Disappointing ET's with 408

-
jimmyray

jimmyray

Well-Known Member
Joined
Jul 17, 2007
Messages
948
Reaction score
30
Well, I have my 408 togehter and running, and have had it to the strip twice now, with disappointing results, best ET of 13.4. See results below - track not running 1/4 due to fog, so 1/4 time is projected. All siad, I have about $6000 in the entire motor.

Motor details:
408 cast crank stroker from Hughes
9.9:1 compression
93 Octane gas
mild port/polish on Edelnbrock al perf heads, closed chamber, fresh valve job
M1 single plane airgap with gasket match (heads too)
Edel 1406 600 cfm carb, vacuum secondaries
Comp roller .544/.541 236/242 110 centerline
FBO ignition, ditributor curved to 16 inital, 34 total @ 2900 rpm
Hooker comp 1 5/8" headers (dented bottoms on driver side, naturally) 3" collector
2.5" pipe to flowmasters into 2" pipe (looks to be OE) into a-body tips
3000 stall TCI streetmaster
727 manual reverse
4.11 sure grip 8.25"


Questions:
I have a Carter 750 mech sec and a holley 750 dbl pump with proform body that I want to test. Expected dif in ET?
Would it be worth reworking the exaust ($600) to 3" tti's, estimated ET?
WHat about TTI headers? I saw a Westtech dyon showing +10 hp over the hookers above 4500 rpm. ET diff?

I read about other similar setup getting mid to high 11's, and I ain't nowhere near that.

Other suggestions?

01.jpg


02.jpg
 
Quick Observation: You may want to rethink that Edel 1406. I think your combo needs a bit more carb. I would play around with the other two and see what you come up with. Then you can start tweaking timing a little.
 
GTXperience said:
Quick Observation: You may want to rethink that Edel 1406. I think your combo needs a bit more carb. I would play around with the other two and see what you come up with. Then you can start tweaking timing a little.
Click to expand...

I am sure that the Edel is limiting mid to high end HP, and maybe even low end torque. I hope to test the other 2 carbs Friday night, but am only hoping for 1/2 second or so gain at best.
 
Did you check your timing marks on the balancer during rebuild. I ran 36 degress total timing on my stroker. Might be a combination of fuel and timing problems
 
Wow. throw that 600 cfm carb as far as you can. you need AT LEAST a 750 if not 800-850. Get a saw and remove the tailpipes. Just put turndowns after the mufflers. Timing seems to be coming in very slowly. I'd like to see full advance by 2000 rpm. How bad are the headers banged up? I'd like to see at least 1 3/4" pipes if not 1 7/8" if you can find them. What are you doing for fuel delivery? At the very least 3/8" line front to back with 3/8" pickup in tank. good electric pump Holley blue will work nicely.
This thing should be a screamer. It should be making at least 550 hp. and you should be running mid to low 11's. what miles per hour are you running?
 
I agree with DusterDon & GTX on lots of this.

600 goes bye bye and make sure delivery is adequate... it's like making a runner do a marathon breathing througha drinking straw. You can do it with a good mechanical as long as the feed line has ample volume.

Get an 850 or 950HP carb. Is got a roller in it!!! That thing will eat up carb. At least put the PF 750 on it. That's still to small for the combo, IMHO

What were the incremintals and trap MPH on the run. 60' 330' etc. The overall ET really doesn't mean anything.

The small tube headers are definitely holding it back. You don't want to ask me about tti headers... that's a meltdown waiting to happen. If it's primarily a street driven car, the tti's are fine. If it's a race car, LOOK ELSEWHERE! There are compromises to be dealt with. That header comparison for your engine is not really valid.

All timing should be in by 2000-2200.
 
run that proform 750. that will get you your topend over that 600. your motor needs to breathe.what are the jets that are in it?
 
I think the guys nailed it pretty good. The 600 carb. is holding you back allot. I personally haven't had much lock with e-brock carbs. I'd say use that Holley and dial it in. Remember jet it for best MPH. I think you'll pick up possibly 3/4 of a second with it. The headers are also a limiting factor but quite possible the stock pipes are the biggest hindrance. Try uncorking the headers and see what it runs. If you unhook it and it goes a second faster you know the exhaust is holding it back allot. The TTI headers showed a nice gain on that little 300 hp engine but don't expect it with your combo. If you noticed the 1-3/4 hookers showed a loss. That's because a little 300 hp engine can't keep up the velocity. If you do want to upgrade the exh. go with a set of 1-3/4 headers, 2-1/2 or 3" pipes to the muffs and don't use tailpipes. Just use turn downs. And get that timing coming in a little quicker. At least by 2500, preferably by 2300.

It looks to me by your parts list that when you get everything dialed in you should be knocking on 11's door.
 
Alot of valid points above.

If it were mine:
1) Swap that carb
2) Larger headers
3) If this didn't get me huge improvements, I would be asking myself if I degreed my cam correctly and probably double check it.

The timeslip would help us alot.
 
850 carb, tti headers , 3in ex get rid of those garbage-master muffs . Remember its not a 360 its a 408 .more cubes need more of everything. that motor should be in the 12s easy.
 
Agree with the guys!

Yep needs more air in and out. In the day even 383's had 700-780 holleys, or a 650 AFB. Heck my dad's 440 had a 780 and that was in 71 when smog restrictions started. Stock q-jets on 400 firebirds were 800cfm. So with a nice 408 I think it is getting starved from about 4k up..


You really need to think of astroker like a bib block in a small package.

So yep get some more card on it, make sure it is jetted good, and sounds like you will also need more flow on the exhaust side too.

On the timing a lot of great replies too above. I would make sure you limit the total to the 34-36 range, but get as much as you can typical 16-18 initial and get it to come in quick like 2500-3000 should be all in.

I think you have at least 50-60HP in that baby that is trapped!
 
Great info!!!

I degreed the cam, and qudruple checked it (literally) because I had never done it before. Went through 3 timing chains before I found one that was not retarded by 4 degrees. So I feel "fairly" confident that is not the issue.

I will try the holley 750 this weekend, which I picked up used from a guy who said he was using it to run mid 11's on his stroker.

May try uncorking the headers. Good idea on the test. If I pick up a lot, I will need to free up the exhaust.

Header's. If not the TTI's what would you recommend? It is primarily a street car, with occasional strip use. Big advantage to TTI's was fit (I'm told) and no underhang around steering.

I am using stock fuel line currently, with a Carter 72 GPH electric fuel pump. Did not install the eccentric on the cam for a mechanical one. I tested it and am realizing about 52 GPH at the carb.

Copy of time slip info below. 1/4 mile times are projected from the 1/8 mile times, as the strip was foggy last Friday, and did not time the 1/4.

01.jpg
 
Email DON at www.4secondsflat.com and get his advice
on the correct distributor, fuel system and carb setup.

My advice is maximize what you have all ready.
The dist will kill any and all hopes of power if setup wrong,
fix it first.
If your not sure on the fuel deliviery system, fix it second.
The exhaust should be 2 1/2 begining to end.
The dented header won't hurt anything.
Use 18" stub pipes if you run uncorked.
Run the 750 with and without a spacer.
Take good notes.


Run it and get some time slips and shift rpm notes.
Ask for more advise.
Repeat 10 more times.

Where will the car see most use?
 
i agree with the other guys a 600 is too small. hell i run a proform 750dp on my 360.

with 4:11 gears that 60' needs to be alot better. how tall of tire? that thing needs to be atleast in the 1.6 60' area.

before you go nuts on headders and exhaust i would open it up and see how it runs. tti headders should have no problem getting you into the 11's.


sure that needs that much timing? been talking with a few local guys and they have been telling me the 408/416 motors don't like alot of timing.

i think you need to work on the tune up.
 
Here's an idea,rather then throw all of these different parts at it and continue to waste money going to the track where the weather conditions are different each time,why don't you do what you should have done before you installed the engine,DYNO THE ENGINE. You will WASTE more time and money screwing around with diferent parts and trips back and forth to the track then you would if you dyno the engine.You guys failed to notice that the 60' is horrible on that car.I think the intake was the wrong choice,the torque converter may also be a problem,you have to upgrade the fuel pump,did you change the valve springs to match the cam ? The spring on the Edelbrocks are not strong enough for a roller cam.Is this a solid or hydraulic roller ?If you do not want to take the engine out and dyno it then you should try to find a chassis dyno.Which ever you do you should bring different things to try,if you are bringing carbs make sure they are cleaned and in good working order.On the street you will not need any more then the 600,yes the larger carbs may make more power on the dyno but the Edelbrocks make more torque and are more responsive for the street.
 
You guys failed to notice that the 60' is horrible on that car
Click to expand...


ummm.. did you read the post right before yours that was posted 20 minutes prior?? it got pointed out.
 
Ok,heres some advive from a guy running 11.0's in his street car...mines a 416 stroker but other then 8 more cubic inches its a pretty similar setup to yours,yes if you have access to a chassie dyno that would be nice seeing as the engine is already in,but from my experience with them dyno's are NOT all they're cracked up to be,had my car on one last season the adjustments that were made looked good on paper,but at the track(where it counts) the car actually went slower,put everything back to where i had them,results car back to running the numbers again,there is nothing like "real" world results,that said the dyno is good to a point,but theres nothing like test/tune to see what its really got..My advice to you a Quick Fuel 850 carb or similar,deffinately a good electric fuel pump,at least 3/8" fuel line tank to carb,deffinately a good set of headers(tti's prefered here) 3" exhaust,and more converter something in the 3500-3800 range,and a different brand tci's don't have the best rep for making a quality product,sorry for being a little harsh but you asked for advice and i like being truthful,,also if you already had'nt put the motor together more compression would help too...On another note once you get the car running properly you'll need to get it to hook,but we'll deal with that after you get it running like it should..
 
may i suggest that now that all your timing chains a stretched redegree the cam in and sit it on a centerline of 104. doing this will make more low end torque for you.
 
The Edelbrock carb is a major part of the problem. When I had one on my car it ran 93 mph in the 1/4. After I swapped it for a 650 DP, my mph went up to 97! The first thing you should do is get that 750 on there, then take it back to the track. After that, tackle your exhaust. It is holding you back, too, IMO. You could use 1 3/4 primaries and you should have 2.5" exhaust all the way out the back.
 
Part of the poor 60' time is the lack of traction. I can only launch at 3000 rpm or so, as it wants to spin. With a 8.25, I'm a little afraid of using slicks, although some say it is not an issue, as that read is strong enough. First time out, I ran a avg of of 14.18, (6 runs). I had it die off a couple of times 1/3 way down the track, no fuel, so I upgraded the fuel pump (had a CHEAP one on at first). Also, we noticed glowing of the spark plug wires at night, and surging at 2000 rpm and up, so I replaced the wires.

While the 330' times dropped about 0.200, the 1/4 times dropped 0.610, to an average of 13.577 (3 runs). Big drop for plug wires and fuel pump, eh?

I reused the tranny/torque converter as it came on the 340 I pulled and set aside.

I woulda liked to do an engine dyno, but no one local had a SB Mopar fixture. May do a chassis dyno at some point, but racing is more fun, and more real world. I've heard builders express bothe opinions on the dyno usefullness, and as an engineer, I can understand both opinions. Since I don't got no spearience, I don't got one myself. (like that grammer adn speliing, eh?)
 
The 60 foot is OK for a high to mid 13s. I run low 11s with untouched heads and a solid cam sim to yours but i run more comp. Do a comp ck let me know psi. I run the tti headers not a problem.I wouldnt change headers unless you go to a w2 head just my 2 cents on headers. Def 850 on carb and 3 in min on exhaust get that straighten out ,test post times well talk conv later.
 
74Burntorange said:
jw what are your suspension setup?
Click to expand...

Not much of one. It has the factory 73 340 rear springs with (uh....) airshocks on the rear, and a 1.00" torsion bar up front with KBY shocks. So it really has no setup at all. I let out some air from the shocks to lower the rear, and lowered the tires to ~18 psi.

I read your post on the other thread about suspension setups. I want the car to handle nicely in the surces, hence the bigger torsion bars, and will likely go with a a bigger front sway and add a rear sway bar. But what would you suggest for better grip at the track? Incidentally, the airshocks allow me to raise the rear about 2" to keep the rear tires rom hitting the front fender lip on a bump or pothole. Maybe compensating for old springs?
 
You must log in or register to reply here.
-

Back
Top