[steve25]

I once had a 71 Tempest .
4 door 350 2bb and with a 2 speed TB 300 trans.

And even with those handycaps once I sharply tuned it would light up the right side tire with ease.

By 3500 rpm the motor was done, but it was no where near the dog that I thought it would be before I purchased it, and sounds like up to 3500 rpm this 2 bbl motor was performing better then the OPs motor.

[HWYSTR455]

I was trying to touch on the chamfers in earlier posts, but even so, I don't believe it will make a drastic loss. Some, yes, but not drastic as what seems to be experienced.

Was the trans prepped for using a non-lockup converter? If not, that can add to issues.

Something is being overlooked or is not as it seems, would suggest going over ignition, fuel, etc.

I'm leaning towards ignition or possibly the trans.

Varying all the way to 40 degrees advance with no noticeable difference is kind of a red flag to me.

What kind of distributor, coil, ignition box (if any), and what is the advance curve? Not just total, but the actual curve?

Provide timing for idle, 1500, 2000, 2500, and 3000.

Wouldn't hurt to verify firing order. Maybe show a couple pics of plugs, including brand and part number.

Might as well provide more in-depth info on carb too (not sure what a 'double barrel' is), model number, jets, power valve, secondary spring, air cleaner, choke verified all the way open, etc.


.

[Dragncar]

Something is not right. Years ago I took a stock 2 barrel 350 in a 69 A body with tall gears and a bootleg rear, stock converter. But a set a old 48s that I lapped the valves and put new seals on. Summit 2801 cam and lifters. I iron intake and stock Q jet, 3 tube headers. Sounded great, ran a low 15. Could have gotten a high 14 with gears and converter IMO.
Not a low of low end but when it hit 3500 RPM it took off.

[HWYSTR455]

My LeMans Sport had a 350 2bbl/th350 when I got it, grandma gears, and it was surprisingly quick for what it was. It would fry a tire just to say.

It is possible that there may be an issue with how the cam was ground, it's been known to happen.


.

[ericwoo]

Originally Posted by NeighborsComplaint

Your cam timing is retarded. You need to degree and advance the cam.

Originally Posted by 400 Lemans

Look at Cliffs post #6 on this thread. He had installed plenty of Crower cams. Save yourself anymore hassle and advance it. https://forums.maxperformanceinc.com...ghlight=degree

You guys are spot on. I checked the cam timing with the original stock timing gears and chain that was only lined up dot to dot. I measured the lobe center at 116 degrees. The Crower 60918 cam card said it should be 108 degrees.

If I am understanding this correctly, that means I am retarded 8 degrees and need to advance it 8 degrees, correct?

That old timing chain had some slack on one side though. I purchased a new Coyles adjustable timing set up to 8 degrees either way.

After reading up a lot about degreeing, I thought I grasped the idea, however I am not so sure now. I did the following when I put the new Coyles timing set on:

1. On the 8 Advanced slot crankshaft gear, the cam came up drastically more retarded than the stock gear dot to dot.
2. When I put this set on Dot to Dot slot crankshaft gear, the lobe center came around 117.75 degrees.
3. Then I put it on the 8 Retarded slot, and the lobe center came at 109 degrees

That confuses me because I thought the 8 Advance slot would have the inverse effect. Am I misunderstanding something here or did Coyles mark the gear wrong?

I'd like to get in on correctly the first time so I dont have to take everything apart again.

[steve25]

If by advancing the crank your rotating it more clockwise then your retarding the cam, it’s that simple.

[400 Lemans]

https://cloyes.com/wp-content/upload...structions.pdf Remember when you use the 8 advance key for example then you will line up the cam gear dot with the 8a mark on the crank sprocket and not the regular dot.

[Jay S]

My reply about the ICL being 107-108 was from response link that was sent to Email which the post had gotten deleted. That last post is now saying it 116*, that is quite a difference. Make sure you are measuring correctly, and know how to use the 8 way timing set, and then double check your work. 8* of advance on a engine already pumping 190* will send the pumping compression quite a bit higher. But hopefully that is the issue and you can get it running correctly.

[ericwoo]

Originally Posted by steve25

If by advancing the crank your rotating it more clockwise then your retarding the cam, it’s that simple.

Got it, so if the manufacturer recommends 108 lob center line but dot to dot comes to around 118, changing the keyway to the max Retarded mark (this being 8R) on the crankshaft is indeed the correct route?

That still only got me to 109 lobe center. If I am reading correctly, smaller blocks like mine may benefit more on the lower side of the recommended 108 instead of the higher side. My 8R keyway is the max for this timing set. Couldn't I just turn the camshaft gear a tooth over so the marks don't line up but advances it further to my preference?

[ericwoo]

Originally Posted by Jay S

My reply about the ICL being 107-108 was from response link that was sent to Email which the post had gotten deleted. That last post is now saying it 116*, that is quite a difference.

My mistake, I posted that and realized I had the dial indicator on the exhaust valve of cylinder 1 which came to measure around 108, so deleted the post.

[steve25]

Don’t forget to lube up that new chain real well before you put the timing cover back on.

[Joe-Touring]

Originally Posted by ericwoo

Got it, so if the manufacturer recommends 108 lob center line but dot to dot comes to around 118, changing the keyway to the max Retarded mark (this being 8R) on the crankshaft is indeed the correct route?

That still only got me to 109 lobe center. If I am reading correctly, smaller blocks like mine may benefit more on the lower side of the recommended 108 instead of the higher side. My 8R keyway is the max for this timing set. Couldn't I just turn the camshaft gear a tooth over so the marks don't line up but advances it further to my preference?

From my understanding, you are currently 10* retarded, so you would need 10* advance. So in order to get closer, you should have the keyway set to 8a and the dot lined up to 8a.

Honestly if you got to 109*, that should be good enough. But if you wanted a bit more adjustment, you could use one of these:

https://www.summitracing.com/parts/mrg-987g

The combination of timing gears and the offset cam key may be able to get you to where you want.

[steve25]

I hope you’re making good progress getting this motor to run as you have hoped and here’s a rule to keep in mind.

As an example let’s use an engine with a 9.5 compression that has the needed good ring and valve seal and and due to that leaks down test at 3% or less hot.

If have it in mind to run 91 octane then your cylinder pressure should test out at 175 psi which would be safe even for a iron headed motor assuming a good state of tune from idle up to full throttle and max rpm.

If you want to keep 93 octane in the car then you should be safe with 180 psi of cylinder cranking pressure and very safe with 175 psi.

If you can’t get these cranking pressures with a motor having a compression of between 9 to 9.5 to one then you either have the wrong Cam in your motor as it relates to it’s compression ratio, or it’s degreed in wrong , it’s really that simple in terms of a high performance street motor.

If you find your motor leak down test at 10% or more then you will never have a high performance street motor, you will simply have yourself a fuel guzzler of a grocery getter / commuter car.

[Schurkey]

Doesn't make sense to pick out a certain percentage of leakdown as being "good" or "bad".

INDICATED leakdown is as much a result of the gauge system used to test it, as the actual cylinder leakage.

Give me some random engine that doesn't actually have holes in the pistons or valves--has at least marginal sealing--and some time with the leakdown tester, and I can get you any "percentage" you ask for, by playing with the orifice size. Large orifices lead to "good" results, small orifices lead to "bad" results--and there's no law or regulation or "industry standard" for the size of the orifice in an automotive leakdown tester.

The FAA regulates aviation leakdown testers, though.

[steve25]

Sorry but the tool has its place for certain and especially if you use it on all of your motors cylinders just after break in and then every 1000 miles in terms of a street motor it provides good guidance.

If you don’t think that using it has any merit then your left with what you read with cylinder pressure measurements and making very accurate compression ratio calculations.

[Schurkey]

Originally Posted by steve25

Sorry but the tool has its place for certain...

...If you don’t think that using it has any merit then your left with what you read with cylinder pressure measurements and making very accurate compression ratio calculations.

I've been doing cylinder leakdown testing since about 1988-ish. For decades, I used a Snap-On MT324 single-gauge leakdown tester. It was unusually sensitive--Iron Duke-powered cars would drive into the shop and show 80% leakage on the cylinders. Newly-rebuilt engines would show ~20% leakage. (Eventually, I found debris in the main orifice. Once cleared-out, it began giving results more in-line with the other leakdown tester.)

In 2012, I bought an aviation-style two-gauge unit with a Continental Teledyne-style Master Orifice built-in. The Master Orifice helps to "test the tester"; and to calibrate expectations.

I never said that leakdown testing wasn't useful. I said that picking out a percentage number and saying that it was "good" or "bad" didn't make sense. Because that number depends on both the actual leakage AND the construction of the test equipment, the test equipment itself can skew the results--the INDICATED leakage. And typical automotive leakdown testers have NO standardization for the crucial component--the main orifice.

[ericwoo]

Originally Posted by Joe-Touring

From my understanding, you are currently 10* retarded, so you would need 10* advance. So in order to get closer, you should have the keyway set to 8a and the dot lined up to 8a.

Yes you are right. I am not sure what I did wrong with those measurements. Being late, tired and frustrated, I must have measured something incorrectly.

Anyway, I lined it up to the 8A and indeed got it measuring at the 108 centerline, as the camshaft recommended.

Appreciate the offset key suggestion. Part of me is wondering if I should advance it more for the camshaft to perform better in my small 350 block and to be move the power band lower to be more street fun to drive

[ericwoo]

Ok, here is the update.

I have the camshaft now dialed into the 108 centerline by putting the crankshaft adjustable key on the 8A mark. Double checked it so I am fairly certain I didnt make any mistake with measuring like before.

Drove it the past 2 days. It does seem to perform slightly better with a slightly better low end, but is still not impressive or fun to drive on the street.

The power seems to really kick in about 3,500-5,000 RPM. I am hoping to test it at the track soon and will let you know the time I get. I am sure it will be in the 14's

I am really thinking the best option for the 350 is for me to put stock heads with a 068 cam and regular Performer intake instead of the RPM Performer.

As others said, I may put these parts on a 400 build if I can find a block.

I am curious about other things I can do to make this 350 work well on the street also.

Someone else mentioned Rhoads lifters and I just came across Jim Hands book discussing it also:
"Real variable duration lifters cause the intake valve to close earlier in the compression stroke to lower RPM power production but restore original lobe at high RPM"

I wonder if this will provide a drastic solution that I need for good street performance.

Also, do you guys think switching to the Edlebrock Performer intake instead of the RPM would help increase port velocity or does that not matter with my overly high flowing heads for the 350?

[Stan Weiss]

Now that you have advanced the cam. Have you done a cranking compression test again? If so can you and tells what the numbers are now?

Stan

[Dragncar]

The Perfomer was always considered a better intake than the RPM for a 350.
If you can not find a good 400 block, consider stroking your 350. Ace at PPR was having very good success putting 4" stroke cranks in 350 making a 383. With your heads and custom pistons getting your CR in the 10.5-11-1 range and a modern ported- thin ring pack getting past 400HP will not be a problem IMO.
+ the engine will not be any cookie cutter and very cool. And it just might like that RPM intake a whole lot better.