What brand and length pushrods are recommended for use in a 383 build? I'm using the 1.6 rockers.

What about pushrod guide plates? anybody recimmend them? what are the pro and cons and does anything need to be done to the LT4 head to install the guide plate?

 

The only correct answer regarding pushrod size is to use the correct length determined by physically checking. Every time I guessed, I was wrong. I only buy pushrods after mocking up a motor.

 

Only way to do it.

 

What Pete said. I have a complete 383,except pushrods, each piece in its original box.Those will be ordered after all the little pieces are one big piece and measurements taken.

 

Guide plates are used win non self aligning rockers.

Buy an adjustable pushrod and a couple of weak test springs so you don't collapse the lifter. There are a wealth of how tos on the web.

 

PR length is something that you need to check to get the EXACT length. Use an adjustable PR checker and start at 7.100" and adjust the length until you get the wear pattern most centered in the valve. Go .050" shorter and watch the wear pattern move. If it gets worse, go .050 longer. It could be anywhere from 7.00 to 7.250 depending on everything done but a 7.100" (Trik Flow 21407100) is what I suggest for people that do not know how (or do not wanna take the time) to do this.

The following is a method of verifying proper valve train geometry. After you have estimated the required pushrod length using a Pushrod Length Checker, use this method to verify that the valve train geometry is correct (using the rockers you are using in your engine):



1
The first step is to install a solid lifter and an adjustable pushrod. Mark the tip of the valve with a marker



2
Install your rocker arm and set it up with zero lash.



3
Rotate the crankshaft clockwise several times. Remove the rocker arm. The contact pattern of the rocker tip will be where the marker has been wiped away from the valve tip. The pattern should be centered on the valve tip, and as narrow as possible. If it is not, experiment with varying the pushrod length to yield the best pattern.



4
Pushrod Too Long: Notice how the pattern is wide, and shifted to the exhaust side of the valve tip.



5
Pushrod Too Short: Notice how the pattern is wide, and shifted to the intake side of the valve tip.



6
Pushrod Length Correct: Notice how the pattern is narrow and is centered on the valve tip.

I have 6 pictures that go with these steps but they did not make it when I cut and pasted this.

Anyone able to post the pics if I email them?

Lloyd

 

From a man who knows. Lloyd Elliot. Surprised you didn't wade into the marathon AFR thread.

Then again, no I am not.

 

HERE is a pretty good tutorial.

 

Thanks guys. It's great to see that there are guys here that give out good info.

Yes, it has to be done after the motor is assembled and some of the methods of finding the correct length that you guys recommend are spot on. The Comp Cams adjustable pushrod tool is a good way to find the correct length after checking your "witness mark"

 

Not sure about this answer on the pushrod guides....

Golen Engine Service installs them. Here's a shot and quote from them.

Besides adding the readily apparent Comp Cams 1.6:1 rocker arms, GES beefs up the valvetrain of its ported LT1 heads by increasing the rocker stud size to 7/16-inch. "We've all seen 3/8-inch studs break," says Chad Golen. He maintains that pushrod guideplates are also a must: "Self-aligning rockers can pop off."


I guess it's the age old question.."what are you going to use the car for? Drag racing or road racing?"

I would think maybe for drag racing your high RPMs will be shorter because the shifting down the track...For a auto X/road race motor maybe it would provide the pushrod with an extra measure of maintaining proper alighnment under sustained high RPM driving when holding you revs up going in and out of curves.

 

Point taken. I should have injected The word "usually."

 

I'm running TrickFlow chromemoly pushrods and their guideplates, best bang for the buck.

 

MK 82,

I am just here to help people with answers and maybe share some of my knowledge with the people that need help.

Most of the people posting in the AFR threads have everything figured out and anything I could add would not help out any of these people at all, LOL.

I did read the first post by Tony Mamo but never clicked back on it to see what others have said.

Lloyd

 

You didn't miss much.

 

I skimmed a few posts before it got too deep and agree with what one person said about picturing what is going on in the engine during low lift flow and how un important it is. This is why people use steep top cuts (37-40 degrees) and eliminate reversion since what flows well one way, flows well the other also.

The AFR 195 cc Eliminators are a REAL nice head and will outperform any aftermarket head in the 195 cc range but if 195 cc is what you need is another question all together. A mild 6000 RPM engine will be a perfect fit but if you try feeding an engine to 6500 RPM or higher, or even add some cubes, you are gonna want certain measurements in certain areas and the 195 will run out of steam.

It has all been written out before how much cross section you need to feed X cubic inch to X RPM and the 195 is gonna be a lil small for a BIG HP set up. If the custoimer still wants good TQ at 1200-1400 RPM AND spin 6500 RPM with good power, that is a compromise you make and you have to pick betwen more HP at high RPM and 5-10 less ft lbs of TQ at 1400 RPM or gain that TQ down low but have less HP at 4500 RPM on up.

If the customer has the gear and stall or a driving style to sacrifice the TQ loss down low, great . . . . lets make some real power with a big head. If he has mild gears and stall or likes lugging around and only wants the big dyno sheet to show his buddies (since the car is not set up for BIG HP), the smaller port would be a better choice and hell, probably even a smaller cam while we are at it.

Lloyd