327 Engine Rebuild - need advice

[Mark P.]

Re: 327 Engine Rebuild - need advice

Hi Duke - I called Crane and discussed the McCagh Special cam in your article. They think the attached specs are for the cam that you are referring to. They said it is a small block chevy OE cam but with the intake and exhaust durations switched. Are the attached specs correct ? They said it would cost $192 to make this cam and isn't in their current catalog. If I get this cam will it be fine for Performance Verification ? Thanks, Mark

[Duke W.]

Re: 327 Engine Rebuild - need advice

Yes, that's the McCagh Special cam. Remember, it must only be used with heads that have been properly massaged to achieve something near 220/170 CFM flow @ 0.4-0.5" valve lift, 28" H20 test depression. CR should be in the range of 10-10.25, which should be achievable with either the Keith Black KB156 or KB157 pistons depending on head gasket thickness. Also use modern aftermarket high strength rods like the Eagle SIR 5700 that cost about $250 for a balanced set.

Search for the article "Compression Ratio Explained" to learn how to manage the compression ratio to be in the target range.

Yes, it will pass a PV. Mike's '57 "283/250" HP FI engine with Powerglide passed a PV and won the Duntov award. It idles butter smooth at 450 in Drive. With a manual transmission idle speed should be about 500 @ 18" in neutral.

Shoot me an email and I'll send you my phone number. It's best that we talk on the phone to make sure you understand the special requirements to use this cam. If you do it right it will have 300 HP low end torque and idle behavior and L-79 top end power with a useable power bandwidth up to at least 6500, but no one will know it's a "cheater motor".

Duke

[Duke W.]

Re: 327 Engine Rebuild - need advice

Good advice. I'm pretty sure you are not a fan of my approach to bore out to the max allowable if boring is needed, even in a car rarely driven.

You never know what might happen in the future. I never recommend boring above the next replacement size that will eliminate all the taper, and that is usually 20 to 30 thou, which means the engine can be bored higher if it ever needs to be rebuilt again. If you go 60 and the engine ever needs to be rebuilt again, it's either sleeve the bores, which is both expensive and not necessarily reliable or scrap the block. It's not worth the extra handful of horsepower to go all the way on the first rebuild.

Duke

[Joe L.]

Re: 327 Engine Rebuild - need advice

You never know what might happen in the future. I never recommend boring above the next replacement size that will eliminate all the taper, and that is usually 20 to 30 thou, which means the engine can be bored higher if it ever needs to be rebuilt again. If you go 60 and the engine ever needs to be rebuilt again, it's either sleeve the bores, which is both expensive and not necessarily reliable or scrap the block. It's not worth the extra handful of horsepower to go all the way on the first rebuild.

Duke

Duke------

The 0.020" overbore often gets overlooked. Most machine shops want to go right to 0.030" since that's what "they're set-up for". I NEVER recommend going to 0.030" unless that much overbore is necessary. Insist on the 0.020" if that is sufficient. In fact, I wish that 0.010" pistons and rings were available. Sometimes, I think an engine could get by with that. For me, the minimum overbore possible is always the way to go.

Lot's of reasons for this, most not even involving maintaining enough material for future rebuilds.

[Duke W.]

Re: 327 Engine Rebuild - need advice

I don't think too many engines, by the time they really need to be bored, would clean up at 10, but if that's all that's needed a specialty outfit like JE can machine the pistons to any dimension you specify, at extra cost, of course.

My 340 HP engine at 115K miles had 3 thou taper in 6 bores and 5 in the other two. (BTW that was virtually the ONLY wear I could measure in the engine that I blame on the crummy foam air filter. It still ran like a scalded cat, but I was worried about the conn. rods and, indeed, found #7 had a crack all the way across a bolt seat. I dodged a lethal bullet!) I wanted to use the OE type forged pistons and the next size was 30 over.

One of the things I like about the KB hypereutectics is that, for most engines, replacement sizes are available in 20, 30, 40, and 60 over, and most original bore engines will clean up fine at 20, so that means the block could likely be rebuilt two more times using 40 and 60 over pistons.

Duke

[Mark P.]

Re: 327 Engine Rebuild - need advice

Hi Joe - can you tell anything from these photos ? I can post others when I get home tonight.

[Joe L.]

Re: 327 Engine Rebuild - need advice

Hi Joe - can you tell anything from these photos ? I can post others when I get home tonight.

Mark------


I believe the GM #10055849 was an internally manufactured GM pump. However, I might be more convinced with some additional photos of the cover as well as areas of the pump body with raised characters.

[Mark P.]

Re: 327 Engine Rebuild - need advice

Joe - here are some more photos. Let me know if it looks like a GM part. How old do you think it is ? Any issues using it for a 300HP 327 ? I would prefer to use this over buying a new Melling pump if I can. Any idea why the white paint was applied ? Thanks, Mark

[Joe L.]

Re: 327 Engine Rebuild - need advice

Joe - here are some more photos. Let me know if it looks like a GM part. How old do you think it is ? Any issues using it for a 300HP 327 ? I would prefer to use this over buying a new Melling pump if I can. Any idea why the white paint was applied ? Thanks, Mark

Mark------

I'm more convinced that this is a pump of internal GM manufacture. The white dye mark is very characteristic of internally manufactured GM components. It's an inspection mark that denotes something, what I do not know.

This pump is probably about 25-30 years old but it's obviously brand new and in as-new condition. At least two supersessive part numbers followed. The most recent of these supercessive part numbers is not of internal GM manufacture. This pump was likely manufactured at GMM's Bay City, Michigan engine components plant.

This is an OEM quality part and is perfect for your application.

[Mark P.]

Re: 327 Engine Rebuild - need advice

Thank.you very much Joe. I feel good about my $39 purchase.