When Stroker Motors Go Bad.... - Page 5

DAVID GAGNARD · #81 (**permalink**) 10-16-2007, 10:52 AM

Not sure from the pic how or what your builder did with the measurements, but the correct thing to do is whether your using clay or play doh, is to clean the piston top, add the clay/paly doh, lighlty smear motor oil on top of the clay so it won't stick to the valves and rotate the engine over..........then, with a razor blade, cut the clay in the middle of the valve relief and carefully remove one half of it, not disturbing the other half, then take your measurement on the thickness of the half left on the piston at the valve relief.............

You must always use solid lifters for this, regarless of what type of camshaft used in the motor......using hydraulic lifters will not give an accurate reading. Summitt/Jegs sells solid lifters in pairs just for this..

the best I can tell in the pic is the measurement was taken from the flat top of the piston????? if so, this measurement is useless and does not tell you anything about piston to valve clearance.

David

Jerry Clayton · #82 (**permalink**) 10-16-2007, 11:05 AM

Looking at that clay, I don't believe he turned the engine over twice to get all 4 strokes in---the exhaust side looks like it wasn't touched, at least as far as the damage indicates

What bothers me is the use of the term studio in the engine builders comments--they are maybe more interested in lighting than measurements

Frank Messina · #83 (**permalink**) 10-16-2007, 11:51 AM

I apologize if I missed the answer to this, but is the builder going to take care of this for you or has he offered another remedy?
Frank

Jac Mac · #84 (**permalink**) 10-16-2007, 12:37 PM

This is prior to check with heads fitted?, as that is intake pocket that he is checking and no evidence of engine having been cycled thru two turns, only head set in place.

Jac Mac

BDR561 · #85 (**permalink**) 10-16-2007, 01:06 PM

Frank,

He said I'm on my own... "If I had paid more for the motor he would consider helping"!!! I'm just trying to figure out what and why and haven't had a chance to get back to the motor to do so yet. I would like his $$ assistance if he as the builder didn't do it right, I have asked for pistons and heads and I would assume all responsibility and costs to rebuild (He said NO). Now trying to figure who's at fault (if anyone).

Jac Mac · #86 (**permalink**) 10-16-2007, 01:52 PM

Did this engine give any indication that anything was amiss in the 400 miles you put on it, were you chasing a perceived valve train noise and rechecking lash etc, did running quality drop off during this time gradually or suddenly, did it ever sneeze or backfire on startup, has the retaining bolt for the front damper ever been found loose or the engine turned over with it loose or not fitted.

The reason I ask is in your gallery you show a pic of the engine with external oil pump, during setup with the heads & valvetrain in place,was the engine EVER turned over(cycled) with the damper bolt not fitted? As someone earlier suggested this could have resulted in a partial shear of the crank key and resulted in the cam timing becoming retarded to cause the damage you have here. I had this happen to me on my old Boss 302 race engine while on the engine stand lashing the valves, fortunately I actually saw it happen, In your situation you would not have been able to notice. I feel that you have to recheck the cam timing before further strip down & recheck your valve to piston clearance. I also note that the engine had been run prior to fitting, was this on a Dyno or Test stand.

Jac Mac

Frank Messina · #87 (**permalink**) 10-16-2007, 02:12 PM

BDR,
Really sorry to hear that he set you adrift like that. Looking at the specs in your profile it doesn't look like this was a bargain basement build to begin with so I'm not sure what he means by "if you paid more". Good luck with your replacement efforts.
Frank

BDR561 · #88 (**permalink**) 10-16-2007, 05:14 PM

Frank,

I got a GREAT deal on the motor... I couldn't have purchased the parts for what I paid and what is still good on the motor is still more than what I paid. This motor was for his own personal poject and he needed the $$,I happened to come by at the right (or wrong) time. Not exactly what I was looking for but everything was new, test ran (on stand) and above all top shelf parts from carb to oil pan.

He feels that he sold it too cheap (he did) and that is his main reason for turning his back. He still claims it was not the clearance.

Jac Mac,

No tell tale signs other than an uneven exhaust note at startup after a 100 miles or so and at low rpm that dissapearded as soon as I blip the throttle. No excessive valve train noise, lash was adjusted during initial build, after 1st test run and at installation by me with no suprises.

Motor failed during normal driving, NOT with me getting on it. I plan to check the clearance and the key tom. evening

BDR561 · #89 (**permalink**) 10-16-2007, 05:22 PM

I'm not sure if the motor was turned over without the bolt, I got the motor ready to bolt in. I will check your key theory tom evening.

Looks like I can switch to Probe forged pistons and be at 10:1 CR if I use a .060 head gasket, now I need to figure which cam to use.

72 block with 9.480 deck height that has been decked .015 = 9.465 deck height.

blykins · #90 (**permalink**) 10-16-2007, 06:31 PM

You found a set of Probes to work with your deck height? That's great....they're good pieces and are very nicely priced.

However, now that I read your post, I'd suggest against using a .060" gasket if you're planning on putting the pistons back down in the hole where they belong. That's a pretty big quench distance.

If you need help selecting a cam, let me know.

Jac Mac · #91 (**permalink**) 10-16-2007, 06:40 PM

Quote:

Originally Posted by blykins

You found a set of Probes to work with your deck height? That's great....they're good pieces and are very nicely priced.

However, now that I read your post, I'd suggest against using a .060" gasket if you're planning on putting the pistons back down in the hole where they belong. That's a pretty big quench distance.

If you need help selecting a cam, let me know.

I assume the 0.060" gasket is to deal with the piston out the top problem with the block- the numbers given suggest that- 4" stroke, 1.280" pin h, 6.200" rod =9.480" therefore 9.465 block + 0.060" gasket= 9.525(0.045" piston to head).

Jac Mac

blykins · #92 (**permalink**) 10-16-2007, 06:42 PM

I think I'd rather snag a custom piston and put things back to a more comfortable state.

BDR561 · #93 (**permalink**) 10-17-2007, 09:54 AM

Cam suggestions appreciated...

AFR 205
Mighty Demon
Victor Sr (Also have a Vic Jr if needed)
solid rollers
1.6 SS roller rockers
4" stroke

Unfortunately I don't have many options with my combination and I'm trying to get it back together in time for the 27th event in Gainsville

blykins · #94 (**permalink**) 10-17-2007, 10:02 AM

So the pistons will sit .015" out of the hole?

BDR561 · #95 (**permalink**) 10-17-2007, 10:10 AM

yes... That's why I have to run a thicker gasket, have the piston shaved or have custom made!! At least, that's what I'm told...

blykins · #96 (**permalink**) 10-17-2007, 10:15 AM

OK, here's the deal and I'll be straight up with you.

I know you're trying to meet a deadline, but if you just start trying to make pieces fit together right now, you're not gonna have a well-built, reliable combo.

You shouldn't have pistons sticking out of the hole by .015" and you're having to compensate by running very thick gaskets.

Now granted, your quench distance is still good at .045", but it's just a backwards way of making a nice street motor.

I just ran some numbers and with those 22cc dish Probe pistons (installed .015" out) with .060" gaskets, and AFR heads, you're gonna need a wild solid roller cam so that you'll be able to run pump gas again. With that wild solid roller comes a very high peak and a ton of lost bottom end power/torque.

If you're dead set on running a solid roller, the smallest cam I can recommend (with you still running pump gas) is the 35-772-8. You will most likely have peak hp at 6800-7000 with that cam and your bottom end will be lacking. Keep in mind that with that same cam timing on my 428FE, peak power came in at 6500 (with out of the box heads) and the peak torque was at 5400.

If it were mine, I'd find another set of pistons that would work with your deck height....or at least give you a larger dish.

My second choice would be to run a hydraulic roller so that the advertised durations would be higher and you would be able to keep the DCR down so you could run a reasonable octane.

BDR561 · #97 (**permalink**) 10-17-2007, 10:17 AM

JE said I could use a .050 head gasket. Is a .035 clearance enough?

blykins · #98 (**permalink**) 10-17-2007, 10:18 AM

The smaller the head gasket, the more compression you have.

.035" clearance where?

BDR561 · #99 (**permalink**) 10-17-2007, 10:25 AM

Blykins,

With how these cars hook up (or lack of) wouldn't it be a good trade to loose some bottom end torque for high end power? The BDR doesn't have a posi so torque and a light weight car will just break the rear loose in a heart beat. I must admit that I did l like the charecteristics of the motor before it went Kaboom... It had a really nice linear power curve that was very manageable without roasting the tires uncontrollably..

The .035 would be piston to head using a .050 head gasket

onefastmustang · #**100** (**permalink**) 10-17-2007, 10:28 AM

Are you sure it's a 72 block?? the 72 block had a 9.503 deck height. Only the 1969 had a 9.480 deck height.