496, AFR290, Straub cam - Chevelle Tech
Performance Our High Performance area

 6Likes
Reply
 
LinkBack Thread Tools Search this Thread Display Modes
post #1 of 32 (permalink) Old Jul 28th, 19, 8:38 AM Thread Starter
Tech Team
 
Join Date: Sep 2018
Posts: 197
Garage
Well, it looks like this this come together before end of summer.

MAHLE +18cc dome, 1.5, 1.5, 3/16”
SCAT 4.25 cast crank (checked OK, no taper in the journals)
SCAT rods (OK)
Internally balanced with SFI damper and flexplate.

The block I picked up in a storage locker deal, bores are straight, no taper or wear, +0.060”. Shop says piston-to-wall clearance is a little high for a street engine, 0.006”, is that reasonable for a street strip engine with forged pistons?

Machine shop has corrected the loose main caps, replaced one cap, knurled the other center caps, and line bored after installing ARP studs.

Next steps are mock assembling to determine the heights for the 0 decking and checking piston to head and valve to piston clearance.

Heads are in for a valve job and spring check up.

Heads and cam were used from the 467 I picked up a few years ago. I thought they were too large for the 9.6:1 467, but I’m confident they’re much better matched to a 10.75:1 496.

Still need to pick up a couple new rocker arms, or a set, of the back set rockers, whichever makes more sense. Guessing the mostly newer set I have now came from Straub as half are marked “INT”. Double check the used pushrod lengths and I should be fairly ready.

Still need to pick up another Moroso 20408 pan, for use with the stock pump with high pressure spring.

For now, Victor Jr intake and 750 vacuum secondary Holley.

Anyhow, considering the cam and heads, the small carb, any guesses for HP?
Attached Thumbnails
Click image for larger version

Name:	87FED216-623A-42E6-A0F1-2C92023B7CAC_1564317498711.jpeg
Views:	34
Size:	108.8 KB
ID:	599156  

Proving every day hindsight is 20/20.
Dragginwagon467 is offline  
Sponsored Links
Advertisement
 
post #2 of 32 (permalink) Old Jul 28th, 19, 8:56 AM
Senior Tech Team
Bob
 
Join Date: Aug 2002
Location: Pa
Posts: 1,298
Did the shop have any problem balancing the crank?
1968 hot rod is online now  
post #3 of 32 (permalink) Old Jul 28th, 19, 9:11 AM Thread Starter
Tech Team
 
Join Date: Sep 2018
Posts: 197
Garage
Quote:
Originally Posted by 1968 hot rod View Post
Did the shop have any problem balancing the crank?
Funny you should mention it, when I bought the crank, it was supposed to be set up for internal balancing, but it did appear to take some weight to get it done.

I don’t have the balancing bill yet so I don’t know how far out it was.
Attached Thumbnails
Click image for larger version

Name:	A9E2B268-C87E-462F-96D5-C29CB652A6A2_1564319397960.jpg
Views:	41
Size:	71.3 KB
ID:	599158   Click image for larger version

Name:	29173193-AF7B-4562-BE96-416371D0F777_1564319416137.jpg
Views:	36
Size:	57.4 KB
ID:	599160  

Proving every day hindsight is 20/20.
Dragginwagon467 is offline  
 
post #4 of 32 (permalink) Old Jul 28th, 19, 10:30 AM
Lifetime Premium Member
Jeff
 
Join Date: Mar 2006
Location: Southwest
Posts: 1,261
Re: 496, AFR290, Straub cam

Quote:
Originally Posted by Dragginwagon467 View Post
Well, it looks like this this come together before end of summer.

MAHLE +18cc dome, 1.5, 1.5, 3/16”
SCAT 4.25 cast crank (checked OK, no taper in the journals)
SCAT rods (OK)
Internally balanced with SFI damper and flexplate.

The block I picked up in a storage locker deal, bores are straight, no taper or wear, +0.060”. Shop says piston-to-wall clearance is a little high for a street engine, 0.006”, is that reasonable for a street strip engine with forged pistons?

Modern pistons have the recommended clearance built into them, as such, you could end up with too much piston to wall clearance. Do you already have the Mahle pistons and how did the shop come to the conclusion of the .006 clearance? Did they mic the bores and then the pistons to come up with that clearance number? Is this a freshly machined block or a used engine pulled apart? Any other blocks you have dibs on? You don't want an oil burner and or lots of blow-by.

Jeff

64 El Camino Pro street, 496, T-400, 9" 3.73


Video:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
fr8dog is offline  
post #5 of 32 (permalink) Old Jul 28th, 19, 10:42 AM
Lifetime Premium Member
Jeff
 
Join Date: Mar 2006
Location: Southwest
Posts: 1,261
Re: 496, AFR290, Straub cam

Here is Mahle's recommendations for Min/Max piston to wall clearance, assuming you have their 18cc 4032 forged units, you're looking at recommended Min/Max of .0041" to .0049".

Their race 2618 forged pistons, in non streetable compression ratios have a looser clearance of .0061" to .0069".

http://www.us.mahle.com/media/usa/mo...c-dome-web.jpg

Jeff

64 El Camino Pro street, 496, T-400, 9" 3.73


Video:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
fr8dog is offline  
post #6 of 32 (permalink) Old Jul 28th, 19, 10:48 AM Thread Starter
Tech Team
 
Join Date: Sep 2018
Posts: 197
Garage
Quote:
Originally Posted by fr8dog View Post
Quote:
Originally Posted by Dragginwagon467 View Post
Well, it looks like this this come together before end of summer.

MAHLE +18cc dome, 1.5, 1.5, 3/16”
SCAT 4.25 cast crank (checked OK, no taper in the journals)
SCAT rods (OK)
Internally balanced with SFI damper and flexplate.

The block I picked up in a storage locker deal, bores are straight, no taper or wear, +0.060”. Shop says piston-to-wall clearance is a little high for a street engine, 0.006”, is that reasonable for a street strip engine with forged pistons?

Modern pistons have the recommended clearance built into them, as such, you could end up with too much piston to wall clearance. Do you already have the Mahle pistons and how did the shop come to the conclusion of the .006 clearance? Did they mic the bores and then the pistons to come up with that clearance number? Is this a freshly machined block or a used engine pulled apart? Any other blocks you have dibs on? You don't want an oil burner and or lots of blow-by.
Quote:
Originally Posted by fr8dog View Post
Here is Mahle's recommendations for Min/Max piston to wall clearance, assuming you have their 18cc 4032 forged units, you're looking at Min/Max of .0041" to .0049".

http://www.us.mahle.com/media/usa/mo...c-dome-web.jpg
Yes, they have the pistons, that’s why they mentioned it. 0.0011” extra PtC clearance on an engine which will see a few hundred/maybe a thousand miles a year, isn’t a big deal is it? There’s no taper, and the rings are file fit.
fr8dog likes this.

Proving every day hindsight is 20/20.
Dragginwagon467 is offline  
post #7 of 32 (permalink) Old Jul 28th, 19, 10:53 AM Thread Starter
Tech Team
 
Join Date: Sep 2018
Posts: 197
Garage
These are the pistons.

https://www.cnc-motorsports.com/mahl...4310-bore.html

Proving every day hindsight is 20/20.
Dragginwagon467 is offline  
post #8 of 32 (permalink) Old Jul 28th, 19, 11:54 AM
Lifetime Premium Member
Jeff
 
Join Date: Mar 2006
Location: Southwest
Posts: 1,261
Re: 496, AFR290, Straub cam

Quote:
Originally Posted by Dragginwagon467 View Post
Yes, they have the pistons, that’s why they mentioned it. 0.0011” extra PtC clearance on an engine which will see a few hundred/maybe a thousand miles a year, isn’t a big deal is it? There’s no taper, and the rings are file fit.
Probably not a huge deal being .0001' over, but the cylinder finish for proper ring seal would be.

Jeff

64 El Camino Pro street, 496, T-400, 9" 3.73


Video:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
fr8dog is offline  
post #9 of 32 (permalink) Old Jul 28th, 19, 1:19 PM Thread Starter
Tech Team
 
Join Date: Sep 2018
Posts: 197
Garage
Quote:
Originally Posted by fr8dog View Post
Quote:
Originally Posted by Dragginwagon467 View Post
Yes, they have the pistons, that’s why they mentioned it. 0.0011” extra PtC clearance on an engine which will see a few hundred/maybe a thousand miles a year, isn’t a big deal is it? There’s no taper, and the rings are file fit.
Probably not a huge deal being .0001' over, but the cylinder finish for proper ring seal would be.
Cylinders will be honed for the rings.

Proving every day hindsight is 20/20.
Dragginwagon467 is offline  
post #10 of 32 (permalink) Old Jul 29th, 19, 3:50 PM
Lifetime Premium Member
Jeff
 
Join Date: Mar 2006
Location: Southwest
Posts: 1,261
Re: 496, AFR290, Straub cam

Quote:
Originally Posted by Dragginwagon467 View Post
Cylinders will be honed for the rings.
Final honing will add more p/w clearance as well. This may be reason enough to look for another block? Being .060 over, have the bores been sonic checked?

Jeff

64 El Camino Pro street, 496, T-400, 9" 3.73


Video:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
fr8dog is offline  
post #11 of 32 (permalink) Old Aug 23rd, 19, 7:40 PM Thread Starter
Tech Team
 
Join Date: Sep 2018
Posts: 197
Garage
Well, it’s build time, pick up the block, rotating assembly, and heads in the AM.

The build won’t go quick but it’ll get there.

I’ll share a few pick along the way, even if it’s open to criticism lol

Proving every day hindsight is 20/20.
Dragginwagon467 is offline  
post #12 of 32 (permalink) Old Aug 24th, 19, 1:03 PM
Senior Tech Team
Alan
 
Join Date: Aug 2009
Location: League City, TX
Posts: 1,857
Re: 496, AFR290, Straub cam

What heads are going on it?

With 10.75 and that cam, it should make some good power if the heads will support it.

1971 Corvette
VortecPro 496"
T400, Tight 10" converter
3.36 gears, 3700lb raceweight
[email protected], 1.51 60'
STOCK APPEARING
ShouldntBeHere is offline  
post #13 of 32 (permalink) Old Aug 24th, 19, 2:31 PM
Tech Team
Alex
 
Join Date: May 2017
Location: Eastern NC
Posts: 212
Re: 496, AFR290, Straub cam

My AFR 290cc heads did just fine on my 9.5-1 468. I think you will be happy and have a good street motor.

1969 Chevelle SS --- 468 FTI Level 4 TH400 AFR 290cc's
1997 S10 SS ---LQ9/4l65e
Chevymec is offline  
post #14 of 32 (permalink) Old Aug 24th, 19, 7:17 PM
Lifetime Premium Member
jackie
 
Join Date: Mar 2012
Location: Houston Texas
Posts: 4,675
Re: 496, AFR290, Straub cam

Did you have the shop hone the block with a deck plate?

As for power, with that compression, head, cam combo, I figure 680 at around 6500.
CNC BLOCKS N/E likes this.

'67 Chevelle Malibu, Catalina Blue, 540 inch Rat, Air Flow Reasearch 290 CNC Heads heads, Custom Hyd Roller, .675 lift, 234, 244 at .050, Lemons Headers, Holley Multiport Fuel Injection, TCI 6X 6Speed Automatic, 12 bolt Posi Eaton TruTrac, 3:31 Richmond Gears, front and rear power disc brakes, Global West Suspension, etc.

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
jackie schmidt is offline  
post #15 of 32 (permalink) Old Aug 25th, 19, 6:06 AM Thread Starter
Tech Team
 
Join Date: Sep 2018
Posts: 197
Garage
Quote:
Originally Posted by fr8dog View Post
Quote:
Originally Posted by Dragginwagon467 View Post
Cylinders will be honed for the rings.
Final honing will add more p/w clearance as well. This may be reason enough to look for another block? Being .060 over, have the bores been sonic checked?
Everything in this block and build could have been a little better...I’ve seen some shady stuff go together and live a happy life. This is far from that...the block does t need sonic checked, it lived 10+ years in a 10 second Nova. The loose main caps killed it, not the bore thickness or hone. The cylinders were ball-honed for ring finish.

Quote:
Originally Posted by ShouldntBeHere View Post
What heads are going on it?

With 10.75 and that cam, it should make some good power if the heads will support it.
AFR 290, as far as I know, they are the factory springs, with about three months of use. They vacuum tested perfect and the decks are flat.

The chambers did make friends with the domes on the previous engine build, just touching the heart-shaped point by the spark plugin several cylinders. This could have happened when the rod bearings failed or could have contributed to the rod bearings failing, I’ll never know - it wasn’t my circus.

To be clear, heads and roller cam came from a basket-case 467 I bought out of a 11.9-second ‘70 Chevelle. This 467 bottom end now lives with swap meet 781 heads, 238/248 hyd cam, and makes about 435 hp with very little tuning.

The block I’m using for the 496 build was a 467 as well, but bearings failed a couple times after a roller lifter failure. This engine came from a 10-second Nova.


Quote:
Originally Posted by Chevymec View Post
My AFR 290cc heads did just fine on my 9.5-1 468. I think you will be happy and have a good street motor.
It should run well, I’m guessing 600+, even with all the compromises.


Quote:
Originally Posted by jackie schmidt View Post
Did you have the shop hone the block with a deck plate?

As for power, with that compression, head, cam combo, I figure 680 at around 6500.
See above, ball hone. The bore is actually quite old but straight.

Without the compromises, I’m guessing you’re on the money.
427L88 and Chevymec like this.

Proving every day hindsight is 20/20.
Dragginwagon467 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevelle Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address. Note, you will be sent a confirmation request to this address.

Email Address:
OR

Log-in










Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome