I had an Archie kit in my v8 car. I put in solid mounts and it felt like it was going to shake the car apart. I had the originals back in the same morning and was much happier.
Put in solid mounts. As long as you run an original engine (not rebuilt) or you have the rebuilt engine properly balanced and don't run a huge camshaft, the vibrations will be minimal. My stock 88 2.5/125C and the poly mounted 4.3/4T60 both shook/vibrated the car more than my 88 with solid mounted SBC/Getrag.
I too have an SBC/manual trans combo with solid mounts all around and find it just fine. Unlike Fieroguru however, mine is not an '88 so the cradle is still isolated from the rest of the car with poly cradle bushings. My current project car is based on an '88 which has the solidly mounted cradle so I opted to use the stock rubber/hydraulic Caddy engine mounts all around.
If I were you, I wouldn't mix solid and rubber mounts because the rubber mounts will allow the back end to move flex up and down and will place bending forces on the front solid mount. This could eventually lead to fatigue failure of the front mount or more likely the engine cradle where the mount attaches to it.
I did mine with solid engine, tranny and cradle mounts. It was too much. I planned to rubber mount the engine and trans, but lucked into a fantastic deal on a crate DOHC and ditched the V8.
------------------ 1986 SE Aero coupe.
3.4 DOHC swap is complete and running, now just have to finish the rest of the car...
I guess I like it too comfy. My car was all new from bumper to bumper and had a new $5,000 custom engine. It ran perfect. With the solids it gave me a headache and the whole thing rumbled like being inside a garbage can with people beating it with their hands. jmo. Smoothness and quietness were like nite and day between solid and rubber mounts.
OK, so I see opinions vary. Mine is a 383 an internally balanced with the Getrag. I just had the engine out to address oil leaks and a shuddering spec clutch. Thinking the shuddering my be partly caused by the tranny mounts I resealed the engine, made the tranny mounts solid and put it back in. Oh, I also cleaned up the clutch and power sanded the flywheel pressure plate and the clutch plate. I did nothing to the engine. I drove it about a mile late at night before going to bed.
The clutch is much smoother but the engine feels like it is running on 7 cylinders at about 2200 RPM. It is bad. Now the engine was upside down on my stand for about a week and a half. Unless I fouled a plug somehow, I have a problem. It sucks. If I decide to go back to stock tranny mounts how can I replace Archies front solid mount? Any ides or links would be appreciated.
fieroguru made a polly mounted engine mount, his thread lost the pictures but if you send him a PM he may still have the pictures. There is not a lot of room to work with so anything you make will have to be small enough to fit and not interfer with the suspension.
My car has been solid mounted for going on 10 years, I wouldn't have it any other way. Sure its not luxury car smooth but its HotRod smooth Good luck hope it works out for you.
For my first SBC install, I modified the front Archie mount so it was poly mounted and ran poly transmission mounts. As the stock transmission mount brackets bent, I remade them in thicker steel. Once they wouldn't bend, I started to crack the rear crossmember on the cradle (88) and after the second crack I went full solid mounts and never had to touch them again.
Here is the poly setup with the remade transmission mounts:
The issue with this first attempt was the poly engine mount wasn't very good at resisting the drive line torque, so the transmission mounts and torque strut had to do most of the work.
Here are the solid mounts I replaced the poly setup with (ran these for 40K miles and never had to touch them again):
For my personal swaps I have started to run 4 rubber control arm bushings for the drive line mounts. I try to get them spread about 24" apart front to back to they have good leverage to resist drive line torque. To do something similar to the SBC, you could mount one of these round rubber mounts (or upgrade to poly) and round off the corner of the Archie bracket to fit the bushing between the engine bracket and the AC compressor. For the rear you could come off the stock SBC engine mount pad and make a mount bracket that goes down to the cradle like this:
Thanks for the ideas and for the pictures especially Fiero Guru. I am not sure what to try. Pulled all the plugs and nothing fouled. Can't stand the new vibration. Have to do something.
What camshaft are you running? The larger camshafts will cause some vibration with their choppy idle, but should smooth out as the RPM get into its powerband.
I don't have the specs in front of me but it is a mild cam. My 383 runs on pump gas/regular and dyno'd at 320 HP 410 ft/lbs. Idles smoothly and was not a problem before. Took it out because of bad pan oil leaks. Because clutch (spec stage 2) chattered Archie suggested solid mounts. I cleaned and sanded clutch, flywheel and pressure plate and solid mounted the trans. Vibration peaks at 2200 rpm in neutral or in gear. I cannot believe the solid mounts made that much difference. I may have to go back to stock mounts on the tranny to find out. Front of engine is still Archie's solid mount.
Did you remove the flywheel? You mentioned your combo was internally balanced but if you took the flywheel off, that might be something to double check.
I don't think locking down the tranny side would make that big of an increase when the engine side was already solid mounted. So my guess is something wasn't installed the same way it was before. Along those line, have you double checked the plug wire routing as swapping 2 cylinders will make a nasty shake (been there before).
I wouldn't think changing the tranny mounts to solid would make much difference either, but some thing has. The engine is internally balanced but I did not remove the flywheel. I removed the clutch to clean it up and the Harmonic dampener pulley is keyed so did not change. While the engine was out I did remove each plug boot, one at a time and smeared on a little boot grease. I only removed one at a time. Just in case I did check the plug wires and as I said pulled one plug at a time to see if any were fouled. I would try running the engine and pulling one wire at a time but that has to be done under a running engine. Probably a dumb idea.
It really feels to me like a cylinder is not firing. I did hook up my timing light and moved the clamp to each plug wire to be sure each wire was firing. This so frustrating. I have ordered new tranny mounts and I can make new engine mounts so it is not solid but I am not convinced.
If you have an inferred temp gun, you can check the primary tube temps as the car is running. If one is cooler than the others then that is the cylinder to focus on.
Thanks Fieroguru. A mechanic I know suggested the same thing today. I will try it. I have early cast iron Corvette manifolds but I think I should be able to see a difference if there is one.
Thought some might like to know the answer is apparently found. I tried infrared thermometer idea from under the car and could find no cold cylinder. My engine has the FAST EZ EFI fuel injection so I reprogrammed to make sure nothing was wrong there thinking way too lean might make one cylinder with a weak plug miss. Still no luck so I thought I would recheck timing. With the light on number 1 cylinder and happily strobing away I revved the engine to check advance and the light quit. Back to idle and it strobed again. Tonight I borrowed a used plug wire and bypassed the #1 wire with the used one and the miss is gone. Put the original wire back in place and it was fine at first but then started missing again when I accelerated. Tomorrow I will buy new wires. I had removed each plug cap and put in some boot grease because I got a free sample. I would guess the connection inside the molded boot must have separated.
Solid mounts on my V8 Archie installed LS376. Drives great, no vibration at all.
Do you have a 88 or pre-88 cradle?
I am thinking about using custom made solid steel mounts on my 88 Fiero (currently with 2.8L V6), because stock rubber mounts are too soft and poly mounts are too expensive.
But I am not sure if solid engine/trans mounts are a good upgrade for 88 Fieros (solid mounted cradle)!?
@ fieroguru As I can see you also have a 88 cradle. Are the vibrations acceptable with solid mounts?
[This message has been edited by Moar (edited 12-07-2015).]
My current project car is based on an '88 which has the solidly mounted cradle so I opted to use the stock rubber/hydraulic Caddy engine mounts all around.
Bloozberry, what year/model are the stock rubber/hydraulic Caddy engine mounts from?
I can't say that I know a lot about the V8 SBC install but my 3800SC swap uses poly mounts and two poly torque struts. While the operation is smooth while driving, there is noticeable vibration at idle. I can live with it, but its certainly not like having rubber mounts. I guess that its a trade off, poly or solid mounts w vibration at idle or no vibration at idle with rubber mounts. The next swap that I will do will use rubber mounts. Rubber mounts have been used on some very powerful engines so they should work well and hold up with a V6. .
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
I am thinking about using custom made solid steel mounts on my 88 Fiero (currently with 2.8L V6), because stock rubber mounts are too soft and poly mounts are too expensive.
But I am not sure if solid engine/trans mounts are a good upgrade for 88 Fieros (solid mounted cradle)!?
@ fieroguru As I can see you also have a 88 cradle. Are the vibrations acceptable with solid mounts?
My Fiero has an '88 cradle swapped into it. It also has a 3.4 V6 with an aggressive camshaft, and urethane drivetrain mounts (all of the mounts, all from Rodney Dickman). At idle, the car shakes like a Harley. But it smooths out when the engine revs up. The solution? Don't let the engine idle much.
For my taste they are too expensive. Price $139. - for two poly mounts! Therefore, I thought about welding my own steel brackets without any rubber or poly. When you already feel harsh vibrations at idle, then I can imagine how the car vibrates with solid steel brackets! I would be already happy if these vibrations go away at higher revs while driving. But I am not sure if this is the case with solid steel engine/trans brackets on a hard mounted 88 cradle
Maybe there is not much difference between poly and solid steel brackets in view of NVH?
BTW, does your Fiero have an auto or manual trans? I have heard that auto trans Fieros already start shaking with a solid dogbone, whereas manual Fieros don´t vibrate much with a solid dogbone. This has to do something with the torque converter idling torque.
[This message has been edited by Moar (edited 12-09-2015).]
That makes sense, considering that an automatic transmission puts constant load on the mounts, whereas a manual only does that when in gear.
Yes, I'm using those transmission mounts. I'm also using Rodney Dickman's urethane front engine mount, and his adjustable dogbone mount with urethane bushings.
My Fiero has a manual transmission. I think the combination of an aggressive camshaft and lightweight flywheel have probably increased the NVH. I'm not sure how much you've modified your engine (if at all), so your experience may differ from mine. But the urethane mounts definitely increased NVH. I don't care about that, because my Fiero is a "weekend warrior". But if it were a daily driver or a boulevard cruiser, it would bother me.
edit: I should mention again that the added NVH is ONLY at idle. When the engine revs up, everything smooths out.
[This message has been edited by Blacktree (edited 12-09-2015).]
Originally posted by Blacktree: That makes sense, considering that an automatic transmission puts constant load on the mounts, whereas a manual only does that when in gear.
Yes, I'm using those transmission mounts. I'm also using Rodney Dickman's urethane front engine mount, and his adjustable dogbone mount with urethane bushings.
My Fiero has a manual transmission. I think the combination of an aggressive camshaft and lightweight flywheel have probably increased the NVH. I'm not sure how much you've modified your engine (if at all), so your experience may differ from mine. But the urethane mounts definitely increased NVH. I don't care about that, because my Fiero is a "weekend warrior". But if it were a daily driver or a boulevard cruiser, it would bother me.
Your cam and flywheel definitely will cause increased vibration at idle. What is your idle speed set to? Just bumping it up another 500-1000 RPM might smooth things out, too.
So far I haven´t made much performance upgrades to my 2.8 V6 engine, because my plan is also a 3.4PR engine swap. I´ve already bought the engine for $300.- (out of a ´94 Firebird).
Of course, I´ll also install an aggressive cam (Crane H-272-2 # 253941) with HD valve springs and new lifters before I install the engine. Maybe even hyper pistons that I can run some nitrous (75-100HP shoot). I´ll use the OEM flywheel from my ´88 2.8 V6 engine (I think the Fiero 2.8L flywheel is already light weight for a 3.4L engine). Or do you even use a lighter one?
Therefore, I´ll also get an engine with choppy idle which may not be a good combination with solid steel engine/trans mounts. But maybe I should just try it out!
Basically I also don’t care much about NVH, but I don´t want that my car feels apart (losses bolts & nuts) due to harsh vibrations.
Fortunately, I also have a manual trans (= less vibrations at idle).
Originally posted by Moar: Basically I also don’t care much about NVH, but I don´t want that my car feels apart (losses bolts & nuts) due to harsh vibrations.
IIRC, the stock Fiero V6 flywheel is around 16 pounds. Compared to a SBC flywheel, that's pretty lightweight. But the one I'm using is aluminum (from Fidanza), and only weighs 8 pounds.
But the one I'm using is aluminum (from Fidanza), and only weighs 8 pounds.
Now it´s clear for me why you have vibrations at idle. Most probably your light weight aluminum flywheel is the main contributor to your idle vibrations. Your flywheel only weights the half of the Stock flywheel! As we know, flywheel weight is not the most important parameter, much more important is the total rot. inertia (flywheel + clutch disc). However, flywheel inertias are seldom stated in item descriptions.
With an 8 lbs flywheel it is even a wonder that the engine doesn´t die at idle. How much does your idle jump up and down? What´s your idle speed?
I have a carbed 350, probably about 290 horse, so it's pretty mild. solid mount in the front, rubber on the trans. 84, so the K-member is a little different than the rest.
I think I put it together about 12 years ago. I haven't had any issues. I don't notice any vibration. The only thing I wish for, I wish the gear drive for my cam was louder... I love that sound. I don't need a tachometer, I can tell how fast the engine is spinning by the whine.
[This message has been edited by buddycraigg (edited 12-20-2015).]
jmo. Smoothness and quietness were like nite and day between solid and rubber mounts.
