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Discussion Starter · #1 ·
I have a 454 .030 over short block I am going to complete here shortly. Just looking to put together something that is a little more than the mild 396's that are in my 3 cars now. I bought the short block years back, its a 73 block with polished steel crank, stock rods, TRW 2349 pistons and it has been balanced. Camshaft is going to be the 502/502 HR, 224/234 and 527/544. Heads are going to be #049's that I did some quick clean up on the ports behind the valves and the short turn lip on the floor. Figure I will spin this motor 5500 max. My question is should I run 2.06/1.72 or have the 2.19/1.88 valves installed ? I have sets of stainless valves in each of the sizes already.
 
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I had a build exactly like that except I ran 22 cc domes w/781's and 2.06/1.72 valves. I give up some compression to you as I was at 9.4:1. I ran the ZZ502 cam for 1 year and thought it ran pretty well. I was knocking down 14.5 mpg in a full body 1971 Monte Carlo, TH400, 3.31 gear and a 2600 stall. It ran 12.99/106 mph spining my street tires pretty bad. Then I pulled the engine and stuck it in my 70 Chevelle, 4-speed, 3.73. I know, not exactly apples to apples. The ONLY change I made to the engine was a Straub HR semi-custom cam designed for the iron 049/781 heads. WOW did that wake up the engine. It starts instantly, has a nice crisp exhaust sound and incredible thorottle response. It pulls hard from 2000 to +6000 & I still get 14 mpg. The funnest street engine I've ever run.
If it were my money I would keep the smaller valves and ditch the ZZ cam for a Straub. Better performance/dollar than larger valves I would think.
That's my opinion and it's worth what you paid for it.
Scott
 

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Yes the 2.06 will be fine that size will support 500hp esp with your 5500 redline. The above mentioned 229/241 claysmith straub roller works excellent in that combo have built both 396 and 454 with small valves and that roller cam
 

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If you have the larger valves ,I would use them and open up the bowls to them. The larger valves ''should'' make more power and if you want more down the road you could give it more cam,intake ,carb etc. On my combo when I had the small comp 270 magnum HR cam it ran 11.70 shifting at 5200 rpm . It was a very mild but pulled pretty good even when it originally had 3.31 gears. I say go for the 2.19 and 1.88 , big blocks need all they can get.
 

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I would consider using the 2.19/1.72 combo. Large exhaust valves are over rated.
 

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You are right there now just put the larger valves in if the heads can take them. The 454 has a good size bore at 4.28 assuming 30 over so you can take advantage of that. They may not be necessary at the lower rpms and pooping around town but thinking ahead or if you want to rev it to say 6,000 rpm that is where they may make some difference. Another option at some point if you want a bigger cam etc. Pulling the heads off again in the future is not too big a job but it is time consuming and you've got to buy new gaskets etc. Do it now so you don't regret not doing it. Going to larger valves is only going to be a plus and not effect the low speed drivability etc. this is not like - oops I put too big a cam in it. Other than the cost it should be a win-win situation. Anybody know what valves came in the stock 1970-1971 LS5 Chevelle that would be a good reference point?
 

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Anybody know what valves came in the stock 1970-1971 LS5 Chevelle that would be a good reference point?
2.06/1.72

FWIW,years ago someone built a 454 and posted the dyno results on this forum, using Speed Pro forged pistons (.270 tall dome) and stock 049 heads with 2.06/1.72 valves.
Cam was an Ultradyne 288/296 hydraulic flat tappet grind: 231/[email protected] .050 110 LSA .550/.575,intake was an RPM Air Gap,carb was a 770 cfm Holley SA,headers 1 3/4" primaries w/3" collectors. Motor made 490 HP
 

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I thought I read somewhere in the How to Hot Rod a BBC that the bigger valves were worth 15 hp (depending on combo of course). You may want to look at some basic porting while you are here. So comes down to a cost/time issue. Furthermore, can this be one of these situations we have all been in when doing something later on - gee I wish I had done BLANK when I had the BLANK off (Match Game - Gene Rayburn now Alec Baldwin).
 

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Discussion Starter · #10 ·
I thought I read somewhere in the How to Hot Rod a BBC that the bigger valves were worth 15 hp (depending on combo of course). You may want to look at some basic porting while you are here. So comes down to a cost/time issue. Furthermore, can this be one of these situations we have all been in when doing something later on - gee I wish I had done BLANK when I had the BLANK off (Match Game - Gene Rayburn now Alec Baldwin).
I did some basic porting to the heads already. There will be no second guessing, or taking the motor apart at a later date to put bigger valves, cam etc in it. As soon as this engine is done I am going to put together another 73 454 block I bought this Summer it is rough bored for .030 but has some minor rust in the cylinders, so I am thinking its gonna need to go to .060 over. Need to have machinist look at it. I am gonna buy good pistons that run 1/16 rings for it, I already have ported 049's for it with 2.19/1.88 and have a lunati HR 231/239 600/600 for it. But now I am really thinking I should sell the lunati cam and buy the Straub roller for the second 454 build.
 

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If you feel like the extra time and effort, put the big valves in.

If you don't feel like the extra time and effort, leave the small valves in. Odds are in this application you'll never be able to tell the difference. The smaller valves will support the application in this case I believe, with no problem.
 

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I run 1.88 exhaust valves in a 900 hp 7500 rpm 540. Don't think 1.88 exhaust valves are worth it in your case.
 

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You're goinna build another bigger, badder motor. Just do a nice job on this one and call it good :)

Save the bigger valves for a bigger build ...
 
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