289/302 Cross breed engine rebuild

[grs44310]

A guy I know with a '76 Bronco used 289 heads on his 302 when he rebuilt it. He also used a 260 Comp Cam, Performer intake and a 625 Holley with headers. This truck runs like a gang raped ape! He tells me the smaller combustion chamber of the 289 head gives a lot better burn as well as higher compression. He runs it on high test pump gas.

My question is: Is a 302 with 289 heads a cost effective way of building a strong running engine? Are 289 heads really that much better than stock 302 heads? I know that the other components of the intake and valve train have a lot to do with how well an enginer performs.

 

[Broncobowsher]

The old 289 heads have a small chamber area that increases ion. Compression does wonders for making an engine run strong, but at the cost of having to use high octane fuel. The small chamber heads are the old poor mans trick of making a low compression engine high compression without changing the pistons.

As for breathing, I will consider the 289 heads a little better then the 302 heads since the 302 heads tend to be smog heads with a nasty bump in the exhaust port that chokes them up.

Other then that it just sounds like he has a nice package of matched parts that is well tuned.

 

[68 Broncoholic]

I've got the 302 block and 289 sport heads. I do seem to pull away from the other bronco guys but I do have 5:89 gears...

 

[mtkawboy]

The blueprint specs on 76 302 heads is 54.7 cc's for the combustion chamber. The 2 barrel 289 heads are 51.99cc's and the 4 barrel & hipo 289 are 47.7 cc's so you need the right heads for a big jump. The hypo heads have the adjustable rockers too. The early motors had flattop pistons where the 76's had 10.4 cc dished pistons too so you will lose some there. Theres also the life of the valve seats if you are going to street drive it on unleaded gas to think about too. You can use Marvel Mystery oil to overcome some of that wear if you dont want to get them changed. If you can find some 47.7 cc 4 barrel ones they should make a big difference with a decent cam and get rid of the 4 degree retarded cam sprocket on the 76. Low gearing will obviously make a huge difference too. Id guess they would take you from the 8.3 -1 compression range to around 9.5 -1+ which is about as far as you can go on todays lite gas

 

[grs44310]

Since my buddy's rig runs so well with the 289/302 setup I was considering doing the same thing. I found a set of 289 heads for $100 that came off a boat motor. They are in great shape and are ported and ploished. I'm sure they are the H.P. 4 barrel heads since they were on a boat. With the right cam and intake they should really make my '77 302 a runner.

 

[Broncobowsher]

Boat motors are typically low ion in order to live under hours of full throttle abuse. Never assume parts, especially boat parts.

 

[Grunt1058]

I got a 351W bored .040 over with a mild cam, 289 Ported and polished heads, JDA short tube headers with an Edelbrock Performer 351W intake manifold and an Edelbrock 600 cfm electric choke carb.

The machinist and my mechanic said my engine should easily/conservatively put out 300 ponies reliably. When she's running good, you can tell. It's a bat out of hell. But, I got some weird fuel delivery problem I'm hoping to rectify this weekend with the install of a new Holley electric fuel pump.

I was also told that not all 289 heads are created equal. There are some 289 heads that are really good heads to have and some that are... ah... I have the "good" ones supposedly.

 

[grs44310]

Broncobowsher,
What do you mean by low or high "ion?"

When I get ready to pull the engine and do the rebuild I will have my machine shop check out the 289 heads and give me some idea of the condition they are in and if they are the "good" ones.

 

[Broncobowsher]

Broncobowsher,
What do you mean by low or high "ion?"

When I get ready to pull the engine and do the rebuild I will have my machine shop check out the 289 heads and give me some idea of the condition they are in and if they are the "good" ones.

for some reasion when I type c o m p r e s s i o n it only comes up as ion

 

[mtkawboy]

http://www.nhra.com/tech_specs/engine/ check the casting numbers here for the 225 or 271 hp heads or whatever you have. You can pick up some with shim head gaskets also instead of the composite type. These specs are legal minimums & it generally takes about a .020 mill job to get there, but it will tell you what you have anyway instead of taking someones word for it

 

[70TEXEB]

The blueprint specs on 76 302 heads is 54.7 cc's for the combustion chamber. The 2 barrel 289 heads are 51.99cc's and the 4 barrel & hipo 289 are 47.7 cc's so you need the right heads for a big jump. The hypo heads have the adjustable rockers too. The early motors had flattop pistons where the 76's had 10.4 cc dished pistons too so you will lose some there. Theres also the life of the valve seats if you are going to street drive it on unleaded gas to think about too. You can use Marvel Mystery oil to overcome some of that wear if you dont want to get them changed. If you can find some 47.7 cc 4 barrel ones they should make a big difference with a decent cam and get rid of the 4 degree retarded cam sprocket on the 76. Low gearing will obviously make a huge difference too. Id guess they would take you from the 8.3 -1 compression range to around 9.5 -1+ which is about as far as you can go on todays lite gas

Not to be rude or make you feel uncomfortable, but are you sure those numbers are correct? I always thought (thought) that early 302 heads were around 60ccs. I have personally compared some 58cc roush heads with some HP 289 heads and the 58cc heads looked shaved compared to the 289 heads, I can't imagine them being 47.7 ccs. Just askin :-*
edited: of course it could have been the chevy valves making it look that way.

 

[mitzel]

70TEXEB
> I always thought (thought) that early 302 heads were around 60ccs.
> I have personally compared some 58cc roush heads with some HP 289
> heads and the 58cc heads looked shaved compared to the 289 heads,
> I can't imagine them being 47.7 ccs.

only the '63 289HiPo casting had smaller combustion chambers,
nominally listed as 49cc from the factory. all of the 'C' (except '68)
and 'A' code 289's and '64-'67 HiPo castings had 54cc chambers. in the
289 to 302 changeover year ('68) both 289 and 302 'F' code (2V) heads
were 63cc, and as 289 parts became scarce many actually shipped with
the 302 casting. '66-'68 289's with CA emissions were machined for
an external air injection manifold.

on the 302 the '68 'J' code (4V) had a unique casting with 53cc chambers.
'68 'F' code (2V) was 63cc. '69-'76 were all 'F' code (2V) with 58cc
chambers. '77 and up 302 and 351 used identical heads (except for
the bolt size) that had jumbo sized 69cc chambers. things may have
changed once more with the E7-up heads but I'm not familiar with those.
'68-'77 heads are available with or without air injection, '78-up all
had air injection. the '68-'74 used an external air injection manifold
similar to the 289 and '75-up have internal air injection ports.

I don't think any of the 289/302 factory heads can really be considered
a high performance part, other than maybe the late model GT40/
GT40P's. I've pretty much concluded I'd go right to the aftermarket
heads on a performance buildup after doing a little pricing on parts and
labor for valves, hardened seats, guideplates, screw in studs, and
porting to work over the factory heads. but for a mild buildup the
factory heads and some home porting can probably work well and/or
there's probably some decent deals if you can find someone selling a
set of heads that have already had hardware upgraded and porting done.

 

[70TEXEB]

Thanks Mitzel, for the good info. And sorry grs44, I didn't mean to hi-jack. I have heard good things about the HP 289 heads as well. It seams that is a fairly common combo that people like. But like mitzel said sometimes can be as costly as getting aftermarket new heads.

 

[mtkawboy]

Specs listed are off NHRA engine specs for legal stock eliminator drag cars which is the bible. Specs are submitted by the manufacturers http://www.nhra.com/tech_specs/engine/ I raced for 15 years and thats what determines legal or illegal. I dont know what to tell you if it doesnt match your info, thats what Ford submitted

 

[mtkawboy]

I guess I should mention that those are minimum specs that are legal. I serously doubt that any of them ever came that way. Like I said previously Ive always had to cut them around .020 to get there. Im just trying to help the guy, not get into a pissing match with anyone. I didnt make the numbers up and Im not saying that the heads I would use either. Personally by the time you put guides, seats & valves in then you would be 3/4 of the way to a set of aftermarket heads. He asked about 289 heads

 

[grs44310]

Thank you everyone for you help and information. It's obvious that it's not as easy as finding a set of bone yard 289 heads and bolting them on. Don't get all bent about who says what, I'm sure there is truth in what each of you contributed. Thank you again!
Greg

 

[peterinman]

I have absolutely no data to back my claim up but I just put my '67 289 intake (stock 2V) and heads on a '71 stock 302 block and it runs strong. Noticably stronger than the 289 did. I also pull away from from my buddies '74 EB. He has the stock 302 with a C4 while I run a toploader. I don't care what the numbers say, its what the foot says.

 

[fordguy]

be sure and do you homework before putting too much money in the old heads the rousch heads and the gt 40s are pretty good deals you may want to invest in a book at amazon http://www.amazon.com/exec/obidos/t...f=sr_1_1/002-0962814-2612064?v=glance&s=books
and read up on the subject it will explain compression and heads in detail

 

[76 explorer]

ya know... ive been thinking about doing the 289 heads on my 302. main reason i havent was i assumed(yes i know what happenes when you assume) the threaded holes in the heads wouldnt be the same as what i have now. would my p/s set-up and all work or have i been thinking right all along? (hoping im wrong)