390 on Dyno (video)

[sport71]

Perhaps you'll discover some easily correctable issues that will resolve the engine's bottleneck and produce some rosier numbers!

I know that I can get to some of the issues corrected, I just don't know how much it will cost?

Here at the local drag strip they have test and tune days. No racing for a flat fee you ca drive it as hard as you want or as easy as you want. Take plug readings, get ET or speed trap answers to minor or Major tuning adjustments.
When the Navy had me in Texas we used to haul 3 motors at a time to a flywheel dyno for a flat 250 a day fee.

That's cool for all day. I bet it was full of guys wanting to tune their motors. You'd probably get alot of input on building a hot motor. Must have been a great expiriance.
When I get the new carb, and get it timed with new plugs. I'll have them do the full pull @ 6200 in third gear. Then I know we'll see them numbers change for sure.
Now do you think that @ 6200 I'll harm my engine with my setup? I think that I've got all the good stuff in it, but I think you would know more than me on this. Thanks, Dragon.
sport

Double-pumper carbs are not recommended for heavy vehicles, especially if you have less than a 3000 stall converter.

I'm learning brother, it's just costing me.

A Vacuum Secondary carb can do the trick and better match the engine's needs

I want to fix up my 770 street avenger. When I get it home I'll post what it has for jets, springs, ect.., and we'll see what can be done with it.

Thanks for the replies

[Ranchero50]

I don't think I'd waste the time and money on a dyno until it's running right. As said above, less carb and better timing, both of which you can do on a quiet evening under a street lamp in an old industrial area. Tuning a carb is more an artform, feeling what the motor is doing at certain throttle settings so you know what to play with. A couple blocks from my house is an area I can open it up safely to test, then bebop back home to adjust it. Usually timing first, then start on the carb. Sounds like you need to find a good friend / racer who knows carb tuning.

Jamie

[Dragon]

We would pay for the dyno time to tune it. Better tuning in a better environment. That is if you don't have any problems but want to get it nailed down. You can adjust for atmospheric conditions as most good dynos take those readings.

[hotrodfeguy]

"Today, I couldn't wait to see what the new cam, and carb would pull at the dyno, they didn't go over 5500, and I wasn't happy with the results. The old motor was pulling 241.23 HP and 267.23 TQ, and now this motor pulled 205.17 HP and 256.36 TQ. "

I would find a new place with a Dyno. There is no way that cam has less power than what you had. Your tires are proff of that at 35MPH in first gear and how far into second! I myself would stick with the 770 its a good carb and a good fit for that 390. Just shop around for a new dyno and see if you can get one that can give you say an hour and willing to rev it over 6k. Also one that will tell you what way to go with the tunning, IE. more or less advance, more or less jetting. A good dyno shop should be able to look at the results and start sending you in the right directions with all of those items. A 390 has no issues going to 6-6500 on stock bottom end. Hell the longer 3.98" stroke in my 428 makes trips with the same cam to 6500. That 390 shares the same stroke as the 427 NASCAR engine that went 8K all day for 500 miles at WOT! Besides do you think all of us racers wait for 5k miles before we hit it on the strip? Heck no. Like said before otherwise take it out to the local track, You can get HP/TQ numbers from the ET and MPH you pull. And you will get more than one pass to tune with. I would opt for the track, Bump the distributor/carb/kickdown each lap and see what it likes best. Time for some truck loving and tire burning

[DuckRyder]

I agree the dynomometer is suspect in this case, what kind of dynomometer is is?

I also agree the 770 Street Avenger would be a better choice of Carburettor, I don't understand why it needs to be worked on if it is new?

A little work on the Governor should get the WOT shift point up on the C6... If you google you can find the TSB relating to the GTA mustang Governor weight modifications.

The engine looks good, I would run it a bit to break it in properly, do some basic tuning and then have it fine tuned on a dynomometer if you can find a place with some V8 Holley experience.

[sport71]

A good dyno shop should be able to look at the results and start sending you in the right directions with all of those items.

I agree 100%. I'm going to a local classic car gathering Sat. I know that I'll find someone who's been there, done that, and who's more than willing to help me out. And I'll try another dyno speed shop.

The engine looks good, I would run it a bit to break it in properly, do some basic tuning and then have it fine tuned on a dynomometer if you can find a place with some V8 Holley experience.

I did the first oil change at 400 miles. Next is to find a place with some V8 Holley experience.

[hotrodfeguy]

Have you gotten it to the track or any new updates?

[RTG_RACING]

Thats a nice truck. Save toat motor and get a good air filter. I am not trying to get down on you in any way. Please don't take it that way. But i have read on many sites that the filter is all show and doesn't work worth a dang.

[hotrodfeguy]

He has a good one on there now.

[sport71]

I havn't taken it to the track YET. The triangle air filter is gone. Now it has the K&N that works good. Oh well, the motor is done, and runs like never before with the new carb. I went ahead and put one with a vacume secondary. It does great burn outs now I've never owned a hot rod before, and let me tell you it is fun. I feel like a little kid with a new toy. I took the truck back to the paint shop to get some defects taken care of. After that at dads shop It's getting a radiator flush, couse it runs kinda warm. Plus we'll be vacumming the A/C system out, and filling it up with freeze 12.
I just hope that with the A/C it won't run hotter.

[Dragon]

Not really hotter but a 20 HP loss that is why modern vehicles use the TPS (Throttle Position Sensor) switch for WOT (Wide Open Throttle) sensing to kick the AC compressor off line. Easy to convert to R134 because if you get caught running R12 then you can get burned. It is outlawed. I have an EPA Freon handlers license and I tell you if they want to the fine can be 10,000 and you could lose the truck.

[sport71]

Not really hotter but a 20 HP loss that is why modern vehicles use the TPS (Throttle Position Sensor) switch for WOT (Wide Open Throttle) sensing to kick the AC compressor off line. Easy to convert to R134 because if you get caught running R12 then you can get burned. It is outlawed. I have an EPA Freon handlers license and I tell you if they want to the fine can be 10,000 and you could lose the truck.

The Freeze12 is EPA approved. It's a substitute for the R12 freon. I hope that my reserch is correct, because I would hate a big fine like that. I just might be wrong

[70_F100]

Based on what I saw, it appears that the Freeze12 conversion is a LOT more expensive than an R134a conversion.

I don't know about the difference in results, but I'm very happy with R134a in my system.

[Dragon]

Freeze 12 is approved sorry just it was not in my package from the EPA. Before I looked it up I found many claims I know are false. When I do my truck I am going to run R134a, too easy for me to adapt to. New TXV and Drier are required anyway. And since our cabs are so small we don't need that huge compressor so I have been looking at the ones on foreign cars and escorts.

One claim is the better cooling. No blend that runs in a cars low pressure system(by HVAC standards) works better than straight Freon.

Freeze 12 a blend of 20% r142B and 80% R134a.

[hotrodfeguy]

"It does great burn outs now I've never owned a hot rod before, and let me tell you it is fun. I feel like a little kid with a new toy"

Thats what we like to hear I think thats a good combo, that would surprise a few cars out there. Like most they don't expect a truck to hustle like that combo and 3.70 gears
I would kill to see one of those burnout clips