gn1 head pushrod length

[buickturbot]

i have stock 109 block with gn1 aluminum heads.put motor apart most of the valve spring dampeners are broken and pushrods are 8.890 long. anyone know if my pushrods are right length ?

 

[turbo nasty]

.

 

[ryan319]

You have to get an adjustable push rod length tool and measure the length that gives you the right amount of preload on the lifters. A quick search should yield all the info you need.

 

[pacecarta]

why would you suspect the pushrod for broken spring dampners

the pushrod just does what its told
id be looking at the spring choice for the gross lift of the cam and the rocker ratio ,


and the typical rod for flat tappet is 8.850 , for roller lifter 8.550 comp(8.7 morel)
lengths vary with setup variations so you need to check what your motor needs
if you are running roller rockers you also need to get the pushrod correctly sized to allow the roller rocker adjuster to be within a certain window so it doesnt block off the oil passage to the rollers

 

[buickturbot]

thanks have shorter set 8.850 on the way

 

[bison]

I still dont see this turning out well unless you actually measured and ordered the correct length set. What did you do about the springs?

 

[ryan319]

thanks have shorter set 8.850 on the way

How much preload does that length give you? Are you running a roller cam?

 

[pacecarta]

going from 8.59 to 8.55 youll just be .040 less on preload , if you already had .030 now you'll be too short , if you had .100 preload youll be at .60

you cant just chose a p-rod on whats common ...rockers , the lifter, if the block was decked , if the head was decked, where the base of the cam is cut at and what gasket you use since you could have a steel shim at .017(.033 pair) or a cometic at .040-.050 or .060 or stock graphite at .060
all these variables can make a difference in the final length

altering the pushrod length wont have any effect on the issue of the broken dampners