| From | Message |
kmiller
Dodge Dakota
JOIN HERE
5/30/2004
12:18:59
|
 Subject: 5.2 Valve Clearence Help
IP: Logged
Message:
I have a 94 Dakota SC 5.2 5spd, that I have been stock piling parts for & final started to install them. I have ran into some troubles installing the cam, NO piston to valve clearence.
It is Comp Cams .512/.512 lift cam but I also have 1.7 Harland Sharp rockers totaling .544 lift. I installed the timing chain by aligning the dots on the 2 sprockets & started to check the degree (installed solid lifter) when I found the valve contacts the piston. I ordered a new timing chain set that is degreeable but dont think that will work.
I was wondering if anyone has installed a simular setup on a 5.2 & if so were new pistons required.
My Ebay Stock Pile
Paxton Sn93 w/ paxta map fuel system (6&8lb pulleys)
2.02 Ported R/T Heads
M1 4bbl intake w/2bbl adapter & lg turtle
52mm Holley TB
FMS 19 lb Inj's
1.7 Harland Sharp RR's
Comp Cams .512 lift cam
MSD6btm
MP Headers
Underdrive pulleys
electric fan
250lph intank walbro fuel pump
MP PCM
.040 cometic head gaskets
ARP studs
I cant wait till its running!!!
|
Ahab
Dodge Dakota
JOIN HERE
5/30/2004
13:30:02
| RE: 5.2 Valve Clearence Help
IP: Logged
Message:
Comp Cams should be able to give you the correct information about the rocker ratio and piston clearance.
|
gen1dak
Dodge Dakota
JOIN HERE
5/30/2004
23:22:16
| RE: 5.2 Valve Clearence Help
IP: Logged
Message:
Okay, now don't take this the wrong way, but how are you able to see the valve contacting the piston?
My point is, at the lifts you're looking at, you run into valvespring retainer-to-valvestem guide clearance issues. Since the Magnum RT heads use the same valvetrain gear, including springs, I'm thinking the seats and guides are not cut down for clearance, and this must be done with valve lifts above .525 to allow adequate retainer-to-guide clearance. The retainers will actually touch at around .550, give-or-take. Factor in what may be a slightly lower installed height for your retainers with the new springs/locks, and the fact that you have 6 thousandths of an inch between your gross lift and the advertised production clearances with the guide, and it's certainly something to check. You'll either have to drop back to 1.6 rockers, swap to a slightly lower-lift cam (probably your most cost-effective choice), or have the spring seats and retainers ground down.
Now, that being said, you're there, and you can see what's going on. If the pistons are actually hitting the valves, ya got me there. Just my 2-cents.
|
kmiller
Dodge Dakota
JOIN HERE
5/30/2004
23:55:58
| RE: 5.2 Valve Clearence Help
IP: Logged
Message:
I actaully used the clay method on the piston & the valve did contact the piston.
|
gen1dak
Dodge Dakota
JOIN HERE
5/31/2004
00:36:01
| RE: 5.2 Valve Clearence Help
IP: Logged
Message:
Ahaa. Hmm. Well now. Intake or exhaust?
|
kmiller
Dodge Dakota
JOIN HERE
5/31/2004
10:45:10
| RE: 5.2 Valve Clearence Help
IP: Logged
Message:
The intake valve, I think I will end up ordering a set of pistons with valve reliefs already machined if I dont find anything wrong. What sucks about this is, Im also working on a 408 short block that I plan to have done this winter (because of finances). So any money I sink into the 318 short block I will only see a few months use from. Like I said before I was hoping that the Cam centerline was to far advanced, but Im waiting for my new chain set before I recheck it.
|
gen1dak
Dodge Dakota
JOIN HERE
6/01/2004
02:55:09
| RE: 5.2 Valve Clearence Help
IP: Logged
Message:
If you're doing the 408 thing, why not just cut back to the 1.6 rockers, save the money on relieved pistons, and funnel it to the 408? Don't know what your goal is for the 318, but that's a lot of lift (speaking in relative terms) for a street 'teen As for piston to valve clearances, they should be a minimum of .100-.120 inches for intake and .120-.140 inches exhaust for stick-shift applications. Automatics can use less clearance, but .090 inches should be the minimum.
On centerlining the cam, CompCams usually grinds their street engine cams with 4 degrees advance factored in for production tolerances, and since most just install the cams "straight up," this works out pretty well. However, you may still gain some clearance from degreeing. No way to know til ya try.
|
nick
Dodge Dakota
JOIN HERE
6/01/2004
21:02:45
| RE: 5.2 Valve Clearence Help
IP: Logged
Message:
I talked with marty at KRC about 1.7rr on my 1997 318 with their 210x cam (512,512 lift) and he cautioned me not to use the 1.6rr related to clearance issues, as you now know with the pistons. i dont think you will gain enough clearance throug degreeing to be able to run these on your 318, notched pistons or a 360-408 piston is needed.
nick
|
DAHEMIKOTA
Dodge Dakota
JOIN HERE
6/07/2004
00:33:01
| RE: 5.2 Valve Clearence Help
IP: Logged
Message:
I run a .620 lift solid lifter cam in my 5.2L for a while. The valve reliefs were .250 deep. The pistons have a .150 dome but the reliefs were below the flat portion of the piston. Like everyone is saying, you have to make sure the springs don't bind or the seals don't get crushed.I also agree with their thinking that a cam with that much lift is too much for the street. My new cam is a .490 lift mechanical and the engine dyno'd at a corrected 550 HP. More than enough to keep up with traffic.
|
| | P 1 |
|
Post a reply to this message:
Username Registration: Optional
All visitors are allowed to post messages
|
