18 Degree 434 Chev - That Doesn't Make Power - Help

[torana434]

Hi, I really need some help guys, I put my 434 ci small block chev together about 6 months ago, and had it at the engine dyno, the thing made just over 600 hp, to say I was @#^$%# pissed would be an understatement, I just couldn’t believe the numbers.

I put the engine into the car and ran it anyway, the motor ran fine but my quickest times were 6.41 @ 108 on the 1/8 and 10.03 @ 134 on the 1/4, with a mid 1.4 60ft, car weighs 3140 lb with driver.

I am pulling the motor out of the car in the next couple of weeks to try and sort out why it is not making the power it should here is everything I know about my engine??

1000cfm Pro Systems 4150 custom built by Patrick,
Dart 18* Intake manifold port matched,
Dart 18* Heads, 2.15 intake 1.6 exhaust, 68cc chambers I think??, 270cc intake runner, flow 352 @ .700 intake and 253 @ .700 exhaust
T @ D Shaft Rockers 1.6 intake and 1.55 Exhaust
Dart Little M block 4.155 bore, 9.010 deck height
JE Forged pistons part # 213107
Eagle 6" H Beam Rods ARP L19 Bolts
Eagle 4" 4340 crankshaft
Howard's roller camshaft part # 111233-10 Duration @ .050 278 intake 286 exhaust, lift at cam .450 intake .426 exhaust
Exhaust manifold 4 into 1, 1 7/8 primary 3 1/2 collector
MSD pro billet dizzy, 6al ignition

Could some of you guys please give me some advice on what and where to look to fix it, to make the power it should, thanks Dean

[sc3314]

The cam is to small, you sure of those specs. The duration looks to be OK I would ad another .300 to lift. That should wake that engine up.

[Racefab57]

The lift looks small to me too! David.

[bbchevy]

I got 720 Intake and 660 Exhaust.
I think that should Be Fine other than maybe go 1.65 on the Exhaust,and then you will be @ 702 on the EX.
Later
G 8)
I was thinking maybe Gear or Converter Probs?
I had a 355 in a 3100 lb S-10 that went 6.50 in the 1/8 with 1.41 60' Times

[jmarksdragster]

An engine with those part should make 700+. I would look closely at cam and cam timing, valve springs. Howard's do have some good components, just not sure if cams are one of them for an engine like yours. Size isn't the issue, just the quality of the grind possibly. Also what size pushrods? 3/8 minimum, 7/16 preferred. Something is definitely amiss....

[itsabird]

i agree with the statement, that combo should be stronger, the lack of lift on the cam, is the thing that jump,s out at me, bigger stick, and good hook, should be a solid 9 sec car.

[OneBadGMC]

The cam is to small, you sure of those specs. The duration looks to be OK I would ad another .300 to lift. That should wake that engine up.

That's lobe lift, not valve lift. Add in the rocker multiplier.

[OneBadGMC]

Personally, I don't think it has enough compression for the camshaft thats in it.

I used the following numbers (head gaskets and deck height were an assumption).

68CC Chamber
-2.5 Dome Volume
.050 Gasket thickness
4.2 Gasket Bore
4.155 Cyl Bore
.010 in the hole
4" stroke

That all comes out to 12.241:1 compression.

Thats a BIG bumpstick for that compression. Of course, that can be adjusted with cam timing, but you didn't say where the intake lobe was closing.

[maxpower671]

i'm thinking gear or convertor too.

what gears? tire size? convertor? RPM?

what is cam installed at?

[jmarksdragster]

While I agree compression would help and the cam specs are not optimum there is some missing power with what he has. Degree the cam, check lift, springs, PR etc.

[bjuice]

if your little over 12 to 1 compression...no surprise to me your HP is close at 600hp and some change,,( whats the TQ ?)...Also your et's are in the ball park for a 600 hp motor and a car that is close to 3200 lb..is this with or without driver.?

also i had a 89 ladder bar camaro 4 plus yrs ago..weighed 3200lb with me in the car...had a 406ci that made 607hp...with a glide and a 4.56 gear..i ran consistant mid 6.30's in the 1/8 at 110mph and a best 1/4 mile of 9.92 at 137 mph...60 fts stayed in the low 1.40 range..

My buddy runs a 18 degree 434ci with approx 15 to 1 compression and it made 740 ish HP on the dyno..( he runs VP Import fuel 120 octane)

[torana434]

You are right onebadgmc, comp ratio is approx. 12.3-1 and the valve lift stated is at the cam. Lift at the valve is .695 on the intake and .635 on the exhaust. Cam was installed as per cam card.

I am running 4.11-1 diff ratio, I leave the line at 5800rpm on the transbrake, powerglide, tyre size is 28 x 10.5 x 15. Pushrod size is 7/16.

http://www.youtube.com/watch?v=kMVL2mBvsik

[OneBadGMC]

You are right onebadgmc, comp ratio is approx. 12.3-1 and the valve lift stated is at the cam. Lift at the valve is .695 on the intake and .635 on the exhaust. Cam was installed as per cam card.

I am running 4.11-1 diff ratio, I leave the line at 5800rpm on the transbrake, powerglide, tyre size is 28 x 10.5 x 15. Pushrod size is 7/16.

http://www.youtube.com/watch?v=kMVL2mBvsik

Time for either more compression or less cam. Take your pick. That cam will require 13 or 14:1 to work right.

I think a 4.30 gear would help substantially too.

[SST4530]

These are the specs listed for the part # you listed.

Chev SB
Duration @ .050": 278/286
Adv. Duration: 316/326
Lift: .570/.570 @ cam
Lobe Center: 110
4400-8200, Works great in big cubic inch small blocks, OK with NOS

If your not planning on running N20 then I would drop to a cam with 106 LC. and up the CR on the engine to about 14:1

[edvancedengines]

All good advice I see here.

In my opinion the headers are also too small for the engine and the heads. That intake is a pig if someone that knows what they are doing does not do some radiusing in the plenum area, and it should also want an open spacer on it too.

In addition to the cam/compression mismatch I'll bet you are not turning enough rpm for the bigger heads to start coming alive.

If this were a nitrous engine the compression would be fine but the cam wouldn't.

You can try this;
Try opening up your valve lash to the point that is maximum. I am guessing that will be appx .028 and see if it tries to wake up any at all. By the increasing of your valve lash you are effectively killing a little of the cams effective duration. If you get an improvement it is very good evidence the cam is too big in duration for the compression you have. The same applies the other way too. By going smaller on valve lash you can mke the cam think it is bigger than it is just for research.

[Rick360]

Several things I see here, some have been mentioned already.

Compression ratio is too low, why are the chambers 68cc? Many 23º heads have smaller chambers. 18º should be around 50cc or less.

Cam is not what I'd choose, but probably not killing 150hp either. More exhaust duration and wider LSA, but get the compression up. Lift is too short, mainly from low ratio on rockers. 1.7 or more on intake and 1.65 on ex would have been better.

Who ported the heads and where did the flow numbers come from? Heads have the biggest potential for killing 150hp. Improper porting or someone giving incorrect flow #'s can make for a really weak engine. Are these the raised runner 18º heads?? The bottom of the intake port is about 1.25" above the deck.

Dart intake, ... not sure if this is the same one I looked at a few years back, but that thing had runners so small it didn't even have enough metal to make it the size I wanted and I was running a 360ci 18º. I sent it back and got an Edelbrock, then spent a ton of time opening it up to a reasonable CSA. If the heads flow good but you put a small intake on it, it wont make any power. To make 750+HP, you will need 3.5sq.in CSA or more.

6AL ignition on an engine that should make well over 700hp??? Get a better ignition for it, especially if you find the problem and it starts making the power it should.

I built (8-9 yrs ago) a 360ci 18º engine that dynoed 750+ @ 8000. Heads were Dart that I ported myself. They flowed pretty close to yours 358@ .750" and [email protected]". With 75 more cubic inches, that should make more power and do it a lot lower rpm.

Rick

[cboggs]

I agree with Rick, .. those numbers are weak for a Dart 18* head,
with a 2,18" valve should flow around 370-380, .. also
270cc might be on the small side if you look at the proper
cross sectional areas for a 2.18" valve and your size engine.

Curtis

[deesac]

the compression is way to low and the cam is to small your taking the 434 out of its working band and a 434 is a high rpm motor were you shifting at and how much torque did the motor have sometimes on a sbc the hp is lower than the torque number we ran best time 6.22 in a 2800lb car 1/8 mile with afr227's and the engine comp is around 15:1 we have 325 in the cylinders do a comp check most likely your down on comp why guys build a 12:1 race motor thats a trailer queen 14:1 or better

[cboggs]

I agree with Rick, .. those numbers are weak for a Dart 18* head,
with a 2,18" valve should flow around 370-380, .. also
270cc might be on the small side if you look at the proper
cross sectional areas for a 2.18" valve and your size engine.

Curtis

I just noticed it's a 2.15" valve, the heads where built with too
small a valve for the application, ..

C

[fishman1]

i ran the numbers on et and horse power chart for a 3140 pound car running 10.03 and it told me you way over 600 hp.......my car last year was running 10.29 and weight is 2380 with 550 hp.....so me being 760 pounds lighter equates to 76 hp more u need to run the same time as me

[cboggs]

who built the heads?,