421 cube pulling truck engine

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CGT
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Re: 421 cube pulling truck engine

Post by CGT » Sat Feb 10, 2018 9:04 am

sjre wrote:
Sat Feb 10, 2018 9:00 am
My guess would be 680 range.You and Randy have the ability to exceed the predictions.
You could be right, maybe I'm just prejudiced against the big chevy because I don't really like them a lot. :o

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Re: 421 cube pulling truck engine

Post by sjre » Sat Feb 10, 2018 9:20 am

CGT, I think you look at torque to predict hp but what if a big block made 700 ft lbs but only 640 hp.where to look ?

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Re: 421 cube pulling truck engine

Post by CGT » Sat Feb 10, 2018 9:37 am

sjre wrote:
Sat Feb 10, 2018 9:20 am
CGT, I think you look at torque to predict hp but what if a big block made 700 ft lbs but only 640 hp.where to look ?
Valve train :D

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Re: 421 cube pulling truck engine

Post by randy331 » Sat Feb 10, 2018 11:00 am

sjre wrote:
Sat Feb 10, 2018 9:20 am
I think you look at torque to predict hp but what if a big block made 700 ft lbs but only 640 hp.where to look ?
I can't see it making 700 LBs. That's almost 1.5 Lbs/cube. The 468 isn't the type of build to produce that kinda TQ. If it did and only made peak HP at 6000 rpm It'd make 720 HP. I'd say this is a 1.3 TQ/cube type of build, and will peak around 6500-6700 area. So I expect in the 675 HP area.

This guy has been around truck pulling a lot and the break for him to go up to the next higher gear is 700 HP.

Guess we'll see how good the head guy is?? :)

Randy

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Re: 421 cube pulling truck engine

Post by sjre » Sun Mar 18, 2018 7:24 am

Randy in another post you finished the bbc .Can you tell us what happened.
thanks.

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Re: 421 cube pulling truck engine

Post by swampbuggy » Sun Mar 18, 2018 7:43 am

morning folks, could not resist inserting this cause it is kinda close to the conversation. My last build was a BBC, 4.530 x 4.000 = 516 , 693tq. @ 5900 855 H.P. @ 6900----more info. if you like. single 1050, N.A. Mark

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Re: 421 cube pulling truck engine

Post by vortecpro » Sun Mar 18, 2018 9:43 am

randy331 wrote:
Fri Feb 09, 2018 8:25 pm
sjre wrote:
Fri Feb 09, 2018 9:15 am
Yes I would like to hear more about the bbc.
It's for one of my son's truck pulling buddys. Mostly stuff he's picked up used. It's under the same rules as the 421 now cause the local group adopted IAMO pro street rules for this coming year.


It's 468 cube, Scat rods, stock 454 crank, in stock block. Has some dome trw pistons that will make it in the 12.3-1 compression range 1/16-1/16-3/16 rings I lowered the tension on.(maybe too much)LOL
781 casting heads I ported with 2.170 intake 1.850 ex Ferrea valves.
Brodix single plane intake with some porting and matched up to the heads good.
Comp cams 268*-280*-112* with .750 net intake lift and .720 net ex lift. Lobes are kinda slow cause valve weight is a little high. Nextec valve springs.
An 850 Baker carb.
Vacuum pump

Hope it runs good.

Randy

https://youtu.be/2KgAilTTZnQ
Racing a NA NHRA stocker should be mandatory before any posting.

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Re: 421 cube pulling truck engine

Post by randy331 » Sun Mar 18, 2018 2:40 pm

sjre wrote:
Sun Mar 18, 2018 7:24 am
Randy in another post you finished the bbc .Can you tell us what happened.
thanks.
Didn't get to finish the dyno session.
After several breakin pulls we started to make some changes and found a little power with some timing, so we added a little more timing, but on the next pull the weight on the flywheel came off at about 5800 rpm and sent it flying through the dyno room. All we could find was a cheap parts store flywheel so we weren't to excited about trying that again. And when we were un hookin it to take the flywheel off we noticed a little water seeping out on the ex port that had been repaired, so we decided to take it home to re group and try again another day.

It was making 580-585 TQ and 680-685 HP with 41* on last pull before the flywheel came apart.

Still had cam position/lash to try,
Jetting,
Vacuum pump,
Was using dyno headers that are likely too big for it, so may pick up some with his smaller ones.
It was pulling 1.8-1.9 " vacuum on that carb, so there'd probably be some power with a bigger carb, and he text me last night and said he found a 4500 series 1250 so we have it to try also.

My goal was 600 LBs and 700 HP may still be able to make that.

Randy

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Re: 421 cube pulling truck engine

Post by vortecpro » Sun Mar 18, 2018 8:25 pm

Can you remember at what RPM the peak HP was?
Racing a NA NHRA stocker should be mandatory before any posting.

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Re: 421 cube pulling truck engine

Post by randy331 » Sun Mar 18, 2018 10:07 pm

vortecpro wrote:
Sun Mar 18, 2018 8:25 pm
Can you remember at what RPM the peak HP was?
Peak TQ 5500ish peak HP 6800 ish

Randy

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Re: 421 cube pulling truck engine

Post by randy331 » Sun May 27, 2018 12:50 pm

MTENGINES wrote:
Sat Jan 20, 2018 3:19 am
Expect 730-750. Anything extra let's you know you are doing a good job. Looks like a cool build, keep us all posted.
Well, dynoed the 421 a couple weeks ago,..and your guess was very close.

By the end of the day (28-30 pulls) it was making 604-606 TQ and 745-747 HP on VP blue and on Sunoco Supreme with a little Maximal added in.
And 612-614 TQ and 750-754 HP on Q16. Nice flat power curve too.
Probably not gonna run Q16 for that much difference. And that's just fine with me. :D
It was pulling 1.8-1.9 inches of vacuum on the Braswell carb listed on the first post, so got a 1.9" venture x 2.125" throttle bore 4500 type carb on the way.

The 355 made it's last hook last weekend, 421 will be in for next hook, (first IAMO points pull)
Now,...I just hope it survives being hooked to a sled.


Randy

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Re: 421 cube pulling truck engine

Post by CGT » Sun May 27, 2018 4:36 pm

randy331 wrote:
Sun May 27, 2018 12:50 pm
MTENGINES wrote:
Sat Jan 20, 2018 3:19 am
Expect 730-750. Anything extra let's you know you are doing a good job. Looks like a cool build, keep us all posted.
Well, dynoed the 421 a couple weeks ago,..and your guess was very close.

By the end of the day (28-30 pulls) it was making 604-606 TQ and 745-747 HP on VP blue and on Sunoco Supreme with a little Maximal added in.
And 612-614 TQ and 750-754 HP on Q16. Nice flat power curve too.
Probably not gonna run Q16 for that much difference. And that's just fine with me. :D
It was pulling 1.8-1.9 inches of vacuum on the Braswell carb listed on the first post, so got a 1.9" venture x 2.125" throttle bore 4500 type carb on the way.

The 355 made it's last hook last weekend, 421 will be in for next hook, (first IAMO points pull)
Now,...I just hope it survives being hooked to a sled.


Randy
Thats a bad bitch there! Cast iron heads lives matter! :twisted:

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Re: 421 cube pulling truck engine

Post by paulzig » Sun May 27, 2018 5:07 pm

CGT wrote:
Sun May 27, 2018 4:36 pm
Cast iron heads lives matter! :twisted:
Even the ones with 30° valve seats? :)

Excellent result out of old cast iron most people would throw away and just go buy a set of AFR's.

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Re: 421 cube pulling truck engine

Post by randy331 » Sun May 27, 2018 9:13 pm

IMG_3301.jpg
Pic of the dyno screen with the last few pulls on it.

Randy
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Re: 421 cube pulling truck engine

Post by Keith Morganstein » Mon May 28, 2018 8:38 am

paulzig wrote:
Sun May 27, 2018 5:07 pm
CGT wrote:
Sun May 27, 2018 4:36 pm
Cast iron heads lives matter! :twisted:
Even the ones with 30° valve seats? :)

Excellent result out of old cast iron most people would throw away and just go buy a set of AFR's.


From the first post: “Heads are GMPP large port vortec bowties”. Many of the pulling class rules require iron heads.
Automotive Machining, cylinder head rebuilding, engine building. Old school shop, semi-retired moonlighter. Can't seem to quit #-o

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