Ahem! Please limit trading discussions to email ONLY! FTE does not allow buy/sell/trade discussions in the forums.

According to the rules I should edit out all of the trade discussions, but I will trust that a warning will suffice and you guys will behave now.

 

Dear DSC, as a 400 owner who has been through this engine many time learning about it, please consider these (and ALL the above advice):
1. do not trust a calculator, do all the measurements and math yourself... CC your heads yourself, measure your bore, etc. Do your own geometry! (the old measure twice, cut once theory)
2. Do not trust anyone else's numbers!!! mic all your journals (at several indident angles) etc, if there is a published factory number that goes with it, YOU check it YOURSELF! Yes, it takes time.
3. Detonation issue: I am thinking, and your new math will confirm, your ratio is too high.
3.1 Distributor: Guessing not it, unless defective, a vac advance adds more advace when ported vac is high, I presume yours has same(or near) total advance, based on RPM, a distributor machine (or timing light) can check this.
4. HV Pumps. I totally agree with Shazam, do not use HV pump... old Daytona Land Speed Holder Mr. Jones (when they ran on the beach in 50's) told me "that will wash out your bearings". Don't know if I agree with the statement prima facia but if tolerence is right, you don't need it.
5. Plastigauge: Use it on as many journals as you need to until you feel confident. Use assembly lube for the fit measurement.
6. Assembly Lube: I do not like the Moly stuff. Rub it between your fingers, kinda rough, eh? Hmmm..... Clevite or similar.
7. Bearings: will be stamped on back as to fit ( to check what you had)
8. Oil guage: the ford factory guage is a POS. get a mechanical guage (sounds like you might have.)
9. Brian has a great point... old harmonic balancers should be thrown it the trash. Get a new one. If you are running the original 78 balancer, it is past it life expectancy. A static timing check will put you within a few degrees and verify the marks are at least close.

Having done this a bit (and will do it a few more times, and learn more), Gl to you and hope some of this is of helps.

 

thanks for the responce. How could my compression be to high if I used the stock pistions for the 351m and the Aussie heads?I am not understanding something here. Don't people just bolt these on? Compression read 170lbs per cyl. please set me straight on this. Thanks Art

 

Never seen or used those heads... however, think of it this way. On any given 351 or whatever the area swept by the piston is constant, so if you start driving the combustion chamber size down you will reach a point where small reductions in chamber size begin to make radical increases in ratio. I think we are all guessing here that you stepped over that line.
Also, I almost forgot, and I think no one has mentioned yet, lean mixtures will also cause detonation.
So the three causes of detonation and/or pre-ignition are:
1. Ratio too high
2. excess advance
3. lean air/fuel
Did I miss any?

Static compression tests are, IMO, a diagnostic tool, unfortunatly what we really want to know is the dynamic cylinder pressure, and the vast majority of us can't afford the thousands of dollars to get that number.

After you CC those heads, compute swept volume, and allow for the head gasket thickness...put you numbers here, I am sure several of us would be happy to check your math for you.

Once more, GL

 

It's not that your compression is to high ... it's that with the Aussie heads you get a quench area because of the D shape combustion chamber.. Well it well only be of benifit if you have Zero to .10 Deck clearance ... and with the 351M pistons I think it's more like .35 to .50 on the deck...So your getting a big hot spot on the back face of the D chamber, that's what's causing your ping ....

 

Also Torque1st I'm very sorry for what I did ... I'll try NOT to do that again ...

 

"How could my compression be to high if I used the stock pistions for the 351m and the Aussie heads?I am not understanding something here. Don't people just bolt these on?"

Normally it's not a problem with the 351M, but based on the compression test, something else is up. The stock chamber size is 78cc, with stock dished pistons that should give 8:1. If the heads are the only change AND if the new heads have a 62cc chamber you will have 9.25:1.
If the heads were milled, the chamber can be as small as 56cc.
a 56cc chamber will give you 9.85:1
If the block has been decked .010
you'll have 10.09:1
A .030 overbore
will give you 10.23:1
If the pistons are flat tops instead of dished
you'll get 11.4:1

I can walk you through any compression calculations, but I need actual measurements to do it accurately.
These are the measurements you need to provide.

Cylinder Head Volume (cc) - 78cc stock
Piston Head Volume (cc) - 13cc stock
Gasket Thickness (in.) - .040" stock
Gasket Bore (in.) - 4.100" stock
Cylinder Bore Diameter (in.) - 4.0 stock
Deck Clearance (in.) - .017" stock
Stroke (in.) - 3.50" stock

 

As Brian indicated without the accurate measurements we are just guessing…

So here is my guess….
Assuming the “Compression read 170lbs per cyl.” is close and the 272H ( 133042 ) is at zero degrees advanced then the intake closes at approx 65 degrees ABDC. Assuming 4.030 bore and stock rods then:
Working the math backwards in my excel sheet I get 8.2 effective compression that yields 10.4 normal compression ratio.

Just my guess…

David

 

Thanks for all the replys, Here is a new bit of Info. I looked on the box of the pistons It says,

Badger Pistons P745-30 (.30 over)

Cyl. Clearance .0015 At 0.93 up from the bottom. Cyl Bore 4.0

The Aussie heads I bought were from the Guy down south. I Bought them them on ebay. He show a picture of them standing on end I do not know the cc's though.

 

Everyone I found the cc's of the Aussie heads. They are 54 cc's. With the above pistons. Is there a problem?

 

Cylinder Head Volume (cc) - 54cc (where did this number come from?)
Piston Head Volume (cc) - 13cc stock
Gasket Thickness (in.) - .040" stock
Gasket Bore (in.) - 4.100" stock
Cylinder Bore Diameter (in.) - 4.030"
Deck Clearance (in.) - .017" stock
Stroke (in.) - 3.50"

3 down, 4 still unknown
Based on the new figures and remaining guesses you're about 10.2:1.

 

54cc's? everything i have seen they were around 58cc's stock.

if they were measured at 54, then i am surprised.

 

My Mistake 58.4'cc. The same heads and the same person I bought them from is selling a pair on ebay now,

This is what I have instaled.

One pair of Austrialian 2V closed chamber heads for 351 Cleveland or similiar motor. These heads fit all Ford "335 Series" engines, 351C, 351C Boss, 351C HO, 351M, 400M, and 302/351 Clevor.They are 100% stock good-rebuildable condition with no prior machining or modifications.All American head valvetrain components are a direct bolt-on replacement. These heads have the following Hi-Performance benefits & features: 1) Disassembled, hi-pressure washed, shot blasted, and thoroughly inspected, featuring like new looks. Pictures represent typical heads.2) 58.4cc "Quench" hi-compression fast-burn closed combustion chambers.3) Small hi-velocity 2v intake ports, 1.34" x 2.00". 4)Small hi-velocity 2v exhaust ports, 1.33" x 1.78". 5) Stock size 2.04" intake x 1.65" exhaust seats.

With these pistons :

Badger Pistons P745-30 (.30 over)

Cyl. Clearance .0015 At 0.93 up from the bottom. Cyl Bore 4.0

Is this a good configuration or trash them, both!!

 

We can keep guessing forever. You should be able to get accurate volume information from the piston and head gasket manufacturers. Deck clearance and combustion chamber volume have to be measured directly. Not what you read somewhere or what the Guy on Ebay told you. You'll never get a consistant number.

That being said, I really don't think the compression is too high. It's close to 10:1. You may not be able to run as much timing advance that has been recommended, but it certainly isn't justification for rebuilding the engine a second time. I do suggest you disassemble everything and check for any damage or incorrectly installed parts. All it will cost is a set of gaskets and your time but at least you'll sleep better knowing everything is OK.

 

I agree with Brian ... check it for damage and then Plastic Gage the Rods and Mains ..... Also do piston to valve clearance on reassembly and set the cam for proper Valve clearance...
Also check for piston to deck height ..Write this all down in a note pad so you have it for future referance...
Maybe you stumbled on to a killer set-up for the 351m..