LS1 Pushrods

[iacs_hsv]

Anyone know if there are any differences between LS1 & SBC pushrods (trying to locate 7.250")?

[ringram]

I thought LS1 were longer. Like 7.4" or something. Or 7.350" anyway.
You want superstiff ones anyway, guys go larger diameter or thicker wall to reduce flex with aftermarket springs which are required with the cam lobes used these days.
Or just get some stock ones if you are stock in the valvetrain dept.

[iacs_hsv]

Thanks Richard,

Agreed - 7.250 is 0.150 under stock, that's the problem... Comp only appear to go down to 7.350 unless I consider SBC parts but I don't know what the differences are? Both are 5/16 OD...

[ringram]

Why so short? Did you mill the heads a load?

[iacs_hsv]

Smaller base circle, milled heads & Crane Gold RR geometry contribute to the gap. I've wiped the stems with an adjustable pushrod, so required dim is bang on...

Edited by iacs_hsv on Monday 18th May 19:30

Edited by iacs_hsv on Monday 18th May 19:32

[stevieturbo]

iacs_hsv said:

Smaller base circle, milled heads & Crane Gold RR geometry contribute to the gap. I've wiped the stems with an adjustable pushrod, so required dim is bang on...

Edited by iacs_hsv on Monday 18th May 19:30

Dont measure an adjustable pushrod, they dont measure correct.

Measure them relative to a PR of a known length.

Smaller base circle will require a longer pushrod.
Milled heads will require a shorter pushrod.

7.250" sounds very wrong. What sort of angle are the rockers sitting on the heads at that ? were there any spacers for the rockers to lift them ?

How much smaller than standard is tbe new cams base circle ?

WHat sort of pre-load are you aiming for ?

[iacs_hsv]

Mate - this is getting a bit off topic... my original question was are the SBC PRs compatible with the LS1 PRs?

Yes - the adj PR is measured *relative* to a Crow Cams 7.400" item (and a stock GM to double check).
Yes - the cam BC will require a longer rod, I was identifying the aggregate changes (+/-) to the VT.
Yes - I've checked the rocker sweep.
No - 7.250 is not horribly wrong (I believe the Cranes came with 7.250s, if you bought the kit - unfortunately Crane are history).
No spacers - these are stud rockers.

Edited by iacs_hsv on Monday 18th May 19:49

Edited by iacs_hsv on Monday 18th May 19:50

Edited by iacs_hsv on Monday 18th May 22:41

[stevieturbo]

Phone any pushrod supplier then, they can advise.

As long as they are hollow, and the correct diameter. They are only a straight shaft. I'd imagine most have the same ball end.

But again, any supplier could tell you that. Phone SDCP for example.

Edited by stevieturbo on Monday 18th May 21:34

[iacs_hsv]

I was struggling to get through to Comp hence the post but finally managed tonight. I too was worried about the ball fitting into my rocker cup but they confirm the 5/16 Gen I & Gen III are the same. Bizarely, they list different part numbers for each motor - hence the confusion.

Now need to find some stock...

[ringram]

Now we are off topic you can tell us what you are building there Mr.
What have you done to the heads?
By your profile it looks like a HC NA setup !?

[MyM8V8]

I just installed Yella Terra Ultralites with CrMoly 7.425 rods. Marvelous.

Get in touch with Pete Knight at Knight racing Services in Daventry. He'll know.

Do you have make and P.No of your checking springs?

Edited by MyM8V8 on Tuesday 19th May 10:39

[stevieturbo]

iacs_hsv said:

No spacers - these are stud rockers.

Some stud rockers come with spacers. You need to check pre-load, as well as the wipe pattern on the rockers. In some instances, spacers may be required to correct rocker geometry ( The Yella Terra's come with some )

[tinker-27]

sbc ones are the same try real steel they stock them and the right price to

[Boosted LS1]

stevieturbo said:

iacs_hsv said:

No spacers - these are stud rockers.

Some stud rockers come with spacers. You need to check pre-load, as well as the wipe pattern on the rockers. In some instances, spacers may be required to correct rocker geometry ( The Yella Terra's come with some )

Yes and they hide them in the bottom of the box, barstewards lol!

[iacs_hsv]

The Comp R lifters I'm using are set zero lash plus 0 to 1/8 turn.

[iacs_hsv]

ringram said:

Now we are off topic you can tell us what you are building there Mr.
What have you done to the heads?
By your profile it looks like a HC NA setup !?

Not in your league mate, just brightening up the old girl.

Heads de-flashed, light chamfering and a polish for the moment with a bit of CR lift to compensate for the overlap dynamics.

Old skool tuning! - is there any other way...

You got a nice set of 243s in the back of your shed for me Rich?

Edited by iacs_hsv on Tuesday 19th May 18:19

[iacs_hsv]

MyM8V8 said:

Do you have make and P.No of your checking springs?

Believe they are Comp Cams #4758 - small enough dia to stay off the seats so you can get a caliper in to measure installed height.

[stevieturbo]

iacs_hsv said:

The Comp R lifters I'm using are set zero lash plus 0 to 1/8 turn.

That really doesnt sound like a lot ??

If its an M8x1.25mm stud, 1/8 turn on that, is only 0.15mm, which is 6thou.


I may be wrong, but Ive never seen a hydraulic lifter run such low preloads on any engine.

[ringram]

iacs_hsv said:

Old skool tuning! - is there any other way...

You got a nice set of 243s in the back of your shed for me Rich?

I did have, but they were attached to my engine which got sold.

Gareth might have some spare 243's soon as he is upgrading his.

[iacs_hsv]

ringram said:

iacs_hsv said:

Old skool tuning! - is there any other way...

You got a nice set of 243s in the back of your shed for me Rich?

I did have, but they were attached to my engine which got sold.

Gareth might have some spare 243's soon as he is upgrading his.

I'm all ears!