Are you sure your supposed to subtract the depth of the cup?
360 LA installing Promaxx Aluminum heads
- Thread starter 74Scooter
- Start date
-
HiFire
Active Member
I used a Trickflow length checker. I called Trickflow and the measurement is from the ball tip to the inside base of the cup. I ended up with 7.100. Ordered pushrods from Smith Bros and I'm getting oil through pushrods. They are sending me 1 so I can check my measurements just incase I measured wrong. I talked to Eric at Smith Bros, great guy to deal with. I should get the part this week.
OK. This is not how I ordered in the past. The pushrod company (I can’t remember who I ordered from last. I think it was Hughesengines.) They said just measure overall length. Bottom of the ball to the top of the cup.
How deep is the cup?
How deep is the cup?
Last edited:
HiFire
Active Member
Not sure. Didn't ask and don't have the tools to measure. When I get it I'll try to remember to take a pick with the adjuster in the cup.
Rat Bastid
Dunamis Metron
There is effective length and overall length. You can measure either way, you just had to tell the pushrod guy how you did the measurement. They can get the length correct.
As Rat noted above.. there is "effective" and "overall" length. The measurements you see online for the premade pushrods are all in effective length as far as I can tell.
The cup in the measuring tool I used is .158
The shortest set of ball/cup pushrods I could lay hands on were Comp 7821-16. Overall length 7.396 and just too long. I cannot even get the rocker shaft to settle in the saddle with the adjusters all the way up.
I spoke with Eric at Smith Bros yesterday as well. He was the one that told me they are 2~3 weeks out on pushrod orders.
I found a set of Edelbrock pushrods that are 6.900 ball/cup but they are 3/8 diameter... think that might be too big and cause issues with the through holes in the head.
What’s the difference from overall length and effective length? I’m guessing effective length doesn’t account for the ball and/or cup?
If I'm reading you correctly... it's the opposite... effective length subtracts the depth of the cup.
I like to give both measurements as I don’t really trust cup size measurements. I have a cheap set of depth gauges but the old school way was to use a ball bearing on known size. This would probably be nice for some of you guys to have in your engine build tool box.
https://www.amazon.com/dp/B0063LMXJ6/?tag=fabo03-20
https://www.amazon.com/dp/B0063LMXJ6/?tag=fabo03-20
Giving both measurements is likely best.
I'm on pace to rebuild an engine once a decade...lol. The back end of a caliper works for me to get the cup depth.
Ok.. using the measuring tool to experiment with pushrod lengths both overall and effective lengths.
6.900 "effective" length is wayyy too short so those eddy rods I found are out of the running.
Found a Melling pushrod (MPR157) that is 7.234 "Overall" length. Quick math -.158 to account for the cup = 7.076 "Effective" length. Just a hair shorter than what I would order a custom set for at 7.100
Set the measuring tool to 7.236 and adjusted to 0 lash. This is what it looks like:
6.900 "effective" length is wayyy too short so those eddy rods I found are out of the running.
Found a Melling pushrod (MPR157) that is 7.234 "Overall" length. Quick math -.158 to account for the cup = 7.076 "Effective" length. Just a hair shorter than what I would order a custom set for at 7.100
Set the measuring tool to 7.236 and adjusted to 0 lash. This is what it looks like:
Looks like you are getting things figured out.
Shower thoughts saved me 2~3 weeks for a custom set. I tried on those Comp 7821-16 pushrods last night (7.396 Overall length)with the adjusters all at 0 thread showing and thought they were too long. For some reason I was thinking the rockers should all remain neutral and free as I tightened the shaft. Apparently "thinking" was my mistake. I've compiled a notepad document I've been referencing with measurements and such as I go. I was looking over the numbers just before I hit the shower... something was bugging me. Then mid shower it hit... some of the rockers are going to be opening valves as you tighten dummy! Why I thought otherwise last night I dunno.
Sooo.. off to the garage I went. Put the Comps back in with adjusters on the rockers set to 0 threads showing & torqued the shaft down 25ft lbs. Set the first 2 rockers to 1/2 turn past zero lash. This is the result. About 1/4 of a thread showing. Realistically a better fit than the set I was going to have made as I was shooting the middle. And to think I was going to return these today.
It’s funny how when we step away sometimes we can refocus. Being a self taught head porter I got to a certain point and hit a wall. I would set a pen and paper by my bed and often jumped up in the middle of the night with a thought and I would drawl a rough sketch so I wouldn’t forget what I wanted to try the next day. I didn’t want to risk forgetting it. Lol
Best possible move, a note pad bed side.
Push rods in and all adjustments made.
Resized hole in intake to 3/8 NPT and installed fittings, going to let the loc-tite ptfe cure over night.... Which is just my way of saying it's hot in the garage and I wanna drink cold beer in the AC..
Resized hole in intake to 3/8 NPT and installed fittings, going to let the loc-tite ptfe cure over night.... Which is just my way of saying it's hot in the garage and I wanna drink cold beer in the AC..
You are moving along nicely. Everything looks great.
I just have had one too many beers, that mirror picture messed me up!
Is this a street car only or street strip? If street strip was is ever ran before the head change? What heads were on it before. Is there a post on your engine build??? Been slow around here lately and looking for some reading.
I have not had any beers and the mirror was making my eyes bulge, twitch & jump. LMAO
I do enjoy the shots from the mirror though. Good idea and nice angles to see what is hard to otherwise get.
Street car only, 74 Challenger. Previous heads were rebuilt stock cast from a longblock that has less than 15k miles on it. Was running ok, just felt like it needed a bit of help to get the performance up a bit. Hydraulic flat tappet cam, .450/.450~110 LSA~218 Dur @ .050. Was punched out .030 when rebuilt.. Moly rings & dished pistons. I would have needed to remove the AC and a lot of other stuff to get the thump stick out in the car and I was not interested in pulling the block. If the block ever comes out it's going back in a 408. Instead I went with a 1.6 ratio roller rocker (stamped stock rocker probably 1.46) that will ramp faster and add about .030 lift. Better flowing closed chamber 63cc heads with bigger valves that should bump the compression from low 8 or less to nearly 9.2. And a new Air gap intake. Should be a hummin' lil 360 with good street manners. Guesstimate at the crank... neighborhood of 400HP and 450TQ, all done by 5500rpm. I could probably squeeze a bit more if I installed longtube headers but I'm not interested in all that would entail. It had Hooker longtubes on it when I bought it and ground clearance was a whopping 2 inches... I bottomed out on everything. I'll stick with these TTI shorty's for now as they make life sooo much easier.
Have a brand new fiberglass TA hood (will be painted matte black after fitment)that will be going on as soon as I get the engine squared away. Here is a shot from when the wife and I drove it out to Monterey last March.
Those inspection mirrors are worth their weight in gold IMHO. My eyes ain't what they used to be so I take a boatload of photos(why not... "film" is cheap...lol.) and double check my work on a 32 inch monitor.
Headers? Use ether TTI, Doug’s or Hooker Super Comp headers @ 1-3/4 primary tube. The Hookers fit excellent. I have a set on my ‘73 -340 Cuda.
Id give it more cam duration and a crap ton of lift with those heads as that cam is a broom stick & unworthy in my world for those heads.
Do as you like and enjoy.
Id give it more cam duration and a crap ton of lift with those heads as that cam is a broom stick & unworthy in my world for those heads.
Do as you like and enjoy.
Had Hooker Super Comp's when I bought it... photo below of the ground clearance. That dimple on the front tube was from where it hit the alignment rack. The TTI shortys will do for now.
The cam is pretty anemic. I'll live with it until I decide to stroke it. I bought the heads in anticipation of a future 408 rotating assembly. Longblock was just not in the time or $$ budget right now. had to have the transmission rebuilt and that put a dent in my beer budget along with a few other unexpected expenses. I'll git there tho.
Do you have a picture of the otherwise with those headers as well.
That’s really low. *I think* your front door is is to low.
That’s really low. *I think* your front door is is to low.
-
