Speed-Talk is running on www.Speed-Talk.com

IMPORTANT: Update your bookmarks to https://www.speed-talk.com/forum/
(Right-click the URL and select "Bookmark this link")

putting a 4.5" stroked crank in a 9.8"deck BBC?

General engine tech -- Drag Racing to Circle Track

Moderator: Team

Post Reply
pdq67
Guru
Guru
Posts: 9575
Joined: Thu Mar 04, 2010 8:05 pm
Location:

putting a 4.5" stroked crank in a 9.8"deck BBC?

Post by pdq67 »

I suppose that some people have done this so just how does an engine run?

Say, a 4.60" bore one.

Looking for stealth max BBC standard deck height engine size is all. I think it will be a 598" engine?

Oh, what length rod do you use?

pdq67
Walter R. Malik
Guru
Guru
Posts: 4883
Joined: Tue Jul 24, 2012 11:15 am
Location: Roseville, Michigan (just north of Detroit)
Contact:

Re: putting a 4.5" stroked crank in a 9.8"deck BBC?

Post by Walter R. Malik »

pdq67 wrote: Mon Jul 27, 2020 9:48 am I suppose that some people have done this so just how does an engine run?

Say, a 4.60" bore one.

Looking for stealth max BBC standard deck height engine size is all. I think it will be a 598" engine?

Oh, what length rod do you use?

pdq67
I have done this but, it is about the limit and needs to be only NA as the top and 2nd ring lands get pretty thin.
4.500" stroke - 6.535" rod - 1.010" Compression height piston.
http://www.rmcompetition.com
Specialty engine building at its finest.
pdq67
Guru
Guru
Posts: 9575
Joined: Thu Mar 04, 2010 8:05 pm
Location:

Re: putting a 4.5" stroked crank in a 9.8"deck BBC?

Post by pdq67 »

Thanks Walter for posting back.

I think JE will make the needed pistons to make this combination.

I do figure flat-tops to hold the CR down, but I would need to calculate it to be sure what the deck should be?

pdq67
doncasanova
New Member
New Member
Posts: 1
Joined: Sat Aug 28, 2010 12:31 pm
Location:

Re: putting a 4.5" stroked crank in a 9.8"deck BBC?

Post by doncasanova »

PDQ - Maybe consider something like this combo:

World merlin 9.850 deck block (#091107)

4.5" crank (center counterweighted)

6.480" rods (Molnar, K1) etc

632 pistons (1.120) comp. height

All shelf parts, & the rod ratio is a tad better than a typical 632.



My 582 std-deck went together no problem using a Brodix iron 4.600 block, Callies compstar 4.375 crank, Molnar 6.480 rods, & CP 632 pistons.

The pistons (#BBC5321-100) came with 1/16- 1/16- 3/16 rings and .180 wrist pins.

Shop used no heavy-metal to balance, & counterweights only needed a few holes drilled.

Got it in my 69 Camaro with a stick & it's a blast.

Hope this helps.........DC
pdq67
Guru
Guru
Posts: 9575
Joined: Thu Mar 04, 2010 8:05 pm
Location:

Re: putting a 4.5" stroked crank in a 9.8"deck BBC?

Post by pdq67 »

^^^^^^^^^^^

Thanks DC for the build spec's.

pdq67
Post Reply