cleaning up the slant six head

[805moparkid]

When I read this thread when it was first created, I was hoping it might turn into a head work for dummies type deal.

With zero head work experience, I feel like my best attempt would be nothing more than me blindy grinding away into a water jacket.

well you cant go wrong with a gasket match to a stock gasket. Also when you have the bigger valves installed have them use the seat cutter kinda deep, then just blend.

 

[/6 Matt]

Thanks for the pics Ed, I've never seen the bottom two before.

So its all really that simple? Just blend and polish? Whats the purpose of the deep cut seats?

 

[805moparkid]

Thanks for the pics Ed, I've never seen the bottom two before.

So its all really that simple? Just blend and polish? Whats the purpose of the deep cut seats?

let me re-phrase that because that would be bad... you will have the old "soft" seats on the exhaust side removed and new hardened seats installed, that process you DO NOT want them to "sink" the seat. as you can see on the above pics the exh seat is close to the water jacket.

What i ment was after the seat is installed they size the the head to the inside of the new seat, normally they only go in like a 1/4" leaving a step, have them take it fairly deep, like double or triple that (i would have to have a head on a bench in process to get you an exact spec) so you have to port less, and its already round. again you just start to blend everything together.

if i was going to build any head again it would be in this order.

1. strip, "hot tank", and mag check
2. Install new guides and seats but ONLY rough in (that way if you knick is they can hone them out.
3. All your porting (now if your new 2&3 may switch which causes some extra work BUT if you hit water near the port opening your not out the money for seats and guide work)
4. If your going for big valves install the bare head on the bare block (use offset dowel pins) to center the head as wanted, then scribe the finish bore onto head face, then open chamber to that line. After you can smooth and polish (if not going crazy just smooth and polish but open up around each valve to unshround them a little)
5. mount gasket to head and install intake/exh (headers or manifold) and scribe the profile of the flanges. remove the int/exh from head and re-align gasket to the intake (then exh) and gasket match them.
6. install new longer studs on the int/exh surface and have it milled
6. The head is basically done now so send it back to the machine shop, do any milling you need, finish install valve seat and guides.

 

[cjh]

When I read this thread when it was first created, I was hoping it might turn into a head work for dummies type deal.

With zero head work experience, I feel like my best attempt would be nothing more than me blindy grinding away into a water jacket.

It isn't HOW much metal you take out, but WHERE you take it from that counts.

 

[1930]

After looking into this the consensus seems that without a flow bench doing much of any work other than port matching could be detrimental to the performance of the head.

It would take someone with the bench and some spare heads to cut a little and then test, cut a bit more and continue with test ect. Even some areas that may look like problem areas may in fact help the flow of the heads because they cause patterns within combustion chamber that help flow.

Not trying to discourage anyone but installing the larger valves appears to be a full out race thing only/higher RPM deal. Not ideal for any kind of street use.

Since the head was originally designed for the smaller engine it will not breathe to full capacity unless it were opened up but again from what I have read ( or not read if referring to slant heads ) no-one has taken the time to do the leg work and document findings.

V-8s more info than one could ask for. Slant engine...just alot of guys cutting and hoping for the best and assuming they made improvements but no real data to prove it.

I plan to clean up my heads still but will not be removing any major material from chamber/bowl area. Will post things though as I go along.

 

[ntsqd]

It isn't HOW much metal you take out, but WHERE you take it from that counts.

^^^^
This.

The thing to keep in mind is that a port that flows 250 CFM at .750" valve lift is useless to all but a very few people. I think that a port that flows 180 CFM at .200" valve lift and 200 CFM at .450" valve lift would be much, much more useful to a lot more people. If this port had little boundary layer, but some turbulence that would be even better. Best yet would be if it did all of the above and introduced significant swirl to the combustion chamber. All of that is asking a lot of a 50 year old port design. None of that will happen without grinding on a lot of ports and then testing them on a flow bench.

Lacking that tool, the time, and a supply of junk heads to R&D with, the general gasket match suggestion is the best that we can do. And truth be known it's very likely that there isn't a whole lot more to be gained in a head for a reasonable street engine (I'm assuming that the bowls aren't totally screwed up). If you're building a race engine and disguising it as a "street" engine then the effort probably is worth the trouble, but my take on this thread is that you aren't who this thread is for. You already know all of this, or should.

 

[805moparkid]

After looking into this the consensus seems that without a flow bench doing much of any work other than port matching could be detrimental to the performance of the head.

It would take someone with the bench and some spare heads to cut a little and then test, cut a bit more and continue with test ect. Even some areas that may look like problem areas may in fact help the flow of the heads because they cause patterns within combustion chamber that help flow.

Not trying to discourage anyone but installing the larger valves appears to be a full out race thing only/higher RPM deal. Not ideal for any kind of street use.

Since the head was originally designed for the smaller engine it will not breathe to full capacity unless it were opened up but again from what I have read ( or not read if referring to slant heads ) no-one has taken the time to do the leg work and document findings.

V-8s more info than one could ask for. Slant engine...just alot of guys cutting and hoping for the best and assuming they made improvements but no real data to prove it.

I plan to clean up my heads still but will not be removing any major material from chamber/bowl area. Will post things though as I go along.

wrong... Where is bill when you need him with the chevy ??302?? and the slant comparison. They share the same cylinder volume and the valve sizes are way different. As I keep saying slants have a problem getting air in, not out, the exhaust port can be ported as far as the intake. You need to get a bigger valve in to increase cylinder fill and therefore increase VE=MPG/HP/TQ. Now on a stocker build I think adding JUST the 1.7 intake and then cleaning up the head would have great results. As far as porting unless you hit water on these ifs going to be better than stock, yes you can open them up to much and hurt flow, but as I stated over and over a gasket match and deep bowl cut, then blending is going to be MILES ahead of stock. You do what ever you want but don't state that info isn't out there as you lead other people down the wrong path.

Chambers, read my last post, relieve the valves to unshroud them and mill to needed CC's for compression. This isn't hard. If your worried about screwing it up put an ad out here for a head work (wild may pick it up but havn't seen him in awhile or even IQ52, Brian, lots of pro's on here) or take it to your local shop and tell them I want a gasket match and bowl work, pay the money and be happy...

But don't say it hasn't been done well or that we are pissing in the wind... A lot of work goes into our motor's and your going to step on the toes of the people trying to help...

 

[805moparkid]

^^^^
This.

The thing to keep in mind is that a port that flows 250 CFM at .750" valve lift is useless to all but a very few people. I think that a port that flows 180 CFM at .200" valve lift and 200 CFM at .450" valve lift would be much, much more useful to a lot more people. If this port had little boundary layer, but some turbulence that would be even better. Best yet would be if it did all of the above and introduced significant swirl to the combustion chamber. All of that is asking a lot of a 50 year old port design. None of that will happen without grinding on a lot of ports and then testing them on a flow bench.

Lacking that tool, the time, and a supply of junk heads to R&D with, the general gasket match suggestion is the best that we can do. And truth be known it's very likely that there isn't a whole lot more to be gained in a head for a reasonable street engine (I'm assuming that the bowls aren't totally screwed up). If you're building a race engine and disguising it as a "street" engine then the effort probably is worth the trouble, but my take on this thread is that you aren't who this thread is for. You already know all of this, or should.

most slant heads don't hit 180cfm fully ported, rare to get a 200 and the one with 210 had no low lift (worse than stock)

 

[ntsqd]

most slant heads don't hit 180cfm fully ported, rare to get a 200 and the one with 210 had no low lift (worse than stock)

About what I figured based on various comments, which is partly why I choose those numbers.

 

[/6 Matt]

Ed, if keeping the stock size exhaust valve instead of going to the popular 1.4", do you think it would be possible/beneficial to go larger than 1.7" on the intake?

 

[kittypancake]

Any suggestions on what I can soak my 1984 cylinder head in?

I am going to re-condition that one I am thinking and leave my already re-built 86 head as a spare.

I have read soak it in vinegar, Coca-Cola, and personally know Lysol toilet bowl cleaner to work very well on de-rusting parts but have never attempted using it on a cylinder head.

Lots of carbon build-up on the head.

Id prefer to maybe stay away from the Lysol, I know its pretty caustic and I am concerned with large amount of flash rusting once the head were removed from the solution in areas that I may not be able to treat without an additional dipping step.

I know I could just pay to have them cleaned but Id like to do as much work myself as possible to save cash and by the time I drop them off, pay to have them cleaned and go pick them up I may have spent quite a bit more than a few bottles of Coke and the Coke might do just as well of a job.

What do you guys use?

I can be posting pictures as I go along if there is any intererst?

Oven cleaner and wire brushes do a good job

 

[805moparkid]

Ed, if keeping the stock size exhaust valve instead of going to the popular 1.4", do you think it would be possible/beneficial to go larger than 1.7" on the intake?

im not going to say yes as i havn't got to play with it yet but lets think about this... my head ported by a Nor-Cal slant guy flows very well, but damn near even on both sides with the 1.7/1.44 valves, that should tell you something.

I finally found someone in phx who has a bench and is willing to do a head for me. The plan is a 1.9x or larger intake valve and 1.44 exh for the next race head. i have to look into some other stuff as well such as valve angle and surface angle, may be messing with that to

 

[cjh]

im not going to say yes as i havn't got to play with it yet but lets think about this... my head ported by a Nor-Cal slant guy flows very well, but damn near even on both sides with the 1.7/1.44 valves, that should tell you something.

I finally found someone in phx who has a bench and is willing to do a head for me. The plan is a 1.9x or larger intake valve and 1.44 exh for the next race head. i have to look into some other stuff as well such as valve angle and surface angle, may be messing with that to

Why not try for an off-the-shelf intake valve size of 1.88" ???? from a 340-360.

 

[1930]

wrong... Where is bill when you need him with the chevy ??302?? and the slant comparison. They share the same cylinder volume and the valve sizes are way different. As I keep saying slants have a problem getting air in, not out, the exhaust port can be ported as far as the intake. You need to get a bigger valve in to increase cylinder fill and therefore increase VE=MPG/HP/TQ. Now on a stocker build I think adding JUST the 1.7 intake and then cleaning up the head would have great results. As far as porting unless you hit water on these ifs going to be better than stock, yes you can open them up to much and hurt flow, but as I stated over and over a gasket match and deep bowl cut, then blending is going to be MILES ahead of stock. You do what ever you want but don't state that info isn't out there as you lead other people down the wrong path.

Chambers, read my last post, relieve the valves to unshroud them and mill to needed CC's for compression. This isn't hard. If your worried about screwing it up put an ad out here for a head work (wild may pick it up but havn't seen him in awhile or even IQ52, Brian, lots of pro's on here) or take it to your local shop and tell them I want a gasket match and bowl work, pay the money and be happy...

But don't say it hasn't been done well or that we are pissing in the wind... A lot of work goes into our motor's and your going to step on the toes of the people trying to help...

I dont know who/where Bill is either but it sounds like it would be nice to hear from him.

As I mentioned I will do the gasket match/blend ect. I dont see how I am leading anyone down the wrong path, extending a word of caution possibly in what I am finding with my re-search.

Next time you decide to do a head and if you have a flow bench avail it would be nice to see the work performed and the numbers achieved. 87 pages of info on this site alone and I have not yet found these definitive results going either way.

Quote.....As far as porting unless you hit water on these ifs going to be better than stock, yes you can open them up to much and hurt flow............My point exactly and this is what as I mentioned someone might be grasping without the proper equipment, its nice to have bragging rights of all the work that has been performed but without concrete solid evidence that advancements have been made and where they came from specifically than again its like pissin in the wind with the auger to a novice like myself.

One with many years of experience doing head work would have learned over time what to do and what not to do and I was hoping this thread would bring out his specifics. So far success to a certain degree.

I will continue looking into avenues such as un-shrouding the chambers like you mentioned. Only makes sense to me at this point, sounds like good solid ideas that could only work.

Thanks

 

[805moparkid]

Why not try for an off-the-shelf intake valve size of 1.88" ???? from a 340-360.

3/8" stems. im looking for 7mm

 

[cjh]

3/8" stems. im looking for 7mm

Aussie Ford Falcons of the AU series 4.0 litre use 2 valves per pot, and have 7mm stems. I think the intakes have a 47mm head (about 1.85")....???
The 'XR6' has 41mm (about 1.61") exhaust valves.
If you wish, I could compare them stem length wise versus Slant valves....???

 

[805moparkid]

Aussie Ford Falcons of the AU series 4.0 litre use 2 valves per pot, and have 7mm stems. I think the intakes have a 47mm head (about 1.85")....???
The 'XR6' has 41mm (about 1.61") exhaust valves.
If you wish, I could compare them stem length wise versus Slant valves....???

that's where things get tricky... the stem height gets interesting. A RRR did with the 318 valves he had special spacers made to correct the swipe of the rocker on the longer valves. I have seen to many split stands and with the spring pressure im looking at will probably have to mill the stock stands off and use billet ones as well as thick "S/S" shafts.

but sure I would be interested if you have them laying around! OAL may be the same but how the retainer sits with the locks and grooves changes alot

 

[1930]

You guys have got to stop using code, Im sure Im not the only one that would like to know what RRR means and after reading it a few times would take a guess that OAL would mean overall length but just a guess.

Not everyone knows how to make text messages

 

[pishta]

ok, see that you found those pics. The red line is my bung in head direction.

 

[805moparkid]

You guys have got to stop using code, Im sure Im not the only one that would like to know what RRR means and after reading it a few times would take a guess that OAL would mean overall length but just a guess.

Not everyone knows how to make text messages

RRR is RustyRatRod, "Rob", on this forum, he used the 318 valves in a slant head ,1.78/1.5, but due to them being .100 longer he had these special wedges made to fit between the stands and the shaft to correct the sweep of the rocker.

and yes OAL is over all length

 

[1930]

Got it, thanks

 

[6pakattack]

Does anyone here have any info on what I could do to my to optimize flow, Id like to see an article with pictures at the very least, a step by step tutorial would be even nicer.

I would just be hacking into the thing without the mentioned help above and chances are I may do more damage than good.

The engine is original to a 1986 W-100 truck, it was of course not built specifically for the truck and I am attempting to optimize the engines capability.

I want people to say I cant believe theres a slant six in that thing, I want to re-engineer a few things with a personal touch so yes I hope something in the way of pictures is also avail.

Thanks for any help

I see your City listed as Brandon. Would that be Brandon Fla ?? If so I have a head that's been milled and has 1.70/1.44 valves with springs retainers, keepers and all ! All that needs to be done is put together, and I can have my engine guy do that if you're interested !

 

[1930]

I see your City listed as Brandon. Would that be Brandon Fla ?? If so I have a head that's been milled and has 1.70/1.44 valves with springs retainers, keepers and all ! All that needs to be done is put together, and I can have my engine guy do that if you're interested !

Sure I am interested, please post what all you know about the head specifically and hopefully some of the experts will chime in on what they think. Thanks

 

[805moparkid]

Sure I am interested, please post what all you know about the head specifically and hopefully some of the experts will chime in on what they think. Thanks

6pack knows his stuff, he just likes to think he can have more compression! :burnout:

 

[cjh]

that's where things get tricky... the stem height gets interesting. A RRR did with the 318 valves he had special spacers made to correct the swipe of the rocker on the longer valves. I have seen to many split stands and with the spring pressure im looking at will probably have to mill the stock stands off and use billet ones as well as thick "S/S" shafts.

but sure I would be interested if you have them laying around! OAL may be the same but how the retainer sits with the locks and grooves changes alot

Also, the AU series used 'Beehive' style valve springs.
I'll see what I can dig up.
I know the earlier 4.0 6's used the same collets and retainers as a slant 6.