3400 With 3.4 RWD Head Gasktets

[sanjay]

Replace the chain and guide, that probably was the noise. My motor has 220,000 miles, tons of WOT daily runs, tons of time at high sustained RPMs and it's whisper quiet after I did the chain and guide. And yeah anything is better than the log manifolds, they are a huge bottleneck, just the design of them makes it hard for the gas to exit the heads, and that's more work for the motor to push out resulting in loss of power and mpg. Headers are best, but 3500 runner style manifolds flow great, you just don't get the scavenging effect as much.

Why change the guide??

Do I have any other choices of timing chain other than the 99- AC Delco? Cloyes Maybe? My parts store can't get me anything.

I'll probably do the 3500 "header" manis in the future but for now I'm good with what I have.

[IsaacHayes]

Replace the chain and guide, that probably was the noise. My motor has 220,000 miles, tons of WOT daily runs, tons of time at high sustained RPMs and it's whisper quiet after I did the chain and guide. And yeah anything is better than the log manifolds, they are a huge bottleneck, just the design of them makes it hard for the gas to exit the heads, and that's more work for the motor to push out resulting in loss of power and mpg. Headers are best, but 3500 runner style manifolds flow great, you just don't get the scavenging effect as much.

[sanjay]

Ok slight update. I finally have the 3100. I went to get it on Friday and that was almost a disaster. The motor was sitting in a body shop so it was covered under a 1/2" thick layer of crud. Then when I got there the owner tell me that the day before his neighbor (2 different mechanics, same building...WTF) broke a rocker bolt on a 3X00 doing a job and he gave one of the rockers out of the engine that was already sold to me to the neighbor. He then starts going on that he should have told me on the phone but he forgot and that if I didn't want to buy it he wouldn't mind..In the end I took it in it's 11 rocker glory anyway for $60CAD.

I tore into the motor on Friday night after a good hose down. The top end and the timign cover are off ans still no signs of whatever was making noise. I'm really hoping for piston slap. I'm hoping not to find bearing issues with the crank since I need it. I'm hoping to have my 3400 bottom end for the 3400/3500 build off the engine stand tonight and this one on. I'm really anxious to see what was making noise. Worst comes to worse I can use the crank out of dying 3.1 but I know for a fact that motor has bottom end issues. I also have another crank that came with the extra 3400 block I'm using for this build but it's way rusted.

In the end I'll probably be keeping the 3100 UIM on the motor just for shits and giggles. Most people knew these cars cam with 3.1's but they can't tell the difference between a gen 2 or gen 3...

Anyway..More on this later when I tear into the bottom end.

[Superdave]

Damon is running the stock fan in a pusher config, no overheating problems yet... i've got an actual slimline pusher on mine and it has gotten warm a few times in traffic but never above 210.

[robertisaar]

3x00s are like the caddy motors from the 60/70s: have LOTS of potential, but are choked due to the overly restrictive stock intake/exhaust

[sanjay]

if it's a DD then i'd just use stock 3x00 logs like you wanted. You could even use the old 3.1 logs to save time on exhaust fabrication. I ran them on my stock 3400 and still had plenty of fun with it.

the flow gains are huge, probably worth 10-15 HP.. but if it's just going to see the streets then there isn't much point to doing all the extra work.

No, the front won't clear the manifold.. you gotta reverse the polarity and move the fan to the front side of the radiator. A slimline fan might fit normally but it looks much better without a fan in the bay IMO.

No real fab is needed to run the 3400 manis. I already have a pre made downpipe. Just gotta cut my exhaust and clamp it on till i can get it to an exhaust shop or 91Z24's house...

I didn't realize the gains would be that big on a motor that's pretty much stock. 10-15 HP is more than noticeable. I probably still won't do this but I'll keep my eyes open for a pair of header style manis..Too bad you didn't make a second crossover pipe when you made RedBirds...I'd have bought it if they'd help that much..

I don't think the fan is going to fit in front of my rad. I have AC and I plan on keeping it. Besides isn't a puller fan 40% less effective when used as a pusher?? I've never shown anyone the fan setup I have in my '89. I modified the top mounting system to push the top of the rad about 1.5" forward. Then I have 2 12" slimline 1450CFM fans mounted to the rad. I should have made a shroud but stock it doesn't have one so whatever. It cools just fine with only 1 fan running so IF I decide to go the route of "header" manis I can just steal one form there..or get a 14" or 16" one..they're dirt cheap form a local guy.

[Superdave]

if it's a DD then i'd just use stock 3x00 logs like you wanted. You could even use the old 3.1 logs to save time on exhaust fabrication. I ran them on my stock 3400 and still had plenty of fun with it.

the flow gains are huge, probably worth 10-15 HP.. but if it's just going to see the streets then there isn't much point to doing all the extra work.

No, the front won't clear the manifold.. you gotta reverse the polarity and move the fan to the front side of the radiator. A slimline fan might fit normally but it looks much better without a fan in the bay IMO.

[sanjay]

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

Thanks Dave..

No Doz..A 3500 top end is not an option. 3500 top end parts are not easy to come by in Canada. When they do come up they are expensive. Bringing them across the border cost a fortune too. A 3500 top end also cause other complication that I don't feel like dealing with like finding a 3500 map sensor & bracket, mounting the coils & ICM, TB adapotor etc... I want to use what I have and what's already paid for.

Dave..yeah $110 is not a bad price for the parts but i still have to pay someone to do the work (~$100) and I still need the 2 "header" manifolds (~$100). Are the gains I'm going to get from this over ported 3400 manis really worth the $300 investment?? Will this setup even clear my rad fan? Again I'd like to use what's already paid for...

I'm not looking for all out performance, just things I can do with the parts in hand and at very little cost. This is in the end a daily driver..

[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.

[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.

[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

[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.

[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]

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...

[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.