Ford A3 head?

[rayy]

I just purchased a 67 fastback. It was wrecked in the 80s. I got to looking under the hood and it has a what I think is a old Ford A3 head. It is on a windsor block and the valve covers act also as a stud girdel. I know this sounds strange. I know very little about these heads looking for some insight. Thanks

[DynoDon]

Picture? I thought the infamous A3 heads were the Jack Roush designed Cleavland style aluminum head??

[rayy]

It is for sure a cleavland head. I will post pics when I get it out of the car.

[rayy]

See if this brings back the good ol days!

[Bryce]

awesome!

[theRG]

These heads were built by Ford along with the B351 and C302 to become aluminum replacements for the Boss 351/Boss 302 service heads that were used in racing in the 70's (modified of course). Most feature higher intake ports and will usually accept the accompanying Roush/FMS manifold, though Edelbrock also cast manifolds with the same part number and the FMS and Roush logo's so they look almost identical. They all also feature the closed-style Cleveland/Boss 302 combustion chamber.

The C302 head was later developed by Robert Yates into the C3 which then went thru many variations in the 90's till it became the SC-1 and later the D3 head. Thus the new FR9 is the 9th generation Ford small block head (although the whole engine is new) modified for competition. The A3 was usually small block class drag race head but also made the rounds at Daytona and Talladega, the B351 was the Boss 351 replacement in Nascar, and the C302 was the 5 liter race head for road racing based on the Boss 302. All these heads will accept Boss 302/Boss 351/and Ford Motorsport SVO valvetrain parts. And most intakes were designed for the A4 and later SVO blocks.

CHI Heads are really a good modern comparison the the old SVO heads as they are 1 to 1 Boss copies and can be used on Cleveland,Windsor, and SVO blocks. The A3 has about a 245cc intake so a smaller port CHI head may be a better bet going forward unless your running forced induction or building a drag car.

[rayy]

Ok it is not a A3 head. I pulled the valve cover off and the #e3zm6049c3.

[funcars]

Ford had all kinds of numbers on all kinds of heads. Somebody must have had flashbacks or something. They did make some early style heads marked with C3 that they also used for marking the early Yates heads. Ford did make a valvecover set-up like you mentioned for the C302/B351/A3 heads. The easy way to tell if if the valve arrangement is the same a cleveland (both valves canted). If the C3 heads are early yates heads they will not have the same canted arrangement and locations as a Cleveland style. Also, Yates heads were intended for shaft rockers and not stud mount.

Hope this helps. If you look up the 335 engine series forum they have a bunch of info and pictures of all of the early aluminum Ford motorsports heads.

[theRG]

Yates heads will date 9/9/91 on the earliest standardized sets. The Ford SVO block was introduced in '88 and the Yates head was adopted by Ford as Nascar standardized cylinder heads in 1992. Before that teams could use the A3/B351/C302 heads in any configuration they wished. Everyone else was running A3/B351's with big domes and big chambers. Yates was running the C302 with flat tops at .000 to +.005 at or out of the bore (in one interview I have from the early 90's he even admits to building plate and short track motors where the piston hit the head intentionally, but out of the bore is now outlawed) with the small kidney bean chamber with less valve cant and more upright angles. Using those valve covers I believe it will be a standard cleveland style valvetrain though so probably just a regular c302 but the date will tell the story.

Yates also did use stud rockers (Crane Gold Race) with stud girdles and without guideplates on from about '88 to '93-'94 which is the latest I have seen pictured on his engines.

[funcars]

RG,
Thanks for the information. It's tough to come by for the motorsport heads. I have a set of ported C302s/intake along with some smaller CHI heads curently on the car. I'm going to swap on the motorsport heads and see how they do. How much improvement came from the Yates heads and what were the biggest benefits?

Thanks

[theRG]

It depends. What CHI heads do you have on the engine now, also what are the engine specs: cam, bore, stroke, compression, piston style. Also, the cars weight, gearing, and use (drag, street/strip, autocross, etc.).

The key to the Yates heads according to Robert Yates is to run a flat top piston with a mirror of the combustion chamber as the dish until you have gotten all the compression you can out of it. I have seen these early C3 Yates engines with as advertised being little as 44cc chambers and 14:1 compression at 4.165" bore when I have been shopping for old Nascar stuff. Engines of that vintage from '92 to around '96 made up too 700bhp or so depending on the track application with the Yates heads.

[funcars]

RG,
Thanks again for more info on the Yates heads. Sounds about right.
For the heads I am swapping on I think I know what to expect - gain some high mid range and top end and give up a little low end plus need add a bit more timing advance. It sounds like you have some understanding so I'll add some background and maybe you can tell me if my thinking sounds right.

Current set-up: mildly ported CHI 185's estimated 195 ports(2.10/1.65 valves) & CHI manifold, 1.75 headers 3 in collectors, 3 in exhaust, 10.6/1 CR, solid roller 256/262 with .660 lift, Al flywheel, 6 stage dry sump, 3.45 stroke x 4.165 bore (376 cu in), flattop pistons, car weight ~3450 lbs, use is road race but street legal too (limited street driving though), gearing is 3/1 with Doug Nash 5 spd 3.00/1 first gear and tight ratios and I only get into 5th on the freeway. Redline kept to 7400 or below for longevity of valve springs, Bryant crank, Carillo rods with pin oiling, SVO block with sealed lifter valley. It pulls hard above 3500 rpm.

New heads: C302s with estimated 225 ports (2.15/1.71 valves), Matching Edelbrock manifold, Flowed at same bench as 185s and intake and exhaust up everywhere and peaked at 60 cfm higher for intake and 20 for exhaust, comp ratio goes up to 11.4/1, I will make new headers with 1.875 tubes and 3.5 collectors (lots of pain!), chambers were welded slightly to give more "heart shape", both heads had excellent valve jobs. Based on the flow numbers I'm guessing gain about 80 hp given the exhaust is adequate.

Thanks