Where's the power?
 

I've been noodling on my current engine for a little over a year. It's running pretty well, but I just can't seem to get the power out of it that I think it should have.

For instance, from an under 20mph roll if I punch it, it will downshift and the tires will squeal but it won't break loose like I would expect. Punching it around 45mph on the freeway on ramp downshifts to 2nd, but it feels more like a station wagon than a performance car.

My setup:
68 400/#16 heads
Dished pistons for lowered compression. The builder never told me what the compression was, I assume it's around 9-9.5:1.
Crower 60916 cam, matched lifters and springs. The shop degreed the cam on install.
Stock rockers
Ram Air Manifolds
13" Continental Stall
3.55 Posi

'68 Q-Jet rebuilt to Cliff's #1 recipe. I'm running 42 rods and 74 jets in the primaries based on Cliff's recommendations. The secondary rods are CE, but the ends have been turned down.

'68 Distributor recurved by SunTuned running a Pertronix. 12 degrees initial, 36 degrees total. I've tried 9-12 degrees initial and 12 gives me better throttle response. I haven't heard any pinging. I'm running ported vacuum off the thermostatic switch on the manifold. I've verified that it's working.

I think this combo should run like a scalded ape, so what am I missing?

Well have u done a cranking comp test just to see what that is? Where did they set the cam at? CE rods are .041 stock so u have a even richer rod then that turned down? How fast is the secondary flaps opening etc. Sounds rich to me on WOT ,least for the carb.

Your converter may be tight for the RPM range of the cam, just from a quick look at the specs. What RPM can you flash the converter to? Once you get the stall matched to your rear end ratio, then maybe some 1.65 rockers will help. I'm positive that you are bogging on your converter and it is feeling like a dog until the revs come up, just as the trans shifts to the next gear and you are back on the low side of your powerband and it feels slow.

Dumber things have happened (I've done them), but make sure your throttle is opening all the way. (when you press the pedal down all the way)

Doing a compression test is a great idea as well.

That sounds like a well thought out combo - should run pretty dang well...

Haven't done a cranking compression test yet. I'm not sure what he set the cam at, I assume straight up. My engine build was such a drawn out process when it came time to pick it up he didn't give much info on it.

I am getting some black smoke out the back when the secondaries open so I'm sure they are too rich, not sure by how much. What rods should I be running? I got the secondary rods from Cliff years ago for my old combo and haven't fiddled with them since. The secondaries kick in smooth, I've probably got about 7/8 of a turn on the air valve spring.

I can't remember the flash RPM on the converter off hand, I'll double check this weekend. This engine does definitely like the higher RPMs so it's possible my converter may need to be restalled.

Throttle is opening all the way, that was one of the first things I checked.

ive asked the same question as my combo is almost identical to yours and on the dyno i have not come close to the 400-420 hp that they say is possible with this combo, my compression is the same as yours and that appears to be to low for this cam, now i have done some tuning, added set try y headers and 3 in exhaust and am going back to the dyno on the 15th weather permitting, 3.73 gearing to replace the 3.23 are an option i am considering, overall i am not overly impressed with my combination but it is getting better than it was at first, time wise my previous set up with smaller 2801 cam was same or slightly better.Getting closer to 10/1 comp may be a winter project for me.search 60916 cam for opinions given to me.

Sounds like you should try a leaner secondary rod set. If your CE rods were turned down, that could be giving you a over rich condition which may be half or all of your problem.

Good thread
 

My setup in my 68 Firebird is similiar to yours and would like to see what others
suggest. My car does currently have 3:08 gears and I know that will take a little
out on launch, but I like the low rpm cruising manners on hwy.

If I may ask where do you have timing at? initial and total.

Have you tried a leaner secondary rod??

The 13" continental I just installed from Cliff actually helped me over the unit
that was installed when I purchased car.

Gerry

Sounds like it could definitely be a culprit. I should still have to stock secondary rods laying around. Might as well give them a shot and see if they wake things up.

Right now I'm running 12 degrees initial with 36 total.

A cranking compression test is definitely in order.
Warm engine, throttle wide open, all plugs out, hot battery and good starter for the most repeatable results.

Probably should double-check the camshaft timing. Just dot-to-dot on the gears doesn't cut it.

Most likely undergeared for your application.

I'll just about guarantee that you're too rich in the secondaries.

HTH!

Some good comments, start with the basics. I'll throw a few comments out as one who raced a 400 for several years that had a real 385-400 HP based on a conservative dyno and track mph.

400-420 HP is going to require some airflow,probably more than some average D ports are going to provide unless ported really well by a guy with a flow bench. Figure stock D ports are around 215-220 cfm @ 28". Using the Superflow formulas with the PERFECT cam,compression ratio, intake, carb you are looking at the 400-440 HP range. Again PERFECTso probably 11-12:1, roller cam etc etc. a 9.5:1 with that cam is not going to get you there unless you up the airflow in and out porting the heads a lot, round port heads, aluminum higher flowing heads(D or round port).

Some folks think 9.5:1 in a 400 is starting to get a little low, a shorter seat duration cam with the same 0.050 might do a little better to not bleed off your compression. As the others said a compression check will give you an idea there, also might suggest if the cam was degreed in correctly.

Also as some of the others briefly mentioned -gears. A 400 is going to need more gears and more convertor to use the higher rpm range. We swapped from a 455 to a 400 shot block when they changed my class to keep my RAIV heads(mroe airflow than a D port)-same cam, same intake, same carb, same exhaust and with the 3.42 it felt like a dog compared to the 455. 4.10s, 4000 stall and it would run with most street/strip 455s.

The #16 heads are small valve that could be hurting HP as well.

Easy things first; x2 on the secondaries. If that doesn't cure it.....

Compression test: Since there was not much info on this engine and you have been fighting this from the start, there is a distinct possibility you have LESS compression than you think. Pistons may be down in the hole .020, UNTOUCHED cylinder heads with possibly MORE combustion chamber volume than you think, cam not installed where it should be, etc. I like to use cranking compression as a ballpark indicator as to how an engine will run at low rpm and whether or not pump gas will be an issue. If you're in the 160's, you will probably need to crank up your ignition timing.


BTW, Have you tried ADVANCING your ignition timing to 16 deg's?

Good luck!

valves
 

My 68 400 has #16 heads as well, and are factory originals.
Mine has the larger valves and I would think the OP does too.

I did measure when motor was redone 7 years ago.

my timing is similar to yours as well. My total comes in around 3400ish rpm.

Thinking my next area of concern is to get rid of current exh setup. Believe a
nice setup with a mandrel bent head pipe and a crossover my help. currently
head pipes look too narrow at curve.

Well,if you're talking about chassis dynos and rear wheel hp figures,there's no way that sorta 400 cid combo will crank out 400 to 420 RWHP,as that's like 500+ hp at the flywheel.

Chassis dyno that sorta 400 cid combo should be somewhere between 300 to 340 RWHP max.

Now at the flywheel,yeah a 400 cid combo like that may be able to make right at 400 hp,but it's probably not gonna hit 420 hp,not without more cam,compression,head flow or something of that sort like Skip mentioned.

That's not necessarily so,sorry.

There are three distinct #16 head castings,a small valve high compression version (1970 2bbl 400),a big valve high compression version ('68/'69 4bbl 400),and the round port SD455 heads.

So they easily could be big valve #16 heads.

Anyhow,I agree that a compression test is a good idea,never hurts to do that.

Also agree it sounds like it could use some further tuning.

Sometimes it takes some serious work (and a little luck) to get these things to run their best.

Good luck with it.

Bret P.

I've got the '68 big valve heads on my car.

I'll try some different secondary rods and do a compression check first. Haven't tried advancing the timing more than 12. Seems rare that a Pontiac likes more than 36-38 total, but every setup is different.

I know the power is there somewhere, I just have to find it.

My 455 ran at 11.2 - 11.5 A/F with CE secondary rods. Moved to a CH and it is at 12.5 - 12.7 A/F. Try in that range. http://quadrajetparts.com/rochester-...ter-p-166.html

Probably wont want more total timing,though it might want more initial timing,you know,to give it that low RPM "pep" you say it seems to be missing,but then you'll probably wanna shorten up the actual advance curve to keep the total timing in check.

FWIW

Bret P.

An easy thing and quick thing to try is to use manifold vacuum for the advance instead of ported. You might be surprised. It will idle higher when you change it, so turn the idle back down.

My mistake, as it turns out I have turned down CH rods in the secondaries (on the right). In the middle are some stock BE rods which appear to have the same diameter tips as the CH, just shorter. On the left are some CT rods I had laying around which are way too big (.0774). I think I pulled them from a '71 Buick Q-Jet.

http://forums.maxperformanceinc.com/...1&d=1347073650

I guess I'll order up a few other sizes to try, but I'll try the stock BE rods in the mean time and see if it helps since they have shorter tips.

Lets get away from downshifts. How does it perform when pulling all the way through the gears from low RPM to where it shifts up. Flat spot, bog, or other drop off in performance up through the gears? How restrictive is your exhaust from the head pipes on back?

Even dumping plumes of black smoke, the combination should still motivate very nicely.

The static compression ratio has a MAJOR impact on power (torque) production with that cam in the 400 engine.

Cam placement is equally as important.

I've had several folks email me with similiar results as you are having. In every case the cam was not advanced enough, ICL up at 112-113 degrees, which is usually where those cams end up at "dot to dot".

I wouldn't use that cam at 9 to 1 compression in a 400 engine, a smaller 068 size cam would be a better overall choice, as it would produce considerably more low end power much earlier in the rpm range.

I can tell you this for certain, with early unported big valve heads, 10 to 1 compression, and that cam, it should just about tear your head off from about 2800-5500rpm's. If it doesn't, something is amiss in the basic "recipe", or tuning is WAY off the mark, on combinations of both.

Right on the dyno with a very basic 400 engine, flat top pistons, unported #16 heads, etc, that cam made 419hp/453 torque.

With KRE heads and a tad more compression 440hp.

The larger 60243 cam made 424hp/465tq, and 450hp with KRE heads.

The even bigger 60919 (RAIV clone) made another 10hp (KRE heads), but idle quality was crap, and the engine was "sluggish" below 3500rpm's. Most likely why Pontiac reserved the RAIV cam for the round port engines, with 3.90 and taller gearing.....IMHO......Cliff

"Right on the dyno with a very basic 400 engine, flat top pistons, unported #16 heads, etc, that cam made 419hp/453 torque."

And what mph and vehicle weight did it run? Superflow formulas just don't show that based on airflow without alot of optimization and they are pretty darned close when you use them,and neither do my dyno results on a conservative dyno(ie engine dyno showed same HP track mph/wt did). Moroso slide shows 419 pushing a 3800 lber to 11.60s @113! Assume a street/strip suspension I'd go less on the ET(low 12s high 11s) but mph is pretty darned close to right on. I just can't see a basic 400 unported D ports running even low 12s @ 108,which is around 365 hp.

The 400ci NHRA stockers running those times(deep 11s or high 10s) with "unported iron heads" have a HUGE cam,loose convertor,lots of gear,open headers and about 20 years of tuning that particular car.

"With KRE heads and a tad more compression 440hp."

I would sure expect the better flowing KRE heads to be worth more than 21 HP over non ported iron D ports, 260 cfm vs 215-220? And then the bigger cam lost 16 hp but picked up 13 ft lbs?

"I just can't see a basic 400 unported D ports running even low 12s @ 108,which is around 365 hp."

Skip, just helped a customer with a similiar engine set up his 68 FB, using the larger 60243 cam, first outing netted mid 12's at over 110mph spinning some on the starting line.

Another customer and good friend of mine has a milder deal with 62's and the 60916 cam, full weight street driven 67 GTO, 3.23 gears and TH400. He runs 13.0's at 108-109mph in hot/humid weather. Don't think he's raced it other than a few passes at Norwalk in August temps. Should be good for solid 12 second runs in good air, and certainly quicker if he put some gear in it, as 3.23's just aren't optimal for that much weight and a pretty "mild" 400 engine.....IMHO.....Cliff

110 in a 3800lber 387 hp and right where my RAIV 400 ran at 3900lbs and 385 dynoed HP. 108 drops us down to 367 hp. Both short of the 419 number.

Heck Norwalk August temps are our late fall temps here:) Cold front today supposed to actually drop it below 90!

I don't know Skip, maybe in the "perfect World" where there is never a head wind, or a brake dragging, etc.

Keep in mind that neither example I gave is any sort of a "race" car, and not optimized for gearing/converter either.

I'd say mid-12's from a "daily driver" Pontiac at 3700-3800lbs in full street trim with a pretty "mild" 400 engine is flat get-er-done, in any weather.......Cliff

I would not have built that engine with a dish piston unless I was building it with a VERY mild cam[204° @ .050" or less]. My guess is the Icon 10 cc dish piston. That's just not enough compression. You should have flat tops and be closer to 10:1 to make that work right. With a tight quench[.040"] and the cam degreed properly, it should run fine on premium pump gas. I would ask the engine builder where he degreed it to. It needs to be installed between 106° to 108°. I would shoot for closer to 106°. If it is straight up, it won't run good no matter what you do. Too many guys install cams straight up. I NEVER install a cam straight up. That's the best way to make a dog out of your combo. Some cams however, are ground with advance into them, and may need to be installed straight up[dot to dot], but they need to be degreed to verify. If a cam is ground on a 112° lobe separation, then, if it is installed with no advance, the intake center line will be 112°. Way too retarded. That cam needs 4-6° advance put into it. The cranking compression test should tell you something.

I installed a roller cam once and installed it straight up so I could get a starting point when I degreed it. As it turned out, installed straight up, the ICL was 96° The cam was ground on a 110° lobe sep. Now, wrap your head around this, I had to retard it 10° to make it 4° advanced! I wanted it at 106°. If that was installed straight up and not degreed, that engine would have bent a bunch of valves on crank over. One can never assume things are done right, especially with camshafts.

Did a compression test this morning. I took a drive around town before I did the test and removed all the plugs. The good news is that every cylinder is in the same ballpark. The bad news is the compression seems really low.

1 - 145psi
3 - 145psi
5 - 145psi
7 - 145psi

2 - 145psi
4 - 145psi
6 - 150psi
8 - 140psi

Does this say anything about how my cam is installed? I could take the front cover off and take a look at the timing set. It's a 9-way set so it should tell me if he advanced it or not.

Plugs 2 and 4 were fouled. Not sure if they just aren't getting good spark or what.

http://forums.maxperformanceinc.com/...1&d=1347132791

http://forums.maxperformanceinc.com/...1&d=1347132777

http://forums.maxperformanceinc.com/...1&d=1347132784

I believe a leak down test would tell you more about why plugs two and four are oil fouled. Pressure readings at cranking could be an inaccurate gauge, bad hose on the tester, or slow cranking. Or they could actually be a little low.

My definition of straight-up is installing the cam according to the cam card. It might not be dot-to-dot because of manufacturing tolerances or machining errors with the cam, crank key slot, or timing gear set. So if the card says install at 106°, then that's the straight up position. IMO Installing that cam 4° advanced would be putting it at 102°. Because of the ambiguity of the term, I usually just avoid using it and refer to what the cam card calls for.

I agree about the cam timing. Tear it down and put the 4 to 6 advance in it and you will be flying in no time. Crowers are nice cams but almost everyone here who runs them has to go through this same thing. Do a search here on it. The rest of the combo sounds good.

Those crower cams are known to be off, u really need to find out what the builder did, or just degree it yourself then u will know, but if it was set straight up, dot to dot. I can almost bet its way retarded with that cam. I would also do a leak down, especially on those two that are fouled.

cam degreeing
 

Out of curiosity has anyone ever degreed the melling spc-7. I set it up dot to dot
and used the napa wide link timing set. Never did degree it and always wondered.

Maybe that will be my winter project. Problem is it's running very well and hate
opening a can of worms.

Verdoro I can blame you for wanting more we are all guilty of it!!!!!!!!!!!!!!!

Gerry

Was the pic of the oily intake runner cyl. # 4? If so, find out where that oil is coming from and that might fix the fouled plugs. #2 and 4 intake runners are right next to each other so maybe your getting a little leakage past the gasket between #2 and #4 runners.

Any possibility the oily 2/4 plugs are due to the PCV valve sucking too much oil?

Since the consensus seems to be that my cam needs to be advanced - is there a way to degree it without removing the cylinder head? Can I pop the timing cover off and move the sprocket ahead 2 or 4 degrees and be done?

This might be a dumb question, but will advancing the cam increase the cylinder pressure? 140-150 seems really low to me.

I've never had to. Put the cam dot to dot with the timing set and the engine runs beautifully and powerfully all the way up to 95-100MPH. Never taken it to the track or anything like that though.

Yes, advancing the cam closes the intake valve sooner, thus increasing cylinder pressure which is what makes torque. It also opens the intake valve sooner so when the piston starts back down the hole, the valve is open farther, thus breathing better as soon as the piston starts sucking. You get more in the cylinder and trap more there. That equals power. That is why retarding the cam just doesn't work.

I would not recommend just changing to the 2 or 4° advance keyway without knowing where it is now. I'd call whoever built it and ask them if they know where it is.

Makes sense. I'll give him a call Monday morning and see if he can remember how he set it up. Based on the way the car runs, I bet he installed it straight up. There's a power curve, but it feels lacking across the board.

I appreciate the advice. The amount of knowledge on here never ceases to amaze me.

Yes. You can remove the timing cover, pull the chain, install an 'offset key,' OR with the 'multiple keyway' gear, you can move that then put it all back together. That's the simple fix, but you still won't know what you have until you degree it.

And yes, you certainly can degree a cam without removing the cylinder head. To be accurate though, you will want to pull the valley cover, install a 'solid' lifter, then put the dial indicator on top of it. Or, you can pull a rocker arm, then put the indicator on top of the pushrod where it protrudes from the cylinder head. Either is fine.

I will say that there is probably no simpler fix to a 'doggy' street engine than by simply advancing the cam, regardless of where it's at now. And with your 140-150 lbs of dynamic compression, I agree you're a little bit low. I think the 160 range would be better, and the quickest way there is by advancing the cam 4 degrees.

Years ago, I did this very thing on an old 400. I had no idea what I had, but I knew it was a lo-po version, and it was just sluggish across the board. I did nothing else except install a 4 degree offset key in the cam, and put it all back together. The first test drive proved the point. After a couple hours of work, the 400 came alive, and the 'seat of the pants' feel was instantly recognizable! And when you're in your early 20's on a budget, I took anything (free) I could get! Of course in those days, I was very "tool poor" and very rudimentary in knowledge, so I have no idea how much I really changed things in actuality. I'm sure there was still more to be found, but it was still a great learning lesson.

Good luck, and keep us posted! :)

You got that right.My engine shop was trying to degree in the crower 60919 cam they got and things werent coming out right. They told me they checked it and it looked like the cam was ground at 123 degree LS! So they called crower and said what they found and ordered another from them (which they had to grind one cause they didnt have one there) The next one they got checked out at 115 LS instead of the 113 its supposed to be. They used it and degreed in at 108 ICL instead of 109.Close enough I guess.

Whoa! Hang on there guys.

Back up to post #29 and reread.

Mick treed me there as I was thinking the same thing when I saw 28.

Fix the oil derrick deal there first and when those 2 plugs dry up like the rest, well then your power will likely be more where you want/expect it.

Remember you've only got a 6 cyl engine here at least up to post 29 anyway.

Good point, but it never felt like it was missing or only running on 6 so I assume they were still firing. I'll have to pick up a leakdown tester and take a closer look, but since it was only the 2 and 4 plugs that were fouled my hunch is it has to do with the PCV valve sucking too much oil.

The PCV is a definite posibilty. Could be the smoke you are getting too.

One other thing on the cam though, there is no way to know where the cam is without degreeing it. I have had a few that needed moved and actually had a timing chain so bad it couldnt be used.

Also, I believe "straight up" to mean 0 degrees advanced or retarded. If the manufaturer recommends it 4 degrees advanced and its ground that way, then you can set it dot to dot and if the chain and cam is right, it should degree in at 4 degrees advanced.

In other words, if the cam is straight up, then the ICL and ECL will be the same number of degrees on each side of TDC. If its advanced, the ICL will be moved closer to TDC. This naturally moves the ECL further away from TDC. You get the idea?

Got things apart. Looks like it was installed with zero advance, correct?

http://forums.maxperformanceinc.com/...1&d=1347236511

That would be correct.....Cliff

yeah - you need to degree those multiple keyway sets. They are not what they always say they are. Heck, I'd rather use advance/retard keys at the cam gear to get it where I want it.

Assuming the cam is ground as advertised (which may or may not be true, but you won't know for sure unless you actually degree it...), I'd say Cliff had it right in an earlier post. Advance that thing, at least 4 degrees. Then put it together, readjust the ignition timing, and see what happens. I'm willing to bet you'll feel a big step in the right direction.

Good luck! Keep us posted... :)

I know degreeing it would be the proper thing to do but I'm going to advance it 4 degrees and see how it runs. It has to be an improvement. I'll do another compression check before I button it up to see if the numbers are better.

I moved the crank gear keyway to A4. It's kind of crazy how little I had to move the crank to get it line up with the cam dot again. I expected a bigger difference, but I guess it is only 4 degrees.

Yeah might as well. The worst you will be is 104° -105° ICL. Since it was running where it was, you should be fine as far as piston to valve clearance is concerned. Those heads have .150"- .200" valve free drop before they even get to the deck, then you have another .040" head gasket, plus how ever far down in the hole the piston is at TDC. In other words, the intake valve would have to be open .200" or more in order to have interference and that cam is not going to have the valve open anywhere near that. I would say maybe .080" at TDC. You should be just fine.

Just want to confirm I've got this setup correctly before I button it all back up. Seems like everything rotates just fine in this position.

http://forums.maxperformanceinc.com/...1&d=1347254843