Stroker Performance Review

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Ivoryk3ys78

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I am not sure if this should go under engine or Racer section.

My brother, father nad I finished building a 408 stroker for my 72 Duster earlier this summer. We had a chance to take it to the track last Friday for test and tune. We wernt able to get more then a couple runs in but I was very disappointed in the performance and I would appreciate any feedback. I will let you know I can not give you feedback on how the car felt. It is my engine and car but I can not see well enough to drive and my brother is the driver. He didn't notice anything wrong though.

Shifting was done at 6500. according to my Desktop Dyno peak power is at 6k and pretty much flat to 6500. It didn't seem to fall off to us at 6500.

This was in Woodburn Oregon so near sea level. I think with the weather the DA was like 1500 that day.


The Engine
360.030
Eagle Cast Crank
Scat I beam rods
KB Icon pistons (O decked, .039 gasket, Compression is 11.2)
Trickflow Powerport 190
(These are the heads that have the weakest springs. 120 at seat. My heads call for 145 seat. I talked to Trickflow and they said should be fine, Two calls to Hoards once I was told it was fine and another call I was told he would feel a bit better if I shimmed. I left it alone and didn't shim.)


Howard Solid Flat Tappet 600/615 254/260 108 at 103.5 centerline
The updated Strip Dominator that shows MP for Mopar so basically M1. Whoever had it beore gasket matched
Howard EDM lifters
Lash set at .012 Cold so should be .018 area hot as is called for.
Proform 650 race carb With Proform upgrade main body so should flow right at 800cfm
68/84 with enlarged PVCR .072 and 2.5Hg High flow power valve ( We had just over 5"HG at a pretty low rpm idle so went with the 2.5. at a more reasonable idle is was closer to 7"HG)

comp Ultra Pro Magnum rocker arms 1.5 No B3Racing correction performed
Smith Brothers 5/16 pushrods
Kevko M302 5qt pan. Broke in with Lucas 30wt break in oil, Using Lucas Hotrod High zinc 10-30
TTI 1 7/8 3.5" collector race headers. 18" extensions at the track
Ignition MP distributor with initial timing adjustmnet plate, Summit ignition box with rev limiter and multi spark below 3500.
Timing 16 initial/35 total

Plugs.. are the NG that Trickflow recommends
Gap is .035

Keep adding things in edits that I forgot.
Fuel system could be a weak link 5/16 line, 5/16 pickup. Carter Muscle car fuel pump. It shows 120gph on Mancini but that must be free flow. On Summit it shows that it is stock flow at 25gph. I just ordered a Carter Strip pump, 3/8 line and 3/8 pickup and an inline regulator.



Chassis
Raceweight 3375
Manual valvebody 727 with Hughes 3500 street/strip 10.25 converter
4.10 with 28/9 Hoosier slicks
XHD Springs and Pinion snubber
CE 90/10 Front CE 60/40 Rear
Frame connectors

Best of the 2 runs we got.
60' 1.715 330' 4.859 1/8 7.515@92 1000' 9.837 1/4 11.814@113.51

I would have expected a much higher MPH then this. I would have expected in the 120 area. This engine shoud make in the 550 range. Watching the video to me it kinda seems like its not pulling hard in third.

We will be checking lash, checking cylinder pressure (has never been done) and doing leakdown test if we see an issue there, making sure WOT(we did of course check this before), We did tune WOT A/F with with a pull largely through second. I want to do it with a long pull through just third and make sure its not falling off. I can't imagine the vacuum going above 2.5 and closing the power valve but I guess its possible.



Anyway. Any feedback is appreciated.

Thanks

Kevin
 
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I can’t really comment on your build components but will say this. If you set the lash at .012 cold it’s definitely not .018 hot. So your hot valve lash is more like .010 since you will have thermal expansion when hot.

edit I have this backwards so disregard my statement.
 
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cudascott said:
I can’t really comment on your build components but will say this. If you set the lash at .012 cold it’s definitely not .018 hot. So your hot valve lash is more like .010 since you will have thermal expansion when hot.
Click to expand...

I believe what your stating would be the cast with cast iron on cast iron but this is aluminum on cast iron so the growth rate is different.
 
It is a bit different but don’t understand how it can increase
 
Last edited:
Ivoryk3ys78 said:
I am not sure if this should go under engine or Racer section.

My brother, father nad I finished building a 408 stroker for my 72 Duster earlier this summer. We had a chance to take it to the track last Friday for test and tune. We wernt able to get more then a couple runs in but I was very disappointed in the performance and I would appreciate any feedback. I will let you know I can not give you feedback on how the car felt. It is my engine and car but I can not see well enough to drive and my brother is the driver. He didn't notice anything wrong though.

The Engine
360.030
Eagle Cast Crank
Scat I beam rods
KB Icon pistons (O decked, .039 gasket, Compression is 11.2)
Trickflow Powerport 190
Howard Solid Flat Tappet 600/615 254/260 108 at 103.5 centerline
The updated Strip Dominator that shows MP for Mopar so basically M1. Whoever had it beore gasket matched
Howard EDM lifters
Lash set at .012 Cold so should be .018 area hot as is called for.
Proform 650 race carb With Proform upgrade main body so should flow right at 800cfm
68/84 with enlarged PVCR .072 and 2.5Hg High flow power valve ( We had just over 5"HG at a pretty low rpm idle so went with the 2.5. at a more reasonable idle is was closer to 7"HG)

comp Ultra Pro Magnum rocker arms 1.5 No B3Racing correction performed
Smith Brothers 5/16 pushrods
Kevko M302 5qt pan. Broke in with Lucas 30wt break in oil, Using Lucas Hotrod High zinc 10-30
TTI 1 7/8 3.5" collector race headers. 18" extensions at the track

Chassis
Raceweight 3375
Manual valvebody 727 with Hughes 3500 street/strip 10.25 converter
4.10 with 28/9 Hoosier slicks
XHD Springs and Pinion snubber
CE 90/10 Front CE 60/40 Rear
Frame connectors

Best of the 2 runs we got.
60' 1.715 330' 4.859 1/8 7.515@92 1000' 9.837 1/4 11.814@113.51

I would have expected a much higher MPH then this. I would have expected in the 120 area. This engine shoud make in the 550 range. Watching the video to me it kinda seems like its not pulling hard in third.

We will be checking lash, checking cylinder pressure (has never been done) and doing leakdown test if we see an issue there, making sure WOT(we did of course check this before), We did tune WOT A/F with with a pull largely through second. I want to do it with a long pull through just third and make sure its not falling off. I can't imagine the vacuum going above 2.5 and closing the power valve but I guess its possible.



Anyway. Any feedback is appreciated.

Thanks

Kevin
Click to expand...

Any idea of what the engine rpm is on the top end of the track?
 
And this is EXACTLY why you use a dyno.

The OP has no clue how much power he makes, so he has no way to baseline his time slip, look at the incrementals and see where he is off.

Or maybe, just maybe it’s running the MPH it should be for the power it makes.

Again, a day on the dyno and he would have something to work with. Now it’s a guess.

OP, what does the car weigh?

You need at least a 4500 converter. At least. Call PTC and talk to them.

The carb is probably ok, but you are WAAAAAAAAY off on the power valve. And your jetting looks wierd. I can’t imagine that engine getting by with a 68 main jet. If you actually have an .072 PVCR that seems very fat too.
 
I haven’t used a power valve since 1976 and that was only for a month. Put a plug in it and jump up around 8 jets sizes and tune from there.
 
pittsburghracer said:
I haven’t used a power valve since 1976 and that was only for a month. Put a plug in it and jump up around 8 jets sizes and tune from there.
Click to expand...


I was under the assumption it’s a street car. A drag car can get away without a power valve, but done correctly the power valve isn’t an issue. You just can’t open it that late.

Once again, the screwed up Holley method of setting power valve timing rears it’s ugly head.
 
I did have the race weight posted. I should be right around 3375.

As far as the power valve I was sizing that based on a low rpm idle of around 5. I took half of that. I guess its possible that the carb size is small enough that it could be pulling enough vacuum especially at the upper rpm that it oculd be closing. Can do a WOT pull in third to check A/F to find out. Can put the 4.5 back in.

As far as jetting and PVCR. It was running 72 in the front and I had 79 in the back. I tuned the carb lean circuit by jetting down until at the 68. This gave a cruise A/f of mid to uppwer 14s and gas mileage of around 11mpg with no drivabilty issues. We did try 66 but that was too lean and the car was trailer hitching.

Then put a power valve block in and sized for WOT. Squared at I think 80 and then 84. at 84 in the pull up to 6 or so on the street in second was doing around 12:1 A/f average. pulled the power valve and put the .072 pvcr valve in based on an Area formula to size up the primary to square to the 84 jets in the back. Went on the street and did another pull to 6 area and it was around 12 average again. No issues driving the car on some cruises with the 68 jets. A/F would maintain in the 14s.

As far as a Dyno. I think anyone would agree that a dyno is the ideal situation. Not everyone has the money for that and a lot of people are stretching there budget just to do what we are already doing. I posted my combo in detail as well as the weight. I have seen a great many milder combos do more mph in the post your 11 second combo. Could this be all the engine has? Possibly but the heds and cam and compression and everything I posted I think it is not at all unreasonable to expect in the mid 500 gross area.

yellow rose said:
And this is EXACTLY why you use a dyno.

The OP has no clue how much power he makes, so he has no way to baseline his time slip, look at the incrementals and see where he is off.

Or maybe, just maybe it’s running the MPH it should be for the power it makes.

Again, a day on the dyno and he would have something to work with. Now it’s a guess.

OP, what does the car weigh?

You need at least a 4500 converter. At least. Call PTC and talk to them.

The carb is probably ok, but you are WAAAAAAAAY off on the power valve. And your jetting looks wierd. I can’t imagine that engine getting by with a 68 main jet. If you actually have an .072 PVCR that seems very fat too.
Click to expand...
 
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Power valve is most likely WAY off. I never tune them by splitting idle vacuum.

Ignition timing both initial and total need to be sorted out. If the distributor is not locked out it's going to want in the 20-24 for initial/idle timing and around 32 total as a guess.

It will take a BUNCH more carb too.

For the first time out, it didn't break and that is good!
 
I am not sure but 4.10 gear with 28 tire calculates to 5600 at 113.5 assuming 10% converter slip would put it 6160 so I would assume 6k or a bit more.

512Stroker said:
Any idea of what the engine rpm is on the top end of the track?
Click to expand...
 
I forgot to post the timing.

It was running 16 initial and 35 total.

crackedback said:
Power valve is most likely WAY off. I never tune them by splitting idle vacuum.

Ignition timing both initial and total need to be sorted out. If the distributor is not locked out it's going to want in the 20-24 for initial/idle timing and around 32 total as a guess.

It will take a BUNCH more carb too.

For the first time out, it didn't break and that is good!
Click to expand...
 
If you called let’s say AED with your combo I’m thinking they’d be recommending a much bigger carb, an 850 of even bigger. I’d be suspicious of a carb body claimed to flow 800 cfm. Carb and focus on getting each circuit sorted, step by step methodically in sequence. Not changing all you are changing seemingly haphazardly
 
If you are running race fuel, then the total might be OK, still more than most quench SB's usually run at that compression.

Pump gas, look hard at the porcelain for signs of detonation. There can be a significant HP lost through even a 2* miss on total with some engines.

I loaned an off the shelf Hughes 3500 converter to Brian and his car leaves HARD. Even with the shelf converter, footbraking, the car ran 1.45ish and 6.90ish in the 1/8 with a 480hp stroker at 3350#
 
You asked for opinions. Here is mine.
If its gonna just be a street car, leave it alone. As others have suggested, play with the carb a little more.
If, however, you want it to run perform much better, the convertor and carb would be two places to attack the ET that would really wake it up. Not in love with the M1 either, if you are gonna keep it on the street it likely would run better with an airgap, as far as seat of the pants
You have a relatively “ big “ intake on it, “big “ headers on it, but a convertor that doesn't match.
I would bet that a good 4800-5000 flash 8 inch convertor and a 950-1000 cfm race 4150 carb would really wake it up. Cam seems a decent choice, i run the next one up Howards sells( 260/264) in my 360 but its soon going in a 418 where it belongs. Good choice you have made, imo.
Its never going to run where it could until you get it to 60 foot. It should be 1.50 ish. The carb and convertor would, i bet, get it there.
I would also throw the snubber in the garbage can.
Your combo has excellent potential. Could run in the 10’s very easily with modest changes.
Get it to come out of the gate, other incrementals will come around and it will pick up rpm on the big end. Gear and tire are fine. Convertor, carb, convertor, carb
 
Thanks a lot. I appreciate the feedback. I don't care if its overly streetable. After all I ride in it and don't drive it with my eyesight. It needs to do some cruising but I don't mind it being at the extreme end.

I guess what disaponted me most is the MPH. Coming up with every bit of the engine combo I put time into and that MPH tells me that the HP for whatever reason is not near what one would expect for this engine built in this weight of car would think.

Yeah.. I was thinking more converter could really help the holeshot. It would not effect MPH though would it?

Would like to test a big carb on it.


B3422w5 said:
You asked for opinions. Here is mine.
If its gonna just be a street car, leave it alone. As others have suggested, play with the carb a little more.
If, however, you want it to run perform much better, the convertor and carb would be two places to attack the ET that would really wake it up. Not in love with the M1 either, if you are gonna keep it on the street it likely would run better with an airgap, as far as seat of the pants
You have a relatively “ big “ intake on it, “big “ headers on it, but a convertor that doesn't match.
I would bet that a good 4800-5000 flash 8 inch convertor and a 950-1000 cfm race 4150 carb would really wake it up. Cam seems a decent choice, i run the next one up Howards sells( 260/264) in my 360 but its soon going in a 418 where it belongs. Good choice you have made, imo.
Its never going to run where it could until you get it to 60 foot. It should be 1.50 ish. The carb and convertor would, i bet, get it there.
I would also throw the snubber in the garbage can.
Your combo has excellent potential. Could run in the 10’s very easily with modest changes.
Get it to come out of the gate, other incrementals will come around and it will pick up rpm on the big end. Gear and tire are fine. Convertor, carb, convertor, carb
Click to expand...
 
I agree with the carb comments.. also no mention of fuel system. Need to make sure it's supplying enough to the carb.
I have nearly an identical built motor, less the 4" crank, and it doesn't like to be shifted above 6500. I'm willing to bet it will run quicker pulling the shifts at 6k. it's sounding kinda rung out at 6500.
 
Ivoryk3ys78 said:
Thanks a lot. I appreciate the feedback. I don't care if its overly streetable. After all I ride in it and don't drive it with my eyesight. It needs to do some cruising but I don't mind it being at the extreme end.

I guess what disaponted me most is the MPH. Coming up with every bit of the engine combo I put time into and that MPH tells me that the HP for whatever reason is not near what one would expect for this engine built in this weight of car would think.

Yeah.. I was thinking more converter could really help the holeshot. It would not effect MPH though would it?

Would like to test a big carb on it.
Click to expand...

Years ago i had Hensley build me a 416
Went in a 3400 pound 70 Duster.All steel, bench seat interior, 300 pound plus driver.... me...lol..CE 3 ways all around, s/s springs, corrected Eddie heads with no porting, tti 1 5/8 to 1 3/4 step headers and flowmasters 750 holley, weiand excellerator, 4.10 gear, 28 tire, 3500 10 inch Coan “ super competition” convertor. Crane 248/258 540/560 solid cam.
Ran 11.70’s... was super diasapointed. Sounded good, but ran 113-114 mph.
Over the winter, took the heads off, sent back to Hensley, had them do a “ stage 2” port on them. Actually very modest work. They maxed at 274@600.
Then put a 1025 rs 4150 race Demon on it, and a PTC 5000 flash 8 inch convertor along with a PRH( on this board) specced 260-266 598/623 lift comp cam.
So... made heads a little better, more carb, convertor, and camshaft.... everything else unchanged..
Results...
10.74@ 124.60 1.46 60 foot.
You already have better heads than i had above.... so you can see for yourself what an otherwise similar combo responds to... btw 727 trans too
 
I was looking at the compression you posted. What cc are the trick flows? Stock they are 60 cc which I think would put your compression at 10.4:1 with icon ic745 dished pistons which are 20.5 CC’s. But that has nothing to do with your 1/4 mile runs. What fuel system are you running? Are you getting enough fuel on the big end? Fuel pump?
 
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