My 365 That Isn't

[Duke W.]

Re: My 365 That Isn't

Guys,
I do know that I am going to go with the 30-30 cam again, and probably will replace the lifters also.

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Thank you in advance,
George

Big mistake! The 30-30 cam is a terrible road engine cam. Use the LT-1 cam. It will idle about the same, but have a lot more low end torque. Search "327 LT-1" on the TDB. Then follow the links to The Corvette Forum for all the system engineering data and chassis dyno tests.

You can replace the cam (and new cams ALWAYS need new lifters) without pulling the block for a complete rebuild.

If you do want to completely rebuild the block, use the F-M L2166 OE replacement pistons. Re-read the compression ratio article. If you absorb it you will measure deck clearance prior to disassembling the block, so you can start the compression ratio management process, and my recommended not to exceed 10.5:1 should be easily achieveable with proper head gasket selection assuming the block and heads have not been excessively milled.

Why did you use a .028" gasket with flat top/valve notched pistons instead of the Fel-Pro .015" shim gasket?

The lobe wear was likely a problem before you did the recent work, but you probably just didn't recognize the symptoms.

Duke

[Joe C.]

Re: My 365 That Isn't

Since you now have to tear down the engine for a complete flush-out and probable replacement of bearings due to debris from the cam failure, make sure that the machinist removes all galley plugs and thoroughly cleans all the oil journals, especially behind the #1 bearing cap. Crank might need polishing and bores might need cleanup hone.

Now you should ask yourself what you want this engine to perform like. There are much better modern hypereutectic pistons available which will provide better oil sealing than the cast L2166NF pistons. Lighter and using thinner rings for lower friction, as well. There are modern retrofit roller cams that are designed to work best with flattop pistons, while delivering the torque of an L75 and the power of a L76. This combination will take full advantage of your ported heads, and those heads will benefit from valve lift as high as .550".

[George C.]

Re: My 365 That Isn't

Duke,
Still reading peoples input and have not made a decisi0n yet on replacing the pistons. My overall interest is preserving or replacing the parts to as they were when delivered from the General.

You ask about the head gaskets, I actually installed the heads with the Fel-pro .015 gaskets and the bolt holes on the Intake manifold would not line up. Further proof the block was decked and I chose not to have the manifold cut to match. So I gambled that the .028 would give me the alignment I needed for the intake manifold.

I don't know any way to tell if the lobe damage was there prior to this work, it is definitely there now. I looked at some other lifters today, and see wear marks that were not there when I first tore it down.

George

[George C.]

Re: My 365 That Isn't

Joe,
Hi, thanks for your input. Not great news, but I am concerned about how to flush out the crap if I decide to just replace the cam & lifters. I am guessing others have done this in the past and been successful.

You are correct I am asking myself what I really want from this motor, and that is why I have asked for opinions. On one hand although the car is not NCRS judging material, I try to keep it as correct as I can. That leads me to want to put the pop-up pistons back in it and replace the Cam with the 30-30 grind.

Lots of other options for modification, and the machinist who did my headwork for me was also talking about the great power curves in the new roller cams. Still reading suggestions and hope to decide my plan this week.

Thank you,
George

[Bruce B.]

Re: My 365 That Isn't

Factory broach marks run parallel to the crank centerline, your block does not have the correct broach marks.
It appears to have been cut with a circular cutter.
Based on your initial post about using a FI unit. You need a good steady vacuum signal which you might not get due to the way the enguine was built.

[George C.]

Re: My 365 That Isn't

Bruce,
Thanks for your post, it's unfortunate but also confirmed that the block has been decked.
I am currently under the belief that if I stay with a 30-30 cam I will have enough vacuum to make the FI happy. Now I just need to decide what to do about the pistons, and the compression ratio. I am getting mixed responses on the 11:1 pistons with today's pump gas.

George

[Bruce B.]

Re: My 365 That Isn't

George,I have a 62 340 HP with 11.25 compression (effective compression is lower according to the "experts") and it runs fine on Shell 93 octane gas with ethanol???.As far as the cam goes I just had a 327 (337" with 0.060 pistons, flat top 10:1) using a L79 hydraulic cam which I choose due to a 114 degree LSA which should produce a good vacuum. I need the vacuum for my Hilborn injection which I modified to a EFI unit or I might just use one of my early Rochester FI units.As soon as I start the engine I will report on it's performance.

[Joe C.]

Re: My 365 That Isn't

OK. You make your intentions crystal clear in post #49. In that case, you should use an actual, verified static compression ratio of 11-11.25:1 with the 30-30 cam.
If you insist on using GM camshafts, then you can use the LT1 with a static compression ratio of 11.0:1. This cam will provide slightly more idle vacuum than the 30-30.

PS: Mine uses an actual, verified SCR of 11.5:1 in conjunction with a solid roller cam whose durations @ .050 are very similar to the 30-30 cam, but whose valve lift is much greater. It runs detonation-free on 93 PON octane pump fuel, uses a much more aggressive spark timing program than the 1964-65 L76/L84, makes 253 ft-lbs of torque @ 1500 RPM, 396 ft-lbs @ 4000 RPM, peak 459 ft-lbs @ 5500 RPM and peak power of 529 HP @ 7000 RPM. All from 331 cubic inches. The key is careful attention to detail.

You are lucky, in a sense, in that your block has already been "decked", which frees you from the ridiculous constraint of not obliterating the stamp pad characters. You are now free to further surface your decks if need-be, allowing you to fine tune your SCR while using a modern composite head gasket and achieving a desirable quench dimension, which is very important in providing detonation resistance. Getting the 30-30 to be happy with the Rochester unit is easy. You can increase the idle speed, you can "tone down" the cam by lashing it @ .030/.030 (the cam should be lashed @ .025/.025, despite what the Shop Manual says), or both.

[Domenic T.]

Re: My 365 That Isn't

I chose to keep mine as the General designed it pistons, cam, head gaskets,and all the rest. The General spent big bucks in the design and I have found that some cam manufactures thought they were better and some were at the expence of gas milage.

I think it by design was to make power on the upper end RPM's and not the lower end torque especially with the light crankshafts they had and offer decent economy.

The small block then went to a heavier crankshaft and tamed down a bit.

I found it to be a delight to drive in town and on the road depending on the rear differential ratio which I would change from time to time along with the transmission ratio to get the full effect of what it was like if it were ordered for racing or road but with solid lifters the MTC to keep it running perfect was increased.

I did find that it is necessary to burn special fuel because of it's high RPM'S and on long trips I used water injection to eliminate the (ping) when forced to use pump gas.

It's a hard choice to make if you want it stock by design.

DOM

[George C.]

Re: My 365 That Isn't

Bruce,
Thank you for your response, I am happy to hear you can run your 340 HP 11.25:1 engine on pump gas. So many posts are from people who are having problems with today’s gas and more than 10:1 compression, and a couple of local guys I talk to are steering me towards no more than 10:1.
Sounds like your new engine will be a beast looking forward to hearing how it works out.
Thank you,
George

[George C.]

Re: My 365 That Isn't

Joe,
Hi, my intentions might have sounded clear, but if I am not confident enough yet to be ordering parts. It sounds like you have a pretty well built motor, great HP and awesome torque, and another report of a hi-po motor running on todays 93 PON fuel.
Can you tell me what pistons you used and what is the dome volume to get you to the verified 11.5:1 SCR?
Thank you,
George

[George C.]

Re: My 365 That Isn't

Dom,
Thank you for your response, and you aren't the only resource reporting less than favorable reports on todays gas. Special fuel and water injection doesn't steer me towards wanting to replace my flat top pistons with the original type 11:1 pistons.
What pistons are you using and how much compression are you creating?

Thanks again,
George

[John M.]

Re: My 365 That Isn't

George,
Maybe these conflicting opinions your getting on detonation are due to different engine configurations. Some of these engines, especially the solid lifter SHPs have high static compression ratios but quite low dynamic compression ratios due to cam configurations such as overlap. Joe and Duke can give you more on these aspects and have already within some of their posts.
John

[Dan H.]

Re: My 365 That Isn't

George, I run my 64 FI on 91 pump gas, 19K in the past 6 years, big pistons and all. I guess the FI is more user friendly to HP engines as far as fuel distribution etc. Can't see the need for anything else if it's running correctly.
Dan

[Joe C.]

Re: My 365 That Isn't

Joe,
Hi, my intentions might have sounded clear, but if I am not confident enough yet to be ordering parts. It sounds like you have a pretty well built motor, great HP and awesome torque, and another report of a hi-po motor running on todays 93 PON fuel.
Can you tell me what pistons you used and what is the dome volume to get you to the verified 11.5:1 SCR?
Thank you,
George

Was able to reuse my old pistons on latest build, so still using FM L2166NF-30. Dome volume is 5.3cc, combustion chambers are 63cc, pistons are .005" out of the hole, and head gasket compressed thickness in .038".