351 heads ?'s

[bnickel]

without knowing the rest of your combo i'd say you'd be lucky to be getting 8.5:1 with the e7's, unless they've been milled. i guess i misunderstood and though you were looking at a set of E7's for 50 bucks or the 351 heads to replace a set of factory 289 heads.

i will say that you'll get a noticeable bump in compression from the 351 heads but without doing anything else to them you won't notice much of a difference if the E7's are already ported but you might see a little bit of an improvement in mileage due to the compression bump.

if you have a die grinder and can get the 351 heads for cheap or free then go to town porting them and just swap the good parts from the e7's over to the 351 heads.

there are several good articles on head porting on the web. also check out teh head flow data here to get a good idea of the fow potential of even a set of stock 351 heads. the D0O (70 model) and C9O (69 model) heads are identical so these would be a direct comparison to the E7 heads.

http://www.jason.fletcher.net/tech/flowdata/castiron.htm

 

[Z06killinSBF]

without knowing the rest of your combo i'd say you'd be lucky to be getting 8.5:1 with the e7's, unless they've been milled. i guess i misunderstood and though you were looking at a set of E7's for 50 bucks or the 351 heads to replace a set of factory 289 heads.

i will say that you'll get a noticeable bump in compression from the 351 heads but without doing anything else to them you won't notice much of a difference if the E7's are already ported but you might see a little bit of an improvement in mileage due to the compression bump.

if you have a die grinder and can get the 351 heads for cheap or free then go to town porting them and just swap the good parts from the e7's over to the 351 heads.

there are several good articles on head porting on the web. also check out teh head flow data here to get a good idea of the fow potential of even a set of stock 351 heads. the D0O (70 model) and C9O (69 model) heads are identical so these would be a direct comparison to the E7 heads.

http://www.jason.fletcher.net/tech/flowdata/castiron.htm

Awesome, by that article, the 351 heads not only out flow but have more compression than the E7's. My heads are only home ported by myself so the 351 heads would get the same work done. I have a die grinder and some carbide bits laying around somewhere. Hmmm....

Thanks for the help everyone.

 

[bnickel]

glad to be of service. hope you got what you were looking for. when i do my long rod motor i'll probably be going the other way and go with a 64cc head to keep the compression where i want it. my plan is to use the FRPP gt-40-x heads with the 64cc chambers and the flat top Keith Black pistons to get around 10-10.25:1 on my 351w.

 

[Edbert]

E7 heads have the huge chambers right? I'm not sure you can mill them enough to compete with 1969 heads in the compression department. That's why they make pop-up pistons

The '69 heads are a bolt-on for 289/302 owners, with the flat top pistons they offer roughly the same CR, and provide bigger vavles and larger ports than 289/302 heads without the need for griding or milling (of course a cleanup run through the mill is usually advised). If you are going to have them machined for screw-ins, have larger valves installed and spend hours with a grinder...the closed chamber 289 heads are fine for most folks since they already own a set to begin with.

 

[bnickel]

imo, the best set of heads to start with with for a 289/302 are the 68 302 4v heads. they are a lot like a 289 hi-po head but have bigger ports and valves and they have the small 54cc chambers, IIRC, but don't have the pushrod guide holes or guideplates so you'd have to add the guideplates.

they don't flow quite as much as the 351 heads but they have the smaller chambers to keep the compression where it should be. a little porting work and they'll flow about as well as the 351 heads too. they are very hard to find though so that's why most people use the 351 heads.

 

[Edbert]

Forgot to qualify my previous statement too...351 heads use larger bolts/studs...289/302 use 7/16 and the big Windsor uses 1/2...so you have to tap your block for them or use shims/shrouds (not the right term) and keep the old ones.

 

[Rusty67]

Upgrading to the larger bolt it the better way to go. A lot of aftermarket heads use the larger bolt. I believe the larger bolt shank helps to reduce head gasket failure.

 

[bnickel]

drilling and tapping a 289 block for 1/2 holes is price prohibitive and not really necessary on anything under 400hp or so. there is a reducer bushing you can get at summit for about 35-40 bucks, any aftermarket head is going to need them as well so spending that money now will save money when he does eventually buy the aftermarket heads. no biggie.

http://store.summitracing.com/partdetail.asp?part=TFS-51400419&autoview=sku

 

[Hack]

imo, the best set of CAST IRON FACTORY heads to start with with for a 289/302 are the 68 302 4v heads. they are a lot like a 289 hi-po head but have bigger ports and valves and they have the small 54cc chambers, IIRC, but don't have the pushrod guide holes or guideplates so you'd have to add the guideplates.

they don't flow quite as much as the 351 heads but they have the smaller chambers to keep the compression where it should be. a little porting work and they'll flow about as well as the 351 heads too. they are very hard to find though so that's why most people use the 351 heads.

Fixed. Of course as we all know aftermarket aluminum heads are much better than anything the factory ever made.

 

[bnickel]

Fixed. Of course as we all know aftermarket aluminum heads are much better than anything the factory ever made.

well yeah, that's what i meant. i was speaking in the context of this thread but thanks for the correction anyway.

 

[D.Hearne]

imo, the best set of heads to start with with for a 289/302 are the 68 302 4v heads. they are a lot like a 289 hi-po head but have bigger ports and valves and they have the small 54cc chambers, IIRC, but don't have the pushrod guide holes or guideplates so you'd have to add the guideplates.

they don't flow quite as much as the 351 heads but they have the smaller chambers to keep the compression where it should be. a little porting work and they'll flow about as well as the 351 heads too. they are very hard to find though so that's why most people use the 351 heads.

The C6OE 289 head is the same casting, same ports and valves as the 68 "J" code 302 head.

 

[D.Hearne]

Forgot to qualify my previous statement too...351 heads use larger bolts/studs...289/302 use 7/16 and the big Windsor uses 1/2...so you have to tap your block for them or use shims/shrouds (not the right term) and keep the old ones.

All you need to do in this case is use the head bolt bushings that are commonly available for the aluminum heads. No need to drill & tap the block for the 1/2" bolts.

 

[bnickel]

The C6OE 289 head is the same casting, same ports and valves as the 68 "J" code 302 head.

i thought it had bigger ports and valves, oh well you can't be right all the time i guess.

 

[D.Hearne]

Some of the books list the 289 heads as having smaller port and valves, which might be true of the earliest ones. I haven't actually seen any of these though, but I have had a couple sets of the C6OE's and they're esentially the same heads as far as ports & valves as the 302's. The "J" code heads are really just recast C6OE's with a new casting number.

 

[bnickel]

ok, i guess i was thinking it was like hi-po 289 head with bigger valves and ports and non adjustable valvetrain.

 

[Edbert]

Ummmm...I thought hipo (K-code) heads had the same valves and ports, just the screw-in studs and slotted push rod openings. Are you sure they had bigger valves and ports?

In fact the earliest 289 through the early 302 (let's say 1970, I have no idea about FoMoCo heads past then other than they were undesirable "smog" units) the size of the valves and ports did not change, only the chambers varied (and the round versus slotted / screw-in versus pressed-in). That is why folks used to always put 351W heads on their 289s...in order to get bigger valves. But the best bet (before we had choices of after market alooominum heads) was to have Chevy 327 valves installed on the small-chamber (early) 289 heads and port them to the manifold. By installing Chevy valves you could get larger than 351W and keep the 289 heads.

 

[danny clemens]

Ummmm...I thought hipo (K-code) heads had the same valves and ports, just the screw-in studs and slotted push rod openings. Are you sure they had bigger valves and ports?

Somebody correct me if I'm wrong but I think all of the early 289 heads had the slotted push rod openings just like the hipo heads. I think the the hipo heads had recessed pockets for the valve springs to sit in.

It's been a long time since I've even seen a set of 289 heads off of the engine.

 

[bnickel]

Ummmm...I thought hipo (K-code) heads had the same valves and ports, just the screw-in studs and slotted push rod openings. Are you sure they had bigger valves and ports?

In fact the earliest 289 through the early 302 (let's say 1970, I have no idea about FoMoCo heads past then other than they were undesirable "smog" units) the size of the valves and ports did not change, only the chambers varied (and the round versus slotted / screw-in versus pressed-in). That is why folks used to always put 351W heads on their 289s...in order to get bigger valves. But the best bet (before we had choices of after market alooominum heads) was to have Chevy 327 valves installed on the small-chamber (early) 289 heads and port them to the manifold. By installing Chevy valves you could get larger than 351W and keep the 289 heads.

what i meant is that i thought they were like the hi-po heads BUT with bigger valves and non-adjustable drivetrain. i guess all this time i was wrong about those heads but i don't really study the 289/302 stuff so much, just the 351 w&c stuff but i was thinking the J-code heads had the 1.84/1.54 valves and non-adjustable valve train on a hi-po 289 head AND i thought the hi-po heads had bigger ports than a standard 289 head. i'm also not as well versed on the pre-69 stuff either since i've always been more of a fan of the 69/70 stuff and i don't normally get to see the early stuff laid out in front of me either. so my apologies for my incorrect assumptions. i do know the J-code heads are fairly sought after though so maybe that's part of where all this came from and i swear i read that in one of my books too.


i have a couple sets of D0 351 sets that i've been playing with as well as the stock ones that are on the car now and i know they are better heads than the E7 heads overall so i'd go with those.

 

[D.Hearne]

Somebody correct me if I'm wrong but I think all of the early 289 heads had the slotted push rod openings just like the hipo heads. I think the the hipo heads had recessed pockets for the valve springs to sit in.

It's been a long time since I've even seen a set of 289 heads off of the engine.

You're dead on right on all counts.

 

[D.Hearne]

I think we're all in agreement as to why the K code heads are sought after, I think the "J" code heads are sought after in a mistaken belief that they were somehow "Hi-po" heads like the 289's "K" code heads for the same reasons.