Hey guys,

I have started my winter 2020 project. My 76 Cutlass 442, which I put in a 455 .03 bored over.
With KB 277 +.030 pistons. +15 cc
I used GA heads - new valves, guides, springs, rockers before being slightly plained they show a 85cc combustion chamber
Lunati cam with the specs:

Stock cast iron olds intake for 4 barrell. Non emissions.
Engine was balanced.
Not a barn burner build.

Lunati blue voodoo Cam Specs
Advertised duration 262/268
Duration at .50 (int/exh) 219/227
Gross valve lift int/exh .499/.510
LSA/ICL 112/108
Valve Lash - Hyd
RPM Range 1300-5500

Fought intake vacuum leak and some coolant leaks before getting it sealed, with individual runner intake seals. We thought it was sealed. This summer when pulling spark plugs and dealing with some pinging, found one plug highly covered with oil and carbon, another one not so bad, and perhaps a few others a little more dirty than others. The two worst were on #5 & 7 cylinders.
During the several years of operation where we thought it was ok, I have had to run 91 octane with an oz of Octane booster per gallon to keep it from pinging on a standard tunning. I don't recall what the mechanic last set it to. It has distributor with coil and electronic unit it it.

When we built the engine the builder thought it would have 10:1 compression, but not sure.. At the time Iowa still had pump gas of 89 octane (ethanoled). In the last 5 plus years Iowa changed fuel standards and now base fuel octane whether it has ethanol or is straight is 87. WIth scattered 91 pumps around, and walmart has a 94 pump at store near me.

I have dealt with pinging since, which mostly seemed to come from in front of me. DS if i ran the engine a bit hard, let alone power burn offs and lesser... If I spiked 91 with kotz, it would stop pinging.

I decided to pull the intake a week ago now that winter is here and I have my shop in order. Popped the intake off and found that the D/s intake gasket failed fully on the bottom of #7 cylinder (where the oil was going that I was noticiably losing) and why that plug was heavily fowled. #5 area gasket was sucking in at the base, and that plug was less dirty but still not as it should of been.

When the engine was built, heads planed and the block deck planed, apparently the machinist didn't shave any off the intake. What he took off wasn't enough to get shorter push rods. So didn't think much of it when re assembling. I have taken the intake to a shop to have shaved a bit so it will better seat.

I was originally thinking of putting in a different cam with overlap (an option the machinist gave me) to bleed off some compression and go down to pump gas. I am not a builder, so don't understand cam specs.

The question I am dealing with now is: re assemble without new cam, and see how well engine will run on pump gas with intake leak fixed. Or replace the cam... I know the specs of the ga heads, the pistons, the cam. But don't know the compression.... WIth the intake off and front of the engine off now is the time to swap cams... At best perhaps I won't have to use the Klotz octane booster with 91..

Any advice from builders on info provided on how the engine will be either assembled with cam or if I should go to another cam to ensure getting off of special gas

 

Get with Mark Remmel (he goes by eficutlass) he can suggest camshaft options with you.

When you took off the manifold were the bolts loose? Depending on what gasket you used it may take several re-torque of the bolts before the stay tight.

There was a thread here a few weeks ago about reoccurring intake gasket leak, read up on that. Lots of good info.

 

An update
Over the holiday's the brother n law and I decided to start tearing into the 455. It has been using excessive oil (whole thing was overhauled and machined 5k miles ago and 8 years ago.

Had pinging issues and vac issues when body was finished and engine was put back in. Fixed vac leak with new reman rochester carb and new intake gasket.
Still had pinging, so ran higher octane gas with klotz added to boost further. Ran break in oil for sometime, as I dont put a lot of miles on the car.

Oil useage only increased and was finding 5 & 7 spark plugs fowling.

Initially thought about lowering what we perceived was high compression by swapping in a new cam.
Once we pulled the intake we found that the lower portion of #7 intake runner had completely sucked in and #5 did to a lesser degree. That was where the oil was being pulled. Pinging came always from that side, now believe it was because it was running too lean on those two cylinders with the leak..
Don't believe the intake was machined at the overhaul, had a machine job clean it up. We laid in dry and ran feeler guages, found tight ally the way around where we could measure. ORdered another set of dual indvidual intake runners, re installed. Now to run a scope in thru carb opening to verify gasket maintained.
Took a it more off as was anticipating a cam swap... Water pump back on, power steering pump on loose. new distributor cap and rotor coming..

 

What intake gaskets are you using? Composition intake gaskets or metal shim gaskets?

 

Your compression is about 9.5:1, no more. So no reason for it to ping other than;
As is typical no mention of grabbing an air/fuel meter to verify carb jetting one way or another.
Vacuum leak will cause pinging/detonation
Oil consumption will cause detonation.
AND AGAIN, AN OVERALL LEAN MIXTURE FROM NOT JETTING THE CARB CORRECTLY WILL ALSO CAUSE DETONATION.
Just wanted to remove all doubt as to my recommendation.
And your builder/mechanic is an idiot if he can’t figure compression ratio, especially since there are a million calculators on the internet. Get another builder.