393 Stroker Balance

[Jim Downard]

I have a question to drivers of 393w stroker motors out there. If anyone out there is running an externally balance motor I have a couple of questions.

1) Is it common that stroked windsors usually need a 28 oz. flywheel for balance. Mine did, and my builder says that it is customarily the norm.

2) With an externally balanced motor, do you still have much if any vibration in the motor. It seems to me that by saying that a 28 oz. flywheel is needed they are simply getting close to balance, and not necessarily going for perfect balance.

3) I was told that a fluid damper up from might take care of any annoying harmonic imbalance that I might have left. True or False?

4) I have 290 miles on my new motor heading for the 500 mile break-in point. I got home last night and oil was RUNNING not dripping from my rear main seal. Man, this bums me out in a BIG way. I DO NOT want to pull the tranny again, let along the motor. CRAP. I guess I gotta do what I gotta do. Does anyone out there know off the top of their head the the rear main seal on a windsor is a push in or if it requires the pulling of the crank.

P.S. Bad news is bad enough, I hope I don't hear any really bad news.

Jim Downard

[Double Venom]

Jim,
Needless to say, that's ugly.

These questions need to be addressed by the Pro engine builder amongst us.

Don, report in please.

DV

[C Man]

Jim, I run a windsor stroker motor. External fluid type harmonic balancer does well on mine past 7k R-S. Now on to the main seal. No need to pull the tranny. Drop the pan , loosen the rear cap insert the two piece velcro seal and offset it. My engine was pouring oil at 1000 miles. The problem is this on strokers. Man they have to breathe big time!. One vlave cover has to breathe and the other exhaust. Keep in mind if your are running PCV that on acceleration (floored) that the engine is only breathing out of one side. I run K@N breather on intake and an oil collecting breather on the other side dumping into a remote collector /breather. High compression stroker motors do not like crankcase oil mist comming through the intake. That is my story and I am sticking to it. C-Man

[dscott]

Jim, It is normal to run a 28oz balancer and flywheel on the windsors. Some of the builders will use the 50oz to cut the cost of the heavy metal needed to balance the crank. You really shouldn't have much in the way of vibration. If the engine was not balanced it should have been. Most of the 393 strokers use the 400 crank and after machining they do need to be balanced. The builder should have done a rotating balance on the crank, flywheel and balancer. The rods and pistons should have had a static balance. Normally if an engine is out of balance you will feel the vibration at certain rpm's (1800,3600,4800). If it is a constant vibration sometimes it will come from the sidepipe mounting. If the pipes are not isolated from the rear mounting point you will feel the engine vibration through the car. The thing that bothers me is that the rear main seal is out after so few miles. If the engine is out of balance the first thing to go is the seal. The vibration will beat the bearings to the point of failure. If you are going to attempt the rear seal replacement I would pull the rear main cap and check the bearing for wear. I would check with the builder and make sure he balanced everything. I hope the news isn't to bad but at this point I would hate to see you lose a motor.
Don

[Jim Downard]

Thanks for the info guys. The motor was built by Indy Mustang Performance in Indianapolis. He said he did balance it and the actual balance weight he gave me was 28.2 oz. Don't know if that matters much or not. My old motor was a 351w bored 30 over and a very reputable local machine shot had it internally balanced. I loved how smooth that motor was. It's a '71 windsor so I'm keeping it. I am however getting a little nervous now as during the cam break-in process I felt noticable vibration between 1500-2000. I also wound it up between 4000-5000 on the way home the other night and felt a high rpm vibration that was concerning me. Now I'm thinking about pulling the motor and sending out the pistons, rods, crank, flywheel, and damper and having it rebalanced internally. It seems that lately there has been way too much incompetence in the world. The only way I feel comfortable anymore is to do it myself. Well, I could always put those rousch 200's on my old windsor. I'll bet it would run better than the old 2 bbl heads that are on it now. Then I'd feel comfortable again. Oh, by the way, I called the builder the other day and he said he never had a seal go out like that before. Of course, what else is he gonna say.

Don, what cam profile would you recommend for a 393 with cast iron rousch 200's, 10.5:1 compression, Edelbrock Performer RPM intake and Edelbrock 750 cfm carb. Mine's rather mild. Runs strong, but idles like a '75 LTD four door.

Jim Downard

[dscott]

Jim, I use the Comp Cams Extreme energy cams in all my motors. The Fords really like the split duration of the Extreme cam. For the non strokers I use the Comp 35-246-4, for the strokers I use the 35-250-4. Both have a semi-radical idle and perform great. The torque curve on the dyno is almost peak from 2500 to 5200 rpm. They make tons of torque and you never have to rev above 6k for peak performance. I like the torque curve low because that's where most guys want it. Since you don't need to rev the engine over 6k it saves on parts and potential higer rpm damage. If you are interested I can give you the specs.
Don

Just a note on cams. I have tried over 20 different cams and head combinations on the dyno. The Comp always comes out on top.

[Jim Downard]

Don,
How do you prefer to balance your motors. I've always thought an internally balanced motor was the way to go, but it sure seems that a lot of people are building externally balanced motors.

On a cam change, Do you think I'll need to cut valve reliefs in the pistons with one of the profiles you recommend. I REALLY want the car to have a somewhat lopey idle. Hell, don't you need the show with the go. I don't have the cam card from my engine in front of me, but I'm remembering numbers like .473 lift and 264 duration. Don't quote me on those, but that's in the ballpark. It's a flat tappet hyd. cam and was supposed to be a 292 dur. with .512 lift. However, the builder said the cam he put in the motor cut me 7 hp, but gained me 23 ft. lb. of torque. I believe he based this on the Dyno 2000 software or some similar package.
In a hypothetical sence, how would you handle this little situation. If the motor was improperly balanced, I really don't want to pull it and send it back to him. I would prefer to remedy it locally. If he would send me new bearings, gaskets, etc. whatever I needed to reassemble the motor, I would take care of the rebalance. But as I mentioned before, I REALLY DO NOT want to ship the motor. I'm not sure how to handle this. It can get really touchy here. Help.

Thanks,
Jim Downard

[dscott]

Jim, Normally cost is the big factor in balancing an engine. Since the stock crank is an externally balanced part there isn't as much heavy metal needed to bring in within specs. It doesn't seem to matter much which way an engine is balanced just that it is done properly. I need to know more detail on your engine. Which type piston and the mfg and number. Also rocker system (roller, ratio). What brand of crank was used. It would also be nice to know how far the piston sits in the hole if you have that number. The cam you have doesn't sound like much for the rest of the engine. If you take the parts to a local shop it usually runs about $200 to balance everything. It sounds fair that the builder would at least send you parts to put it back together. The vibration you have at 1500 to 2000 does sound like a balance problem but it's not always in the motor. If the shop didn't use your flywheel and harmonic balancer to do the rotating balance the problem could be with either of those parts. If it's a stock windsor balancer from the old engine they have been known to spin out of balance on the isomer band. I have also seen people use a 50oz flywheel by mistake which creates quite a vibration
Don

[DAVID GAGNARD]

Jim;

What crank are you using?????? If it is a Scat crank,they are NOT balanced at all from the manufacterer and as per their instructions your entire rotating assy. needs to be balanced before engine assy. I'm not that familar with the 400 crank, so I can not comment on using that one.....

Stock type heads are real restrictive on a 393 stroker,so I would suggest any good aftermarket head,I prefer aluminum. I plan to use the AFR heads on my upcoming 393.

I'm using stock type iron heads that have been extensively reworked (ported-polished-bowls blended& gasket matched,screw-in studs-guide plates,new valve guides,also 1.90/1.60 valves) and they are supposed to be on par with stock out of the box aluminum Edlebrock heads. I got the heads for $75.00 off the stock engine and for what I have spent on them I could have bought any aluminum heads on the market with money left over.....This is on a 351-W. I'm running a comp cam with 272 dur./484 lift on intake,284 dur. 512 lift on exhaust and it idles smoothly at 750-800 rpm and pulls well to 6000 rpms. Very pleased with this cam. Going a little bigger for the 393 and will use a roller hydraulic cam as well.

David

[Jim Downard]

Don, The pistons are Keith Black Hypereutectic ( however it's spelled) The piston numbers I don't have in front of me, but I can get them. 1.6 Crane roller rockers and Jim at IndyMustang uses Scat cranks. It has a stock harmonic balancer, but the flywheel he sent me had to have additional holes drilled for the Ford Motorsports 10.5" clutch. It must have been an older flywheel. Anyway, they didn't center punch the holes before drilling allowing the bit to walk a little. In addition, the holder of the drill seemed to have difficulty holding the drill perpendicular to the flywheel. Drilled crooked, Tapped crooked. Flywheel on shop floor. Followed by call to Jeg's for a brand new Ford Motorsporst 28 oz. flywheel. I'm thinking of pulling the crank and taking the pistons out throught the bottom. Oh crap, just not thought the main bearings may interfere with that plan. Damn, now I may have to pull the heads. Well, we'll find out soon enough. I'll get back to you on the KB piston numbers and the actual cam profile. I'm starting to think it was easier for Indy Mustang to put a mild cam and save cutting reliefs for the valves than to go through the piston/valve clearance procedure. Any thoughts.

Jim Downard

[Jim Downard]

Don, I've got the numbers off my build sheet. Pistons - KB 192, Rockers - Comp. Cams roller rockers, Cam - SAE Duration 280 int./ 289 exh. .050 duration 204 int./214 exh. Lift .450 int/ .474 exh. This is even milder that I originally thought. Why put Rousch 200's and pocket port them if you're going put such a wimpy cam in it? He changed the CR from 11:1 that I requested to 10.5:1 without consulting me, as well as the cam change from the original 292 dur. .512 lift cam. The deeper I dig the more disappointed I am. Well, onward and upward I always say. Your thoughts when you get the chance.

Thanks,
Jim Downard

[Jack21]

I'm not sure I would take anything back to Indy Mustang after what you've been telling us. Pretty sloppy work. Be more inclined to verify what they did and didn't do through a competent local machinist. Makes another good case against mail order engines.

Been eyeballing the same combo. Scat stroker crank. Might re-use the existing reworked rods. The KB part number for their 393 stroker pistons is #364. Also looking at Total Seal or Childs& Albert zero gap ring (1st or 2nd) set.

Am using a CompCams retrofit hydraulic roller and it works quite well. Single pattern, though. 224/224@.050. .533 lift w/ 1.6 rocker arms.

[dscott]

Jim, The KB192 pistons are for a 289. The stock pistons are sometimes used in the strokers to save money and machining costs. Nothing wrong with doing this since the KB pistons are good quality. The do have valve reliefs cut in them already so you should be able to go to at least a .550 lift without any danger of hitting the piston. In my opinion the engine should be taken apart to check all the clearances and deck height to the piston top. Since you replaced the flywheel you should have everything rebalanced. If the builder added or subtracted weight from the original flywheel you could be way out of balance. I know this is a real setback for you but at this point I would play it safe. It won't cost much to have everything checked and put in new bearings and gaskets.
Don

PS. If you were closer I would check everything for you for free. I hate to see this happen. Unless you feel like a road trip!

[Double Venom]

Jim,

This really sucks buddy! I'll buy you a "Cool" beverage tomorrow at the meeting!

DV -- We need your support and attendance! Have you bought your raffle tickets yet? 300 Cobras -- think about that for a second or two! Have you registered?

[Jack21]

Coupla things to consider while motor is apart.

Compression ratio. Might want to dial the CR around 9.5 - 9.75:1 to run motor on pump gas with iron heads. You can go 1/2 to 1 point higher with aluminum heads. My TFS' dialed in at 9.65:1, a little conservative, but runs fine on pump gas.

Cam. That is a wimpy cam for a 351 Cobra motor. No wonder it idles like a stocker. (I put a cam like that in a full size Olds 455 station wagon some years back. Lotsa low end grunt.) Hydraulic roller is the way to go, but they're a tad pricy. To upgrade later, there's some machining that needs to be done to the lifter valley. If you do it now, the cam can be installed later with the motor in the car.

One more thing. These cars corner like roller coasters. Now would be the time to put a baffled oil pan on the motor. Canton makes a 9 qt., and (I think) Milodon makes an 8 qt.

Oops. What kind of valve stem seals did this turkey put on your Rousch heads. Probably the rubber ones that came with the gaskets. You want to replace these with teflon, or teflon insert seals.

Add a thread to the Consumer Watch secton about this vendor.

[Jim Downard]

Don, when it's said that heads are pocket ported. Just where exactly are they talking. Jim at Indy Mustang commented on porting the heads, but I looked inside the intake and exhaust ports and could see no visible signs of porting. I used to race motocross and am familiar with what an untouched casting and a ported casting will look like. I was just wondering if the pocket porting work was done where I couldn't see it from the ports, or if I'd been duped again.
When I pull the motor down, I'll use a dial indicator and get the piston to deck height and I'll also do it to the head deck to valve distance. If I got you those numbers do you think you could tell me wether or not the comp cams 35-250-4 would work in my car. Just wondering.

Thanks for all your help.

Jim Downard

[Double Venom]

Jim,

Man, I'd always heard Indy was supposed to be a premier engine building service. Anything else I can do to help?
DV

[dscott]

Jim, No problem, just get me the numbers and I can work out the compression and the valve clearance. I need to know the chamber volume of the heads also. The pocket porting is done on the underside of the valves so you can't see it. It's just a matter of cleaning up the bowls for better air flow. It's the first step in any porting job. I would think they should have port matched the heads and the intake also.
Don

[aaronwolfpack]

You really gotta check on the year of your motor. If it's old, it might have a 2 piece rear main seal. I've hear of mechanics removing the rear cap and rotating the seal around in order to install a new one. The other thing that makes this a reach is that there was a small metal spike on the seal groove to keep it from rotating. Most mechanics don't really see a purpose for this, and file it down or knock it out. Anyway, that's probably about the only hope. Good luck.

[dscott]

Jim, we never did hear the outcome of your engine. Unfortunately I just rebuilt an engine from a guy that bought it from Indy Jim. It lasted 9 miles. The motor wasn't anything close to what he said it was. Stock windsor heads that he said produced over 400hp. It may have been closer to 260hp. Stock windsor heads are very poor. The engine had been sleeved which is ok if done properly. This engine looked like he put in a sleeve and reused the original rods which obviously were bent. It exploded the piston and sent the rod through the block. Total loss of the motor. The only thing we could save was the oil pan, timing cover and injection system. The other engine is a 460 and is getting water in the oil. Probably another improper sleeve job.
I would stay away from this guy. He promotes high horsepower and very low cost. You can't have both. The 351 that he sold I could not build because the price was lower that what I pay for parts. Unfortunately the customer has double money in his engine. He has no way of test running his engines and uses numbers from desktop dyno. Buyer beware!
Don