906 Heads

[BBodyBarrett]

I'm looking at a 68 Roadrunner to buy however it has a 1965 cast number engine. Haven't dealt with anything earlier than 1968. My question is will 906 heads fit the 65 engine and a cam upgrade to 484-284 make the 65 model engine comparable to the 68 and 69 engines. Thanks

 

[Kern Dog]

Yes.

 

[Steve009]

Yes I have 69 906 heads off a roadrunner on my 64 block

 

[Steve009]

Yes I have 69 906 heads off a roadrunner on my 64 block

Sorry I meant 68 -906 heads

 

[PurpleBeeper]

A few things I would point out (but others on this site know a lot more than I do).

1. Any year 906 head will bolt up on a 65 big block motor.
2. 65 engines used closed chamber heads & I think you'd have a pretty large compression drop by adding 906 (open chamber) heads IF you are keeping the stock bottom end of the motor (I think 65 pistons set pretty far down in the cylinder). You might want to look for 915 closed-chamber heads (same big valves as 906's & basically the same ports) OR machine out the stock 65 heads (or other closed chamber, non-915 head) to accept the lager exhaust valves from the 906/915 heads.
3. If you rebuild the whole motor, maybe just use pistons for a 68/69 383 style piston (stick out of the block slightly) and use your 906 heads. With the correct cam (383 Roadrunner 68+ cam or 440 HP cam which are the same) you will end up with the exact same engine as a 68/69 Road Runner.... except I think the newer 68+ 383 exhaust manifolds flow "slightly" better.
4. Besides cam, closed chamber heads with smaller exhaust valves, lower setting pistons & exhaust manifolds, the 65 motor is identical to the 68/69 motor and stock (or aftermarket parts for that matter) are easy to find.

If it were me (it's not) and I didn't have a lot of extra cash (which I don't), I'd buy the car if the price was right, leave the closed chamber heads on it (find some 915's if I could) and put that 284/484 cam in it. If I had a little more cash, I'd have my heads re-done for the larger exhaust valve.

 

[Steve009]

Another thing to consider if you don’t already have the 906 heads are the edelbrock e streets. By the time you buy the heads, rebuild them, and have someone port them really well, the e streets aren’t a huge jump in price for decent aluminum heads. I’ve been debating them for a while.

 

[BBodyBarrett]

A few things I would point out (but others on this site know a lot more than I do).

1. Any year 906 head will bolt up on a 65 big block motor.
2. 65 engines used closed chamber heads & I think you'd have a pretty large compression drop by adding 906 (open chamber) heads IF you are keeping the stock bottom end of the motor (I think 65 pistons set pretty far down in the cylinder). You might want to look for 915 closed-chamber heads (same big valves as 906's & basically the same ports) OR machine out the stock 65 heads (or other closed chamber, non-915 head) to accept the lager exhaust valves from the 906/915 heads.
3. If you rebuild the whole motor, maybe just use pistons for a 68/69 383 style piston (stick out of the block slightly) and use your 906 heads. With the correct cam (383 Roadrunner 68+ cam or 440 HP cam which are the same) you will end up with the exact same engine as a 68/69 Road Runner.... except I think the newer 68+ 383 exhaust manifolds flow "slightly" better.
4. Besides cam, closed chamber heads with smaller exhaust valves, lower setting pistons & exhaust manifolds, the 65 motor is identical to the 68/69 motor and stock (or aftermarket parts for that matter) are easy to find.

If it were me (it's not) and I didn't have a lot of extra cash (which I don't), I'd buy the car if the price was right, leave the closed chamber heads on it (find some 915's if I could) and put that 284/484 cam in it. If I had a little more cash, I'd have my heads re-done for the larger exhaust valve.

Thanks for the info, I was not aware the 65 heads were closed chamber. My friend has offered to sell me some 915 heads if I buy the car I will put the 915s on.

 

[PurpleBeeper]

Thanks for the info, I was not aware the 65 heads were closed chamber. My friend has offered to sell me some 915 heads if I buy the car I will put the 915s on.

That's a reasonable plan for "stock-ish" motor that's not too expensive. The 915's used to be the "hot ticket" before all these aftermarket aluminum heads came out. Many people (like me) used to put them on '68+ 440's to boost compression ratio about 1/2 point without changing pistons.

If you go this route & ever end up rebuilding the bottom end of the motor, don't use the 68/69-style 383 pistons unless you have some thick head gaskets. Since they stick up out of the block, they will hit closed chamber heads (or be very, very close) with stock style head gaskets. They're not a problem with the 906-style open chamber heads that came out in '68, but will be a problem with any closed-chamber head. I "think" the 68/69 383 pistons are the only stock big block pistons that stuck up out of the block from the factory.

 

[wyrmrider]

you beat me to it on the pistons coming outside the block some 383's and IDK if those pistons are available except custom for some Stock racers
I have a 440 built that way using 6 pack TRW pistons
also 65- check your bore- most 65 unless really late were 413 if this is a Raised block motor
is this the original engine?
see if it's been bored B-4
looks like someone changed the heads so let's find out what else they changed
give us the deck clearance that you have now- machinist rule accuracy is ok
if out of the block- how much
and if aftermarket piston give the distance from the center of the pin to the deck- again machinist rule and Iball is ok - give the piston number from the inside of the piston
once you have the block data we can all chime in on head choices
given what compression ratio you want to end up with
regular or premium
towing or big cam
what gears
etc
IS this a low block or a RB? you did not say
doesn't matter

 

[Cranky]

Best way to build an engine is to know your deck height of the block and the compression height of the piston. Then you will know exactly what you are dealing with. Same thing with installing a cam. Don't go with the dot to dot method but degree it in so that way you know exactly where it is dialed in at. Even a stock engine benefits from that. Anyways....most (max wedge not so much) heads interchange with all the other big blocks but you need to know the differences between closed chamber and open chamber heads since they all will bolt on. For instance, a closed chamber head can boost the compression ratio too high if you have a block with '0' deck pistons and are using a .020 head gasket. Lots to know if you want to do things right....

 

[wyrmrider]

Best way to build an engine is to know your deck height of the block and the compression height of the piston. Then you will know exactly what you are dealing with. Same thing with installing a cam. Don't go with the dot to dot method but degree it in so that way you know exactly where it is dialed in at. Even a stock engine benefits from that. Anyways....most (max wedge not so much) heads interchange with all the other big blocks but you need to know the differences between closed chamber and open chamber heads since they all will bolt on. For instance, a closed chamber head can boost the compression ratio too high if you have a block with '0' deck pistons and are using a .020 head gasket. Lots to know if you want to do things right....

 

[wyrmrider]

Exactly right
Ideally you want a oiston with a flat top next to a closed chamber head and about .035 piston to head or 0 deck on the piston and a comp gasket
One of my 440's is +.015 out of the block and I have to use thicker "Marine" gaskets to get about .030- works great but takes some work to get there
NO WAY to have street compression with a closed chamber head and 0.0 deck pistons
If you are using factory pistons cc them
the ccs found in the specs are the minimums
On my motor i swapped the open chamber heads for 915's and had to open the chambers to get the compression down for motorhome use
YOU WILL NEED hard seats in stock heads for any long durability application- I like the durabond sintered iron ones- hard to find specs on lots of chepo aftermarket stuff
and new guides-I like the inserts
I knurl to get some oil retention then ream and hone to size (with the valves or new valves in hand)
with all that work the aftermarket AL heads start to make since unless you can do the work - but you have to pull those apart and check
best to buy bare and spec your own valves and springs and valve stem seals
or if this is a matching number deal and you want it to look stock I did that for a Superbird 383 4 speed car- real stock with a 440 crank and rods...