462 Stroker - Disappointed

[rockhouse66]

So I mentioned in another thread that my 462 stroker looked strong on the dyno but isn't equally strong in the car.  It pulls strong, but I was looking for shredded tires in 1st gear with a touch of the throttle.  Maybe my expectations were too high?  This engine is in a '69 Mustang coupe with 4-speed and 3.50 Tru Trac and Polyglas tires.

This dyno run was with CJ iron exhaust manifolds to open duct and smog installed and functional.  About 515 TQ and 430 HP.

[rockhouse66]

More details of this build;

428 w/4.25 stroke, 9.8:1 CR, ported CJ heads, port matched CJ intake, stock CJ carb (same one used on the dyno).  Cam details are Comp hydraulic roller cam 224/224 @ .050”, .616 lift, 104 ICL, 110 LSA.

Distributor is CJ but has been curved so initial is around 15 and total all in at about 2000 is 35.  I tried a 750 double pumper with no noticeable difference.  Though it ran best at about 34-35 total on the dyno, I have bumped it up a little to see if it made a difference with no improvement.

Basically, I got just what I wanted from this build.  I wanted a very mild acting and sounding engine and the target was 500 TQ and 425HP, which I got and then some.  Pulls very strong in 4th gear.  However, I anticipated tire shredding torque in 1st gear and I can floor it at 2000 in 1st with no drama - just fairly strong acceleration.  My 66 Mustang with a 347 stroker is much faster (still won't shred tires though).

My suspicion is that the combo is just not well matched in some way - most likely the restrictive stock exhaust system with transverse muffler, which I really don't want to change.  This is a rare almost show car - '69 CJ Grande w/4 speed - 1 of 9 built.

[fastback 427]

That should shred those tires. What's different with the engine installed in the car compared to the dyno? Such as fuel pump, air cleaner, distributor? Can you give us more build details like cam, carb,intake ?

[rockhouse66]

See post #2 above.  The differences are the Q code air cleaner and the exhaust system is now complete including the transverse muffler.

[machoneman]

I wonder if the internals of the muffler collapsed? Not unusual especially with a transverse unit. Any way to disconnect some pipes and make a run? Same with popping off the air cleaner assembly for a test run?

[rockhouse66]

I would expect some farting noises from a collapsed muffler, but that would be worth a try if I can get the darn clamps apart.  It will sound faster for sure!  And the air cleaner would be easy, so I should have already tried that.

I do know that engines that make great dyno numbers don't always drive that well on the street, but you would think over 500 TQ would be noticeable no matter what the driveability is like.

[ScotiaFE]

Part of the problem is the gear box.
If you are still running the close ratio gear set it will have a
Starting Line Ratio of 7.31. That is very low for giddy up factor.
To get the real giddy up and lite the tires feel you pretty much have to get
into the 10's for the SLR.
For real fun on the street a SLR of high 11's or 12's increases the fun factor a lot.

[cjshaker]

You also did not mention rear gearing, at least that I saw. If you've got 3.25/3.50 gears, or something similar, coupled with a close ratio tranny, that certainly wouldn't help. What size tires are you running? A 275/60 tire or something close to that effectively lowers your ratio even further.

Even with the stock exhaust, that car should be ripping the tires off in first gear. Also, that's a pretty mild cam for a big engine. Can you post the dyno results? Peak torque doesn't tell anything about the power down low, and 2000rpm is pretty low. Even mild engines don't get into the power curve until about 3000 or so.

Big engine, mild cam, low gears (numerically) and a close ratio tranny could all add up to lackluster performance.

[rockhouse66]

3.50 gear with CR 4-speed and F70-14 Polyglas.  The actual dyno results are in the curve in the first post.  You have to click on the pdf file to see it.  Looks pretty "normal" to me - and stout for the mild cam too.  Obviously, I'm stumped.  But maybe tall 1st gear, 3.5 rear and Tru Trac doing it's job is the answer.  Nonetheless, when I stomp on my 347 66 Mustang, the front end jumps up and the car takes off like a rocket ship.  This car - it goes but.... not like that.

[cjshaker]

Ah, sorry, I didn't see the pdf file. Yes, it seems to have pretty decent torque down low.

Just out of curiosity, how does it act if you run it slowly up to 3000-3500 and then stomp on it? It should be really pushing you back in the seat at that point.

Did you get any air/fuel ratio data with the dyno runs? Perhaps the secondaries are opening up early and causing it to bog (do you get any black soot out of the exhaust when pushing it at 2k?). Or maybe they are opening up late, or not at all? It's not uncommon to tie open secondaries on the dyno because they don't want to open by themselves. It's also not uncommon to have to tune all parameters of an engine once it's installed in a car. Jetting and timing is about the only thing that can be determined during a dyno operation.

[My427stang]

I have a 445 pickup with 3.50s and a 33 inch tall tire, it's got an 11:1 SLR, but 33 inch tall tires, more cam and less cubes.  It violently burns the tires in first.

I think you have something wrong.  Was that dyno done with the manifolds on, and is there any different parts at all since the dyno?

The exhaust is literally choking it, but it should still burn the tires off idle. 

If it was mine, I'd go with a low gear conversion on a rare car, then if you weren't happy, might have to have a show exhaust and a driver exhaust

[ScotiaFE]

Ah yes the old CR.
IF you were to do the gear swap to the wide ratio, I don't know what the cost today is
and if you live in Nova Scotia it costs twice as much as the US.
It is the most cost effective way to do massive burnouts.
The swap will increase your SLR to 9.73 with the polies.
Do the WR swap and a 4.?? rear gear and you will have no traction and do 300 foot burnouts when ever you want. 

A little old 390 stockish with hyd cam, but with a good gear set.

https://www.youtube.com/watch?v=7S8mriRKzUc

[Nightmist66]

Howie, in the vid., did you have the Jerico in yet and also was it the 3.25 gear in the description?

I have a wheezed out little 390 with a mild hyd. flat tappet in mine and even with the drag radials and Cal Tracs, I have no problem putting some rubber down.

[ScotiaFE]

Howie, in the vid., did you have the Jerico in yet and also was it the 3.25 gear in the description?

I have a wheezed out little 390 with a mild hyd. flat tappet in mine and even with the drag radials and Cal Tracs, I have no problem putting some rubber down.

It was a pretty stock 390 with iron heads, Wide Ratio Top Loader and believe it or not a 3.25 highway gear.
The Jerico with much steeper rear gear will get a smidge of air.

[rockhouse66]

The AFR ran in the 14's from 2500-4000 RPM and then in the 15's after that.  I have an Innovate LM-2 but didn't get a bung installed this Summer so now it won't happen until Spring.  Hope to do some more tuning with that gadget.  I know this is too lean, and maybe with the air cleaner in place, much too lean?