Help with cam selection, chevy inline 6. i screwed up

[chevyfreak]

I'm turning to the knowledgeable people on here.
In need of cam duration specs for my chevy inline 6.
Was a 250ci, now 266ci.
Bore is 4.0" stroke at 3.53". Balanced.
Pistons at 0 deck and a small dish in center of piston 6cc.
Chamber size at 75cc and gasket compressed at 0.039".
Calculated compression ratio at 9.15 to 1 but probably more realistic at 9 to 1.
Intake ports is std siamesed type with bolt boss removed and port clean up. Intake valve 1.74". Exhaust ports only had a clean up and 1.5" valve. Z28 type springs. Specs on springs is, Seat pressure at 114lbs at 1.710 height. Open pressure is 318 at 1.210 height. Rockers 1.75 ratio, max lift as per spring details is 0.500"
Qjet carb from a 327. 4bbl intake. Hei dizzy.
1 5/8 headers, 6 into 1 collector, 3" down to 2.5".
Full exhaust and one muffler.
Manual 5spd trans. 3.23 final ratio with 14" wheels.
More a street car with occasional racing at the track. About 3000lbs in weight.

Currently a stock cam, runs decent but lacks power from 3000rpm and flatlines at 4400rpm
As per internet stock specs it at 172/172 at 050 lift on a 105lsa. .388 lift. (The 105lsa is a bit weird).

Now for the screw up part.
I took an old cam and had it grinded for added duration.(wont be doing that again). As per cam grinder it is at 220deg at 0.050, and its a turd. Very low idle vacuum, 8 inches, cant go lower than 1000rpm idle, stumbles of the line and doesnt really pull as rpm goes up.
The stock cam drives better but same way as a stock 250 and lacks the power above 3000rpm.

I just want it to run as good as possible with street duty and have a higher top end rpm and power for when there is some track time.
Been thinking of going to 1.94 intake valve on a spare head but need to unshroud chamber for bigger valve. And probably mill a bit so chamber size stays about the same.
Any recommendations on cam sizes?

Thanks.
Chevyfreak.

[Old School]

Would it be possible that the reground cam is for solid lifters and you put hydraulic lifters on it? I did that about 50 years ago and mine acted just like you described.

[chevyfreak]

Would it be possible that the reground cam is for solid lifters and you put hydraulic lifters on it? I did that about 50 years ago and mine acted just like you described.

When i took it in i told him i want to keep it hyd. But now that you mention it , it is possible that it were grounded for solid by mistake. Will maybe try it on another build to see what happens.

Chevyfreak

[pdq67]

I kinda like the spec's of the old stock Chevy -929 hi-cam that was used in about ALL the base, lo-po- V-8's through the years.

I think it is like--

195/202, 112/108, .390"/.410" lift.

Sucker pulls like a freight-train so you might consider getting one for a 6-banger.

Or ask CamKing for his recommendation as well as others. I figure that Mike will be glad to help you..

(at http://jonescams.com/)..

pdq67

[My427stang]

I am not a 6 cyl guy, but I'd likely be about where you are. Depends on how the head flows and of course need more info than just .050, but my gut says 216-ish intake, 224-ish exhaust. The issue is that we don't have any other cam info. Do you have the entire lobe design and LSA/ICL?

This is just a Sunday AM WAG but I given that you don't want it to rev too high, but do want to race it a little and want vacuum, 268/270 adv, 216/224-ish @ .050. I'd likely have that ground on 106 installed straight up on 106 to pull on the port a little harder, and it still is only 57 degrees overlap, but you could go 108 LSA as well if you wanted it to have even more vacuum

I wonder if your current low vacuum is because of a real lazy lobe? Even the stock 105 LSA if ground at 280 advertised .006, single pattern is only 70 degrees overlap, but who knows what the grinder's ramps are like. I also wonder if maybe you have another issue? Vacuum leak? Timing curve issue?

[chevyfreak]

I wonder if your current low vacuum is because of a real lazy lobe? Even the stock 105 LSA if ground at 280 advertised .006, single pattern is only 70 degrees overlap, but who knows what the grinder's ramps are like. I also wonder if maybe you have another issue? Vacuum leak? Timing curve issue?

Thanks for your input.
No vacuum leak. When i changed cam and lifters for a stock cam , idle smoothed out and can bring it to idle as low as 700rpm without dying. Plenty of vacuum with stock cam, idle i have 21" and cruising it stays around 16". The grinded cam only gave me 9" at idle, even after i advanced the cam 1 tooth , idle vacuum only picked up to 10.5".
I tried several timing curves to see , it wanted alot of advance, static was at 26deg and a quick mech advance.

I have a feeling something went wrong on regrinding the cam , cam not currently with me so i cant measure the lobes to see. Took a bit of a drive to a friend about 3hrs drive, and after struggling with the setup, i borrowed a stock cam and lifters from him , installed stock cam and drive back home were way more pleasant, just the lack of power in the higher rpms.

Chevyfreak.

[chevyfreak]

I kinda like the spec's of the old stock Chevy -929 hi-cam that was used in about ALL the base, lo-po- V-8's through the years.

I think it is like--

195/202, 112/108, .390"/.410" lift.

Sucker pulls like a freight-train so you might consider getting one for a 6-banger.

Or ask CamKing for his recommendation as well as others. I figure that Mike will be glad to help you..

(at http://jonescams.com/)..

pdq67

I have a 204/214 crane in my 327, runs very nice.
Have thought of it but after this cockup of mine i 'd rather ask first, then see and get a cam that's properly made and not a stocker send in for regrinding. Was a chance i took, cam had a couple of bad pitted lobes and price to regrind were only $35 ( converted price to us dollar).

Chevyfreak.

[PackardV8]

get a cam that's properly made and not a stocker send in for regrinding. Was a chance i took, cam had a couple of bad pitted lobes and price to regrind were only $35 ( converted price to us dollar). Chevyfreak.

We face the same problem with cam cores. They may exist, but it's doubtful for that obsolete engine you're going to find an affordable hydraulic lifter cam ground on a new core. Most of what's available today will be a regrind. Having said that, being reground is not a problem if you get one with the proper specs for your application and use new lifters.

[chevyfreak]

We face the same problem with cam cores. They may exist, but it's doubtful for that obsolete engine you're going to find an affordable hydraulic lifter cam ground on a new core. Most of what's available today will be a regrind. Having said that, being reground is not a problem if you get one with the proper specs for your application and use new lifters.

Unfortunatly no one around here really keeps spares for them. Can find rings bearings and gasket set but no more pistons, pushrods,valves etc, That we either buy 283 or 307 pistons , from the v8 shops as they import some of the major v8 parts. Other small parts i get from summit mostly. I just dont want to take another old cam for regrinding,
I would rather import a cam get it properly running but due to the cost ( by time the shipping and import duties is added final price almost jumps 2,5 to 3 times the starting price), i dont just want to go and order one and choose the wrong one.

Chevyfreak.

[CamKing]

Is this the same engine as a 292 Chevy Inline 6 ?

[chevyfreak]

Is this the same engine as a 292 Chevy Inline 6 ?

Same family yes. a 250ci, i bored it open to 4".

Chevyfreak.

[CamKing]

Is this the same engine as a 292 Chevy Inline 6 ?

Same family yes. a 250ci, i bored it open to 4".

I have a new cam core on the shelf.

[chevyfreak]

Is this the same engine as a 292 Chevy Inline 6 ?

Same family yes. a 250ci, i bored it open to 4".

I have a new cam core on the shelf.

Will send a pm.
Chevyfreak.

[PackardV8]

Is this the same engine as a 292 Chevy Inline 6 ?. . . . I have a new cam core on the shelf.

Same family yes. a 250ci, i bored it open to 4". Chevyfreak.

Yes, same family, but No, not the same cam core; I checked and the 292" cam has a different distributor gear location than the 194", 230", 250".

Maybe, if Mike will make a duration and lift recommendation, I'll get you a good 250" regrind for a SpeedTalk price, ship it down to OZ and list it on the customs form as a gift.

A bit OT, but those engines have a chronic problem with harmonic vibration. Sustained high RPM will throw the balancer and break the flywheel bolts. The 292" has three dowel pins on the flywheel flange added as OEM.

[chevyfreak]

Is this the same engine as a 292 Chevy Inline 6 ?. . . . I have a new cam core on the shelf.

Same family yes. a 250ci, i bored it open to 4". Chevyfreak.

Yes, same family, but No, not the same cam core; I checked and the 292" cam has a different distributor gear location than the 194", 230", 250".

Maybe, if Mike will make a duration and lift recommendation, I'll get you a good 250" regrind for a SpeedTalk price, ship it down to OZ and list it on the customs form as a gift.

Dizzy is in same place. The 292 fuel pump moved and cam have clearance notches. Can use a 292 cam in other blocks just no mech fuel pump but to use the 230/250 cam in a 292 the pump cam have to be removed as it interferes with longer stroke and some cams have to get the notches. Some have them some dont. From gm the cam actually have both places for pump cam but only one is ground the other removed.
Im from south africa btw,
I pm'd mike, will await his recommendation.
Rpm wil be below 6000rpm, had assembly balanced and the bigger damper added. More a good streeter with some high rpm blasts at the track. Never intended it for a high hp build, just something else from the normal 250 build.

Chevyfreak.