Need some advice

I finished the rebuild on my 466 with iron CJ heads. It is 11:1 compression, heads have 2.25 and 1.76 stainless valves and thermactor bosses removed and plugged. Combustion chambers are between 70-71 CC's. Cam is a Voodoo 276/284 (233/241 @ .050) lift is .587/.606 with 1.8 rockers, 110 LSA and 106 ICL. lifters are Lunati hydraulic race lifters, recommended preload is 0-.030", I have them adjusted to 0 plus 1/8th turn, should be around .012". Intake is a Performer RPM.

The problem I am having is low vacuum...6-7in at idle and unburned fuel smell. I have tried adjusting the idle AFR, timing and idle speed but regardless of the settings still very strong fuel smell. When I bring the rpm's up it goes rich to 8-9:1 AFR. I've tried three different carbs and they all act a little different but the results are still the same. The third carb is a new Pro Systems 4150. It seems to idle best at 800 rpm with 10 initial, idle afr is 13-14 to 1. The 850 vacuum secondary carb I have that was on the engine before and worked good, idles best at 12 initial. but both carbs go rich when the throttle plate is opened. I also tried a 850 dbl pumper and it goes rich when the throttle is opened but this carb pegged the AFR gauge lean at idle. This carb was also the worst as far as fuel smell. This carb is jetted 76 front with a 4.5PV, 88 rear with jet extensions and blocked power valve. The Pro Systems carb is 76 front and 86 rear.

The cam I have should pull about 12" vacuum at idle. I installed it with the timing marks facing each other and degree'd it intake CL at 106.

I drove it once with the 850 vac sec carb. It seemed to have plenty of power very responsive throttle.
I did two compression and leakdown tests so far and both times compression is 195-200 (130-140 on first stroke) and leakdown is 2% or less.

Not sure what to try or check next. any ideas?

Have you tried a smaller power valve?

4.5 is the smallest I've tried so far, did not make a difference. Had a 6.5 initially.

Why do you believe you should have more idle vacuum...? Sounds like a vacuum leak ... somewhere.

Also, you should probably shorten the timing curve in the distributor so there is about 18 degrees initial and 36 total, for starters.

I talked to Lunati, they said it should have at least 12in vacuum. I've had engines with much more duration and overlap that had 8-10in at idle. I tried initial timing settings from 10 to 20 degree's, still lots of unburned fuel smell at idle. I am thinking that with a cam of this duration 14-16 initial is where it should be but 18 is definitely in the ball park. This cam only has 60 degrees of overlap, maybe it's just gonna be stinky at idle, but still doesn't explain why it goes so rich when the throttle is opened a little, especially with no load and higher vacuum. I thought maybe a vacuum leak so I checked everywhere I could and found nothing. If there is a leak it has to be on the valley side of the intake. I put my hands over the breather holes and didn't feel suction felt or notice any rpm change.

Before I rebuilt the engine, the 850 vacuum secondary carb ran between 12 - 13:1 AFR and idled at 13.5:1 with 10 degrees initial, 34 total. That was with a cam that was 214/218 @ .050 and 15-15.5 in of vacuum @ 700 rpm

I'll keep messing with it, sooner or later I'll get it right. I will try a lower power valve just to completely rule that out as a problem. I'll try more initial timing and a little more idle speed

Need to go they and tune the carb or try a different one.

Most cam company's don't have a clue how to get vacuum in a 429 SCJ headed engine. The air speed is so slow at and idle (BIG SLOW PORTS) your going to have trouble getting vacuum.

Problem is if you cam it to be happy with the vacuum, it probably wont run to suit you.

Somebody like Randy may can tune it (MORE THAN IDLE AIR SCREWS) and help it.

I spent some time on the car today. Yesterday, it idled pretty good. today not as good, made some adjustments it improved. Drove it and it has a slight hesitation when starting out, sounded good up to 3000 rpm then the engine got real loud like valvetrain noise or something. I don't know for sure, never heard anything like it before. Maybe at higher rpms it leaned out, I am so pissed at at this engine about ready to take a hammer to it.

I checked the rockers and pushrods, everything looked fine. Pulled the plugs and found #4 wet with oil, most plugs were black and the threads have oil on them, two were very clean. At this point I am certain the intake is sucking oil/air.

I will do another compression and leakdown test just to make sure nothing changed from the previous tests. Then I will pull the intake and go from there. Hopefully I will find the problem before I blow this car up.

For what it's worth I had a Edelbrock RPM intake years ago for a windsor that came out of the box with milling defects. It took us a about a week to find it. When the metal is all shiny and new it looks good until you put a straight edge on it. Very frustrating I know. Another RPM intake for a 390 that the distributor hole was off center. I don't have a lot of faith in Edelbrock machining to say the least. They were both minor enough that I could fix them with hand tools but I don't think I will be buying any more edelbogg stuff.

69BOSS wrote:I finished the rebuild on my 466 with iron CJ heads. It is 11:1 compression, heads have 2.25 and 1.76 stainless valves and thermactor bosses removed and plugged. Combustion chambers are between 70-71 CC's.  Cam is a Voodoo 276/284 (233/241 @ .050) lift is .587/.606 with 1.8 rockers, 110 LSA and 106 ICL. lifters are Lunati hydraulic race lifters, recommended preload is 0-.030", I have them adjusted to 0 plus 1/8th turn, should be around .012". Intake is a Performer RPM.

I put together a similarly-cammed 4.3 stroke 528 engine for customer, has aluminum SCJ heads, 233@0.050" intake lobe phased at 107*, 1.8 rockers, 10.1:1 C/R, Holley 850 cfm, and it pulls 15 inches at idle.  Your engine is notably smaller in displacement but it ought to have more than 8 inches of vacuum...

https://www.youtube.com/watch?v=IDtsDCAgmc4

69BOSS wrote:The problem I am having is low vacuum...6-7in at idle and unburned fuel smell.
The cam I have should pull about 12" vacuum at idle. I installed it with the timing marks facing each other and degree'd  it intake CL at 106.

You must have a vacuum leak somewhere.  I once sprayed a short blast of a flammable into an oil filler cap of a running engine and several seconds later after meandering its way down into the crankcase and up to the underside of the intake manifold, the engine's idle speed would rise....not that I'm recommending you try this.

You are right, it should have a lot more vacuum. I just got done looking at the rockers and pushrods, don't see anything wrong. Did a cold leakage test and # 4 is reading 18%, sounds like its all in the crankcase. Can't hear any leakage in the intake or exhaust. The rest are 4%. Previous tests both warm and cold were less than 2%. # 4 plug is wet with oil. Looks like this engine is coming back out. What a pain!!!

I have a 557 with P51 heads, I may just have to put that together, I was saving it for my other car, I just have to see whats wrong with this and go from there. Very frustrated right now.

Pull those breathers and check for blowby with it running even though you did a leak down test and see what it looks like. Sounds like rings to me. Not good. Holley's like to be spotlessly clean also. I would completely go through it from scratch myself. Sounds like two problems are more to me, maybe?

I put a 5 gas analyzer on it today. What I found is that the AFR gauge I was using is way off. At idle it read 10% CO2 and 3% CO. HC was crazy high at 3000ppm, (really smells) and AFR was 14.7. At 1500, CO2 went to 14, CO to 1.5% and HC to 600PPM, AFR was still around 14.7. Timing at 18*. I drove it, I think the carb is just on the lean side, I can hear a whistle in the carb if I goose the throttle (no load) and a slight hesitation when starting out. The valvetrain sounds pretty loud at over 2500 rpm, but maybe because the hood is not on and the top is down. Other than needing some fine tuning I think it might be okay. Feels like lot of torque, reved fast in first gear, seemed like 2nd and third were a little slower to rev but no pinging. So I think I can still work with the advance curve and carb tuning. I need to get the AFR gauge calibrated, the gas analyzer is good but slow to respond to changes.

The carb is a Pro Systems HP main body with billet base plate and blocks. It has 750 venturi size with 1-3/4 throttle plates. front jets are 76, rear 86. It has the clear sights for float level. Right now the level is just above the bottom of the sight glass. I am thinking it should be closer to the middle, ???

69BOSS wrote:I finished the rebuild on my 466 with iron CJ heads. It is 11:1 compression, heads have 2.25 and 1.76 stainless valves and thermactor bosses removed and plugged. Combustion chambers are between 70-71 CC's.  Cam is a Voodoo 276/284 (233/241 @ .050) lift is .587/.606 with 1.8 rockers, 110 LSA and 106 ICL. lifters are Lunati hydraulic race lifters, recommended preload is 0-.030", I have them adjusted to 0 plus 1/8th turn, should be around .012". Intake is a Performer RPM.

The problem I am having is low vacuum...6-7in at idle and unburned fuel smell. I have tried adjusting the idle AFR, timing and idle speed but regardless of the settings still very strong fuel smell.  When I bring the rpm's up it goes rich to 8-9:1 AFR. I've tried three different carbs and they all act a little different but the results are still the same. The third carb is a new Pro Systems 4150. It seems to idle best at 800 rpm with 10 initial, idle afr is 13-14 to 1. The 850 vacuum secondary carb I have that was on the engine before and worked good, idles best at 12 initial. but both carbs go rich when the throttle plate is opened.  I also tried a 850 dbl pumper and it goes rich when the throttle is opened but this carb pegged the AFR gauge lean at idle. This carb was also the worst as far as fuel smell. This carb is jetted 76 front with a 4.5PV, 88 rear with jet extensions and blocked power valve. The Pro Systems carb is 76 front and 86 rear.

The cam I have should pull about 12" vacuum at idle. I installed it with the timing marks facing each other and degree'd  it intake CL at 106.

I drove it once with the 850 vac sec carb. It seemed to have plenty of power very responsive throttle.
I did two compression and leakdown tests so far and both times compression is 195-200 (130-140 on first stroke) and leakdown is 2% or less.

Not sure what to try or check next. any ideas?

First if you have Lunati hyd roller lifters and they are Morels. 1/8 of turn dont' get it. You need at least .030" of pre-load on the lifter for it to function correctly. If the heads have been ported and the stock I/E ratio has been maintained, she needs a ton more exhaust duration and the vacuum will come up.

Hi,

The lifters are Lunati race hydraulic flat tappets. Their recommended preload is 0-.030". They say they have tight tolerances and require less preload than their regular flat tappets. I have since changed it from from 1/8th turn to just over 1/4 turn (about .018-.020). Didn't make any difference. At this point, it seems like some tuning may be all I need. It runs good when driving, has lots of torque and the throttle is very responsive.

I have read your previous responses as you have already stated these cam companies don't know how to pull vacuum from these oversize ports. After reading the thread on cams and how generic the profiles are, I am sure you are right. I bet the cam I have would work a lot better in a small port BBF. I've noticed that when comparing cams by spec's, they can have almost identical numbers but very different operating ranges. It seems to me trying to compare cams by the specs is almost impossible.

I wish I would have known all this before I bought the cam and put it all together. I don't know who you are, but I assume at the least you are a cam grinder or engine builder, or all of the above, you may want to clue me in.

If so, I might be willing to change the cam and related parts, not so much because of the idle/vacuum, but for best midrange and peak power. I will work with this and tune till I can get it to run its best and if I don't like it, then I will definitely change it and most likely go to a roller cam. Then again, I may just say screw it and put my 557 short block together with the P51 heads. The reason I didn't do that in the first place is I figured the 466 would be just fine for my ragtop street cruiser.

My bottom line is, while this is not a race car, I don't want these late model cars or even worse a tuner car to be able to pull away from me. My mission statement is, lol, yes it's a 45 year old carbureted pushrod engine but it will kick your ass!

the rpm is a dual pattern base. both spreadbore and squarebore. there is a plate you sandwich between a squarebore carb and the intake. with out it there is very little surface for the carb to seal to the intake. just saying, bob

Yep, good point, I have it.

69BOSS wrote:Hi,

The lifters are Lunati race hydraulic flat tappets. Their recommended preload is 0-.030". They say they have tight tolerances and require less preload than their regular flat tappets. I have since changed it from from 1/8th turn to just over 1/4 turn (about .018-.020). Didn't make any difference. At this point, it seems like some tuning may be all I need. It runs good when driving, has lots of torque and the throttle is very responsive.

I have read your previous responses as you have already stated these cam companies don't know how to pull vacuum from these oversize ports. After reading the thread on cams and how generic the profiles are, I am sure you are right. I bet the cam I have would work a lot better in a small port BBF. I've noticed that when comparing cams by spec's, they can have almost identical numbers but very different operating ranges. It seems to me trying to compare cams by the specs is almost impossible.

I wish I would have known all this before I bought the cam and put it all together. I don't know who you are, but I assume at the least you are a cam grinder or engine builder, or all of the above, you may want to clue me in.

If so, I might be willing to change the cam and related parts, not so much because of the idle/vacuum, but for best midrange and peak power. I will work with this and tune till I can get it to run its best and if I don't like it, then I will definitely change it and most likely go to a roller cam. Then again, I may just say screw it and put my 557 short block together with the P51 heads. The reason I didn't do that in the first place is I figured the 466 would be just fine for my ragtop street cruiser.

My bottom line is, while this is not a race car, I don't want these late model cars or even worse a tuner car to be able to pull away from me. My mission statement is, lol, yes it's a 45 year old carbureted pushrod engine but it will kick your ass!

My apologizes on the lifter, I assumed, and got in trouble, that it was a hyd roller. The pre-load is good.

Chris Straub is my name. No guru, no expert, just a guy that has grown up in this industry and have had the opportunity to have many great mentors. Cams were a hobby for several years then the internet came. Since then I have gotten a pretty good reputation on designing engine combinations to meet customers expectations. I have some engine builders that use me and tell their customers, I have some that keep me secret. Doesn't really matter to me as it all pays the same.

The engineers at ford understood air in makes power, but the exhaust port suffers from this. It's not a problem but needs to be addressed with time. Poor flowing port just needs more time. Hookin78 on here has camshaft in a BB Ford that I need a few years back that makes 900+ HP with a home ported set of SCJ heads. It's a impressive piece but it is not a std 10 or 14 degree split. When I designed Ed Morel FE engine for his Thunderbolt I told him at 482CID with a set of Medium Riser BT heads it would make north of 800HP. Jon Kaase told Ed no way. Well 860HP later Jon is on my website wearing a Straub Tech T shirt in Ed Morels office......http://www.straubtechnologies.com/straub-tech-t-shirts/ Jon told Ed hell it makes more power then some of my 385 stuff.

There is no magic head, cam, intake, carb, and or part. It is all about combination of parts. I have customers with $8K engines that out run $30K engines. That 611 Thor engine was a very nice build and yes $60K is a bundle, but if you had over $120K in a HEMI Ford and got beat....well it don't feel to good.

Your combo with cam change would be like Bob's. Nice increase.

It's been a while, but I finally got it sorted out. This is where it seems to work best... 24 initial, 38 total in by 2000, 78 primary jets and 86 secondary w/PV blocked. 11" vacuum at 800 rpm. It feels like it has more torque, snappy throttle response and pulls harder than it did with the old set up. I hope to get it to the strip so I can see what the actual difference will be.

One problem I had was loud valvetrain noise over 3000 rpm. I was using comp cams rollers with a 1.8 ratio. I switched to Crane gold rockers with a 1.73 ratio and that quieted it down. I am thinking the 1.8 ratio was too much for the aggressive cam lobes.

It sure is running good now, thanks to all who helped!

Staci