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Fast92stang
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12 Posts
Discussion Starter #1
Hey guys, this one has me right stumped.. along with my local performance shop too.. I have a 1995 302 out of a gt mustang(wrecked), made a 347 stroker out of it, installed into my 92 foxbody.
It has a rattle coming from what seems to be the top end.. and nothing I do is helping it, at all. Heres some specs:

HV Melling oil pump
Comp Cam 35-552-8
roller rockers 1.6:1
comp hi tech push rods (intially 6.4" then tried stock 6.25" no change in noise but the long ones did blow out 2 sets of guides :wank2:... )
procomp 3038 heads
msd billet dist with bronze gear (ps my engine goes thru dist. gears.. i think from the hv oil pump??)
air gap intake

anyways the rattle ONLY happens when you are juuuust feathering the throttle, at ANY rpm, and ANY temperature, however worse when cold. as soon as you put any amount of load on it, it disapears. completely!:angry:

can ANYONE, ANYWHERE help me with this?? has anyone else out there had this issue?? Please! I got almost every tech in town stumped on it too...

Before I overhauled the engine I did hear it running, no noises.

-Steve
 

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Administrator
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4,980 Posts
Hi s.cody. Noises can be very tricky. Does it have hydraulic lifters and are they working correctly. That sort of noise i have often heard coming from rockers but I'm sure they will have been checked. What about valve guides are they in good shape?
 

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Fast92stang
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12 Posts
Discussion Starter #3
Hi Big Block Ford, It has Comp Cam Hyd. Roller lifters in it. I rolled the engine over to tdc #1 and popped the valve springs off to check the guides too, found little but some play in the guides. So took the heads off and took them down to my local perf shop. He said they 'really are not THAT bad'. And I guess I did check them incorrectly. He instructed to hold the valve closed and check for movement... I slid the valve down about a 1/4" and found the top of the valve moved 1/8"... But decided to not chance it...they are currently getting a fresh set of manganese bronze guides, debating on new valves as well.
Engine only had 600 miles on those heads but the valves looked like they had 20,000 just by looking at them. I think I might try a new set of lifters.. ive found good and bad about the lifters..some made in China, some made here in USA.. so i'd like to try a standard set of OEM Ford ones..
The Rockers i purchased off of ebay, they resemble the comp Golds. Came outta Tennesee, if you ebay search this it is exactly what I have: SBF FORD ALUMINUM 1.6 RATIO 3/8 ROLLER ROCKERS RR5005 . I think my only option at this point is to try different lifters... if it still rattles then try rockers? after that... maybe a Coyote Swap haha :p
 

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Fast92stang
Joined
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12 Posts
Discussion Starter #4
So finally solved the rattle... and its such an intersting cause it makes sense. Installed a larger carburator, rattle is GONE. figured i'd let you guys know maybe it'll help someone else. Only took me 3 different top ends to figure that one out. LOL. Oh well, I learnt a lot. :)
 

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Administrator
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4,980 Posts
Thanks for letting us know but the carby?. Considering it was from just feathering the throttle then where was the rattle coming from. Too much vacum?. I would have thought undercarbed would only show up at wide open throttle.
 
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