on my heads to open the pushrod slots a bit..

i have one of those 5-speed variable rpm Dremels with the flexible cable...

what would be the best bit and oil to use for cutting these down? the whole is small, maybe slightly larger than a pushrod so the bit needs to be fairly tiny..

what metal is best to cut with, one designed for steel?

thanks!
Colin
Webmaster: www.IROC-Z.org

 

Not a real good idea...

Those slots are your rocker alignment mechanism. They are relatively precision-machined, maybe .012" wider than the pushrod diameter.

If you have self-aligning rockers, you need to be absolutely certain there is clearance at all times from the pushrod to the head. Drilling a 1/2" hole is a better choice.

What are you attempting to accomplish?

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"So many Mustangs, so little time..."
ICON Motorsports

 

alright, this is the story...

i got my '86 IROC and i knew the motor wouldn't last... about 40,000mi later it cratered, breaking a piston... looking at the piston i could tell that the motor's noise originally came from a broken piston skirt..

anyways, my friend totalled his '89 IROC (got hit by a dump truck, lmao) so he sold me the salvage title for a grand... i put the shortblock in and got the '86 heads rebuilt so that i wouldn't have the change the intake (the car is TPI) and chip (to delete the 9th injector so it would start good in the morning)

when i started assembling the engine i noticed that the pushrods are alot shorter i guess that's cuz the lifters are taller..

i also noticed that the pushrod guides were much smaller than the centerbolt heads, but when i cranked the engine over on the stand there seemed to be enough clearance (but not much!)

i started the car on Monday, and omg it runs horrible... my guess is that the pushrods may be binding in the pushrod guides as not all of them are doing it, and nothing was done to the shortblock other than changing over the oil pan... the only difference i can tell which would cause trouble are the guides there... i looked at pics of my '87's heads and sure enough there is more room, i'm assuming because of the pushrod angles being larger?

i just want to open those holes a bit, not much, enough for clearance only... maybe 3/32" each way, if that...

 

oh.. i am also using the self-aligning rockers from the '89 engine...

so:
'89 shortblock
'86 heads
'89 lifters
'89 cam
'89 pushrods
'89 rockers

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Webmaster: www.IROC-Z.org

 

You'd be better off to just drill them then. Take no chances; if the pushrod and the rocker tip are both trying to align the rocker, there will be binding, and what will most likely end up happening is the pushrod will either get bent, or will be forced out of its seat in the rocker, and will rapidly wipe somthing out.

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"So many Mustangs, so little time..."
ICON Motorsports

 

thanks man

so i should be alright then if i open up those holes quite a bit? i'm assuming then that if i opened them only slightly that i should go with the NON-self aligning rockers but if i am going to go WITH the self-aligning rockers that i should give a good deal of clearance? ie. 1/8 on either side...

thanks for the heads up

what bit and oil would be best for cutting?

 

If you're going with SA rockers OR guide plates, you would want to open them up; if you're using non-SA rockers and NO guide plates, you'd want to leave them alone.

Any bit that works fast would be fine, I would assume a fairly coarse stone or burr would be best; I would think a drill would be the quickest way out. Motor oil or ATF would be a good tool lube in either case.

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"So many Mustangs, so little time..."
ICON Motorsports