I changed my engine project in mid-stream from a 383 to a 327. Several design considerations changed, including the intended RPM range for the engine. Now I need to know what to think about when choosing a distributor and ignition system for a 327 which will see 7000 rpm fairly often in running up and down our mountain canyons around here, and could also see 7500 rpm more than just a little.

Summit guy told me to think about billet construction and ball bearing shaft mounting. What else is there to take into consideration?

This is a 67 chevelle, and I wonder about issues concerning HEI style vs traditional. I've been told that HEI caps sometimes won't clear the firewall enough to allow adjusting timing very much.

Also, what about timing advance?? Summit guy also told me that vacuum advance is not useful in this kind of engine, go with mechanical. What do you guys think about all this? Any recommendations for a certain brand/model?

Thanks as usual for all replies...

Randalf, I had a distrib built by someone local. With the tight clearances of his rebuild, he claimed it's good till 8, maybe higher, before you MIGHT get scatter. I suppose some of those ultra trick billet things are just as good as my stock one. The difference is that mine cost 160 w Ignitor/ Hei's are 175.

I would not run a street car that cruises at all w/o vacuum advance. Sure if it's a 5.13 drag car you take out occasionally, but not for anything you drive more than once in a while.

The HEI came in my 67 (replaced it) and clerance was not a probelm at all. I ran them in a 75 and 72 Nova w/o problems. The clearance issue might appear for some models, but I find funky manifolds are a real problem ( like my tripower ).

At 7500 you might need an MSD type unit. I feel my stock system with HiPo coil will support 7000 on the high side, but really my shift point is 6700 with the 427. Stock should work there, but like everything else that's a function of rpm, that extra 800 revs would require allot more juice. But someone with more ignition experience should answer that one.

Good luck with your spinin' 327. That's always been my favorite small block, and like it's big cousin the 427, their geometry is perfect for revs.

[This message has been edited by Gene Chas (edited 08-17-99).]

Thanks for the reply, Gene. Interesting that a 427 would have been my choice if a big block project turned my head more than the mouse. Have you ever talked to anyone that ran an aluminum block 427? I love cornering, so the issue of weight in the front end is always high concern for me. An all-aluminum 427 RAT seems a God-like motor to me, what do you think?

Randalf, a properly prepared HEI with all Delco internal parts is good to 9000RPM with 750 HP in a Late model stock car engine I built. Skip the hype, go with proven parts. http://www.chevelles.com/forum/smile.gif

Tom

I really wouldn't trust any junkyard HEI above 5 grand, if that. Some legends may be based on truth. I'd say a better bet is a Mallory Unilite.

I myself have seen HEI put on distributor a machine at GM school and turn 9000 rpm and other after market brands not turn as high but I would consider a rebuit unit over a bone yard.

P.S.
if you decied to go with HEI change out resistor wire from fuse box on firewall to distributor.

And to further obfuscate your decision, I personally wouldn't run a Unilite. IMHO, optics are too fragile for under the hood. Stick with a mechanical like HEI or a small base w/ Pertronix. The stock HEI module ( well my experience with these is circa 1977/8)will not hold up above 6000.

When I was working in a machine shop ( some auto) we all drooled for the ZL1. Well, for a cool 5G's you can own an aluminum big block. That's just for the block. And yes, if I won the lottery, the first thing I'd do ( gearhead wise ) is to order one up and biuld me a ZL1. At the risk of blasphemie, I would probably put it in a light 68/9 Camaro modeled after the Penske/Sunoco road race car. Cool huh?



[This message has been edited by Gene Chas (edited 08-18-99).]

randalf
I took a 6 dollar h.e.i.from the u-pull yard,rebuilt it,all delco.accel hei intence-i-fire kit,m.s.d-6a.great results,7500 rpm,no misfires at all.oh yea,missed a shift,saw the tach go to 8200(my heart was in my throat)but it didnt miss a beat.clearance not a problem.go with vac advance on the street.as for those high priced units,all I know is I saved 150-250 bucks,guess what,same results.H.E.I.=high energy ignition.67rat member #199

[This message has been edited by 67RAT (edited 08-18-99).]

Gene...installed a Unilite on my LS-6 in 1990. And have put it through hell since then. Extremely dependable and reliable. From personal experience...fragile, it is not. Coupled with the MSD-6AL, it's been by far the most reliable thing on the car! I highly recommend it.



[This message has been edited by Larry (edited 08-18-99).]

larry
your right,after a flashback I remembered that I had a unilite in a small block,ran it for 7 year with no problems.as I recall the price was not bad either.only problem I had was flash over under the cap,a little grease took care of that.I like my h.e.i. because it was cheap,like me,and it works.67rat member #199

Hey 67RAT...no arguments here...I'll take "cheap" and it works over $$ and it works, anytime. If an HEI can do it, I say go for it.

Larry, I must have had a bum unit, but it was in a second hand "race" disbtrib I bought. I replaced the module in my stock HEI ( the aforementioned 6000 rpm problem I had ) and way I went without a hitch. With a MSD6 ( no AL back then, just 5,6,7 ) and Mallory coil. That was back when I had to have trick stuff whether I needed it or not.

Oh BTW, randalf that just reminded me. I spun that 350 LT1 to a little over 7 one night. Valve float. With a solid cam. Thank God nothing broke. Use battleship springs baby. Don't float 'em.

Hey RAT, 8200, sheeeeet that's just warmin' that 'lil 427 up. YEOW!



[This message has been edited by Gene Chas (edited 08-19-99).]

If you go with the HEI, which I would highly recommend, here is a piece of advice. I did testing on a distibutor machine with different modules. Some of the cheap parts store modules did some funny things at certain rpms. For example, one "broke up" between about 5000 and 5500 but was fine afterwards. However, I never saw a genuine GM have any problems. It might cost a bit more, but I'd get one from the GM dealer.

Ran a unilite converion in my 73 vette for 107 miles, no problems.

I like the early GM cast iron distributor with a unilite conversion and a MSD 6A or one of the newer units. Turn these as hard as you like, no problems.

The HEI is also a good choice, used those in local dirt track cars, spin them 8000 no problem for a whole year. When they tell you that is all you can use, you make the best of it. For a self contained system it's hard to beat.

For street driving, use a vacuum unit, mechanical advance for the street sucks!

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Wally
Gold #67
67 malibu

[This message has been edited by Wally (edited 08-20-99).]

Wally, I picked up ( I mean lifted up) one of those old Vette distribs at a local resto shop. Really liked the heft of it. Nice and heavy. The tach drive didn;t work. So what. Kind of regret not using one. They're cool.Would've been more "L88-ish".

Gene, they make them with and without the tach drive. I have several, one brand new NOS 73 unit with tach drive, not cheap. I also have 4 or 5 other units. If you get the feeling like it's time to do the big motor with way cool GM stuff with vacuum advance let me know.

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Wally
Gold #67
67 malibu

Ok it's been a few days since I've been able to log in here. Thanks a lot for all the advice, I think I will go ahead with the GM HEI unit. If I can't get what I want out of it, I can always spend more money later on the aftermarket stuff.

Thanks again

dont laugh but i have a stock single point with mallory 102x points with a crane hi-6 iginition box in my 383. i shift it at 7200 and it works fine. i dont know how high they will rev before the points float but i havent had any problem. just thougt i would add something different