Hello Where dose one find the intake adapters ?
do headers that are on a 77 1/2 to 79 f250 4x4 fit in a set of v4 us made heads?
Im woundering if v4 open chamber heads is the way I want to go..
this is what I am running as of now..
79 f250 4x4 converted 351m now 400+cid
flat top pistons spring hight .1880
cyl head vol is measured at 72cc cast # mcc d 5aea-2a
piston head vol 4cc cylinder bore 4.040
deck clearance is .077
cam is clevite duration 214/224 lift 510/536 advertised 280/290 center line 110 ( time set is at 0 or tdc)
carter 625 on a duel plane edelbrok 4v intake for the 400
all runs into 3" exahust with simple glasspacs then 5" bologny cut stacks in the bed.
C6 auto with a 2000 stahl
has the HEI distributer and is timed at 10 btc...ONLY rUns on 93 oct mabe 91...89 is right out...
so I would like to know should I get a set of pre 75 v2 cleveland open chamber heads and put big valves in them....or go with a set ov v4 open
chamber heads?
I have both intakes...I dont mind buying adapter plates...I dont want to find new headers...
any direction would be great...any one with numbers for comp and cr ?
I be back later.
PS this an on the street toy only run 31"tires..some times off in the corn field
Thanks.
J.P.

 

http://www.tmeyerinc.com/what'snew.html

 

I modeled both as much as I could. I don't have flow data for open chamber 4V heads, and my flow data for the 2V heads is for ported heads. My results say that there is hardley any difference.

I used 76.2cc for the 2V heads, and 75.4 for the 4V heads, and used 4V valves for both simulations.
The CR is 9.08:1 for the 2V, and 9.14:1 for the 4V.

For the 2V heads, torque = 376@2000 RPM, and 416@4000 RPM, HP = 363@5000 RPM.
For the 4V heads, torque = 383@2000 RPM, and 415@4000 RPM, HP = 363@5000 RPM.

The Dynamic Compression Ratio is 6.97:1 with the 2V heads and 7.02:1 with the 4V heads.

With 72cc (?) heads, the CR is 9.42:1, and the DCR is 7.22:1. I am suprised that you can't run on lower Octane fuel with that DCR, but neither of those heads will help much. How about your advance curve. What is your total advance?
The IVC on that cam comes out to 70 degrees ABDC, you should be able to run with less cam, and an IVC of 60 degrees ABDC, or with a lot higher CR.

 

With 72cc (?) heads...that # came from milling the heads...head gaskets I am useing are .041 thick. I measured the volume with alcahol and seringe..they must have been cut before I got to them...What is your total advance? I have no idea shoot me a link to how I do that..the unit is out of truck and I thought now would be a good time to putz with it again..as gas is around $3.50 now and as a toy, MPG is moot.. cam change is out..should I port pre 1975 v2 heads and go with large valves? or work on the distriburter first? or find some closed chamber heads?aussi or US V4..AND The IVC on that cam .. whats IVC ?.
thank you.
J.P.

 

Closed chamber heads will not help, because your pistons are 0.077" in the hole.

Buy, borrow, or rent a timing light with a delay dial on it. You can use this to dial in your advance, while someone revs up the motor. Your total advance occurs when the advance stops increasing. The total advance should be around 34 degrees. The RPM at which it reaches maximum is important also. You don't want it to reach 34 degrees at too low an RPM range.

IVC is the Intake Valve Closing angle. It is the angle of the crankshaft when the intake valve closes. Compression begins approximatly when the intake valve closes. If the intake valve never closes, there is no compression. The Dynamic Compression Ratio is the compression ratio calculated based on the stroke remaining after the intake valve closes. In the case of a 400 with a 70 degree IVC, the stroke used for this calculation is 2.96".

Does your pinging occur at light throttle, or under heavy load?

What kind of heads are on it now?

 

cyl head vol is measured at 72cc cast# on the heads is mcc d5aea-2a..

pinging occurs at light throttle on 89 oct.
no spark knock ever with 93 oct..
how would I go about getting like you say higher CR... The IVC on that cam comes out to 70 degrees ABDC, you should be able to run with less cam, and an IVC of 60 degrees ABDC, or with a lot higher CR...As far as total advance that will have to wait till I drop the pac back in... chainging my time chain set up from tdc to 4* before or after.. would that add any thing to zip with that cam?.. what would I gain if I buy another block and have it decked and use my stuff to rebuild it?..
check back later.. Thank you. J.P.

 

Light throttle pinging indicates lean mixture and/or too much ignition timing advance too early. You should try to richen the mixture by changing the metering rods to get one stage richer in Cruise Mode. You can use the chart from the Edelbrock website to find the jet/metering rod combo. You can also use Edelbrock parts in a Carter. You can also go to stiffer springs to get you into Power Mode sooner. Check your ignition timing advance curve.

Advancing the cam timing 4 degrees will close the intake valves 4 degrees sooner, and increase your Dynamic Compression Ratio 7.46:1. It will improve the torque at low RPM, but reduce torque and HP at higher RPM.

A nice set of Alloy heads with about 64cc chambers will work very well with what you have. The DCR would be about 8.0:1. The alloys resist detonation due to the better thermal dissapation.

Edelbrock, CHI and AFD make nice 2V alloy heads. I prefer CHI or AFD, but the Edelbrocks seem to be OK. I am using CHI-3V heads, but the 2V heads will work fine on your motor.

A set of those heads will be cheaper than starting over.

 

Hello ...OK so for now I will go ahead and pop the time cover and set the gear to 4* advanced from TDC and when I get the engine back in I will look at my total advance and what RPM it is at also.....and look into Edelbrock, CHI and AFD make nice 2V alloy heads....I will close this chapter with one last question.....when I advance the timeing gear to 4* advanced...will I have to re set the distributer...or leave it as is...as it is correct now?...and a thank you for your time and knowlage....
stay tuned for the continuing saga.
Thanks much. J.P.

 

Advancing the cam 4 degrees will also advance the dist., since the cam drives the dist. So you will have to reset the dist timing.

I wouldn't rush into changing the cam timing if you are considering changing heads. A set of heads that gives you higher compression will be better suited to your cam at zero degrees.