Firebird 3.4 to 3500 swap

[Jawz]

Hello Gents,
I got a couple questions for the guys who have done or know about the 3500 swap on a firebird or camero.

1. Rods. will the 3.4l rods work for the 3500 heads or will i have to go with the 3500 rods?

2. LIM. There is a lip on the timing chain cover on the top that is hitting the thermostat housing and it keeps it from getting its seal. What to do to take care of that?

I would be very much appreciated if someone can help me out with this .. Thanks!

[Guest]

Hello Gents,
I got a couple questions for the guys who have done or know about the 3500 swap on a firebird or camero.

1. Rods. will the 3.4l rods work for the 3500 heads or will i have to go with the 3500 rods?

You mean pushrods? "Rods" generally refers to the connecting rods. No the 3.4 pushrods will not work with the 3500 heads. These need to be custom length when doing the hybrid swap (genI/II bottom end with a gen III top end).

2. LIM. There is a lip on the timing chain cover on the top that is hitting the thermostat housing and it keeps it from getting its seal. What to do to take care of that?

I would be very much appreciated if someone can help me out with this .. Thanks!

Cut the tab off the timing cover.

[Jawz]

Yes i meant pushrods, my mistake. And where would i be able to get them at?

Also i kinda figured i was just gonna have to cut the tab off just wanted to make sure.

[trotterlg]

I did a 3100 swap and found the longer pushrods will work for the shorter ones, and you can find some (I think from a ford) that will work for your long ones. I take it you are using a flat tappet cam with aluminum heads? And right, just cut the little tab off the timing cover. Larry

[Jawz]

Ok, i got that tab cut off. The lower intake mani fits perfectly now.
But i have another question. With the 3500 cylinder head, is there two different lengths of pushrods for it? ive got the tool to determine the length of pushrod that i need for it but for the pushrod that goes on the intake valve rocker doesnt seem to be the same length that would go for the exhaust valve rocker. can any one help me out with this?

[Guest]

That's correct, two different length of pushrods are needed for the genII and genIII engines/heads.

[1988GTU]

Better start hammering the project out. Starting to get cold now haha

Nothing sucks more than swapping in the snow.

[Jawz]

I have a garage, that has heating along with my house so im all good lol

And figuring out these two pushrod lengths are pretty much the only thing stopping me for a bit from putting it all back together.

[trotterlg]

If it is like a 3.1 to 3100 swap the long pushrod will work in place of the short ones and you will just need to buy 6 longer ones. I found some stock ford pushrods that fit my swap perfect. Larry

[Guest]

If it is like a 3.1 to 3100 swap the long pushrod will work in place of the short ones and you will just need to buy 6 longer ones. I found some stock ford pushrods that fit my swap perfect. Larry

He, along with everyone else is better to check actual length, because there has been a few different sizes discovered based on exactly what cam is being used, which head gasket, and if the deck or heads have been milled in anyway.

[ForcedFirebird]

He, along with everyone else is better to check actual length, because there has been a few different sizes discovered based on exactly what cam is being used, which head gasket, and if the deck or heads have been milled in anyway.

This.

I have been lucky once and was able to use the Gen2 push rods. Depends on the cam base circle.

[Jawz]

I didnt want to have any future problems if some managed to fit or not. So i just had them custom made to the length i need. Its better to do it right the first time and not have to worry about later times.

[trotterlg]

If you measure the height of a roller lifter and the height of a flat tappet lifter you can see what length of pushrod you will need. Juat happens that the long one works for the short one in a 3.1/3100 swap from rollers to flat tappet. Larry

[Guest]

If you measure the height of a roller lifter and the height of a flat tappet lifter you can see what length of pushrod you will need. Juat happens that the long one works for the short one in a 3.1/3100 swap from rollers to flat tappet. Larry

You can't use that idea. You'd have to use trigonometry to find the length difference, since the pushrod is not inline with the lifte, and only if the only change is the lifter itself, which will never be the case. The difference in length of the lifters is not the same as the difference in length of the pushrods. It will be close, since the angle is not very far off being inline, but it is not the same.

Going back to what I said earlier, decking the block or head will cause the rockers to move closer to the lifters needing a change in pushrod length, using a different thickness head gasket will also change that required length. Then the cam profile can also change that required length.

In short, you can't use the blanket statement of "You can use X and Y pushrods", because they may not work in everybody's application.

[trotterlg]

Seeing that hydrolic lifters have an adjustment range around .200 inch I think the small difference caused by a head gasket or angle of the pushrod can pretty much be overlooked except under the most extreme cases. I think you are way over worrying the problem. Larry