Stroker Performance Review

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That's a 360 car, isn't it?


Yes a stock crank 360 with one of Racer Browns tweeked .520 lift solid lifter cam. That was such a fun simple combo. Going back a lot of years but it had SPS flat tops, the cam above, K1 rods, set of Edelbrock heads I did with 2.05 valves, ported Victor340 intake, and a 850 APD alcohol carb. 727 trans, 4.30 ( 8 3/4) and caltracs. 3200 pounds and it ran 10.50’s. Heads are sitting here collecting dusts because he always wants the set I did with 2.08 valves now. I hate selling stuff. Especially if it worked well.
 
I said I had bought the converter for the 318 not had it built for it. It is a Hughes 10.25 Street/Strip 3500 converter. An off the shelf converter.


I would be concerned about the output too..
But you said your converter was built for a 318 ?!?! My money is on THAT being the problem, for the most part. Your new motor is driving through it.
I don't know what converter you have (who made it) but I would send it back and correct it for your new combo. Maybe $250, more if they change the stator. (probably)
If you have a stock 10 3/4 lying around, throw it in, shift it at 5800 and see how it MPH's... if it gains 4-5 mph, you've found your issue.

TrickFlows QC is probably a lot better than Edelbrock's QC... I had a OOTB E Streets in my shop a couple weeks ago, and the Valve seat run-out was horrendous!
Don't put too much stock in the Leak-Down testers.. They are finiky with piston possition and tend to show a false negative.
A compression check should suffice, as long as they're consistent, cyl to cyl.
 
I am basing the engine output of fo the MPH at the end of the 1/4 from my own experience seeing different 60ft with both street tires blowing off and getting a 2.4 60' and a car getting a 1.7 60' that the MPH does not change much. My understanding is that the car weight and your MPH at the end is your dragstrip dyno. I certainly can see a better converter getting the car performing better in ET but please correct me if I am wrong I don't expect it to effect the MPH much unless the one I have is horribly inefficient.

I would expect the converter to help 60' and ET.




The point that’s trying to be made about the converter is........ the OP is basing the engines power output by the cars performance data.

Many things affect the cars performance other than the power output of the engine.
The converter being probably the next biggest player.
If the converter sucks(and many do), the cars performance will be way off, making the power output appear to be low.

This is where having dyno tested the motor is probably the most valuable.
If the motor made 550hp.......... but the car is running 450hp ET’s........ you know where not to spend any money.
On the motor.

Of course, without the dyno....... the builder is “assuming” that magic combo of parts “should” make 550hp....... but without testing, who knows?
Maybe it’s actually only making 450hp(or 475, or 500, or 600??).

The question as to whether there is sufficient valve spring load to maintain valvetrain control to the RPM they’re turning the motor would have been answered as well.
 
OK, my bad... didn't quite understand. it will still need to be corrected for that combo... I'm not a real fan of off-the-shelf converters..
 
BTW, what is your trap RPM? (gear, tire size, type of tire?)
 
Brother is driver I am not sure exactly what the trap rpm was. It is 4.10 gears 28/9 Hoosier bias ply slicks at 15lbs, 205/70/14 radials in the front. MPH was 113.5. So if I assumed 8% converter slip would be 6k at that speed.


BTW, what is your trap RPM? (gear, tire size, type of tire?)
 
Brother is driver I am not sure exactly what the trap rpm was. It is 4.10 gears 28/9 Hoosier bias ply slicks at 15lbs, 205/70/14 radials in the front. MPH was 113.5. So if I assumed 8% converter slip would be 6k at that speed.

Your math is pretty good, but that bias tire is going to grow a little bit too.
8% is too much though.. if the trap RPM is 6k. Like I said, not a fan of shelf converters...

My 9 1/2" Lupo is about 4%
 
I certainly can see a better converter getting the car performing better in ET but please correct me if I am wrong I don't expect it to effect the MPH much unless the one I have is horribly inefficient.

Okay.
You’re wrong.

Simply put, a poorly functioning converter will make both the ET and speed numbers look bad.
Period.
I’ve seen that scenario play out countless times in the last 40 years.

Unfortunately........ the best way to see how bad a converter really is...... is to replace it with a good one.

IMO, the converter you have is a poor match for the motor combo....... but it’s not cheap or particularly fun to find out if I’m right or not.

I’m not implying it’s the sole item responsible for the poor performance though.

When I learned all this stuff, there was no internet, and not a lot of people to ask for advice........ so you tried things and just figured it out.
Or you didn’t.

Sounds like you have a plan....... so just work your way through your checklist and see how it goes.

One last thought......... which do you feel is the more likely scenario.......
A-the motor is down 100hp, or
B-the converter is a problem

I’m going with..... C-it’s some of both
 
Your math is pretty good, but that bias tire is going to grow a little bit too.
8% is too much though.. if the trap RPM is 6k. Like I said, not a fan of shelf converters...

My 9 1/2" Lupo is about 4%

My feelings on the converter slip thing are.... for a “race car” with a race converter...... up to about 10% slip isn’t uncommon to see....... even in cars that run very well.

However....... 8% out of a 10” street converter in a car running “enough” gear is pretty high.

My friends old GTO Stocker with an auto.......
433hp(on the dyno), 3600lbs race weight.......5500 stall 8” ATI, 4.56’s, 9x30 Radial slicks.......11.33@117, low-1.50’s 60’....... 6000 shift, about 64-6500 thru the lights.

My 383(485hp) in my car(3670lb B body) with the flat steel hood on it went as good as 119mph, 4.56’s 9x29.5 radial slicks, 68-6900 out the back.......8” Dynamic, 5400 flash behind that motor.
 
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When I learned all this stuff, there was no internet, and not a lot of people to ask for advice....

We're not that much better off, are we? LOL
 
I sure don't mind being wrong. I just wish I understood how the converter could have a large effect on MPH.

The 8% slip I through out there was not a measured amoutn of slip. I just thought it would get the math int he ballpark.

Thanks for the advice. Converter is definitely the $$ change so work my way through lower cost things first and save the converter for a year down the road.


Okay.
You’re wrong.

Simply put, a poorly functioning converter will make both the ET and speed numbers look bad.
Period.
I’ve seen that scenario play out countless times in the last 40 years.

Unfortunately........ the best way to see how bad a converter really is...... is to replace it with a good one.

IMO, the converter you have is a poor match for the motor combo....... but it’s not cheap or particularly fun to find out if I’m right or not.

I’m not implying it’s the sole item responsible for the poor performance though.

When I learned all this stuff, there was no internet, and not a lot of people to ask for advice........ so you tried things and just figured it out.
Or you didn’t.

Sounds like you have a plan....... so just work your way through your checklist and see how it goes.

One last thought......... which do you feel is the more likely scenario.......
A-the motor is down 100hp, or
B-the converter is a problem

I’m going with..... C-it’s some of both
 
Sometimes it doesn’t “click” until you experience it first hand.

You could start a post about it and see if there are any fabo members with examples of a speed increase with a converter swap.

I watched the video of the run....... you’re right, it does sound pretty flat in high gear........ so maybe there’s more speed in it with the current converter if you find a reason for it to be down on power.

Do you know what the rpm is at the finish line?
 
Sometimes it doesn’t “click” until you experience it first hand.

You could start a post about it and see if there are any fabo members with examples of a speed increase with a converter swap.

I watched the video of the run....... you’re right, it does sound pretty flat in high gear........ so maybe there’s more speed in it with the current converter if you find a reason for it to be down on power.

Do you know what the rpm is at the finish line?
Are you reading any of the other post? He just got done saying he doesn't drive the car and he can only calculate that but he said that already as well...
 
Are you reading any of the other post? He just got done saying he doesn't drive the car and he can only calculate that but he said that already as well...

You’re misinterpreting what I’m saying......
My point was...... if they try a better converter and the speed picks up...... the light bulb will come on........ that a converter can affect the speed along with the ET.
 
Was there anyone close enough to the starting line to see if there was any wheel spin at the launch?
The 60’ times are pretty soft........ although the 1/8 mile and 1/4 mile times match up pretty well.
The 7.515 works out to an 11.79, so only off 2 hun.

Making better use of the 113.5 speed could get the car into the 11.50’s.
 
Ask me..... I once ran a GER
:D

Most who were playing with cars in the 80’s have GER experience.
I actually had a 10” that worked fine.
I ran it for a couple years, sold it...... and that guy ran it for a long time.
It was worth at least .2 over the stock 11” unit he had behind his 383.
 
Remember guys he has since found out his carb wasn’t opening the whole way. A little bit is fine but his sounds like it was a fair amount.
 
Well........ there are plenty of people to ask now......... but to what I think is your point...... that’s not necessarily a good thing.

Unfortunate, isn't it? A little discernment, goes a long way.. just like it used to be.
 
Unfortunate, isn't it? A little discernment, goes a long way.. just like it used to be.

Honestly....... (and maybe I’m just losing it), I don’t remember asking a lot of questions.
I just tried stuff I thought would work.
Sometimes it did...... sometimes it didn’t.
 
GERRRRRR, that was the least I said, when I found out it was a POS !
I had a 9” J version of theirs back around 1986, what after seeing their many ads in the car magazines of the time. Lots of good sounding Mumbo-jumbo in them as I recall. :rolleyes: Would love to see those ads again for giggles!
 
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