new cam-head porting combo

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tom340

tom340

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I'm set for this year, just gonna enjoy the added performance of the TTI headers....... but I'm planning ahead already for the next step.

as is now : Fresh 372" balanced stroker motor. Less than 5,000 mi. since rebuild. Using 308 heads, valves upgraded to the 2.02's. Currently no porting, they flow tested real well (as is). KB forged pistons, I believe they are 10.5:1 and the machinist used #051 head gaskets to get me down to about 9.9:1 to use with a fairly mild cam. The cam now is .500 lift, 226/230 dur at .050" and 112 lobe seperation angle. Also using 1.5 roller rockers. I thought about swapping in a more aggresive hydraulic just for this summer but didnt want to pull heads for thinner gaskets to bump compression, so just gonna be patient and do all at once.

No tuning on the dyno- they pulled 428hp and just under 450 ft. lbs tq. No timing adjustments, 650 Eddy Thunder carb right out of box. Also they had to use small tube Chevy headers 1 5/8- as the plan was for me to use the manifolds until I had more mad $$ for the tti's. Lennys Ultimate 10" converter (3800 stall) and tti's finaly installed the car runs really strong. (converter is loose-built for planned modifications)
Ran at Lebanon (with manifolds-street tires-3.55's) and was doing 106-107mph trap speeds. That was 2 summers ago, huge difference now with the tti's!!

The plan-
Have the 308's stage II ported, and also port match the edelbrock performer rpm intake. This isnt now, or going to be a race only car. Street /strip, not looking to go radical. Not seeking to max out a low ET, just wishing to increase @ 60-70 HP over the current setup with head work and cam. Want to be able to go low 12's, keep it reliable for street. Some homework on camshafts and compression ratio needed. Mostly how much to bump compression ratio for a longer duration cam to get the most from it.
My "thoughts" are something like Hughes .540-.548, 232/237 and 110 with someting close to 10.5:1. Leaning towards a roller cam.

Would love to hear ideas
 
If you go and port the heads and swap in a cam your carb will be to small, converter and gearing will be off.
 
AdamR said:
If you go and port the heads and swap in a cam your carb will be to small, converter and gearing will be off.
Click to expand...


yep, that I know about the carb. Its too small now for "optimum " performance. Its really responsive. Only lacks a few ponies way up above 6K. "maybee" pick up 6 hp with an 800. converter is perfect match. Already went over this (converter specs) with Lenny. Told him current setup is very temporary-already had an idea what we would wind up doing so he went real loose. I can brake stall almost 4K right now) gear ratio, well to be honest like what I got. Not really after quickest possible ET. My brother has full porting by Hughes engines and a stupid radical cam, same gears and his car is simply- absolutely nuts. BTW, he's using a shelf purchased B&M converter for like $300.00
 
your brothers car is a big block isnt it ? Your converter is was designed by Lenny for your currant combo, change the cam and it will be off.
 
No need for a compresion raise. At 9.9-1, your good to go.

Tested with what tube size on the header? 1-5/8?
 
Was wondering about the dyno headers.
 
SBC headers? Interesting adaptors...
I think you'll be hard pressed to keep the charactore of thec ar and get another 70hp from those heads. Stage two on 308s will get you around 260-270 depending on bench and porter and to use them to that level the cam has to get a bit larger. Making the gears and convertor wrong. I think it's going fast now, and the hreaders will pick it up considerably. I'd expect to see 2-3 mph more as a result of swapping them. But to go much quicker, you'll need more gear, or more convertor. That's the problem with the stock stroke 340s. You have to rev them to really get them to run hard. Low 12s in a street car is moving. I'd be looking at gearing the current combo you have rather than more power because the character of that power needs to change from street/mild to racey/wild. That and the convertor will work almost as well with a deeper gear. You need to make that ET back in the 60'. The MPH already says 12.50-60s.
 
moper said:
I think you'll be hard pressed to keep the charactore of thec ar and get another 70hp from those heads. Stage two on 308s will get you around 260-270 depending on bench and porter and to use them to that level the cam has to get a bit larger. Making the gears and convertor wrong. I think it's going fast now, and the hreaders will pick it up considerably. I'd expect to see 2-3 mph more as a result of swapping them. But to go much quicker, you'll need more gear, or more convertor. That's the problem with the stock stroke 340s. You have to rev them to really get them to run hard. Low 12s in a street car is moving. I'd be looking at gearing the current combo you have rather than more power because the character of that power needs to change from street/mild to racey/wild. That and the convertor will work almost as well with a deeper gear. You need to make that ET back in the 60'. The MPH already says 12.50-60s.
Click to expand...

yer right, cant use this cam. need more aggressive. Converter is overkill for what I have now. was specifically built for ported heads and more aggressive cam. I'm dealing with the isssue of a very loose converter right now-but a WAY better condition with what I had with the previous one :) I'd love to run this setup NOW, after a dyno tune and with some sticky sneakers. I'm blowing the hides off this ride just by sticking it off idle.
 
moper said:
That's the problem with the stock stroke 340s. You have to rev them to really get them to run hard. .
Click to expand...

Not actually a stock stroke 340, Its a 372 so its more like a stock stroke 360,
 
Thinking of taking my buddies new 4.10 pumpkin off his hands just for a day of racing at the track or a change of pace. (def need some sticky sneaks) For some reason he made a radical decision and dropped all the way down to 3.91s!!
 
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