break away torque short block

[steve cowan]

hi guys,
what are you finding with turning over SBC short engine with tension wrench.
i am 383,scat rotating assembly,SRP pistons 1/16,1/16 3/16. MAHLE rings with a oil ring at 16 pounds checked.The oil rings say STD tension but this is a bit less than i have used previously.
this is street/strip deal.
i am breaking away at 20-23 pounds with tension wrench,also using belt drive and ATI balancer is fitted.just curious what other people are finding,
thanks

[mag2555]

Sounds perfectly normal for break away to me for a un- fired motor!

[jed]

X2

[zums]

hi guys,
what are you finding with turning over SBC short engine with tension wrench.
i am 383,scat rotating assembly,SRP pistons 1/16,1/16 3/16. MAHLE rings with a oil ring at 16 pounds checked.The oil rings say STD tension but this is a bit less than i have used previously.
this is street/strip deal.
i am breaking away at 20-23 pounds with tension wrench,also using belt drive and ATI balancer is fitted.just curious what other people are finding,
thanks

Steve, alot of things can effect that, bore finish, and oil viscosity are two more influences, on a 4.125 bore 10/30 oil same 1/16 Mahle ring pack as you i have 14lbs, std oil ring, just for a reference point, just the crank and seal =1 lb add a cam and chain to that 4-5 lbs, the rest incrementally climbed from rods and piston, this is a typical bore finish, not a super slick only need 10 runs out of it minimum friction finish
Tom

[CGT]

hi guys,
what are you finding with turning over SBC short engine with tension wrench.
i am 383,scat rotating assembly,SRP pistons 1/16,1/16 3/16. MAHLE rings with a oil ring at 16 pounds checked.The oil rings say STD tension but this is a bit less than i have used previously.
this is street/strip deal.
i am breaking away at 20-23 pounds with tension wrench,also using belt drive and ATI balancer is fitted.just curious what other people are finding,
thanks

That sounds about right for that to me. I just haven't had one that took 20lbs for awhile now.

[geraldtson]

Don't know if you can use this as comparison but i just checked 4.125 x 3.875 stroke 415 .043x.043 LT oil and it came in at 10lbs with just short block,no damper or accessories,no flywheel. Not sure of accuracy of this old beam type wrench but should be close.

[Dragsinger]

Steve,

the belt drive adds more rotating resistance than a chain. I "think" it is because of the cam bearing/journal load without engine oil pressure. In a running engine, I have not seen any measurable difference between chain & belt. However, my testing is limited and inclusive. I do like the adjustability of a belt drive.

In another note, some engines I build are limited on cam install position because of the valve to piston clearance. I just finished a build that only had happy clearance numbers where I wanted the intake centerline. Two degrees, either way, was too close for comfort. So, in some cases, the adjustability comes down to convenience and is not changed once dialed in.

[cjperformance]

Steve,

the belt drive adds more rotating resistance than a chain. I "think" it is because of the cam bearing/journal load without engine oil pressure. In a running engine, I have not seen any measurable difference between chain & belt. However, my testing is limited and inclusive. I do like the adjustability of a belt drive.

In another note, some engines I build are limited on cam install position because of the valve to piston clearance. I just finished a build that only had happy clearance numbers where I wanted the intake centerline. Two degrees, either way, was too close for comfort. So, in some cases, the adjustability comes down to convenience and is not changed once dialed in.

How do you check breakaway TQ in a running engine!? just stirring, i had to ask though!!
Yes tensioned up belt does add resistance to breakaway TQ.

Steve- sounds fine/average mate, just different oil on bores and lube on bearings etc will change the Breakaway TQ #. If everything is machined and clearanced correctly dont get too hung up on pre run breakaway. Strip clean relube differenlty now and you will get a different breakaway TQ. Fact.

[Dragsinger]

Craig,

I did not make myself clear. I have changed two different engines from chain to belt during a rebuild where the engine was simply renewed without changing the combination. In those two cases, the engine performance on track remained the same WC [with chain] WB [with belt]

And more feedback, the engines I build are SBC 355 - 413 CI range in local bracket race cars. All run well, all win races and are built on the conservative side. About 730 horse is my top combination and about 8200 RPM the upper limit. In all those builds, most are Cloyes Iwiss chain or Roll Master Iwiss, usually with the two-piece adjustable upper gear. Never a chain failure in many years of doing this.

Just FYI

[cjperformance]

Craig,

I did not make myself clear. I have changed two different engines from chain to belt during a rebuild where the engine was simply renewed without changing the combination. In those two cases, the engine performance on track remained the same WC [with chain] WB [with belt]

And more feedback, the engines I build are SBC 355 - 413 CI range in local bracket race cars. All run well, all win races and are built on the conservative side. About 730 horse is my top combination and about 8200 RPM the upper limit. In all those builds, most are Cloyes Iwiss chain or Roll Master Iwiss, usually with the two-piece adjustable upper gear. Never a chain failure in many years of doing this.

Just FYI

I know where you're coming from, just like a gag whenever i can pop one in!
Agree, nothing at all wrong with RM or cloyes & iwis chain.

[steve cowan]

thanks for everyone's responses,
the last freshen up on this short block(2 years ago)using the same rotating assembly,i had the block plate honed with new pistons and i had thoughts of using a 150 shot so i fitted Total Seal
chrome top ring,napier second and a 20 pound oil ring which was all of 20 pounds plus,to turn the short block was 30-32 lbs/ft,the block sealed up well 3-4 % leak and had good oil control as far as not puking into the catch can.
well i never bothered with the N2O so this time i went with the Mahle 315-0072-0.035''
i had intentions of trying a lighter oil ring and played around trying to modify some old expanders but did not like where it was heading so i scraped the idea and was happy enough with the Mahle oil ring,i can see the benefit on a lite oil ring but i made the mistake years ago of using a low tension oil ring with no vacuum pump on a street car type deal and lets just say it was messy and did not work for me at all