What pushrod length checker to start with on SBC?

[ChuckN]

There’s multiple lengths out there and I know there’s probably no one answer. A quick search revealed that a 6.8-7.8” would likely cover it, but thought I might hear from those who know the best starting point. Thanks in advance.

 

[Ricko1966]

There’s multiple lengths out there and I know there’s probably no one answer. A quick search revealed that a 6.8-7.8” would likely cover it, but thought I might hear from those who know the best starting point. Thanks in advance.

Why are you checking your pushrod lengths. It's a great idea I usually do,and just because you can tighten or loosen the rocker nuts to set lash ,doesn't mean the geometry is right and not leaving lift on the table or wearing out valve guides. But if I know the changes you made or are making I can answer your question better.

 

[ChuckN]

Why are you checking your pushrod lengths. It's a great idea I usually do,and just can tighten or the nuts,doesn't mean the geometry is right and not leaving lift on the table or wearing out valve guides. But if I know the changes you made or are making I can answer your question better.

I’m preparing for some new cylinder heads, and will be going with different rocker arms. Maybe a different cam, too.

 

[Ricko1966]

I’m preparing for some new cylinder heads, and will be going with different rocker arms. Maybe a different cam, too.

OE roller,flat tappet,or retro roller?

 

[xm20k]

6.8"-7.8” is the range I used when setting up my 388. Depends on the parts being used. Mine ended up at 7.4 Howards link bar roller lifters and Eddy heads.

 

[Ricko1966]

6.8"-7.8” is the range I used when setting up my 388. Depends on the parts being used. Mine ended up at 7.4 Howards link bar roller lifters and Eddy heads.

Oh h#ll Yea if you can get something with that much range that would do all SBC. I always made them from used pushrods not prebought,didn't realize you had that much adjustment with premades.

 

[xm20k]

Not very expensive either. Under $25

Pardon Our Interruption

 

[ChuckN]

OE roller,flat tappet,or retro roller?

Flat tappet. I’ve heard horror stories, but apparently if you use the original GM performance that’s with the hardened foot, they tend to survive better. While I’m at it, do you have any other helpful hints for start up procedure?

Cam would theoretically be XE 274 comp cam. Just under .500 lift for both intake and exhaust. I already have a 2500 stall and a 3.42 rear gear.

 

[Ricko1966]

Flat tappet. I’ve heard horror stories, but apparently if you use the original GM performance that’s with the hardened foot, they tend to survive better. While I’m at it, do you have any other helpful hints for start up procedure?

Cam would theoretically be XE 274 comp cam. Just under .500 lift for both intake and exhaust. I already have a 2500 stall and a 3.42 rear gear.

My suggestions on a flat tappet don't run an an xe series, too aggressive of ramps,trying to run too much ramp like a roller on old school lifter technology. Other suggestions run break in springs or run break in rockers( yes they are different) these will make the first miles while the cam is work hardening easier on it. Prelube the engine,prime the carb,set your carb as close and distributor as close as possible to spec so there's no jacking around getting it started and the rpms up. Ask for help a day or 2 before but I or some others on here can help you. I can set them like they were parked running hit the key they light off.Have a fan in front of the car blowing through the radiator,if you have to bring the rpms down just turn it off it off and restart it bring the Rs back up. Give it a little extra break in time with the break in oil of your choosing. I drain the oil hot right after break in. Change it again in 500 miles when you swap springs or rockers. Oh yea verify all lifters spin free in their bores on install and sacrifice some junk valve covers so you can verify the push rods are spinning.If the pushrods are spinning,the lifters are spinning which means the cam isn't wiping on the lifter. And run the lightest springs recommended for your choice. All that done,I do not think you will have a problem.IMHO not doing those things is what kills flat tappet cams.

 

[xm20k]

Break in rockers is the easiest route but at 3-400 might as well just go roller cam not everyone has the ability/desire to swap springs even though it is cheaper.

 

[ChuckN]

Break in rockers is the easiest route but at 3-400 might as well just go roller cam not everyone has the ability/desire to swap springs even though it is cheaper.

I hear ya. I’ll wait to make my final decision when I pull the cam. If it’s close enough to what I’m aiming for, I’ll just keep it.

The only undesirable thing about converting to rollers is obviously the cost. But the cost of screwing something up with a flat tappet cam is likely a total engine loss.

@Ricko1966 I’ll take your advice to heart. That’s not the first time I’ve heard that about the ramps of the XE series. Then there’s guys who swear they’ve had no issues but might not be worth the hassle.

 

[DonN]

I use a Comp Cam 7702-1. It's a 6.8 to 7.8 inch long adjustable push rod. Used i when I installed the Com Cam's Retro-fit hydraulic rolled cam in my SB 406.

 

[Craig Nedrow]

https://www.gmsquarebody.com/threads/bbc-489-build.45389/page-6

This is my 489 build. Well I think the whole build is interesting. Starting on page 6 you’ll see what I did to set my length and how to do it. There are many YouTube videos as well but it’s one thing watching a video and another thing doing it. get some dykem steel blue for your valve tips And look at my pictures they give you a pretty good idea what needs to be done. you can buy custom length push rods. I got mine from Manly great company.

 

[Ricko1966]

https://www.gmsquarebody.com/threads/bbc-489-build.45389/page-6

This is my 489 build. Well I think the whole build is interesting. Starting on page 6 you’ll see what I did to set my length and how to do it. There are many YouTube videos as well but it’s one thing watching a video and another thing doing it. get some **** steel blue for your valve tips And look at my pictures they give you a pretty good idea what needs to be done. you can buy custom length push rods. I got mine from Manly great company.

Also look from some you tube videos on doing the 1/2 lift method, that's how I learned and it is dirt simple once you understand it. If you look at a rocker it travels in an arc,not straight in and out like the valve,so if at 1/2 lift your rocker is at 90* to the valve stem then 1/2 the side to side motion of the arc was used getting to 1/2 lift the arc will be pushing the opposite direction the second 1/2 of the lift. Least pressure and wear on guides most in and out travel on the valve itself. And the beauty is you just have to bring the cam to 1/2 lift,adjust pushrod length so you have 90* at the stem. Done, measure the pushrod,no trial and error no rotating the engine over and over.

 

[ChuckN]

Also look from some you tube videos on doing the 1/2 lift method, that's how I learned and it is dirt simple once you understand it. If you look at a rocker it travels in an arc,not straight in and out like the valve,so if at 1/2 lift your rocker is at 90* to the valve stem then 1/2 the side to side motion of the arc was used getting to 1/2 lift the arc will be pushing the opposite direction the second 1/2 of the lift. Least pressure and wear on guides most in and out travel on the valve itself. And the beauty is you just have to bring the cam to 1/2 lift,adjust pushrod length so you have 90* at the stem. Done, measure the pushrod,no trial and error no rotating the engine over and over.

That’s how Derek from Vice Grip Garage does it. I found he describes it very well in part 2 of his 454 build.