[tom s]

I say take it to a chassis dyno and see what its doing.Power time it and check AFRs.They will tell you if the carb is getting full throttle.Tom

[Jay S]

It is asking a lot out of a untuned 600 DP 4160 Holley to make much more than 320HP.

[chiphead]

This may be a good application for a Q-jet. The small primaries will give the low RPM venturi velocity required to be responsive and meter fuel properly until the airflow demands increase to open the secondaries.

My first pontiac was a 60 over 350 with 670 heads, '68 iron intake, late 70s olds Q-jet, XE256 cam. Super comp headers and 3" exhaust. Stock converter, TH350 with redneck shift kit, 3.23 gears in a '67 Lemans. It would run low 14s. Wasn't a world beater but was fun for what it was. Would easily do the dairy queen burnout with 235/70-15 Firestones. Was a bit soft below 2200 RPM and had a slight lope. Maybe 8.9 compression with 76CC heads.

Late one night my GF at the time and her girlfriend "borrowed" the car and went terrorizing the good people of Jackson MS. I didn't wake up until I heard it chip 2nd down the street.
Another time I barely lost a top end run against a early '60 thunderbird. Car developed a vibration about 115 and I got out of it.

Good times.

[HWYSTR455]

The power band of an Edelbrock RPM is 1500-6500, and is fine for your application. People run them on SBCs all day long and do fine.

Your cam makes power to around 4800, beyond that it flattens out. You should be doing pretty good up to that 4800 though.

**I think the combo of not having the cam degreed and the small carb are the areas to focus on. You should have at least a 670 on there. A 700 or maybe 750 dialed in would be best.**

Usually, smaller displacement engines like more gear, but 355s should work 'good', and your stall should be fine too.

You could be suffering from lack of fuel, you should check your delivery, and fuel psi.

Your SCR may be lower than you think, but even so, it's not going to make a huge difference unless it's really low. CR test is in order.

Have someone who knows how to degree a cam help you, and same with your 750 carb if you still have it. Check your fuel system. Think that is the best approach for now.

EDIT: There's time to get it ready for summer if you get to it.


.

[php600]

If it has a throttle cable on it.
I was driving my LS Sonoma to work and it lost power. On the way home I wrung it out really good (been trying to blow it for bout 7 years). Got it home and thought, yep, she's done...
On a hunch I popped the hood jammed a broom on the peddle and the throttle barley moved, and the cable coiled up like a spring.

[grivera]

The power band for the 60916 is listed as 2000-4800 but its listed for 326-455. I can only assume it’s closer to 52-5500 in a 350, depending on how it’s degreed.

[ta man]

Originally Posted by ericwoo

Interesting. I appreciate the numbers for me to check. I was wondering if I should change out the intake manifold from the RPM Performer to the standard Performer. I read that somewhere online and then another place said to go with the RPM

The heads were a little bit of an investment so I would like to see if I can get those to work. I thought about taking them off to port them but you're suggesting I should definitely not do that?

I kinda get the impression that the engine isn't really flowing well. I did recently stumble on the suggestion of checking the pushrod length and that if they are too short, the valves won't open to its full potential. I do not believe I checked that and hope to get to that today.

Check your pushrod length before doing anything else. They wont be the right length if the heads were swapped on and the original pushrods were used. Who assembled it?

[Schurkey]

Originally Posted by ericwoo

my car is still kind of sluggish IMO.

I have a hard time seeing my 350 producing much more than 300 horsepower.
[*]600 cfm double barrel Holley carb (I tried putting a 750 double pumper and it was bogging down the engine)[/list]
Any idea of what I can look at that may be wrong with this set up? Or what upgrade I should do to get this thing to over 350 horsepower?

I was expecting some decent power but boy this thing is kind of a dog.

PRIMARY problem is that you started with a 350 when there's no penalty for going 400+ cubes. On a mild engine, every cubic inch is one horsepower and 1 1/4 ft/lbs of torque. ~50 cubes = more better. 100+ cubes = happiness.

Secondary problems:
600 cfm DOUBLE BARREL Holley carb??? Apparently with no tuning

Cam installed "dot-to-dot" when there's a half-dozen things that all are needed to be precisely machined for that to be accurate--and "accurate" may still not be "optimum".

No mention of timing advance tuning

No mention of piston design/quench distance/ring package/block honing


As said--compression test needed. Fuel pressure test needed, with engine at WFO and max RPM. Verify throttle plates open fully, and the trans TV cable and shift-points match the torque curve.

[ericwoo]

Originally Posted by grivera

That all sounds great! Who assembled the top end, installed/degreed cam, determined pushrod length, etc? What does the fuel system consist of? fuel line size, mechanical pump, etc?

Kauffman sold us the completed heads with new everything of course. I just installed it with my father a very long time ago but just got it on the road the past year and trying to figure it out. If I recall, we didnt degreed it but lined it up dot to dot with the original timing chain. I believe we were told the original pushrods should work but will double check the geometry this week.

Fuel system- original mechanical pump and

Originally Posted by Stan Weiss

Have you done a cranking compression test? If so what are see seeing.

Stan

So here are the numbers. Oddly the cylinders on the passenger side were similar and the cylinders on the driver size were similar but the 2 heads were drastically different.

Driver side head

• # 1: 160 psi
• # 3: 165 psi
• # 5: 160 psi
• # 7: 163 psi

Passenger side head

• # 2: 192 psi
• # 4: 188 psi
• # 5: 190 psi
• # 8: 185 psi

Searching online, I am reading that may indicate one side needs a new head gasket. I do recall taking the passenger side head off so may have used a different head gasket- would that be the reason for the large difference? Any ideas?

[ericwoo]

Originally Posted by Schurkey

PRIMARY problem is that you started with a 350 when there's no penalty for going 400+ cubes. On a mild engine, every cubic inch is one horsepower and 1 1/4 ft/lbs of torque. ~50 cubes = more better. 100+ cubes = happiness.

Secondary problems:
600 cfm DOUBLE BARREL Holley carb??? Apparently with no tuning

Yes, a 400 would be great. If I can get this 350 to produce 375 horsepower with some adjustments, I would be happy though since I am not into competitive racing. Just want a high performance street vehicle to take racing a few times for fun.

opps, I meant to type 600 cfm four barrel holley carb. It actually has a vac secondary. The other one I tried was a 750 double pumper but sold it since it was too much carb

[PunchT37]

Originally Posted by ericwoo

Kauffman sold us the completed heads with new everything of course. I just installed it with my father a very long time ago but just got it on the road the past year and trying to figure it out. If I recall, we didnt degreed it but lined it up dot to dot with the original timing chain. I believe we were told the original pushrods should work but will double check the geometry this week.

Fuel system- original mechanical pump and



So here are the numbers. Oddly the cylinders on the passenger side were similar and the cylinders on the driver size were similar but the 2 heads were drastically different.

Driver side head

• # 1: 160 psi
• # 3: 165 psi
• # 5: 160 psi
• # 7: 163 psi

Passenger side head

• # 2: 192 psi
• # 4: 188 psi
• # 5: 190 psi
• # 8: 185 psi

Searching online, I am reading that may indicate one side needs a new head gasket. I do recall taking the passenger side head off so may have used a different head gasket- would that be the reason for the large difference? Any ideas?

That engine should be strong for a 350.


I would re check my head bolt torque and my valve adjustments. Are those stock head bolts? Valve train geometry correct?

[Jay S]

A 600 vaccuum secondary is more of a 250 or 300 HP carb, that is not even worth tuning. I wouldn’t go wild changing anything until you switch carbs to something that matches your expected power levels. The 750 DP is a much better choice for tuning efforts.

[blueghoast]

Have you tried running more timing with the allum-heads and only
around 10:1 compression I would try 38-40 degrees of timing, it
should like it, don't hurt to try and don't cost nothing. If you put a
different thickness head gasket on one side that would make a differance
in compression from side to side.

GT

[steve25]

Something is by far not right with those cranking compression differences from bank to bank and a different head gasket that might have been used unless crazy thick would not make for those psi differences.

You need to do a leak down test and if that checks out pull both heads and CC them .

Did this motor by chance start out life as a 2BBl ?

[chiphead]

The higher compression numbers on one side can be a few things:

Battery going dead during testing. The faster the engine cranks, the higher the numbers. Did you test the passenger side first? Did the battery get weak or did you boost it at any point during the test?

Valvetrain adjustment or geometry. If the intake valve closes earlier for any reason, the cranking compression will be higher. Rocker adjustment, valvetrain geometry, lifters not pumped up prior to test, etc will result in higher numbers. In my case, I found that one intake lifter that did not pump up gave 185 PSI when all the other cylinders pumped 165.

Odd airflow or intake issue. A restriction in the intake system can cause low numbers, but not very common. Same for exhaust restriction, stuck heat riser, etc.

Smaller combustion space: One head could have smaller chambers than the other (did you CC both heads?) Or the wrong head gasket or strange deck height issue.

[Stan Weiss]

Originally Posted by ericwoo

Kauffman sold us the completed heads with new everything of course. I just installed it with my father a very long time ago but just got it on the road the past year and trying to figure it out. If I recall, we didnt degreed it but lined it up dot to dot with the original timing chain. I believe we were told the original pushrods should work but will double check the geometry this week.

Fuel system- original mechanical pump and



So here are the numbers. Oddly the cylinders on the passenger side were similar and the cylinders on the driver size were similar but the 2 heads were drastically different.

Driver side head

• # 1: 160 psi
• # 3: 165 psi
• # 5: 160 psi
• # 7: 163 psi

Passenger side head

• # 2: 192 psi
• # 4: 188 psi
• # 5: 190 psi
• # 8: 185 psi

Searching online, I am reading that may indicate one side needs a new head gasket. I do recall taking the passenger side head off so may have used a different head gasket- would that be the reason for the large difference? Any ideas?

I don't know why the difference from side to side, but that is like the difference in 1 point of CR or about 10 cc's difference in total volume from side to side.

Stan

[ericwoo]

Originally Posted by chiphead

Did you test the passenger side first? Did the battery get weak or did you boost it at any point during the test?

Smaller combustion space: One head could have smaller chambers than the other (did you CC both heads?) Or the wrong head gasket or strange deck height issue.

I did the driver side first but then hooked the battery charger up before doing the passenger side. The starter while turning the passenger side may have even turned slightly slower but not much.

Originally Posted by steve25

You need to do a leak down test and if that checks out pull both heads and CC them .

Did this motor by chance start out life as a 2BBl ?

Originally Posted by PunchT37

I would re check my head bolt torque and my valve adjustments. Are those stock head bolts? Valve train geometry correct?

Appreciate all the suggestions. Yes, I am thinking of doing the following in order:
1. Check valve geometry, adjustments and head bolt torque
2. Leak down test
3. if is okay, I will take the heads off to cc- mill them evenly if needed and install new head gaskets

The head bolts are the new ARP brand.

Originally Posted by blueghoast

Have you tried running more timing with the allum-heads and only
around 10:1 compression I would try 38-40 degrees of timing, it
should like it, don't hurt to try and don't cost nothing. If you put a
different thickness head gasket on one side that would make a difference
in compression from side to side.

GT

I think I have gotten it up to 40 degrees in the past when I tested various timing adjustments and never saw significant performance improvement. With everyone's help in brainstorming potential issues, I am thinking I need to focus on the heads whether it is a leak, valve geometry or heads being milled differently. The timing adjustments and carb changes never improved much.

[Formulas]

I personally would run down why the compression is so different ... .. . I don't know KRE heads do they have a part number that's visible under the valve cover? Might have two different chamber sizes or maybe one head got milled twice

[Jay S]

I would expect putting a battery charge on between banks would effect the result on a pump test. At very least you need to do it again before make any conclusions.

I had a Pontiac that the factory deck machining height was off .018” between banks.

[74Grandville]

60916 >>> INT/EXH - Dur @ .050” Lift: 221°/229° RR: 1.5/1.5 Gross Lift: .455”/.470” LSA: 112°

I agree with others, advance the cam to 108/109 centerline. try a smaller intake like the performer to increase port velocity.

you need to make sure the torque convert and gear is correct for the setup. that engine should want to rev.