GarrettM

iTrader: (6)

Ok guys here is my problem. We did a cam install last weekend and put in an MS3 cam with stock 853 heads. We installed patriot dual gold springs and TSP 7.400" pushrods.

So heres my problem. In the process we decided to go ahead and install new LS7 lifters, so we pulled the passenger side head and swapped out the lifters no problem. THEN we went to pull the drivers side head and it wouldnt come off. It had ARP headbolts and whoever owned the car before torqued them WAY beyond spec and rounded one off. So after three days of trying we abandoned hope on getting that head off.

So now im sitting here with LS7 lifters on the passenger side and LS1 lifters on the drivers side. I talked to a GM Tech and he said "Oh its no biggie the LS7's are stock replacements." but I know that the plunger height is .050" taller so with the 7.400's all around my preload will be different on each side of the motor.

Is having a different preload on each side a catastrophoc problem or what. I was told by several shops that it is a problem that can be addressed by different length pushrods on each side to even it out. I know that my best course of action is to get a PR checker and measure then go from there. But for right now can I run what I have without risk of serious damage till I do??? Or does anyone have an idea on the lengths I may need to run to stay out of trouble?

P.S. - Please dont tell me I need to run the same lifters on each side or start talking about how to get the head off, I know all of this and wish I could but as of right now this is the situation I am faced with and am looking for advice on how to make the best of it. Thanks in advance!!

Sales2@Texas-speed

iTrader: (5)

Like I told you yesterday on the phone, you need to measure for pushrod length and order 8 of each length...they will be different lengths. It costs the same amount of money to get 8 of one length and 8 of another as it does to get 16 of the same length. Any vendor/sponsor here that is worth his/her weight in salt should be able to get 8 of one length and 8 of the other for you!

TooLateVTEC

iTrader: (2)

Wait, isnt 7.4" push rods stock length?

I thought I read that somewhere, do some research and find out if thats true.

If it is, and the 7.4's you have are the correct length to use with the LS7's than you dont need another set.

GarrettM

iTrader: (6)

Yea Matt thats what im going to do. After I got off the phone with you I got ahold of a guy that has a PR Checker and this weekend im going to get that done and get some ordered. Problem is the my employer is getting tired of me driving a company vehicle so they are telling me that I need to be driving my car by Friday. So im just curious if it will be ok to baby it to and from work till I can measure and get my rods in.

Yes stock length is 7.400" but the cam has a smaller base circle I believe and the LS7's have a different plunger depth. All of which can effect the need for different pushrod length.

Sales2@Texas-speed

iTrader: (5)

The stock pushrod's gauge length is actually 7.38x"....the aftermarket ones you have are 7.400" gauge length, which accounts for the slight difference in base circle diameter on many of the aftermarket camshafts.

http://www.trendperform.com/measuring.html

There's a little reading about measuring for pushrod length and gauge length versus tip-to-tip length for anyone who's interested.

TooLateVTEC

iTrader: (2)

I forgot about reading the MS3 cam part, sorry.

Then yes, 2 difference lengths will be needed.

LS7 lifters plunger is HIGHER than a stock LS1 lifter.

Heres a pic

GarrettM

iTrader: (6)

Im sorry my mistake on the stock length thanks for the correction.

GarrettM

iTrader: (6)

Bump... So guys anybody think I can get by for a week or so babying it for a week or so till i measure and order pushrods. I just dont know if having the little different preload is catastrophic or just stressfull and need to fix it soon.

NXZ28

iTrader: (45)

The correct answer here is "No". I have driven around with too short and too long of pushrods before. Even raced the car a few times. This was my learning curve with aftermarket cams and non-adjustable rocker arms. Engine was driven and raced apprx 5K miles. Back then, the sewing machine noise was refered to as normal for larger cams and the LS1. Then came a lifter failure and I decide to check things more thoroughly. I think you could get by for a short period of time and taking it easy on the rpms. This is just my opinion from past experience with pushrods and aftermarket cams.

Taspeed

iTrader: (1)

if it were me, i would pull the motor and get the other head off.

SOMbitch

iTrader: (8)

Sears sells sockets especially for stripped bolts. I would give that a try next.....

HotSilverBird

Extremely easy way to remove the striped head bolt is to simply use a die grinder or demel tool and remove the head of bolt. After the the rest of the bolts are removed pull the head and use a vise grips to remove the shaft.