I can only say that all the helpful people on this forum should be bottled up and sold. Thanks so much in advance!

Ok, I'm in the home-stretch with my '78 shortbox restoration and I'm doing the 351M now.

I've got my aussie heads done and they look great. I've scanned and searched this forum for all of my rebuild info, but I have just a couple more questions to be answered this weekend before they start working on the block Monday.

1. I'm keeping the stock pistons and want to be sure I understand this "quench" thing with the Aussie heads. From reading here, I understand that these work better with the 351M because the pistons come closer to "zero deck" than with a 400, correct? But, to make the best use of this combination, should I have the machine shop mill the block to make this the best combination, and if so, how much? Knowing the head gasket adds about .030, what should I do?

2. If the block is milled, does that mean I need to take the intake down (Edelbrock Performer) to him because it too will need to be "shaved" some amount? How about the heads? Hopefully I don't have to do anything to them as they are stock and perfect.

3. I've replaced everything except the rocker arms and don't want to cheap-out on this last step. Rather than put the stamped ones back on, I'd like to put roller rockers on. I've read others doing it, but does anyone have the specific part numbers to order so I don't have to do machining on these heads? What did you get and were they hard to setup?


Again, thanks in advance for advice. The block and rotating assembly was dropped off at the shop yesterday to clean everything up and get it prepped for assembly. Just need to know if there is anything else I should order to really make this all work perfect.


Parts going into this rebuild: (in no particular order)
1. Comp Cams X-Treme Energy 4x4 cam with 210/218 duration @ 0.050" lift-.508/.524 lift with 1.7 rocker arms(#32-000-5)Grind #(FC 5402/5442 H111), 1000-5200 RPM Range
2. Comp Cams lifters, push rods, dual springs
3. New Balancer
4. New double roller timing chain
5. Edelbrock Performer
6. Holley 600 (fancy polished one! hehe)
7. Hedman fenderwell ceramic coated headers
8. Rebuilt Aussie heads, valves, 3-angle etc.
9. ??? roller rockers and conversion kit. (need numbers!)

John

 

Optimal quench distance is .040" -.045" so assuming your heads are the Aussie 302C closed chamber variety you're looking at getting the piston tops to around .010" below the deck. Your machinist should "square up" the deck and then measure the height to see what you're going to need as far as piston compression height. Also keep in mind that many 'stock rebuild' type pistons have a reduced compression height of .010" or more to make up for the fact that many rebuilders automatically deck the block as part of the rebuild process.

Have you figured out what your C.R. is going to be with the stock dished pistons and the Aussie heads?

Crane makes a conversion kit P/N 52655-16 which converts the stock heads without any machining. Once installed you can put any flavor of stud mounted roller rocker on you like.

 

You can get your conversion kit though summit, But I ran some with one step bigger cam and they flexed and ate up my vaves and vaveguids.I get the dogears cut off and have them redrilled for 7/16 studes, BBchevy studes and guidplates will work. I would say it depens on how much you cut off the block more then .020, you will probly have to take the same amout off the intake. If you don't mined wine I would put in a geardrive, make them wonder what is under the hood . The one I got was not that hard install but I did have git it cut on before I could put it in. And you can tune your cam to get it all the power out of it. I think we fiugerd that the gasket is about .038 compressed. My quiench is .046,,, And the way I understand this is from the top of the piston to flat surfas of the head.

 

Most of the time I have heard 0.040 for a compressed gasket thickness.

Watch your compression ratio.

 

I'll use .040 for an estimated gasket thickness on the heads. So, if I read everyone correctly, I should make sure the machinist gets me about .005 to the top of the deck with the pistons to make these small chambers aussie heads work best. I don't mind using 93 octane if it will keep them from pinging.

Any recommendations as to which roller rockers you've used and liked? I'll search the forum some more for setup info unless someone has a reference website for me to look at. I'm always appreciative for quality links when it comes to getting this done right.

Also, anyone have a link to that excellent rebuild that guy did to a 78-79 bronco where he documented everything from restoring all the parts etc? I remember something about it being from Alaska or something, but I cannot find it in my favorites anymore.

(being over 40, the memory is the first to go!)

Thanks again everyone.

John

 

According to my numbers the Cam Intake Valve Closing occurs at 35 degrees ABDC. This means that your dynamic stroke is 3.26". The dynamic compression with 62cc heads, 0.040 gasket, 3cc piston valve relief, and 0.010 deck clearance is 9.87:1. That is well above the maximum DCR of 8.5:1 for 91 Octane. Even 93 Octane will not be enough for this motor.

If you go to zero deck clearance to get a quench effect, you will increase the DCR to 10.16:1. Even with a quench effect that is too high.

These calculations are for a flattop piston. If you have a dish you could be OK. Let me know what pistons you are using, and if you are bored oversize.

 

These are aftermarket pistons that I 'inherited' with the motor. It was rebuilt by someone before I got it and do have a dish in the center of them. As far as who's, I am not sure. The had a "made in Canada" cast inside and a part number (from memory so this may not be valid) of Zxxxx. Can't remember. But there were valve reliefs in both sides and were dished. As far as overbore, I cannot tell and will find out Monday when they check the block. The crank was already 10/10 and looks to only need a polish to clean it up.

Thanks in advance.

John

 

If you don't want to machine the dog ears off, you could use ford motorsport part #M-6564-C351. This rocker arm is a bolt on rocker arm, just like stock, that comes with everything you need to run a standard hydraulic cam. Ran these on the 400 in my grandpa's race truck, turned 6500, no problem. These are pedestal mount rockers. Hope this helps.

 

BTW, cost is around 325.00 out of PAW.

 

I have Crane roller rockers on mine, They do rattle a little but can't hear it over gear drive. So it's all go.

 

I opted to order the Ford roller rockers (M-6564-C351) from Summit for $259.

I'll try to get the piston info Monday.

Thanks again everyone!

John

 

Lifted 78,

sorry about bein off on the price, bought them over 7 years ago. But hey, at least i was wrong in a good way!!!!!!!

 

I double-checked the cam specs and I posted the wrong ones for my motor. Here's what I really have:

32-000-5
Grind # FC 5433/5216 H110
Lift: Intake .516 Exhaust .520
Duration at .050 224 / 230

INT Timing Open 2 BTOC Close 42 ABOC
EXH Timing Open 45 BBDC Close 5 ATDC


So maybe Danlee could redo the math to see what this combination will do?

Thanks, again, in advance!

John

 

That cam is similar to the Crane H278-2 that I have been using in my 400. The Crane has a little more lift. I just removed it to go to a hydraulic roller @ 0.595 lift.
I actually need the Seat-to-Seat numbers for the DCR program, but I used an IVC of 70 degrees. That is close to the 72 degrees IVC of the Crane cam.
The Dynamic Stroke Length is 2.65"
Using a 10cc dish and 3cc valve relief, 0.040 gasket, 0 deck clearance, 62cc combustion chamber, the DCR is 7.3:1.
That should be OK with 87 or 89 Octane.

 

Danlee (can I call you Dan?)

I figured out DCR as Dynamic Compression Ratio, but what is IVC?

Also, what is the difference between Static Compression Ratio and DCR? Are most motors rated in SCR?

I looked at this as a reasonable option seeing that my '03 Mercury Marauder with the 4.6 DOHC motor runs 10.1 compression on Premium and puts out well over 340 hp to the rear wheels. (specs here)

Where do I download or get the program everyone is talking about that does the desktop dyno thing?

New Parts Dept.
I've added a Mallory Unilite vacuum advance distributor to my parts list last night and need to decide on the coil yet. Honestly, I just can't wait to get this together!