Thread: 327 mods

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Hi all, I'm Rob from Australia. I'm about to take delivery of a customised 1970 Holden (GM) Utility (pick up). It's powered by a Chev 327 that transmits its torque through a TH350 trannie and a v8 3.08:1 ratio banjo diff that so far, has stood up well. I'm a 39y/o 'A' grade mechanic who's finally getting his v8. This is what I want to know guys. What mods have you guys done to these engines that have been really effective without you having to take out a mortgage to obtain? I don't know yet if the heads are the double hump (or whatever u call em') type, what compression it has or what cam it has. It has a Holley carb of unknown CFM. I'm willing to change the camshaft, rockers (roller tipped only), valve springs and intake manifold. I'd also give the heads a 3 angle valve job, raise the compression, clean up the ports whilst matching them to the intake manifold ports. My friend has offered me a Camaro alloy intake (the current one is iron) - are these any good or should I fit an E/B Performer one? It has the standard cast exhaust manifolds, which I'd like to keep as I like their appearance and they fit the tight engine bay quite neatly. Has anyone been able to get respectable performance gains while still retaining these cast headers? The rest of the exhaust system appears to be free flowing as the twin outlets let it be known that there's a Chevy 8 under the hood. I don't know if the exhaust has a balance pipe fitted, but get the feeling it does'nt due to the beat of the note. The engine pulls like a demon off the line but becomes real weazy around 4,000rpm - almost as if the cam is advanced. I want the engine to have real presence so I don't mind it idling with a little anger. I'd prefer to retain the standard torque converter but would change to a higher stall type if needed. Again I'd like it take off well but more importantly, it needs to get up and boogie as the revs climb. I don't want to push it beyond 5,500 or maybe 6,000rpm as I don't want to touch the bottom end $. So, if any of you have been in a similar situation and are willing to share your secrets with an Aussie (pronounced ozzie) then please, let Rob know.
Or maybe even put me onto a site that caters for my questions. Have any of you seen the retro dress up kits for the S/B offered by proformparts? I gotta get that kit. Bloody awesome and not a bit of chrome to be seen! (yeah, yeah, I know I show my age fargin). One more thing. Do you think I should stick with the TH350? Or should I update to a TH700. I've heard the 4speeders are a little on the weak side. If so, what can be done to beef them up. I've been told to use a vette' servo as well as a transgo shift kit. Thanks for putting up with my huge ask. I hope your day is a good one. Cheers! Rob

Welcome Rob, looks like you've already gotten into the swing and have been helpful. Fargin? Ya gotta love the www!

To perform, these engines gotta breath. Running out of oomph at 4k with a 3.08 sounds like you've got a rag caught in it (figuratively of course). Probably you need to figure out the heads, and carb, at least, before really pinning it down. You could be right about the cam being off a bit, or it could simply be timing, or the advance isn't functioning correctly. Carb should be 600-650 cfm if it's a mild cam, and "small" heads. I've gone to 750 but the engine really needs to move air to do that.

Your desire to keep the iron manifolds may fit the compartment restrictions, but they could impede your ability to improve the breathing. You didn't say whether they were the logs, or the ram horns. Ram horns flow slightly better, and the fuelie Vette versions have a larger outlet. Otherwise you may have to consider block hugger types, especially the "flat" collector Hookers.

You didn't state which model Camaro intake it was, but the factory manifolds were pretty good in their day. The older style Performer was essentially the same manifold (P/N 2101 I think?) but the newer ones are a slight improvement. Their newer airgap model might be better if you don't need any heat to the plenum for all around operation.

As for the trans, the 350, especially with the 3.08, should fit just fine. They'll handle all the torque a 327 will dish, and I agree with the Transgo over. say a B&M, for shift improvement. The extra gear in the 700 would be good if you were planning to drop the gear ratio into the 4's. It was the early models of the 700 that gave them a bad name, as well as the 200's that came about in the same era. The later 700's were corrected by GM on the fly, and have stood up well. Raising the stall is popular (though sometimes a boy racer thing), but really only has advantages if the car is pretty light, or you really need to get the launch into the power band.

Thankyou Bob for at least giving me a logical and realistic reply. As I said, I don't won't to outlay big bucks (no blower, 6:1 pistons, twin predators, steel crank or wateva fargin alright!). Yes I'd be doing the basic preliminaries upon delivery, like checking its ignition advance. I'm also a little suspect that the carb is having a major lean out at the upper rev range. I can check all these things at work as I have access to a 4 gas anilyser scope but, unfortunately no rollers. At this stage I don't know what kind of Camaro intake or even what kind of exhaust headers it has. Are the ram horns the ones that look like 2 eyebrows? I get the feeling it may have the logs, dam it! My friend James is also giving me his Chevy hot rod engine mod book that should maybe help identify a few things for me. Again, thankyou Bob and look forward to more contact from you and Streets fargin. Rob

Eyebrows? Yeah, that'll work for a visual! Just watch those four "eyes", they can have a bite?!!

High. It's me again. I've noticed there's been about 45 viewings of my post but only two guys offering help. Where's that good ol' American spirit gone? Don't you want to help? Or do you think I should just gamble on matching individual parts and end up with an unsatisfactory result. Yes, I'm a mechanic. But I don't play around with engines trying this and that - that's real experience I hav'nt had and that cannot be substituted with just books. So, even if you're not so sure, tell me what you know or what's under you hood and what works. I'm all ears. Show me that you guys are willing to help. Rob

High(?) Rob.
If you scroll down the home page you'll see that there are more guests than members reading the posts. You have to join to reply. I dont have a lot of experience with modifying engines. I'm usually satisfied with the performance of a stock engine. The last Chevy engine I rebuilt I used an Edelbrock performer plus intake manifold (p/n 2101) and the performer plus camshaft (p/n 2102). I used a pair of block hugger headers. You can find these parts in the Summit catalog. They have a website at www.summitracing.com and they'll ship to Aussieland. I think their catalog is free but they may charge for postage if you're not in the states.
You still haven't given us the transalation for fargin but maybe it's something you shouldn't put on a family oriented website.
AL

Club327, I just saw your post this morning, didn't have time to reply to it then, But when I swapped out my 350 for 327 in my camaro, I used the stock heads that came with the engine and the intake from the 350 I was pulling out of it, Engine ran great, had enough power for me, Not quite sure what exactly it was running as far as HP, but I do know I could break a brand new set of tires loose taking off, and from 1st to 2nd, and I do know that I could do a "brake stand" until I couldn't see from all the smoke. I guess it all depends on what you want and how much you are willing to spend. Me I would look more at going as much stock as possible for a daily driver, if you want one for racing then you will need to look at the pocketbook to see what you can get.
But I am a firm believer in stock, after all GM has more money than me to test what works.

Rob, just a thought here. It could be that some folks are waiting for an update from you since you indicated you weren't sure of your base line condition. My thoughts were predicated on some broad generalities for that same reason. Once you've defined what hardware you do have, and have used your skill to refine the tune for what's there now, there would be a better chance to make meaningful suggestions. Especially when your budget comes into play. As an example, on the 327 I currently have I've got aluminum heads, done that way so I could push the compression ratio to 10 to 1. But you may not want to toss that kind of cash at yours once you have it in possession.

BTW, loved your auto trans function post, good job!

Hi (high? woops). Thanx to all of you for your replies. It's trully appreciated. Like I said, I'm all ears regardless of how inexperienced any of you are. Al, that's the kind of track I want to go down, ie. E/B performer 2 manifold and cam set - something like that. Now these block hugger headers, they sound good mate! Are they compact and do they offer improved upper RPM breathing and scavanging? Let me now how any of you went with these please. Streets, I did ask to keep it simple and cost effective - and what did you recommend me to do? You said fit a GMC 89-2 blower, twin predators, 6:1 pistons and so on. No one will take you seriously with those kind of comments. I think you show your youth and I admire you enthusiasm, so don't be offended with what I said. You obviously know quite a lot and I value any constructive help you can give. Rob

Streets, that's 58 in dog years, right?

Rob here's a pic of the "flat" collector, block huggers I referred to. Probably too short to have much scavenging effect, though a proper head pipe could help a wee bit. They're more for fit, though the smoothness of the tubing will help flow some. Get them ceramic coated in and out and they perform even better.

What heads do you have???Do they have a little sybol cast into them that looks like a camels back,two humps on a block and no acsesory bolt holes???If not really we need to know what valves ya got in your heads,if ya got little 1.72 valves and we recomend a cam thinking ya got 1.94 or 2.02 double humps you'll end up with a torqueless pig that also can't rev.Take a valve cover off and look at the last three #s of the casting # ,look them up at www.mortec.com that should tell ya a little.
As for compression I dunno.But if they are no-double humps I would assume an 8.5:1 ratio(as this is a typical non-Hipo ratio) for cam selection and 9.5:1 with double humps(if they are origanal to the motor).
I would say on the intake if the Z28 intake is a aluminum and has no EGR valve use it,if not get a performer eddy.
As for Ramshorns etc....I wouldn't use anything less than blockhugger headers.For street I would keep any headers in the 1 5/8 pimary range any bigger you give up lowend torque.
For a street motor with 3.08s I say the TH350 will fit the bill great.The only reason I would use a TH700r4 or TH2004r is if I had a real nasty gear that needs to be calmed down on the highway.These trannys are expensive in comparison to the TH350.

Thankyou Bob for the pic. I did'nt realise those headers were going to be of the tubular type and was surprised with what I saw. They look real compact and although there's no obvious scavange effect with the design, they appear to be able flow the exhaust in the right direction - away from each other and downwards. That's a lot better than the conflict that would be occuring inside those logs (hey I'm learning fast!). Do you really think that ceramic coating them makes a noticeable difference? I'm a little sceptical, but am curious just the same. Do those headers have a standard flat flange to connect the pipes with? Or are they a slip fit? Thanks again Bob. And if any of you find anymore spelling or gramma errors, please refrain from correcting me. I never realised I was sitting for some kind of English test! He he. Hey Streets, whatever kind of solvent you're sniffing could you let me know what it is? Coz when I'm gonna be a 58y/o like you, I wanna have the same outlook! Shoemaker, I'll be picking the car up this afternoon as it's not raining anymore and I'm choosing to keep it out of the rain. It's gonna be my occasional fling car! Right now it's 10:14 am. So you guys would be in la la land catching some ZZZZ's, as your time is currently 3:29am. See, we're not as backwards as you guys may think. I'll do a quick check over with fingers crossed, for the double hump markings on the heads. Those tips u gave me for the numbers found when the rockers are removed are going to be real helpfull. Did'nt know that one! So you also agree about the block huggers hey? Good, looks like I can so far settle on one thing. Bye for now and have a good weekend to all my friends here. Rob

Rob, if it's going to be your "fling car", as a retread, I'd advise you don't let your wife catch on!

The headers have a standard (for us anyway) three inch, flat flange, three bolt collector. Most often they come with a matching reducer to go down to 2 1/2". Yes, I'm a firm believer in the ceramic coating. It prolongs the life of the header by significantly inhibiting corrosion. It retains the heat within the header better, giving just a modicum of performance increase, but more importantly, lowers under hood temps. Smoothes the inside of the tubing even more for better flow, and they look better.

To give you a leg up, here's a link to a head I.D. chart, so you don't have to deal with verbal pictures. http://www.angelfire.com/tx5/randysr...Headguide.html

As someone who probably wouldn't have gotten out of high school unless they threw me out, I don't play the english teacher much. It's just that my brain sees something out of place and "blips" for a moment. But it's really no big deal in the long run.

Hey Bob, you're a gem. I looked up that site and saw plenty of info and stuff. My heads are not the double humps. They have a short and a long squared off shapes that dont really match with anything there. There's no accessory holes in the heads either. Will take a look at the numbers under the rocker covers to crossmatch them with the charts. A retread? Does that mean you've been married twice? Well, my wife thought it would be a good idea if I just packed up and leave early last year. Very easy for them to do over here, as they'd be earning $500 - $800 a week net, through child welfare as well as from child maintenance from the X hubbies. We've got big probs over here, sorry to say - lots of broken families. Not my idea of a good start to life.
So this car is well and trully my new love (when I'm actually not with the female variety) and I'm absolutely over the moon over it. Someone's spent over $20,000 on this beast and I got it for $6000 (about $4600 US). Every body bolt and washer are stainless steel - the bolts are of the unbreako type. Ever body part has been attended to in detail with TLC including the underside. The interior is fully retrimmed including the hood lining and sun visors - this is stuff that I don't usually want to tackle as I'm impatient, so it's a real bonus. I made a few errors when I first road tested it Bob. That weezy top end performance I was telling you about is actually the transition stage between the carb primaries and secondaries. I never actually got out of the primary stage. There seems to be a 500rpm hole before the secondaries become effective. I can live with it for now as it really lifts its skirt and howls like I was always expecting it to do. Gotta love you yanks. It has rams horns manifolds which I'm quite content to keep for now. The other thing is the diff ratio. I get the feeling it may be a 3.55 or lower ratio. I'm always wanting to shift into a higher gear when at cruising speeds. So who nows. maybe a TH700 maybe just the ticket hey? I'll keep you posted about the heads and will try to send a picture if you're interested. Cheers!

Looks like I need a stronger spring to slow down the opening of the vacuum secondaries. I'll get a kit with the various springs to try. The head casting number is 3911032 - it's a Canadian casting. The only info I can get is that it's for a 307 and 327, used in trucks and has either 67cc or 70cc chambers. No mention of valves sizes. What do you guys know about these?