3400 With 3.4 RWD Head Gasktets

[sanjay]

What would the compression ratio be? Would you be worried about piston to valve clearance with a stock cam?? Advantages, dis-advantages??

I could have sworn I've seen the answers to both these questions but after spending the weekend searching (while those of you who probably answer these questions were having fun at the meet..lol) I've yet to come up with anything.

[Superdave]

typically you want .040" or so between the piston and the head. the stock 3400 piston pops out .020" and the gaskets are .060" compressed so it's a "perfect" setup.

with the 3.4 IH gaskets you'll have .020" of clearance and will most likely have problems.


Rods stretch at high RPM's, .020" just isn't enough clearance.

[sanjay]

typically you want .040" or so between the piston and the head. the stock 3400 piston pops out .020" and the gaskets are .060" compressed so it's a "perfect" setup.

with the 3.4 IH gaskets you'll have .020" of clearance and will most likely have problems.


Rods stretch at high RPM's, .020" just isn't enough clearance.

Thank you. That's exactly what I needed..

May as well throw another question out there.

For a stock cam, at what point is porting just too much?? As in, is there any point of doing a WOT like porting job when using a stock cam or is a simple gasket match & cleanup sufficient??

[95Grand-Am]

I have used the rwd headgaskets in a 3400 and I thought it worked great. As long as you have good bearings and the pistons arn't loose keep the revs under 6000 and don't plan on running it 100,000 miles it should be fine. The piston to head clearance won't be in the safe zone so you are rolling the dice. It worked good for me, It depends on weather you want to take chances. I would recomend decking the block to 8.810" and use the .060" head gaskets this close but safer.

[robertisaar]

For a stock cam, at what point is porting just too much?? As in, is there any point of doing a WOT like porting job when using a stock cam or is a simple gasket match & cleanup sufficient??

gasket match + cleanup would help, but if you're going to do it, you might as well get a light porting going on... the TB is more restrictive than the intakes, but you might see a little gain...

[sanjay]

The inlet will be opened for use with a 62mm TB..

[robertisaar]

i that case, assuming a good port job, you will see gains...

exhaust would be next in line if you don't want to mess with the heads...

[sanjay]

i that case, assuming a good port job, you will see gains...

exhaust would be next in line if you don't want to mess with the heads...

Exhaust, as in the manifolds?? I'm planning on using some 3500 log manifolds.

I don't mind messing with the heads but i don't want to do anything that will hurt performance or over port and kill velocity, especially when I'm restricted by the amount of air the stock cam can move.

I don't know if I'm correct but I assume that at a certain point if your heads can flow more than your cam then the extra port work is useless and probably hurt performance by bringing down velocity..

[Superdave]

3500 log manifolds are no better than 3400 log manifolds, the 3500 "header" manifolds are MUCH better. And they fit well in a jbody engine bay.


what heads are you using? 3400 or 3500? (i forgot). If they're 3500 then don't mess with them at all.

[robertisaar]

that is the simplest way of putting it and is correct, once you pass that threshold, you won't gain anything AND you'll start losing power in the bottom...

and X2 SD...

[sanjay]

I guess I'm going to have to explain this better. This is for my 94Z daily driver. The 3.1 had bottom end issues but it's still going. Eventually I want to replace it but I don't see the reason of doing all that work to still have a Gen 2 motor.

Originally I had wanted to do the Gen 3 2800 but when I started to compare the benefits of doing a 2800 Vs a almost stock 3100 (just port work and a 62mm tb) I favored the reliability of the pretty much stock 3100.

The 3100 I'm getting tomorrow was making a "sound". The mechanic is convinced it's the timing chain guide but I'm thinking piston slap. Either way I won't know before I tear into it.

I have a "spare" 3400 bottom end minus pistons and rods at home that was for sale but the buyer thinks it's too rough. I managed to buy a set pf pistons and rods off of him for $30 so now I have a complete bottom end.

So now I'm thinking since I already have all the parts why not just go 3400..It's the same advantages as a stock 3100 but more power.

The list of parts for use on this motor are:
Stock 3400 bottom end
Stock 3100 large port top end
62mm TB
26915 Valve Springs
Alum Flywheel
FDP UDP
Good Tune
Maybe a 3500 UIM but a 3400 for now
3500 log style exhaust manifold (maybe)

So since everything is already in pieces I figure why not do some porting since i have a nice standard abrasives porting kit as well as some agressive cutting bits for aluminum here at my disposal. I already need to open up the the UIM inlet so I may as well do a little more work if I'm going to see gains.

Dave the 3500 heads I have are for my 3400/3500 Hybrid for my more extreme and ever going '89 Z summer car project. Though I've stolen a number of parts off of it for the '94 the 3500 top end is staying with that car.

I was under the impression that the 3500 log manifolds had larger ports than the 3400 log manifolds. Is that not true? Can the 3400 log manifolds be opened up to the 3500 port size?? The fab required to use the "header" style manifolds is not in the budget for this car nor do i have the skills necessary or equipment to complete this task.

The entire swap need to be completed over a weekend with no access to a welder and that's going to include splitting the tranny case for a TG LSD Insert install. I already have a downpipe made for 3400 log manifolds from my '89 that I used before I put the headers on so that should fit the 3500 or 3400 log manifolds, whichever I use.

I'll consider the 3500 "header" style manifolds only if the whole combo of parts required to use them come in round $100 CAD.. Won't these just be overkill anyway compared to the flow of the cam/lightly ported heads or will they still help?

Do you have any pics of the setup you did for Redbird, especially the back and how it connected to the j body exhaust?

[robertisaar]

better manifolds help ANYTHING...

from scooters to BBCs, a better exhaust translates into better VE, meaning more torque/power, and most of the time, fuel economy.

[no_doz]

why use crap heads on a good engine? 3400/3500 topends arent that expensive & are much more worth while.

flow sheets

http://60degreev6.com/forum/f70

[1QUICKHATCH]

The 3500 log manifolds have alittle bit larger runners but the big restriction is at the outlet like the 3400 manifolds. If you can, try to open up the outlet a little bit but just try to keep the same contour that is allready there. As for the heads with a stock cam I would blend the bowls and a gasket match on the intake side.

[Superdave]

why use crap heads on a good engine? 3400/3500 topends arent that expensive & are much more worth while.

flow sheets

http://60degreev6.com/forum/f70

large port 3100 top ends are the same as 3400..


sanjay, i spent about $60 on U bends and 3 bolt flanges, IIRC the 3500 manifold flanges were around $50 from Forced Firebird. The whole fab process was fairly easy. Lots of pics in this thread: http://www.v6z24.com/jbodyforum/litt...t,project.html

1QUICKHATCH is right, they made the ports larger to match the 3500 heads but the tube diameter, crossover and downpipe is still the same old stuff.