Thanks for the good info. I can sure see how the 3400 cam is an upgrade. The info gives me a good base line for having my 3400 cam reground. I don't want to go overboard with the regrind. One of the cam lobes has some pitting. I hope it's good enough to regrind. I'm kicking myself for throwing away the original 2.8 heads off my 87. Now I have to use the ones off the donor motor. I wonder if the 3400 rockers could be made to work. I would have to lose the base and make guide plates. Probably smarter to use the narrow aftermarket rockers and poly locks. Thanks for sharing all the info you probably had to painfully research!
If you're gonna redo the whole cam, just increase the lift to what you want and retain the 1.5 rockers. Save some money right there. You can create a cam with .300" lift and with 1.5's that will be .450 and if you eventually upgrade to 1.6's you'd have .480".
[This message has been edited by lou_dias (edited 02-23-2016).]
I'm assuming you're going to be using iron heads? If so, then you can use the Comp Cams roller-tip rockers. They come in 1.5:1 and 1.6:1 ratios, and are pretty inexpensive. Switching to narrow-body SBC rockers with the required conversion studs will cost about twice as much, but will give you full-roller rockers.
I don't have the iron heads off the donor car yet. Everything on the 85 car is solid rust so the cradle is taking a lot of extra time to get out. I have been working on my 87 for years. I always grease everything going back together. I have had that one since new so it never got a chance to rust. I have a ton more sympathy for all the folks that are working with the rusty stuff.
Are the iron heads able to be drilled and tapped to put in 7/16 sbc rocker studs? I have no idea what size studs the stock 2.8 have.
I don't have the iron heads off the donor car yet. Everything on the 85 car is solid rust so the cradle is taking a lot of extra time to get out. I have been working on my 87 for years. I always grease everything going back together. I have had that one since new so it never got a chance to rust. I have a ton more sympathy for all the folks that are working with the rusty stuff.
Are the iron heads able to be drilled and tapped to put in 7/16 sbc rocker studs? I have no idea what size studs the stock 2.8 have.
Originally posted by woodyhere: Are the iron heads able to be drilled and tapped to put in 7/16 sbc rocker studs? I have no idea what size studs the stock 2.8 have.
The 2.8 V6 heads have 10x1.5mm threads for the rocker studs. But they can be drilled and tapped for 7/16" SBC studs.
Thanks for the info. I still am going to look at using the 3400 rockers either with modified stands or no stand and guide plates. I just want to see if I can make them work. If not, the heads go to the mill for a drill and tap!
There is a lot of static about the aluminum heads but I like to see the spirit and passion you have to be different. Reminds me of a picture of an Eagle just about to grab a mouse. The mouse is giving him the finger!
Thanks for the info. I still am going to look at using the 3400 rockers either with modified stands or no stand and guide plates. I just want to see if I can make them work. If not, the heads go to the mill for a drill and tap!
There is a lot of static about the aluminum heads but I like to see the spirit and passion you have to be different. Reminds me of a picture of an Eagle just about to grab a mouse. The mouse is giving him the finger!
If I can save $180 by doing a little drilling and tapping, shouldn't I? Lou please don't get the idea I don't value your opinion or experience. Like you, I like to think outside the box. I have a set of barely used roller rockers (normal sbc width) that I can easily mill clearance into to fit the Fiero Cast heads. I have a set of heads with the sbc studs that could be reused. I'm just lookin around the shop to see what can be reused. I may be able to machine the rocker base from the 3400 to fit the Fiero heads and use the roller rockers from the 3400. I'm going to take a look at the 3400 behive springs, retainers and locks too. I'm definitely going to put some lighter valves in. I spent the last 3 days getting the cradle out of the 85GT. I used every air powered thing I have and still did some cutting. The car has just about every option, all which still work, and is a total unrepairable rust bucket. All this stuff, harness and all is going into my cheapy 84 to make it look look an 85GT. Did you do any reprograming on the 2.8 cpu to get the car to run right? What did you feel was a useable redline? Do you have a source for the 17 pound injectors? If the 17 pound injectors run a little lean is it possible to up the fuel pressure to help fix that?
No offense taken, I was just trying to understand your logic. I like things that bolt up. I showed you a picture of my rockers because of the clearances on the pushrod end of the rockers so that you know what you're getting into.
Since my latest build used an 88, I just ordered the Camaro 3.4 injectors brand new. No reprogramming done.
My prior build using an '87 ECM, I used (off ebay for like $30 for 16 of them) Mustang 5.0 V8 stock 19# fuel injectors (which flow like GM 22# injectors) so I definitely need reprogramming to lower the base pulse width by about 20%. Mustang injectors are pintle-style so work well with the older ECM's. 88's use Multech injectors and work well with the Camaro Multech injectors.
If you want to save money, you could just try increasing the base fuel pressure from 39psi to 47psi retaining the stock injectors.
[This message has been edited by lou_dias (edited 02-24-2016).]
Originally posted by woodyhere: I have your build on my favorites and study the pictures and comments often!
My original build was a wonderful beast, out-performing my 4.9 ... then I decided to change it. That's where things went south...and also trolls showed up. Right around page 12 or so, Brucepts posted from flow #'s for the stock intake which shows it can support a 3.4 up to about 5800 rpm once you fix the neck restriction.
I'm tempted to put the Fiero intake back on but I actually stuck that old intake (now DAWG-modded) on my 88 that I just built. (Which totally needs a bigger exhaust!!!).
The injector issue is another thing that the old Fiero ECM handled well and the '7730 seems to not like (running A1 code). Makes me wonder if I should install different style injectors (Multech) to go with the A1 code. The problems is I changed too many things at once (from the original build) so I was chasing multiple problems. The initial conversion of the harness caused my injector duty cycle to be at 100% for a couple of months...at one point fire was coming out of my pcv breathers... Didn't figure that out until the flames were coming out...
I have put myself in the same boat to many times. I'll change to many things at once being pretty sure I can keep track of everything and you know the outcome. I was running a 400 GM block in my 87. Too many changes at one time and it's now a weight in the back of my plow truck. The crack in one cylinder looked just like a smiley face! I have the throttle body from the 3.4 . I'm going to see if it's possible to get it to work on the Fiero upper intake. Lots of fun stuff to experiment with.
Originally posted by lou_dias: The injector issue is another thing that the old Fiero ECM handled well and the '7730 seems to not like (running A1 code). Makes me wonder if I should install different style injectors (Multech) to go with the A1 code. The problems is I changed too many things at once (from the original build) so I was chasing multiple problems.
I'm using 19lb/hr multec injectors with the 7730 ECM (running A1 code), and my 3.4 V6 runs well. The WBO2 shows pretty reasonable AFR numbers, which is nice too.
I'm using 19lb/hr multec injectors with the 7730 ECM (running A1 code), and my 3.4 V6 runs well. The WBO2 shows pretty reasonable AFR numbers, which is nice too.
Right! That's why I said I am NOT using them on my 'race' car. I'm using pintle-style injectors from a Ford Mustang. ... and have had issues.
To recap - my 87 ran great with the Mustang pintle injectors and Fiero ECM. Ran blah-ish when I converted to '7730 with A1 code. 88's came standard with multech injectors hence the code is different for 88 V6 and my *new* 3.4 runs great with the Camaro (stock) multech 17# injectors on the stock 88 ECM.
I have 2 86's, an 87 and an 88. 86GT is a stock 2.8 4spd. 86SE->GT 4T40-E sled-o-matic that only goed to 3rd gear and is a 3100 top-end with 3400 heads and block running the 1996 3100 PCM (which is actually the same one the Camaro 3.4 uses). My 87GT is the 3.4 hybrid running Mustang injectors and '7730 with Trueleo intake and headers on 2.5" exhaust. My 88 Formula is a 3.4 hybrid with Camaro pistons and injectors and stock Fiero ECM.
[This message has been edited by lou_dias (edited 02-25-2016).]
I have put myself in the same boat to many times. I'll change to many things at once being pretty sure I can keep track of everything and you know the outcome. I was running a 400 GM block in my 87. Too many changes at one time and it's now a weight in the back of my plow truck. The crack in one cylinder looked just like a smiley face! I have the throttle body from the 3.4 . I'm going to see if it's possible to get it to work on the Fiero upper intake. Lots of fun stuff to experiment with.
You can bore the stock Fiero TB to 57mm. I believe the Camaro TB isn't much (if any) bigger than the stock Fiero TB, however the Camaro intake doesn't have the neck restriction. I read in another thread that it also is 52mm and that is probably why the Camaro 3.4 is rated at 160hp and 3400's are rated between 180-185 (along with cam difference and savings from 'roller' design) and 9.4 or so compression ratio not to mention larger exhaust ports mated to larger exhaust manifolds. The AL guys will swear it's all in 'da heads though... Since you seem capable of doing your own machining, I would just do the DAWG-mod to the neck of the stock intake along with gasket-matching and polishing. I would also shorten the intake like I did.
Remember, my 87GT using a ported Fiero intake but STOCK neck restriction did make 187rwhp at 4100-4200 rpm with a 57mm throttle body and ported heads. So the limitation was there on the neck infront of a 3.4: 4200 rpm. For a 2.8, it was "ok". Removing the neck restriction it would have done better and at a higher RPM. If it was on a dynojet, it would have been about 5% higher at 196rwhp. (Yes, I've used about 5 different shops in my area). Mustang dynometers vary wildly...this one was tuned to within 5% of a dynojet. Another was about 15% lower than a dynojet. My dyno #'s between 3 different dynojet dynos have been consistent. It would have been real interesting to see what power I would have made with the stock 9.7" brakes and 15" tires... The heavier than stock 16x8's w/12" brakes moved the rotating mass to the outside perimeter over stock...
I know you're a V8 guy... My 4.9 with stock brakes but 17" wheels put down 170rwhp/265ft*lbs on that Mustang dyno using the Allante intake and Bosch Design 3 injectors and a short Fiero Factory exhaust with a decent tune. It did that same amount on a pig-rich poor tune a year earlier on a dynojet. Sadly, I sold that car once I got it running right... Needed the money at the time but kicking myself now.
[This message has been edited by lou_dias (edited 02-25-2016).]
Those are some impressive dyno numbers in anyone's book. The 3400 throttle body is noticeably larger just by the naked eye. It also has an oval inlet. That being said, it doesn't mean I can adapt it to the Fiero manifold and stay relatively stock looking, but I'll give it a try. I have to take a break from the fun stuff for a short time. My window business is ramping up and I need to get the shop cleaned up. It's going to be 50 degrees on Saturday so the pressure washer won't freeze up when I use it. I'm going to blast the running gear from the donor car. I hope I can come close to duplicating your results. I am definitely going to modify the neck on the intake. I have been wondering if the 3400 manifolds, which are cast, are really bigger. I'm going to do a fill them with water and compare volume to volume. I know this is really a crude way to do the but they don't look larger inside than the tube 2.8 headers. I'll let you know what I find out.
When I recently ported the heads on my 'race' engine to 1.375" exhaust ports and ended up running into the vertical threaded holes. This is why GM went with the "D" shape to increase flow...to not run into those cast cavities for alternator brackets and such. So, logic says a larger O bore would have worked on Gen3 heads but "safety" said "oh crap" let's just square off 2 corners to increase flow. AL guys will just call it a 'superior design' rather than a casting limitation though...which is why all headers have perfectly round ports which is what they end up bolting on to them...but I digress.
On my 88 heads, I just limited the port job on the exhaust side to 1.25"...but remember, I don't know what I'm talking about...
The 3400 tb is 58 mm. I would need to take the flange off the 3400 motor and weld it on the 2.8 fiero neck. That does seem like a lot of work. I looked into the cast 3400 exhaust manifolds and there are some big restrictions in the manifold. Looks pretty small inside! I'm not a died in the wool V8 guy. It takes a lot more effort to get good HP out of 205 cu. in. than 427 inches. Everyone and anyone can build a 500 hp Chevy. Everything doesn't boil down to HP though, some stuff is just plain fun to do. I hope the 3.4 will just be quick and clean.
The 3400 tb is 58 mm. I would need to take the flange off the 3400 motor and weld it on the 2.8 fiero neck. That does seem like a lot of work. I looked into the cast 3400 exhaust manifolds and there are some big restrictions in the manifold. Looks pretty small inside! I'm not a died in the wool V8 guy. It takes a lot more effort to get good HP out of 205 cu. in. than 427 inches. Everyone and anyone can build a 500 hp Chevy. Everything doesn't boil down to HP though, some stuff is just plain fun to do. I hope the 3.4 will just be quick and clean.
The tube side of the Fiero TB is already 57mm, the 'neck' side is 52mm. All you need to do is take it apart and bore the neck side to match the other side. Worst case is to need a new butterfly too. The Fiero Store sells a 56mm TB. On page 11 or so thread, Brucepts flowbenched a 57mm TB with DAWG intake mode and fiero middle intake and found that it flowed enough for a 3.4 to 6000rpm. It was something like 387 cfm... In a perfect world at 100% efficiency, a 3.4 creates 400cfm at 6000rpm.
