .050, 112 lobe centre.


Fix

Ended up getting a non-gapless file back set from Totalseal. The whole issue was the "super low tension oil rings" that came with the kit from VPW. My fault for not checking, but when you order a low compression piston set with the kit and specify it is for towing, you would think the salesman would put the right ring kit in, not a set for racing requiring a vacuum pump. They cant even supply a standard tension oil ring set. Not bagging VPW, I get great service from them, just this instance where it all went wrong and never should have. Oil restrictor kit was fitted from start. The new set has standard tension oil rings, so it should be all good now.
 

·
82XE 351c
Joined
·
628 Posts
Discussion Starter #18
thankyou brenx, we were not aware of that issue!

Funny thing is, that story could have been for us just as easy, everything except his cam is the same almost.....

We had just fitted a vacume tank before this happened also! OK so next things to check is what rings he was supplied...

This would explain the very very low vacume, and the oil comsumption..
 

·
74 XB Fairmont
Joined
·
5,113 Posts
Some oil consumption with a 408c is normal. A lot isn't. I showed another forum user the oil consumption of my 393. The same oil's been in my engine since Dec 05. Oil's still sitting on the full mark ;) No oil consumption at all is fantastic.
 

·
82XE 351c
Joined
·
628 Posts
Discussion Starter #20
yeah my 351c is the same, I can go 6 mnths without needing oil. I tend to change it before i need to top it up, but i change it often...

is there any more info on this subject? i am looking for the ring specs that we used now...
 
1 - 20 of 21 Posts
Top