83 Crossfire TA

iTrader: (2)

I've never done this kind of thing with factory heads (tons of times with aftermarket stuff) so I'm hoping that you guys could save me some fumbling around.

What's required to get factory 305 heads (081 or 416 castings) to tolerate .502" (with 1.5rr's) or .535" (with 1.6rr's) valve lift?

What I'm doing: I have an 87 TA with an LB9 and all sorts of oddball parts floating around (and not enough room to pull the 305 and swap it for a 350, so don't even go there, if I had the time and the place I have a 350 L98 and a set of Canfield heads that will eventually find their way in it). the 305 is a bit on the wasted side, has a few miles on it but the worst thing about it is that it needs valve stem seals. I also have a couple of sets of 305 heads sitting around that i can swap on to it as well as a few roller cams I may try and basically I'm hoping to see how fast I can go with a mostly stock 305.

As far as more detailed questions:

Anyone have suggestions of a cheap/easy combination that will work?

Otherwise I've seen a few mentions of Manley 22410-16 springs and 23652-16 retainers, seems like the springs have about the right spring rate, list an installed height of 1.750" and coil bind at 1.150", so that should be around .600" till coil bind, and should be more than safe to .550" lift, and reasonably cheap. I wonder what the deal is with the +.050" retainer, what is the installed height of a factory valve job/is it needed to get that installed height?

Does that assembly clear the factory valve stem seals? At what lift does the retainer hit the seal?

I'm assuming that you would have to pin rocker studs or replace them with threaded studs, but what about guiding the pushrods? Are the factory broached pushrod holes good enough (maybe lengthen the slots if necessary), or so you install guideplates or SA rockers?

Basically, I want to keep things as stock as possible but still have something that will not fall apart when I start it (a lot of this is about running cheap and fast with what parts I have sitting around, and not wanting to sink any real money into high mile 305 parts).

Atilla the Fun

Where to start? some plus fifty retainers create more retainer to rocker interference issues than plus fifty locks. Still, it's better than trying .100"-longer valves. Those really screw with the valvetrain geometry. Better to use the plus fifty parts with aftermarket rockers. Using the plus fifty stuff is helpful for high lift, but more intended for the inherent spring issues than for retainer to seal clearance, which is better remedied by cutting the guides. As for choosing a spring package for .536" lift, I would go with COMP 26915s, but for a budget spring that will work with .503", www.competitionproducts.com has their 98111 springs. If you want to use 1.6"1 rockers, you may need to buy a pushrod slot lengthening drill guide, called a louis tool, for the 416 heads. If any of your heads have pushrod holes instead of slots, you may need to drill them larger. Also, if you intend to reuse any valves that have wear ridges on them at the point of the max lift with their original cam and rockers, you'll need to cut the guides shorter. This is still not ideal, but it will work if your stems and guides aren't too worn.

Stekman

+1 on the +.050 keepers.

Generally on stockers, .470-.480ish +/- is the accepted area of max lift before clearance issues arises.

Another spring option: I've used Isky 235D springs many times with great success.

Pinning the studs, at the very least, would be a wise move - really any time you increase the spring pressures. Pinning would be just fine with the springs you're looking at. If you'd like a threaded rocker stud, without the hassle of milling the stud boss for the hex, Mr. Gasket makes a stud, threaded w/o the shoulder. Installed via jam nuts. Both cheap options. Here's the Mr. Gasket studs: http://store.summitracing.com/partde...5&autoview=sku

I've run similar lift numbers on a set of 416's using stock pushrod guidance without issues. Stock guidance will be adequate.

83 Crossfire TA

iTrader: (2)

Thanks guys… Some of this is useful; some of it missed the point.

It’s good to know that I can just do whatever the heads originally did for guidance, that was one of my bigger worries. The other one that I’m wondering about is if the retainer to seal clearance will be sufficient without any changes, which neither of you say anything about in your suggestions.

As far as where you missed the point, well, I just want to swap enough parts to make things functional, I intend to keep the stock valves and any other pieces. I doubt the stock rockers will come close to tolerating that kind of lift, even if I lengthened the slots on them. If I go with 1.5 rockers I’ll probably pin the studs, if I decide to go with 1.6 rockers, well I have some 7/16” 1.6 scorpion roller rockers, and if I do that I’ll just pull the stock studs, drill and tap them for the 7/16” studs… unnecessary, but I have them sitting around and don’t have any 3/8” studs or rockers sitting around.

Same thing with the .050 retainers… I got those part numbers from other threads on this board and was trying to figure out why they were all listing +.050” retainers. I’ve seen stock setups with stock height retainers hit the inside/bottom of roller rockers, so I can’t imagine +.050” retainers would be a good thing.

I’m pretty sure that I have a Louis tool somewhere, but even if I can’t find it I could lengthened the pushrod slots easily enough on my Bridgeport. I’m pretty sure that I also have one of the comp valve guide mandrel’s and matching cutter around somewhere…

That being said, will any of the small diameter springs clear the stock seals, and will the stock seals have enough clearance for that kind of lift? Can you just cut down the stock valve guides and use the stock seals? Or am I stuck cutting down the heads and using PC seals?

Atilla, will those Beehive springs that you list work with a hydraulic roller cam? The spring rates on them seem a bit on the light side, but I know that some of that spring rate is traditionally used to control harmonics, which beehive springs do through their shape.

Stekman

+050 keepers moves the bottom of the retainer up said amount, thus increasing retainer to seal clearance. You can measure your current setup (caliper) and see the actual clearance, then you'll have a pretty good idea as to what your numbers are. .530" is pretty much maxed out, at least in my opinion for the +050 equipment - usually on lift numbers as such, I go ahead and cut down the guides. Don't forsee any issues with a 1.5 rocker, though. Again, a measurement will give more concrete information as to what actual clearances are.

It really isn't that big of a deal to put a little notch on the inside of a rocker body to clear a retainer. Done it many, many times.

235D's clear stock bosses. The beehives in reference would as well, as their lower ID is similar. Not sure on the other springs. Have no personal experience with them.

26915's would work just fine on a hyd. roller.

83 Crossfire TA

iTrader: (2)

So does anyone know what the typical installed height with the factory valves is on those heads? Am I reading correctly that it sounds like if I need some room I can just cut down the valvestems some and still use the factory style seals? (I'd love to grab some parts to play with on the way home the next few days before I get a chance to tear them down)

83 Crossfire TA

iTrader: (2)

Also, it sounds a lot like factory heads can pretty much deal with lifts around .500" with just a spring swap, where I'm going to get into the rest of this is if I go with the 1.6 rockers... is that right?

I'll have to look, I think I might have a set of the cheap, roller tip rockers in 1.5 that I was going to use on a truck engine...

Atilla the Fun

for me, 105 pounds on the intake seat with GM 1.94" valves and 90 pounds on the seat exhaust with stock GM 1.50" valves has proven perfectly adequate for 6200 rpm with 1.5:1 rockers and stock GM hydraulic roller lifters.
With the retainer to seal, I prefer to just cut the guides down towards the spring seats, then use "positive" rubber seals on the intakes, they're usually blue, with a silver spring band around them. For the exhausts I just use umbrella seals.
The 98111s will clear these seals just fine.
I think the Scorpions would clear if you used plus fifty retainers and plus fifty locks, but for just .536" lift, that shouldn't be necessary. The 235Ds are good, but the main advantage of the beehives over them or the 98111s is that with the beehives, you about eliminate any dips in the torque curve. Any dips you do get would be entirely from tuning.
And installing the 26915s at 1.700" would get you more seat pressure than their rating at 1.800".

tony_cogliandro

iTrader: (3)

here is what i am doing - i got a zz4 cam which is – 208/221 @ 0.50 with .474/.510 – lobe 112.
474/510. that means the valves will already be .510 at the exhaust.

Lift formula – max lift divided by rocker ratio multiplied by new ration = max lift.

then i am going to get 1.6 for the intake which will raise me to .5056.

but the max list for 081 heads is about .470 so then you need to shim it to make sure you dont hit.

get .05 thick on the botton and .05 on top and the offset locks and shims will gain you clearance. remember that 10 percent locks have more holding power. more angle to grab. 7percent is the stock. and your valve stems are 11/32 if they are stock.

now you need to ugrade spring to handle the extra lift. if you get a used zz4 cam you can have them toss in the springs and probably the lifters for 10.00 more.

Not worth the upgrade until you have LOADS of spring pressure.

the zz4 2nd gen is 7.122 push rods for self guiding rockers which is what I have.


Zz4 1st gen pushrod length is 7.194 – call them 7.2.

you have one more problem. your cam will work and so will the heads but you stand the chance of pulling out a stud with the extra spring pressure. you can get them drilled and taped so you can use screw on studs, and shave them at the same time and you will not need .05 shims, or you can spend less money and just have them pinned so they will not pull up. they dont have to come out - they just need to move a small amount to mess with your engine. and once they move a little they will move a lot.

the good thing about using your stock heads you will never raise the suspicion of the smog tester.

oh, one more thing. your trans - if it is stock 700r4 - it will lock in at 1500 rpm and shift at about 3,000 - which means you will have to change it to make use of all those rpms you are going to be spinning. so be prepared to change the trans shift points at some time.

and i lied - there is something else - that posi you have - is probably - as i just learned - a governor lock - which means one wheel will have to spin 100 rpm faster than the other wheel before it kicks in - and it is not really designed for lots or hight speed high torque runs.
should not hold you back - but factor that into your future repairs project.

did i mention headers - you need them too. no sinse in increasing performance if it cant pass the gas. and do something to get more air into your tpi - you will need it too. and maybe some new injectors too.

as far as what kind to get - that is personal preference.

a 081 can be accomplished with 110.00 for zz4 cam, springs, rods. shims 25.00. pinning the rockers - 40-80 dollars. and no matter what you do you will have to pull the heads so gaskets - heads - 40.00 each or 149.00 a pain for the best reuseable.
good luck

83 Crossfire TA

iTrader: (2)

Wow… I got a chance to pull an intake/exhaust pair apart and not exactly as expected for a set of 416’s that I thought I knew the history of. This factory head thing is turning out to be more of an adventure then I expected.

First, did 416’s come from the factory with fairly hefty springs and dampers (these are originally off my 83 crossfire TA)??? And by hefty I mean something along the lines of I wish I had a good way to measure spring rates on these high mile springs, I’m betting they’re pretty close to what I need for this roller cam. Last set of high mile factory springs I came near I was able to compress by leaning on them with the palm of my hand, not a chance with these. When I put a socket over the retainer and smacked it with a hammer to knock the retainers/keepers loose it took 3 swings before I even moved the springs, I really didn’t expect to have to give it that hard a swing on factory springs, and I could actually see the arms on my matco compressor flexing when compressing the springs.

Second, forget all the numbers tossed around about stock retainers and seal clearances just short of .500”, the intake has a standard rubber seal that makes contact at .465”. The exhaust has umbrella seals with .525” clearance before they make contact.

As close as I can measure using the back, depth gauge part of a dial caliper, both the intake and exhaust have an installed height of almost exactly 1.70”, but that raises another question… the exhaust side has the thick rotators on it and the exhaust seat pockets are cut significantly deeper to compensate. With standard, matching aftermarket retainers I’m betting the exhaust will have an installed height .1” higher or so, should I plan on finding some shims to compensate?

When putting aftermarket springs/retainers on stock heads, should I plan on installing new o-rings in the valve o-ring grooves?

83 Crossfire TA

iTrader: (2)

check out the attachment... I thought that I'd post a picture of the spring/damper that I took off the 416's, have you ever seen a spring like that from the factory on an early 80's SBC head?

While I'm at it, what do you guys think of either one of these Summit spring packages, both look like they should be in about the right range to work for what I need:

http://store.summitracing.com/partde...36+4294866930+

http://store.summitracing.com/partde...36+4294866930+

Stekman

Yea, the difference in the intake and exhaust clearance numbers sounds right. Not so much for the intake, a lot more for the exhaust.

If you're planning to get aftermarket retainers (not a bad idea - the rotators are heavy), then yes, shims would be suggested to make up for the installed height difference. I think it's around .100" or so. A spring mic would be helpful in determining.

You don't need the o-rings if you're using a positive style seal. If you're planning on leaving the exhaust side as-is (not installing a positive), then I would install the o-ring.

Of the 2 sets of springs you show, I would go with the 174000 and set them at the 1.750" installed. Depending on what cam you're using, seat pressure is good, not going to hurt. And the added installed height gives a bit of breather room on retainer-boss clearance.

83 Crossfire TA

iTrader: (2)

the more I look at this the more questions I have...

PC seals don't need the sheild or o-ring, but will they hurt if I put them in (probably shouldn't get into my thought process there)?

This is meant to be short term, fun experiment, so again, I don't want to spend any real money on this, but taking these apart I'm finding that the intake valve guides are tight, the exhaust have a little bit of play. I know what the spec numbers are suppoed to be, but at what point is the play high enough that I'll just hammer out the seats/ruin the seals right away (measured with dial indicator on the stem, I guess the valve about 1/16" off the seat, though I'm not clear that the published spec is with the valve off the seat)?

Will stock exhaust valves live without rotators?

F-BIRD'88

When I do up the 416 heads:
I drill and pin the rocker studs.
shorten the valve guide boss top by .200" for posi seals and high lift.
Use stock type replacement GM SBC retainers and locks.
Shim the springs up to 1.70" on both in and ex. using a Comp 4753 shim kit.
Lunati 73943, isky 205D or isly 235D (1.75" ish installed) springs work well.
Summit has two new SBC spring retainer locks, seal deal sets that look comparable.
Competition Products has similar spring package deals.

Stekman

O-rings can be used with PC seals. Won't hurt anything.

Not sure what the max. play is on guide wear that you'd be "safe" with. However, I've seen a head with just a touch under .005" and that was a ton. Though, I measure with a small hole gauge, so I am not really familiar with measuring with the valve play or how accurate it is. Personally, I would consider replacement around the .003" maybe .004" range. I guess it really depends on how "short term" you're thinking.

Valves will be fine sans rotators.

83 Crossfire TA

iTrader: (2)

I'll be happy if I get 10,000-20,000 street miles out of it without smoking, but I really honestly suspect that I'll blow up the engine in 5-10,000miles with what I have planned for it. I figure that if I do it I'll go with viton rather than teflon PC seals... I don't see teflon ones having enough give to last long with loose valve guides.

So I pulled everything that I have sitting around apart and started measuring with a dial gauge in the thrust direction with the valves a little off the seat. the 416's that I have are the best, with .002-.003" play on the intakes, most in the .0025-just under.003", the exhaust was in the .003-.004" range (though I had one that measured just over .004" a few days ago but I couldn't reproduce it today, even with the same valve). Seems like depending on who's numbers I use I'm either just inside or just outside the service or "replace" limit. (except for Chevy High performance that lists .001" intake and .0015" exhaust, which doesn't seem right)

Any opinions? Should I try them like they are?

tony_cogliandro

iTrader: (3)

atilla turned me on to comp also. he knows more than anyone about those heads. if you stick with heads that are not going to be running 0ver .500 +- you can use the springs he recommends and not have to pin the studs. anything bigger they will have to be pinned.
i have some 081's and im getting stainless valves 1.94 and 1.5 and with a decent zzr cam the 1.6 rockers will get me to .503 and the 1.5 in the exhaust will be .510.
the rockers and valves can be use on the next set of heads you get when you blow these off the block. lol.

83 Crossfire TA

iTrader: (2)

huh... I just pulled my '83, '87, '97 Trans Am shop manuals and checked their published numbers ('83 and '87 are the years that all the engine parts that I'm playing with, '97 was the only newer one that I have sitting around that covered a small block that GM used some sort of positive seal on rather than the old school umbrella's used in 83 and 87).

Interestingly, the '97 manual actually recommends the exact procedure that I did to measure clearance, and all list .0010-.0027 as the production range and the service range of .0037" for the intake and .0047" for the exhaust.

That said, it looks like I'm roughly .0010" below the service limit on all the valves that I could measure (2 are stuck). Assuming that I can get the 2 stuck ones loose without damaging them I think I'm going to try them like they are.

Tony... FWIW, I'm going with a 224/224/114 cam with .535" lift, and I've decided that pinning the studs is more work than it's worth and doing that will cost me a set of 3/8" stud rockers... Since I have some 7/16", 1.6 rockers and matching threaded studs, I'm just going to mill the tops of the stud bosses and then drill, tap and thread them for the studs.