If you know or can find out I'm curious exactly what 427 and 428 heads you have. Look for the casting number. Most are between the center 2 sparkplug holes. Some guys just don't know except what they hear and beleive. Reason I ask some of the 427 heads have a wider valve spacing. And the 428 heads are either CJ's or numerous other std FE heads that came on the 428 and other engines besides. No sense dumping a ton of money into a regular set of heads if they are shot when a pair of good core heads might be in order. Also if they are really 427 specific or 428CJ heads you can sell a set to help fund the others possibly. It helps to know exactly what you have and are working with. Just a thought....

G.

 

If my rusty brains correct with all the data I recall 427 MR heads on a 428 (4.130") bore you had to notch the bore for valve clearance. 427 LR heads will work on 4.05" 360/390 bore motors without notching the bore.
Strange how the 427 LR heads have 1.34" x 2.34" ports while the MR had 1.34" x 1.94" ports and flowed the same what I have read in the past.
Look at the motor specs Barry R produced with 1.65" exhaust valves were talking 752 HP on pump gas.

 

Well JMO... with my forgotten brain cells..about the FE builds..As I have other things now in my head... But I remember the Valve spacing being wider in the 427 heads...

and I believe with the slightly smaller port..that was to keep the Air/fuel Velocity up for some low end.....

But all this is just speculation .. as I have lost all of my reference Data....on the desk top confuser...

But I do know depending on what the heads will flow... (handle) some times a larger Intake Valve will make more top end power....and some times not....and that also appies to the Exh. Valve's.....Going with a little smaller Exh.. Valve will bring in the TQ earlier than a Larger Valve will... As I remember?

RJ

 

The 427 LR heads have the same valve spacing as regular FE heads, MR, HR and tunnel ports have a wider valve spacing. The wider spacing will contact the cylinder walls on small bore motors even if they could clear on the smaller than 4.230" 427 bores you will have the gas flow inhibited by shrouding from the cylinder wall.

From around 1964 onward on 427 LR heads the intake port had a venturi ring under the seat to help enhance low end torque by increasing the low rpm fuel mixture velocity.
I have run 427 LR heads with this venturi ring and without on the same 454 motor years ago and honesty could not tell the difference between the two at low rpm's. Maybe the larger displacement helped keep the gas velocity higher than a 427 motor. I know there were more cfms of flow with the venturi ring removed with a valve held at .530" off the seat, this with a tulip intake valve vs a OEM nail head design valve.

Russ, i'll have to dig out the photos I took months ago on the C4 heads I freshened up in February and send 'em to ya I know you asked about them waaaay back then.

 

I appreciate that carl... I really would..... See just goes to show you what I know..I never heard of a venturi ring under the intake valve??

And yes The more displacement would mean....More velocity in the intake with the same port size for a given RPM.. at a given Carb flow..that would match what the heads were capable of handling along with the right cam and CR...

Buy why would ford make a 427 LR head with a smaller Valve spread? That one I dont understand? we are both machinst....and it just doesnt make sense.... Smaller Valve's in the same location....I know that..but a different Valve spread?

RJ

 

Russ that's where the MR came in handy with the shorter 1.94" port that flows the same plus wider spaced and larger valves. I could never match my funds to when the opportunity came up to purchase MR heads hence the last 414 build with LR heads. That was suppose to be another 454 build with 88cc chambered MR heads, ended up with a baby 414 motor that has served me well for a daily runner.
Now a 4.310" bore x 4.250" stroke with BT heads and MPI would make a nice little 496" daily street driven motor.

 

Well Carl, that makes sense.....on the heads....

My finances are also in the ****ter....even after getting rid of the 428 Stroker build parts...So I have decised to go another way... But Not for the 70 F250.... I still have a 428 crank....and I'll street port the C4's I have...Go with another Cam choice... and bring the CR back up to 9.5 to 1...and keep the long tube Hedmans on it...do a little diffrent exh, system on it... and leave it at that..other than some new paint and change the wheels and tires out too... i have droped about 500lbs of weight from the truck now..and maybe look for some more in the ash tray come spring?? LOL

But I just spent a Butt load of money on the new Heating and Air system in the house.....LOL... But thats life...

RJ

 

Yeah a cold wife in the winter isn't something you want to tangle with not alone an overheated one blowing a gasket in the summer heat.
My AC is a removed panel on the furnace blower, cold air return sealed off to suck under the house cold air thru the heating ducts. Poor mans AC that gives a little under the house wood smell. Hell the blower fan relay took a dump, costs $26 to replace with a 3 day wait, took that sucker apart and adjusted the points works great saved $26.

 

Well thats COOL... I did a deverter valve in one of the fresh air returns... One when closed will claim fresh air from inside the house as normal....when switched for summer A/C I can either have the outside unit pull it in...or pull it from the basement also....If I use the other valve, it will divert air from the basement and into the Out side condenser.. So the A/c doesnt have to work so hard also...

I also added Vents to the duct work in the basement , about an inch below the floor to keep them heated during the winter months... I have a Trane XR13 2 1/2 ton unit...and I added 2 15KW heating strips to it.. the unit itself is good for 60K BTU...but in weather below 32 degrees it looses half of the BTU's... so with the heating strips ...It should be a kick *** unit.... So much for the power bill...LOL

RJ

 

No problem just tap ahead of the meter for unlimited power this also works great for hot tub heaters and welders. This should also be good for 18 months in the slammer.
Now the energy companies are speaking about higher home heating bills this winter, great for the elderly on fixed income or those with no income.

 

Carl, LMAO.......

When I was doing the rebuild on the 70 back when I lived in SoCal....remember when we had the four equaly spaced prongs on the back side of the meter... I cut the security wire to the meter...and turned it up side down...and would run it that way for a few days..and then turn it back around....I almost got busted once...So I only did it there after when the Mill was being used or one of the electric welders...

Need less to say ...about a year later I was asked to move from that rental...LOL...

RJ

Sorry didnt mean to This......

 

I "may have done it", had the PG&E seals and the crimp tool that would emboss the lead seal. You "could" install a dummy meter for welding and heating up the hot tub after a water change, it can happen.
I souldn't tell all the things I or we did as electricians that would cause jail time.
Now back to the thread.

 

almost sounds like the valve guides are too tight ?

 

Rereading this thread and Bear's reply it sounds like you have standard 390/428 chambered heads and the PO went to larger 427 chambered heads lowering the CR hence stopping the detonation problems he had. You have the casting numbers on said 428 CJ and 427 heads?
Built right with those 427 heads it should run great besides those heads are worth more than you think for certain performance people, don't let someone talk you out of them cheaply.

 

If you used an aftermarket cam did you replace the dowel in the front. Cam wont turn with the crank if it isnt there.