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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
If you use studs w/o a hex, DON'T use vise-grips to put them in. Put 2 nuts on them jammed together and use a box wrench. Use the "high-temp automotive thread sealer with PTFE" from Loctite/Permatex (same company, 2 names, can't recall which brand name they assigned that product to) found hanging on a card at yer local parts emporium on the threads.
What does "perfect geometry" consist of? What did your adjustable push rod measure when you put a pair of "checking" springs on, "solidified" a lifter, spun the motor through a couple of cycles, and adjusted the adj PR in increments until the witness mark left by the rocker tip on the valve stem was as narrow as possible?
Alright, I've checked the geometry, and I get perfect rocker geometry... right when the rocker hits the flare at the base of the stud. Obviously this isn't going to work, so I'll need to either get new studs, or cut the bosses down, or both. I'm leaning towards different studs as that seems easier. Something like this, as it looks like they have significantly more clearance compared to the ones I'm using (though I'm not sure of the downsides to these and I'd have to toque them down with vise grips).
I was going through some pics and found this. If your heads were set up correctly for screw-in studs (with hex), and/or guide plates or self-guiding rockers, this is what they should look like. Notice the pushrod slots have been drilled out. You MUST use only 1 method of guiding the rocker.
Sorry for being absent so long, been busy. Anyways, here's a picture of the clearance I've got with the stock setup vs. the new rockers. Adjustable pushrod is set to the same length as stock.
Eugh, bad picture. Anyway, yeah the rockers aren't tightened down but I think the problem is pretty plain to see even without that. The Comp rockers are a lot bigger than stock, in every direction.
Where on the valve stem tip is the contact point of each rocker? How does that contact point move as you sweep thru the lift curve?
I think that those comp rockers are designed to allow use on Fords and ok on chev sb's. but not ideal.
The tip contact point does not need to be right centered on the valve. Just needs to have a reasonable sweep across the valve thru the lift curve and stay away from the edge.. They are what they are..
If mine I would sell off those rockers and the cam.
This would allow buying a different better cam and good oem stock style hi perf rockers with the long slot.. for high lift. You will end up with more power and torque and less headaches..
Summit, Howards, Elgin, Pioneer, all sell these better than oem stock style HD rockers in 1.5 and 1.6 ratio and also split sets..
Not all roller rocker are like these specific comp rockers..
Reguardless, if 1.6 ratio the pushrod guide slot in the head has to be lengthened a bit towards the rocker stud. (or the guideplates repositioned)
Like I said I do it by hand with a 5/16 rat tail file in a drill. The rat tail file in a drill cuts fast.. (longer slot, not wider)
Last edited by F-BIRD'88; Feb 19, 2021 at 10:37 AM.
Looks like those roller rockers would be better if with longer +.100" , +.150" valves and longer pushrods.
(or better on a Ford head)
Do you have another stock head casting to measure and compare rocker stud boss height? Stock vs machined? I forget the spec for how much needs to be machined down for screwin studs with hex + guideplates.... Someone smart will know.
I just drill and pin the studs on these budget head deals.
Last edited by F-BIRD'88; Feb 19, 2021 at 10:39 AM.
Nothing is wrong with that online CR calc..
Read the directions and enter the numbers correctly
using correct - number where needed.
and correct decimal point.
It works correctly...
Note: Just like with flat tappet cams and lifters and high perf springs and higher rpms , the stock style high perf ball/stud rocker arms also need the correct motor oil with zinc (and some moly) or a correct Moly/Zinc additive to reduce wear and friction. This is true on any situation where metal on metal slid contact is seem especislly with elevated spring force and rpm.
Lifter bores. etc Cold starts,, momentary loss of oil wedge etc...
Less wear less friction, less heat, more net power, extended engine service life..
Check the geometry using a stock gm rocker and pushrod..
Using a solid lifter--: How does the rocker contact point AND SWEEP now look with the stock rocker as you go thru the lift cycle?
How is it with the roller rocker? Can you improve the SWEEP by playing with the pushrod length?
You will not get it perfect. Those are not perfect design roller rockers.
Where on the valve stem tip is the contact point of each rocker? How does that contact point move as you sweep thru the lift curve?
I think that those comp rockers are designed to allow use on Fords and ok on chev sb's. but not ideal.
The tip contact point does not need to be right centered on the valve. Just needs to have a reasonable sweep across the valve thru the lift curve and stay away from the edge.. They are what they are..
If mine I would sell off those rockers and the cam.
This would allow buying a different better cam and good oem stock style hi perf rockers with the long slot.. for high lift. You will end up with more power and torque and less headaches..
Summit, Howards, Elgin, Pioneer, all sell these better than oem stock style HD rockers in 1.5 and 1.6 ratio and also split sets..
Not all roller rocker are like these specific comp rockers..
Reguardless, if 1.6 ratio the pushrod guide slot in the head has to be lengthened a bit towards the rocker stud. (or the guideplates repositioned)
Like I said I do it by hand with a 5/16 rat tail file in a drill. The rat tail file in a drill cuts fast.. (longer slot, not wider)
You'll notice the '87 and up part of that. My motor is an '84 with 601 heads. I'd have to drill out the guides if I wanted to use those rockers, and I don't. The Proform tool is also garbage as stated by MANY reviews on many different sites. I don't see why I would buy yet another set of rockers for a hundred bucks when I already have a set that'll work fine with $53 in new studs that will also get rid of some of the problems I have with the current ones, which are set up to run with guide plates and have a chamfer on the bottom which causes them to sit higher than they should. And why would I get a stock-alike set of rockers? That's just spending money to add friction to the whole assembly.
I've got the new cam in, the one Sofa recommended. No idea why I would've gone with a cam that starts being effective at 2,000 rpm, like I said it's a street motor with a stock torque converter. Geometry is the same as with stock pushrods; the only difference is that the full roller rockers are much larger. The stud bosses haven't been cut at all. If needs be, I'll either get the tool that cuts them down or I'll take them to a machine shop. I'm going to try to make it work with the new studs first.
The Elgin rockrrs are available in self aligning type snd conventional type.. Its just a different part number.
...but why would I even get them if they're just worse?
Anyway, I did check the roller travel over the tip of the valve last night. I get barely any movement with the old pushrods, so I'll probably check those for length and order some that are the same. Another strange thing; the pushrod never hit the end of the slot. I had about 1/32" of space between the pushrod and the end of slot at minimum. And I haven't started modifying the cylinder head that's on the engine.
On a stock type rocker, initialy when brand new there is more friction. But once broke in and yhe ball creates a friendly seat in the rocker, the running friction drops A LOT. The running friction is low..
Where a roller rocker has low friction when new (and can handle higher load force when new... As the roller Wears (and they do) friction INCREASES...
Rollers like to roll but not back and forth.. This loadsvand unloads the rollers creating wear over time ghat cannot be adjusted over time.
Stock type rockers are efficient and low friction within the stock and mildvprrf range of use and tend to last longer in that application. Not to mention quiet and LIGHT WEIGHT.. rollers are more MASS but can handle much higher load forces of a full race cam valvetrain. Stock rockers are more friendly to the rocker stud being out of position or tilted.. Rollers cannot tolerate this and will wear quickly. And wear the valve stem andvguide too if the rocker stud is slightly tilted.
On a stock type rocker, initialy when brand new there is more friction. But once broke in and yhe ball creates a friendly seat in the rocker, the running friction drops A LOT. The running friction is low..
Where a roller rocker has low friction when new (and can handle higher load force when new... As the roller Wears (and they do) friction INCREASES...
Rollers like to roll but not back and forth.. This loadsvand unloads the rollers creating wear over time ghat cannot be adjusted over time.
Stock type rockers are efficient and low friction within the stock and mildvprrf range of use and tend to last longer in that application. Not to mention quiet and LIGHT WEIGHT.. rollers are more MASS but can handle much higher load forces of a full race cam valvetrain. Stock rockers are more friendly to the rocker stud being out of position or tilted.. Rollers cannot tolerate this and will wear quickly. And wear the valve stem andvguide too if the rocker stud is slightly tilted.
Okay, so I've put some more thought into this. The 601 heads I've got, after further inspection, seriously need to be taken apart and cleaned - not to mention more machine work to actually make them usable. There wouldn't be much of a point in this, as the CFM in those looks like it suffers pretty heavily with the larger valves because they're too close to the side of the head and not much air can get around them. All that in mind, I've been looking into alternate choices in heads (yet again) and found these which look like they're going to be the best thing for a 305. they do have a larger combustion chamber than the 601s at 56CC, BUT! I was also looking for some better head gaskets, as the .038" compressed thickness of the Permatorques seemed really excessive. However, I'm not comfortable using the spray-n'-pray shim gasket method. After some looking, I found these gaskets which have a .028" compressed thickness. All together I should have right around a 10:1 compression ratio, basically the same as the 601s and thicker gaskets.
I'll consider getting a stockalike set of rockers but at this point I can't return the rollers. I'd already opened them to test the geometry before anyone responded on here. Let me know if you see any problems with my plan.
Good choice for the head gasket, but did you notice that the heads are Not in Stock ?
Yeah, I've emailed them to find out if they're coming back or have been discontinued. I may have to buy one of the more expensive options that's still in stock (when I get the money, that is). Looks like the only difference between them is spring diameter, besides the set that's meant for 86-92 engines.
The true chamber volume of the #601 heads can vary some... You have to CC your heads to see what you got. Some are 53cc. Many are bigger than...
If once properly ported and chamber deshrouded for 1.94 valves think 60-62cc prior to milling.
Flow is pretty modest in as cast form..
Does get much better with full home porting.
The bigger the valves the more chamber deshrouding needed around the valves for flow gain..
If you flow water thru the ports (garden hose) you can see the port to chamber thru flow pattern.
You can see where most of the flow goes and where it doesn't matter so much for your purpose.
I put a pair of Etec170s on the L30 305 I had in my 99 Tahoe. The heads had been on the 350 in my Express van until I overheated it. Had them surfaced 0.020" to get them trued up. They cc'd about 62cc. I used the 0.028" thick GM performance L31 head gaskets that were thinner than the stock L30 gaskets. Cam was a 218/218 @ .050 cam, 1.6 rockers for 0.484 lift and a 110 LSA and 106 ICL. Used Rhoads Original lifters on it with oiling grooves. Ran very strong in the Tahoe, in the 280 RWHP range. Ran all day long on 87 octane happily.
Trick Flow refuse to respond to me, and everyone that carries their products is suspiciously out of every kind of Super 23-175 head. Question: is there much of a difference between the gen 1 heads and those meant for 1987-95 SBCs? or do I just need a different intake?
Ah, they're the '87-'96 heads. Still don't know what the difference is.
Pre 1987, the intake manifold bolts were straight into head, perpendicular to the intake mounting surface.
In 1987, the angle was changed. All this means is that you will need an intake manifold to match the bolt angle. https://www.hotrod.com/articles/hrdp...s-short-block/
Notice that the Trick Flow heads have angled spark plugs. That could be an issue with some brands of headers.
Last edited by NoEmissions84TA; Mar 13, 2021 at 06:47 PM.
Pre 1987, the intake manifold bolts were straight into head, perpendicular to the intake mounting surface.
In 1987, the angle was changed. All this means is that you will need an intake manifold to match the bolt angle. https://www.hotrod.com/articles/hrdp...s-short-block/
Notice that the Trick Flow heads have angled spark plugs. That could be an issue with some brands of headers.
OH, FER CHRISSAKES. I've been wondering that this whole time. That makes things significantly easier. I've got Heddman headers, so the angled spark plugs shouldn't be an issue, if they angle upwards like I assume they do.
Edit: I'll also need different valve covers. Oh well, too bad, at least I can send the other ones back. Definitely keeping the Proform load spreader for perimeter bolt covers though, as it appears to be the only quality product Proform has ever made (at least if the reviews are anything to go by). I think I'll go with the 305 HG I listed earlier, on second thought. Yeah they're more expensive but I like the peace of mind all that extra material between the cylinders gives me.
Last edited by IneptusMechanic; Mar 14, 2021 at 03:22 AM.
Reason: edit
Progress has been made! I managed to snag the last two of these heads. Glad to finally make it look something like an engine again.
Both heads are on and torqued down. New pushrods ordered, 7.800" looks like it's going to be the best here. Forgot to remove the inner springs from the driver side head before install so that'll be fun to fix.
Last edited by IneptusMechanic; Apr 2, 2021 at 04:51 AM.
Reason: info
Fun fact: the Hedman Headers specifically made for third-gens comes within about a quarter inch of the A/C box on the passenger side (and yes, I'm keeping the A/C working), and the same distance from the brake lines on the driver side. Hopefully heat wrap is enough to keep the A/C box from melting.
NOPE. No, please, anything but Proform. I do have a Summit tool that's nearly identical, though. I just forgot to remove the inner springs on the driver's side head before installation. The whole compressor part of it swivels so it won't be a huge issue, just need a day to do it. Spent my last day off getting the oil pan, starter, and TC cover back on the car, so most of the stuff underneath it is done now. Sawzalled the old Y-pipe off too. I do most of the work at night (10:30pm or later) so using the air compressor that late probably wouldn't make the neighbors happy.
I do have a question, though. Should I be replacing the distributor during this rebuild? Old one seems fine despite being a crappy Chinesium unit, but I would assume replacing it is good practice when replacing the cam.
If the diz shaft runs true does not wobble or deflect side to side, the shaft bushings are good.
If the diz gear is worn can be replaced if needed.
New cap and rotor is nice as needed.
If the diz shaft runs true does not wobble or deflect side to side, the shaft bushings are good.
If the diz gear is worn can be replaced if needed.
New cap and rotor is nice as needed.
Whole thing's new, no play in anything or any wear, it's just low quality. PO was a bit of a cheapskate. Might end up replacing it later on if I feel like it, then.
Upgrading to new, name brand does not mean anything anymore. Everything is 99% made offshore now. New does not mean better - or quality.
I that distributor is functioning properly, then run it.
Don't do this...………
Last edited by NoEmissions84TA; Apr 9, 2021 at 08:24 PM.
Just rebuilt a HEI I had laying around that I pulled out of a late 70s or early 80s G20 van (think it was a 79 van because I have a California special Q-Jet off of one and I think I grabbed them both off a 70K mile wrecked van) in the wrecking yard nearly 20 years ago. Was still all OEM down to the cap and rotor. Was in need of a good cleaning, new advance weight pivot pins and swapped all the old electronics minus the pickup coil for Accel and put a MSD cap and rotor on it. Runs GREAT.
The heads I'm using have a different thread pitch and size than original for the fan switch - anyone see an issue with using the port on the rear of the intake manifold? It's a post-'86 intake, so coolant does flow through that part.
Best thing to do is, go to Home Depot or the like, and get a brass bushing that's ½" NPT on the outside and 3/8" NPT inside; and put it in the right place in the head.
56cc. 
