70 dart 470 ci drag car build.

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92b said:
As far as timing is concerned, have you reached the point where the motor is losing power anywhere in the curve yet from too much?
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Yeah it seems that 23 initial is the losing power point, 18 is not quite there but the sweet spot is 21 as it is now.
 
PRH said:
What I find fairly often, when running the timing locked out, is that when you’re hovering around whatever timing is giving the best results, is that slightly retarded will often make the peak TQ numbers better than the setting which yields the best HP number.

And then there’s the combos that are almost impervious to the timing unless you make a fairly big change.
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I have a very heavy spring tight unlocked curve and what you explained about the locked is pretty much what my engine is doing too. We had 24 in yesterday and it really struggled to get up to 6300 from about 6000, and I backed it down to 20 it ran hard through the pull, added 1 more degree of timing and it loved it all the way across the pull.
I was running 18 to get a good pull with the fairly restrictive dyno exhaust system.
It's about a 20 hp difference in peak but picked up everywhere besides 3000-3300 where it loses 5 ft lbs.
 
Everyone has their own way of testing…….but “if it were me”, I’d be setting the timing at 6000 on that thing.
 
PRH said:
Everyone has their own way of testing…….but “if it were me”, I’d be setting the timing at 6000 on that thing.
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I can check where it is at at 6000 next time. In the next day or 2
 
Along those same lines with everyone doing it their own way……..
I assume you’re planning on a converter that flashes in the 5000 range……..
If that’s the case, I’d be starting the pulls about 1000 higher than what you’re doing now………and I’d extend the top of the pull to an rpm point that I’d expect to see at the end of track.

I’d be curious to see how well the curve hangs on.
All the tests I’ve done using that manifold(albeit an unmodified one) have had the curve fall off pretty fast. Way faster than a “racy” single plane.

The TR made more peak power(and it occurred at a lower rpm), but wasn’t that good when you got well beyond the peak.
 
PRH said:
Along those same lines with everyone doing it their own way……..
I assume you’re planning on a converter that flashes in the 5000 range……..
If that’s the case, I’d be starting the pulls about 1000 higher than what you’re doing now………and I’d extend the top of the pull to an rpm point that I’d expect to see at the end of track.

I’d be curious to see how well the curve hangs on.
All the tests I’ve done using that manifold(albeit an unmodified one) have had the curve fall off pretty fast. Way faster than a “racy” single plane.

The TR made more peak power(and it occurred at a lower rpm), but wasn’t that good when you got well beyond the peak.
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Yes on the converter and I guess it might be 6900 at the end of the run. The dyno has an estimator on it for et and mph, said today 9.98 at 136 I believe. So I'll recheck those numbers.
 
PRH said:
Along those same lines with everyone doing it their own way……..
I assume you’re planning on a converter that flashes in the 5000 range……..
If that’s the case, I’d be starting the pulls about 1000 higher than what you’re doing now………and I’d extend the top of the pull to an rpm point that I’d expect to see at the end of track.

I’d be curious to see how well the curve hangs on.
All the tests I’ve done using that manifold(albeit an unmodified one) have had the curve fall off pretty fast. Way faster than a “racy” single plane.

The TR made more peak power(and it occurred at a lower rpm), but wasn’t that good when you got well beyond the peak.
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Do you recall the specs of the 264-268 cam you made for Andy f ? Basically just trying to figure out the lsa .
I'm not sure if you had a chance of reading what my engine has for camshaft and a deep port match in the 240s, I think I might not have enough camshaft, CSA or valve spring pressures to run up to 6900 or 7000 and not negative effects.
I might be needing to look into a gear change
 
Okay I ordered a set of 4.10s and now I have set my mind at ease a bit .
I'll be making power in the range of those gears best .
But will take the next tests out to 6700 just to see what it will do.
Thanks for the summit code Pittsburghracer
 
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PRH said:
Everyone has their own way of testing…….but “if it were me”, I’d be setting the timing at 6000 on that thing.
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I haven’t checked initial timing since my 1972 Cutlass back in the 1980’s. Everything is in before 1100 rpm and total time that sucker. Non locked out distributor.
 
pittsburghracer said:
I haven’t checked initial timing since my 1972 Cutlass back in the 1980’s. Everything is in before 1100 rpm and total time that sucker. Non locked out distributor.
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We put my distributor on Tim's machine and put a great curve in it, we did timing sweeps after the engine was broken it, so we've been very close to the higher rpm all in timing (5500) based off our initial, another benefit of having a dyno.
My msd box retards the timing a few degrees up in the rpm range
 
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pittsburghracer said:
I haven’t checked initial timing since my 1972 Cutlass back in the 1980’s. Everything is in before 1100 rpm and total time that sucker. Non locked out distributor.
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Why do you go all in before 1100 ?
 
MOPARMAGA said:
Okay I ordered a set of 4.10s and now I have set my mind at ease a bit .
I'll be making power in the range of those gears best .
But will take the next tests out to 6700 just to see what it will do.
Thanks for the summit code Pittsburghracer
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Man I wish you would have said something, I have 3 sets of 4.10s for a dana 60.
 
MOPARMAGA said:
Why do you go all in before 1100 ?
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This MSD distributor always came in early and it’s worked good for me. Remember I’m staged and when the tree starts I’m at 4300rpm. Then it flashes to 5760 and it shifts at 6700. It drives around the pits like a street car. My son locked his out but I never bothered. I may be off by a few rpm but trust me it’s in early.
 
PRH said:
Along those same lines with everyone doing it their own way……..
I assume you’re planning on a converter that flashes in the 5000 range……..
If that’s the case, I’d be starting the pulls about 1000 higher than what you’re doing now………and I’d extend the top of the pull to an rpm point that I’d expect to see at the end of track.

I’d be curious to see how well the curve hangs on.
All the tests I’ve done using that manifold(albeit an unmodified one) have had the curve fall off pretty fast. Way faster than a “racy” single plane.

The TR made more peak power(and it occurred at a lower rpm), but wasn’t that good when you got well beyond the peak.
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So I elected to buy another gear set 4.10 last night...but this morning we did run a test out to 6800 and it only fell off about 20 hp.
I will post the graphs and stuff tomorrow at some point.
We're going to run a few tests on 110 octane tomorrow, just to see if there's any power to be had with it vs. the 100ll av gas.
 
Sorry I’ve had a few adult beverages around the campfire with friends at the track but why is this engine running of of guts this early.
 
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pittsburghracer said:
Sorry I’ve had a few adult beverages around the campfire with friends at the track but why is this engine running of of guts these early.
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I suppose it's the 471 cubes with standard port heads with gasket match ports, pretty small duration 264-268 108 lsa sft cam .660-.680 lift
It was making 660 at 6800
We could run it out to 7000 and it would still be making 650 HP but I don't really see that as necessary.
I am happy with what it's doing and it's right at my goal for et and mph.
Which is 10.00s and just under 135
 
Sorry if you were reading that while I edited 5 times
 
this morning we did run a test out to 6800 and it only fell off about 20 hp.
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Sounds like the work you did on the manifold is paying off……. Nice job.
On a low deck 452 I tested years ago, a basically ootb TR lost 37hp from its peak at 6200, to 6800.
Then another 76hp by 7300.
It had all the classic signs of a valve train control issue……other than it sounded fine.
I would have probably explored that some, but I’d already made a bunch of pulls with a single plane and a dominator, and it had a very nice curve up top with that combo on it(lost 27hp from its peak at 6500 up to 7300).
The TR lost 113hp from its peak at 6200 to the end of the pull at 7300.

Peak to peak the TR was up 20tq/26Hp to the single plane………but at 7300 the single plane was up 60hp.

Some formula I found at the time showed the TR to be tuned for about 6000rpm on that combo, which seemed pretty close.
 
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PRH said:
Sounds like the work you did on the manifold is paying off……. Nice job.
On a low deck 452 I tested years ago, a basically ootb TR lost 37hp from its peak at 6200, to 6800.
Then another 76hp by 7300.
It had all the classic signs of a valve train control issue……other than it sounded fine.
I would have probably explored that some, but I’d already made a bunch of pulls with a single plane and a dominator, and it had a very nice curve up top with that combo on it(lost 27hp from its peak at 6500 up to 7300).
The TR lost 113hp from its peak at 6200 to the end of the pull at 7300.

Peak to peak the TR was up 20tq/26Hp to the single plane………but at 7300 the single plane was up 60hp.

Some formula I found at the time showed the TR to be tuned for about 6000rpm on that combo, which seemed pretty close.
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Thanks, when you said it would be a good idea to test out to the finish line rpm I was wondering what it was doing too because at the end of the last few pulls at 6300 the hp graph line was still carrying on straight out.
I can't remember what the loss from peak HP was but I'll show that but since it peaks at 57-5800.
Now some people might think 5800-6800, **** that's only 1000 rpm but under load that's a lot more rpm in my book...I was nervous but I'm pretty impressed with this build and to here Tim actually say that was pretty cool too.
 
PRH said:
Sounds like the work you did on the manifold is paying off……. Nice job.
On a low deck 452 I tested years ago, a basically ootb TR lost 37hp from its peak at 6200, to 6800.
Then another 76hp by 7300.
It had all the classic signs of a valve train control issue……other than it sounded fine.
I would have probably explored that some, but I’d already made a bunch of pulls with a single plane and a dominator, and it had a very nice curve up top with that combo on it(lost 27hp from its peak at 6500 up to 7300).
The TR lost 113hp from its peak at 6200 to the end of the pull at 7300.

Peak to peak the TR was up 20tq/26Hp to the single plane………but at 7300 the single plane was up 60hp.

Some formula I found at the time showed the TR to be tuned for about 6000rpm on that combo, which seemed pretty close.
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Oh yeah and to clarify, which I see I didn't in my post you responded to is, it fell off from the end of the normal 6300 pull about 20hp.
 
So, what’s loss from peak power to 6800?
And, that 6800 is about 1000rpm past peak?

Nonetheless, if you’re still making decent power at the rpm point you’ll be seeing at the finish line…..it should run good in the car.
 
PRH said:
So, what’s loss from peak power to 6800?
And, that 6800 is about 1000rpm past peak?

Nonetheless, if you’re still making decent power at the rpm point you’ll be seeing at the finish line…..it should run good in the car.
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We're making some sonoco 110 tests.
I'll run one out to 6800 for you real quick and post what it says. So far the sonoco is slightly down on power vs av gas.
 
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