Pushrod length?

**2001TransAm** · 05-02-2009, 04:07 AM

I have the PRC 2.5 5.3L heads for my 01 LS1 and I already have Alum. 1.7 roller rockers for them, I also have the MS3 cam. Should I buy the stock length 7.4 pushrods? Im not changing the stroke or bore.

**Hi-Po** · 05-02-2009, 08:16 AM

Heads been milled?

**Mr. Luos** · 05-02-2009, 06:21 PM

You should ALWAYS test it with a head swap.

**mark21742** · 05-02-2009, 09:22 PM

call up summit or jegs and buy a pushrod lenght checker....they are pretty cheap and can save lots of headaches

**2001TransAm** · 05-05-2009, 05:49 PM

I guess i dont understand why I need a pushrod checker, I know they are only 15-20 bucks but if i didnt change the ratio of the rockers and the lifters are going to be the same as the stock ones, shouldnt the pushrod length be stock 7.4?

**mark21742** · 05-05-2009, 06:22 PM

Originally Posted by 2001TransAm

I guess i dont understand why I need a pushrod checker, I know they are only 15-20 bucks but if i didnt change the ratio of the rockers and the lifters are going to be the same as the stock ones, shouldnt the pushrod length be stock 7.4?

should be, but its just a step to be sure.
my cam called for longr pushrods, but after checking I still had to use stock lenght pushrods.....so you never know till you check

**pjeff7** · 05-05-2009, 08:32 PM

yeah man, it's better to be safe than sorry when it comes to the pushrods. My PRC 215's aer alot taller than the stock heads. Needed a 7.5 PR.

**2001TransAm** · 05-06-2009, 05:25 PM

Thanks guys.

**mrr23** · 05-16-2009, 05:36 PM

bore and stroke, rockers arms, or lifters do not matter, when it comes to the length of the pushrods. in a non adjustable valvetrain, what matters is the deck height of the heads and block, camshaft base circle, and head gasket thickness. are you using a thinner head gasket? how much was cut off the heads? was the block decked? anytime you change these areas, you are changing the total distance from the lifter to the rocker.

milling the heads, milling the block, and using thinner head gaskets bring the valvetrain closer to the cam. in a non-adjustable valvetrain, you will need shorter pushrods to compensate for this. if you know how much was cut off the heads, block, and how much thinner the head gasket is from stock, then you just shorten the pushrod that much. if not, then you'll need a checker.

**Hurley711** · 05-16-2009, 08:45 PM

$20 is worth the headache saved if you put in the wrong length

**mark21742** · 05-17-2009, 07:52 AM

Originally Posted by mrr23

bore and stroke, rockers arms, or lifters do not matter, when it comes to the length of the pushrods. in a non adjustable valvetrain, what matters is the deck height of the heads and block, camshaft base circle, and head gasket thickness. are you using a thinner head gasket? how much was cut off the heads? was the block decked? anytime you change these areas, you are changing the total distance from the lifter to the rocker.

milling the heads, milling the block, and using thinner head gaskets bring the valvetrain closer to the cam. in a non-adjustable valvetrain, you will need shorter pushrods to compensate for this. if you know how much was cut off the heads, block, and how much thinner the head gasket is from stock, then you just shorten the pushrod that much. if not, then you'll need a checker.

well said, (i should have milled them the last time i had them off) but right now i'm just on the loose side of clearance with my cam swap, after i mill mine it should put me right where i should be