Same engine, different pushrod length??
#1
TECH Regular
Thread Starter
Same engine, different pushrod length??
So I measured for pushrod length on the engine Im building. I keep getting 2 different lengths. Im using the comp cams pushrod length checker with a base length of 6.8 and 0.050 per turn. For the intake Im getting 10 turns for zero lash. For the exhaust Im getting 9.75 turns for zero lash. Ive done it many times trying to see if there was an error on my part and I keep getting the same numbers. So with that being said, should I run the same length pushrod, or get separate lengths for intake and exhaust? I was looking for a 0.070 preload and heres the numbers I came up with.
intake: (10 x 0.050) + 6.8 + 0.070= 7.37 intake rod length.
exhaust: (9.75 x 0.050) + 6.8 + 0.070= 7.3575 exhaust rod length.
the length options I see from tsp are 7.350, 7.375, and I already have 7.4. Should I just run all 7.375 rods and call it a day?
intake: (10 x 0.050) + 6.8 + 0.070= 7.37 intake rod length.
exhaust: (9.75 x 0.050) + 6.8 + 0.070= 7.3575 exhaust rod length.
the length options I see from tsp are 7.350, 7.375, and I already have 7.4. Should I just run all 7.375 rods and call it a day?
#4
TECH Regular
Thread Starter
or they dont even measure at all. I really dont want to get different length rods but I will if I have to. Wouldnt the only real difference using the same rod for both (assuming my measurements are correct) just a slight difference in the preload? And the lifters are ls7 style lifters from Texas speed.
#7
TECH Addict
iTrader: (28)
I measured for every single one on mine, thought it was weird but they all came out consistent and used diff sizes for intake and exhaust sides to get what preload i wanted. Called up manton and they shipped them next day air for no extra charge. They also have different sizes and tappered ones than the usual ones all the online places stock if you have the head clearance to run stronger/larger ones.
i would just make sure you mark them incase you forget or someone in the future takes it apart as most just toss all the p-rods into one big pile..
i would just make sure you mark them incase you forget or someone in the future takes it apart as most just toss all the p-rods into one big pile..
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#8
TECH Regular
Thread Starter
So I measured the passenger side and these are what I got
#2 ex- 9.75
In- 9.75
#4 ex- 9.5
In- 9.75
#6 ex- 9.5
In- 9.75
#8 ex- 9.5
In- 9.75
seems consistent that there’s a 1/4 turn difference between intake and exhaust lengths except on the number 2 cylinder. Guess I’ll measure the driver’s side and see what numbers I come up with for those.
#2 ex- 9.75
In- 9.75
#4 ex- 9.5
In- 9.75
#6 ex- 9.5
In- 9.75
#8 ex- 9.5
In- 9.75
seems consistent that there’s a 1/4 turn difference between intake and exhaust lengths except on the number 2 cylinder. Guess I’ll measure the driver’s side and see what numbers I come up with for those.
#10
TECH Regular
Thread Starter
would there be any harm to running the same length rod for everything? If I ran a 7.35 rod then on the 9.75 turn valves they would have a .0625 preload and on the 9.5 turn valves they would have a .075 preload. Thats a difference of 0.0125. And I believe both of those preload numbers are within the acceptable range of the ls7 style lifter.