I picked up this set of adjustable rockers at a swap meet, and need some help identifying what they are, who made them, etc... After doing some investigating, standard rockers don't have the "offset" like these, and also have cupped adjustable feet instead of these ball-type ones. You can see that there are different markings on them as well. Let me know what you think they are!
strange looking, don't line up crosswise like normal How long is the ***embly? Chr 19 5/16" DeSoto 18 5/16 Dodge 17 3/16
Exactly, they don't line up like a standard rocker. They fit onto my 331 Hemi heads, so they are the standard size for 331/354/392 Chrysler products...
Alright! Now we are getting somewhere, I figured the best place to look would be the HAMB! So are the Gotha rockers something special? I know that they would take different pushrods. Also, did Polys have adjustable intakes always? I would love to find out a little more history about these and if this is something desirable or not... This is the first hemi I have built and first set of adjustables that I bought - then I found a set of 300 adjustables which threw me off because they were so different! Thanks for the help, you guys rock!
All the shafts are the same diameter - that could be ***embled from mis-matched parts from DeSoto, Dodge hemi or poly, &. Do the long ends line up with the stems?
The exhaust rockers are definitely Gotha rockers. I did a little digging and found a previous post that someone had found an NOS set shown below. These are identical to what I have, I am just curious what the benefit of the Poly intake rockers other than adjustable, and did they have the ball-style adjuster foot that matched the Gotha exhaust rockers? Boy I wish that I had a scan of that sheet on the bottom that showed the information about the push rod conversions, etc... (not to mention the decal!)
Oh, and yes - the long ends do line up with the stems - forgot to mention that. Just went out and put them on the heads for the first time. Everything lines up perfect. Just need to figure out what length/brand pushrods I will need to get. I did find that Isky makes pushrods with a cup on one end and ball on the other, so I am thinking that I can get these to work - anyone out there done it and have guidance? http://www.iskycams.com/pdfcatalog/2004-05/page28.pdf
I've never read any explanation for use of the poly rockers on other engines. I suspect it's one of the usual things: 1. I wonder what happens if you do this? 2. it fits 3. it didn't break 4. there doesn't seem to be any problem 5. therefore, it's a good idea. The actual engineering on the Dodge, DeSoto and Chrysler is far more complex than simply scaling up the dimensions. All the points of geometry in the valve gear is different, not only between hemi and poly, and between families, but even between high and low deck - a total of 9 choices (plus, intake and exhaust are completely different). The 331 tappet angle (average pushrod angle) is 61.5°, or 16.5° from the bore axis. The 331 intake valve stem is 26.5° from the bore axis, so the delta angle between the rocker's 2 levers is 43°. Except for some trucks, the only common adjustable poly rocker is the poly A 318, etc. at 59° or 14° from bore axis, pretty close to the 331. However, its intake stem is only inclined 19° (total 33°). The 331 intake rocker and poly A intake rocker are 10° different, and this cannot be made up by adjustment, pushrod length, stand milling, lash caps or taller valves. The effect (***uming that the pushrod and stem ends actually reach the pushrod and valve during full travel) is that the geometry is way off, and reduces lift, increases spring requirements, increases guide and stem wear. However: if the lobe height went up, the rocker delta angle should go down (angle change calculation: arcsine = lift change × 50%), so a really big cam will partially correct the poly angle error, but nowhere enough to make it work.
I'm ***uming that these are poly A because they're far the most common poly rocker, and almost all of them are adjustable (except 326). The other (reasonably) common adjustable poly intake rocker is the Dodge truck 270, etc. (no Chrysler poly trucks, AFAIK?), and it's much smaller than the poly A due to the very small max bore size of this smallest Chrysler V8 (oopsss... exception: 4.7 OHC).
I will start by saying that member Panic is a technical wizard. Those who dont pay attention to his explainations.....should. ( I just wish I could understand half of it) Without posting a ton of pictures, I believe the intake rockers shown are Dodge 270 type poly rockers. The early 50's Dodge poly rockers have a rounded adjuster end, unlike their hemi counterpart. The A polys that I have with a casting number starting in 22, which indicates a 61 or 62 vintage, as shown in the pictures, have an angled adjuster end (ala Dodge hemi...go figure.) The Dodges also use an adjusting screw with a 7/16 hex head, vs the 3/8 head on the A arm adjuster.
Thanks for clearing that up - I haven't seen a 270 rocker in quite a while and all my photos are too small to be useful. The improved math is pretty similar, and not encouraging. The Dodge (low-deck blocks only) tappet angle is 65°, making it 20° away from the bank axis. The intake stem angle is 21°, so the difference between the Chrysler (33°) and the 270 is 8° (rather than 10°). This is not the entire picture, though. The 270 block (and all hemi-based blocks) inherit their tappet angle from the parent hemi engine, and it's designed to provide ideal pushrod alignment (minimal dog-leg) for the original hemi rocker positions. Even though the new single shaft and rockers for the poly were probably the best choices I have a gut feeling that there is some mis-alignment between the tappet and the pushrod (as found in the notoriously bad LA engines) when the pushrod reaches the intake rocker. This definitely affect the geometry, but with a really big drawing to scale and measure or factory data I can't factor it in to tell how much change, and whether good or bad.
Very interesting information - I am by no means familar with all the terms thrown around, but am trying to learn more about these engines. Thanks for all the great responses, it really answered what I wanted to know!
Here's the Dodge low-deck poly. Look how the accurate hemi-inherited 65° tappet angles are not too good when lined up with the poly rockers.
I don't know if this helps at all.. But the 383 that we built for may Cuda we used Slant 6 adjustable rockers.. And they look a lot like the ones that yall are showing and talking about..
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