Going from 289 flat tappet to roller 302, which pushrods?

[jb1dsl]

I have a 289 with flat tappet cam, edelbrock heads and roller rockers. Will these push rods be right when I change to a roller cam 302? I bought the hardened push rods when i changed to aluminium heads, so does flat tappet and roller cams use the same push rod?

 

[D.Hearne]

No, roller lifters are taller, so the pushrods will need to be shorter. Actual length will need to be determined once you've done the swap and everything's back in place. You'll need length checking pushrods, unless the supplier of the cam and lifters can recommend what length rods you need.

 

[fasttback]

As every cam/head guru has told me, you should always check your valve geometry when new parts (non-stock) are added or old ones modified.

Buy an adjustable push rod...it will give you the answer.

 

[jb1dsl]

I checked with edelbrock . It looks like they are say 6.400 length instead of the 6.805 length I have for my flat tappet cam. So it is definitely shorter.

 

[D.Hearne]

What cam and lifters you using?

 

[jb1dsl]

edelbrock roller rpm cam, factory lifters.

 

[jb1dsl]

I looked at comp cams and it says 6.400 for a roller retrofit and 6.25 for a factory roller motor. I guess the 6.25 is for factory heads and 6.4 is for aluminum heads according to edelbrock website

 

[D.Hearne]

You'd have to use a reduced base circle cam to use factory style 5.0 lifters in a 289 block. Otherwise the lifters poke up too far out of their bores and uncover the oiling bands.

 

[jb1dsl]

im using this in a 94 roller 302

 

[fasttback]

I checked with edelbrock . It looks like they are say 6.400 length instead of the 6.805 length I have for my flat tappet cam. So it is definitely shorter.

Sounds like that might get you there, but has anything been decked (block or heads), rocker arms (ratio change), modifications to valve spring height, and head gasket thickness? All of these lead to changes in the pushrod length to some degree.

I'm running a 1968 302 block (zero decked), new Canfield 195, and a custom solid roller camshaft. My pushrod length went from 6.80 to 7.05". My two sets of rocker arms (1.60 and 1.72:1) required 7.10 and 7.00" so I settled on 7.05. If you want to squeeze every little bit of horsepower out of your motor, I recommend checking the pushrod length.

 

[SoCalCruising]

If you are using a standard base circle cam, a roller block, standard in-line heads, and factory lifters, your length will probably be between 6.3 - 6.4". I use 6.350" exhaust and 6.300" intake, determined by adjustable pushrod. What yours needs depends on your combination of parts and what machining has/will be done, so use the adjustable pushrod - don't guess at it.

 

[jb1dsl]

Its a standard roller 302, edlbrock rpm heads (stud mount,shaved 0.020), edelbrock rpm roller cam. crane gold 1.6 roller rockers and factory lifters.

 

[jb1dsl]

i called edelbrock and they said the 6.400 is for a reduced base circle cam and their retrofit lifters. He said it would be the factory length which I believe is 6.25.

 

[D.Hearne]

i called edelbrock and they said the 6.400 is for a reduced base circle cam and their retrofit lifters. He said it would be the factory length which I believe is 6.25.

That's what I would think, unless the Ed heads are taller than stock. I thought you were putting all this in a 289, that's the reason I asked. With my Canfield heads on a .010 decked roller 5.0 block and the heads milled .060, the factory 6.25 rods were perfect. (Z303 cam and Comp 1.7 roller rockers)

 

[jb1dsl]

5\16 or 3\8's, i can't remember?

i think these are the ones I need

http://store.summitracing.com/partdetail.asp?part=CCA-7826-16&autoview=sku

 

[fasttback]

If cash is a concern, here is some info to make your own pushrod checker (from another web site):

"Simply take an old push rod and cut it about 1 to 1.5 inches from the end. Use a 1/4"-20 tap to cut threads into the open ends, and then screw in a short piece of 1/4-in. threaded rod. Use some nuts to lock the rod in position. Now you've got an adjustable tool that you can use to properly calculate and order the exact length pushrod. "

note: don't try to use a harden pushrod for this.